[PATCH v8 00/11] unwind, arm64: add sframe unwinder for kernel

[PATCH v8 00/11] unwind, arm64: add sframe unwinder for kernel

[Dylan Hatch]

Implement a generic kernel sframe-based [1] unwinder. The main goal is
to improve reliable stacktrace on arm64 by unwinding across exception
boundaries.

On x86, the ORC unwinder provides reliable stacktrace through similar
methodology, but arm64 lacks the necessary support from objtool to
create ORC unwind tables.

Currently, there is a sframe unwinder proposed for userspace [2], along
with an RFC for an .eh_frame unwinder [5]. This patch series implements
a similar SFrame lookup library to [2], but with many simplifications to
account for the fact that user access is not necessary. The intent here
is to continue to leave the door open for common usage of definitions
and algorithms between kernel and user unwind in the future, while at
the same time keeping these patches strictly constrained the minimal set
of features necessary for arm64 kernel unwind.

Unlike past versions of this series, these patches apply directly to
v7.3-rc3 rather than depending upon [2]. To make this possible, I've
adopted a number of patches from [2] with significant squashes and
changes made in order to coherently suit the kernel unwind use case.
I've done my best to maintain appropriate authorship on these changes,
and have added 'Co-developed-by' trailers to attribute shared authorship
as accurately as possible. Please let me know if you see any
discrepencies in my work here.

Currently, only GNU Binutils support sframe. This series relies on the
Sframe V3 format, which is supported in binutils 2.46.

This full series is available on github: [4].

Ref:
[1]: https://sourceware.org/binutils/docs/sframe-spec.html
[2]: https://lore.kernel.org/all/20260505121718.3572346-1-jremus@linux.ibm.com/
[3]: https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git/log/?h=sframe/core
[4]: https://github.com/dylanbhatch/linux/tree/sframe-v7
[5]: https://lore.kernel.org/all/20260821195259.2688377-1-jremus@linux.ibm.com/

---

Summary of changes since v7:
 - (sashiko): Put .cfi_startproc right after SYM_START to account for
   potential alignment bytes ahead of the actual function symbol.
 - (sashiko) Use __always_inline for IP validation helper.
 - (sashiko) Move .sframe module init and sframe section fields to arch
   generic code.
 - (sashiko) Make sframe_find() noinstr.
 - (sashiko) Add preempt_notrace and instrumentation to
   __sframe_module_find() code path.
 - (sashiko) Block tracing and kprobe on the sframe_find code path.
 - (shashiko) remove KCOV, KCSAN, and KASAN instrumentation from
   sframe.o (copying over ORC's shoulder).

Dylan Hatch (6):
  arm64, unwind: build kernel with sframe V3 info
  module, sframe: Add sframe support for modules
  arm64/sframe: Validate IP addresses
  sframe: Add debug helpers with object name
  arm64, crypto/lib: Annotate leaf functions with CFI info
  unwind: arm64: Use sframe to unwind interrupt frames

Jens Remus (1):
  sframe: Separate reading of FRE from reading of FRE data words

Josh Poimboeuf (3):
  arm64/sframe: Read vmlinux .sframe header
  sframe: Add support for reading vmlinux .sframe contents
  sframe: Add .sframe validation option

Weinan Liu (1):
  arm64: entry: add unwind info for call_on_irq_stack()

 MAINTAINERS                            |   4 +-
 Makefile                               |   8 +
 arch/Kconfig                           |  49 ++
 arch/arm64/Kconfig                     |   1 +
 arch/arm64/Makefile                    |   2 +-
 arch/arm64/crypto/aes-ce-ccm-core.S    |  12 +-
 arch/arm64/crypto/aes-neonbs-core.S    |  16 +-
 arch/arm64/crypto/ghash-ce-core.S      |  12 +-
 arch/arm64/crypto/sm4-ce-ccm-core.S    |  16 +-
 arch/arm64/crypto/sm4-ce-cipher-core.S |   4 +-
 arch/arm64/crypto/sm4-ce-core.S        |  44 +-
 arch/arm64/crypto/sm4-ce-gcm-core.S    |  16 +-
 arch/arm64/crypto/sm4-neon-core.S      |  12 +-
 arch/arm64/include/asm/linkage.h       |  32 ++
 arch/arm64/include/asm/module.h        |   1 +
 arch/arm64/include/asm/module.lds.h    |   2 +
 arch/arm64/include/asm/sections.h      |   1 +
 arch/arm64/include/asm/unwind_sframe.h |  32 ++
 arch/arm64/kernel/entry.S              |  14 +
 arch/arm64/kernel/setup.c              |   2 +
 arch/arm64/kernel/stacktrace.c         | 184 ++++++-
 arch/arm64/kernel/vdso/Makefile        |   2 +-
 arch/arm64/kernel/vmlinux.lds.S        |  14 +
 arch/arm64/lib/clear_page.S            |   4 +-
 arch/arm64/lib/clear_user.S            |   4 +-
 arch/arm64/lib/copy_from_user.S        |   4 +-
 arch/arm64/lib/copy_page.S             |   4 +-
 arch/arm64/lib/copy_to_user.S          |   4 +-
 arch/arm64/lib/memchr.S                |   4 +-
 arch/arm64/lib/memcmp.S                |   4 +-
 arch/arm64/lib/memcpy.S                |   8 +-
 arch/arm64/lib/memset.S                |   8 +-
 arch/arm64/lib/mte.S                   |  28 +-
 arch/arm64/lib/strchr.S                |   4 +-
 arch/arm64/lib/strcmp.S                |   4 +-
 arch/arm64/lib/strlen.S                |   4 +-
 arch/arm64/lib/strncmp.S               |   4 +-
 arch/arm64/lib/strnlen.S               |   4 +-
 arch/arm64/lib/tishift.S               |  12 +-
 include/asm-generic/sections.h         |   4 +
 include/asm-generic/vmlinux.lds.h      |  15 +
 include/linux/module.h                 |   5 +
 include/linux/sframe.h                 |  43 ++
 include/linux/unwind_types.h           |  34 ++
 kernel/module/main.c                   |  21 +
 kernel/unwind/Makefile                 |   5 +-
 kernel/unwind/sframe.c                 | 710 +++++++++++++++++++++++++
 kernel/unwind/sframe.h                 |  79 +++
 kernel/unwind/sframe_debug.h           |  34 ++
 49 files changed, 1401 insertions(+), 133 deletions(-)
 create mode 100644 arch/arm64/include/asm/unwind_sframe.h
 create mode 100644 include/linux/sframe.h
 create mode 100644 include/linux/unwind_types.h
 create mode 100644 kernel/unwind/sframe.c
 create mode 100644 kernel/unwind/sframe.h
 create mode 100644 kernel/unwind/sframe_debug.h

-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 01/11] arm64, unwind: build kernel with sframe V3 info

[Dylan Hatch]

To generate a .sframe section, build with -Wa,--gsframe-3 flags. Also,
add unwind-table options to ensure the necessary CFI directives are
emitted by the compiler, but discard .eh_frame unless
CONFIG_UNWIND_TABLES is explicitly enabled.

This will be used for in-kernel reliable stacktrace in
cases where the frame pointer alone is insufficient.

Currently, the sframe format only supports arm64, x86_64 and s390x
architectures.

Co-developed-by: Weinan Liu <wnliu@google.com>
Signed-off-by: Weinan Liu <wnliu@google.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 MAINTAINERS                         |  3 ++-
 Makefile                            |  8 ++++++++
 arch/Kconfig                        | 31 +++++++++++++++++++++++++++++
 arch/arm64/Kconfig                  |  1 +
 arch/arm64/Makefile                 |  2 +-
 arch/arm64/include/asm/module.lds.h |  2 ++
 arch/arm64/kernel/vdso/Makefile     |  2 +-
 arch/arm64/kernel/vmlinux.lds.S     | 12 +++++++++++
 include/asm-generic/sections.h      |  4 ++++
 include/asm-generic/vmlinux.lds.h   | 15 ++++++++++++++
 10 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 65e8a4b5c90b1..36d7ee1f6ea5e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -28537,10 +28537,11 @@ F:	Documentation/driver-api/uio-howto.rst
 F:	drivers/uio/
 F:	include/linux/uio_driver.h
 
-USERSPACE STACK UNWINDING
+STACK UNWINDING
 M:	Josh Poimboeuf <jpoimboe@kernel.org>
 M:	Steven Rostedt <rostedt@goodmis.org>
 S:	Maintained
+F:	arch/*/include/asm/unwind_sframe.h
 F:	include/linux/unwind*.h
 F:	kernel/unwind/
 
diff --git a/Makefile b/Makefile
index 7c855e6fe5448..5c2ca98a86786 100644
--- a/Makefile
+++ b/Makefile
@@ -1197,6 +1197,14 @@ CFLAGS_GCOV	+= $(call try-run,\
 endif
 export CFLAGS_GCOV
 
+# build with sframe table
+ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+CC_FLAGS_SFRAME := -Wa,--gsframe-3
+KBUILD_CFLAGS	+= $(CC_FLAGS_SFRAME)
+KBUILD_AFLAGS	+= $(CC_FLAGS_SFRAME)
+export CC_FLAGS_SFRAME
+endif
+
 # change __FILE__ to the relative path to the source directory
 ifdef building_out_of_srctree
 KBUILD_CPPFLAGS += -fmacro-prefix-map=$(srcroot)/=
diff --git a/arch/Kconfig b/arch/Kconfig
index 45c6577723623..cc59a5da80915 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -507,6 +507,37 @@ config HAVE_UNWIND_USER_FP
 	bool
 	select UNWIND_USER
 
+config AS_SFRAME
+	bool
+
+config AS_SFRAME3
+	def_bool $(as-instr,.cfi_startproc\n.cfi_endproc,-Wa$(comma)--gsframe-3)
+	select AS_SFRAME
+
+config UNWIND_SFRAME_LOOKUP
+	bool
+
+config ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+	bool
+	help
+	  An architecture can select this if it enables the SFrame (Simple
+	  Frame) unwinder for unwinding kernel stack traces. It uses an unwind
+	  table that is directly generated by the toolchain based on DWARF CFI
+	  information.
+
+config HAVE_UNWIND_KERNEL_SFRAME
+	bool "Sframe unwinder"
+	depends on AS_SFRAME3
+	depends on 64BIT
+	depends on ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
+	select UNWIND_SFRAME_LOOKUP
+	help
+	  This option enables the SFrame (Simple Frame) unwinder for unwinding
+	  kernel stack traces. It uses an unwind table that is directly
+	  generated by the toolchain based on DWARF CFI information. In
+	  practice, this can provide more reliable stacktrace results than
+	  unwinding with frame pointers alone.
+
 config HAVE_PERF_REGS
 	bool
 	help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index cab741a695f52..b438d04044486 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -87,6 +87,7 @@ config ARM64
 	select ARCH_SUPPORTS_SCHED_SMT
 	select ARCH_SUPPORTS_SCHED_CLUSTER
 	select ARCH_SUPPORTS_SCHED_MC
+	select ARCH_SUPPORTS_UNWIND_KERNEL_SFRAME
 	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
 	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
 	select ARCH_WANT_DEFAULT_BPF_JIT
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 6b005c8fef706..ae1c23579ad2f 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -55,7 +55,7 @@ KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)
 KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
 
 # Avoid generating .eh_frame* sections.
-ifneq ($(CONFIG_UNWIND_TABLES),y)
+ifeq ($(filter y, $(CONFIG_UNWIND_TABLES) $(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)),)
 KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
 KBUILD_AFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
 KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n
diff --git a/arch/arm64/include/asm/module.lds.h b/arch/arm64/include/asm/module.lds.h
index 603f92a8a73ed..034cb635e8bcc 100644
--- a/arch/arm64/include/asm/module.lds.h
+++ b/arch/arm64/include/asm/module.lds.h
@@ -10,5 +10,7 @@ SECTIONS {
 	 * put it into the .init allocation.
 	 */
 	.init.eh_frame 0 : { *(.eh_frame) }
+#elif defined(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)
+	/DISCARD/ : { *(.eh_frame) }
 #endif
 }
diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile
index f6619e1cb2ce7..f6d1f59fb11c3 100644
--- a/arch/arm64/kernel/vdso/Makefile
+++ b/arch/arm64/kernel/vdso/Makefile
@@ -38,7 +38,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO
 CC_FLAGS_REMOVE_VDSO := $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \
 			$(RANDSTRUCT_CFLAGS) $(KSTACK_ERASE_CFLAGS) \
 			$(GCC_PLUGINS_CFLAGS) \
-			$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \
+			$(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(CC_FLAGS_SFRAME) \
 			-Wmissing-prototypes -Wmissing-declarations
 
 CC_FLAGS_ADD_VDSO := -O2 -mcmodel=tiny -fasynchronous-unwind-tables $(CONFIG_CC_OPT_INLINE_MEMSET)
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index af1d720209764..eb1f54829503c 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -145,14 +145,25 @@ jiffies = jiffies_64;
 #endif
 
 #ifdef CONFIG_UNWIND_TABLES
+
 #define UNWIND_DATA_SECTIONS				\
 	.eh_frame : {					\
 		__pi___eh_frame_start = .;		\
 		*(.eh_frame)				\
 		__pi___eh_frame_end = .;		\
 	}
+#define SFRAME_DISCARDS
+
+#elif defined(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)
+
+#define UNWIND_DATA_SECTIONS
+#define SFRAME_DISCARDS *(.eh_frame)
+
 #else
+
 #define UNWIND_DATA_SECTIONS
+#define SFRAME_DISCARDS
+
 #endif
 
 /*
@@ -184,6 +195,7 @@ SECTIONS
 		*(.interp .dynamic)
 		*(.dynsym .dynstr .hash .gnu.hash)
 		*(.ARM.attributes)
+		SFRAME_DISCARDS
 	}
 
 	. = KIMAGE_VADDR;
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 0755bc39b0d80..336d27011a580 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -31,6 +31,7 @@
  *	__irqentry_text_start, __irqentry_text_end
  *	__softirqentry_text_start, __softirqentry_text_end
  *	__start_opd, __end_opd
+ *	__start_sframe, __end_sframe
  */
 extern char _text[], _stext[], _etext[];
 extern char _data[], _sdata[], _edata[];
@@ -53,6 +54,9 @@ extern char __ctors_start[], __ctors_end[];
 /* Start and end of .opd section - used for function descriptors. */
 extern char __start_opd[], __end_opd[];
 
+/* Start and end of .sframe section - used for stack unwinding. */
+extern char __start_sframe[], __end_sframe[];
+
 /* Start and end of instrumentation protected text section */
 extern char __noinstr_text_start[], __noinstr_text_end[];
 
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index b2988aa12f664..278f5764d990d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -491,6 +491,8 @@
 		*(.rodata1)						\
 	}								\
 									\
+	SFRAME								\
+									\
 	/* PCI quirks */						\
 	.pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {	\
 		BOUNDED_SECTION_PRE_LABEL(.pci_fixup_early,  _pci_fixups_early,  __start, __end) \
@@ -912,6 +914,19 @@
 #define TRACEDATA
 #endif
 
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+#define SFRAME							\
+	/* sframe */						\
+	.sframe : AT(ADDR(.sframe) - LOAD_OFFSET) {		\
+		__start_sframe = .;			\
+		KEEP(*(.sframe))				\
+		KEEP(*(.init.sframe))				\
+		__end_sframe = .;			\
+	}
+#else
+#define SFRAME
+#endif
+
 #ifdef CONFIG_PRINTK_INDEX
 #define PRINTK_INDEX							\
 	.printk_index : AT(ADDR(.printk_index) - LOAD_OFFSET) {		\
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 02/11] arm64/sframe: Read vmlinux .sframe header

[Dylan Hatch]

From: Josh Poimboeuf <jpoimboe@kernel.org>

In preparation for unwinding kernel space stacks with sframe, add basic
sframe compile infrastructure and support for reading the .sframe
section header. Add init_sframe_table() to read the vmlinux .sframe
header at boot.

[ Jens Remus: Add support for SFrame V3.  Add support for PC-relative
FDE function start offset.  Cleanup includes and indentation. ]

[ Dylan Hatch: Repurpose patch for arm64 vmlinux. ]

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Indu Bhagat <ibhagatgnu@gmail.com>
Co-developed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Co-developed-by: Dylan Hatch <dylanbhatch@google.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>

---

Changes since v7:
 - (shashiko) remove KCOV, KCSAN, and KASAN instrumentation from
   sframe.o (copying over ORC's shoulder).
---
 MAINTAINERS               |  1 +
 arch/arm64/kernel/setup.c |  2 +
 include/linux/sframe.h    | 32 ++++++++++++++++
 kernel/unwind/Makefile    |  9 ++++-
 kernel/unwind/sframe.c    | 80 +++++++++++++++++++++++++++++++++++++++
 kernel/unwind/sframe.h    | 78 ++++++++++++++++++++++++++++++++++++++
 6 files changed, 201 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/sframe.h
 create mode 100644 kernel/unwind/sframe.c
 create mode 100644 kernel/unwind/sframe.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 36d7ee1f6ea5e..d2b62b26f5e94 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -28542,6 +28542,7 @@ M:	Josh Poimboeuf <jpoimboe@kernel.org>
 M:	Steven Rostedt <rostedt@goodmis.org>
 S:	Maintained
 F:	arch/*/include/asm/unwind_sframe.h
+F:	include/linux/sframe.h
 F:	include/linux/unwind*.h
 F:	kernel/unwind/
 
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 29c6100f0c50b..84983df605ed5 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -32,6 +32,7 @@
 #include <linux/sched/task.h>
 #include <linux/scs.h>
 #include <linux/mm.h>
+#include <linux/sframe.h>
 
 #include <asm/acpi.h>
 #include <asm/fixmap.h>
@@ -373,6 +374,7 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
 			"This indicates a broken bootloader or old kernel\n",
 			boot_args[1], boot_args[2], boot_args[3]);
 	}
+	init_sframe_table();
 }
 
 static inline bool cpu_can_disable(unsigned int cpu)
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
new file mode 100644
index 0000000000000..54e5cb76cb92c
--- /dev/null
+++ b/include/linux/sframe.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SFRAME_H
+#define _LINUX_SFRAME_H
+
+#include <linux/init.h>
+
+#ifdef CONFIG_UNWIND_SFRAME_LOOKUP
+
+struct sframe_section {
+	unsigned long	sframe_start;
+	unsigned long	sframe_end;
+
+	unsigned long	fdes_start;
+	unsigned long	fres_start;
+	unsigned long	fres_end;
+	unsigned int	num_fdes;
+
+	signed char	ra_off;
+	signed char	fp_off;
+};
+
+extern struct sframe_section kernel_sfsec __ro_after_init;
+
+void __init init_sframe_table(void);
+
+#else /* !CONFIG_UNWIND_SFRAME_LOOKUP */
+
+static inline void __init init_sframe_table(void) {}
+
+#endif /* CONFIG_UNWIND_SFRAME_LOOKUP */
+
+#endif /* _LINUX_SFRAME_H */
diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile
index eae37bea54fdb..c5d953e48fe82 100644
--- a/kernel/unwind/Makefile
+++ b/kernel/unwind/Makefile
@@ -1 +1,8 @@
- obj-$(CONFIG_UNWIND_USER)	+= user.o deferred.o
+ obj-$(CONFIG_UNWIND_USER)		+= user.o deferred.o
+
+ KCOV_INSTRUMENT_sframe.o	:= n
+ KASAN_SANITIZE_sframe.o	:= n
+ KCSAN_SANITIZE_sframe.o	:= n
+
+ CFLAGS_REMOVE_sframe.o = $(CC_FLAGS_FTRACE)
+ obj-$(CONFIG_UNWIND_SFRAME_LOOKUP)	+= sframe.o
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
new file mode 100644
index 0000000000000..d43a3b2367fca
--- /dev/null
+++ b/kernel/unwind/sframe.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Kernel sframe access functions
+ */
+
+#define pr_fmt(fmt)	"sframe: " fmt
+
+#include <linux/mm.h>
+#include <linux/string_helpers.h>
+#include <linux/sframe.h>
+#include <asm/sections.h>
+
+#include "sframe.h"
+
+static bool sframe_init __ro_after_init;
+struct sframe_section kernel_sfsec __ro_after_init;
+
+static int sframe_read_header(struct sframe_section *sec)
+{
+	unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end;
+	struct sframe_header *shdr;
+	unsigned int num_fdes;
+
+	header_end = sec->sframe_start + sizeof(struct sframe_header);
+	if (header_end >= sec->sframe_end) {
+		pr_debug("header struct doesn't fit in section\n");
+		return -EINVAL;
+	}
+
+	shdr = (struct sframe_header *)sec->sframe_start;
+
+	if (shdr->preamble.magic != SFRAME_MAGIC ||
+	    shdr->preamble.version != SFRAME_VERSION_3 ||
+	    !(shdr->preamble.flags & SFRAME_F_FDE_SORTED) ||
+	    !(shdr->preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
+	    shdr->auxhdr_len) {
+		pr_debug("bad/unsupported sframe header\n");
+		return -EINVAL;
+	}
+
+	if (!shdr->num_fdes || !shdr->num_fres) {
+		pr_debug("no fde/fre entries\n");
+		return -EINVAL;
+	}
+
+	num_fdes   = shdr->num_fdes;
+	fdes_start = header_end + shdr->fdes_off;
+	fdes_end   = fdes_start + (num_fdes * sizeof(struct sframe_fde_v3));
+
+	fres_start = header_end + shdr->fres_off;
+	fres_end   = fres_start + shdr->fre_len;
+
+	if (fres_start < fdes_end || fres_end > sec->sframe_end || fres_end < sec->sframe_start) {
+		pr_debug("inconsistent fde/fre offsets\n");
+		return -EINVAL;
+	}
+
+	sec->num_fdes		= num_fdes;
+	sec->fdes_start		= fdes_start;
+	sec->fres_start		= fres_start;
+	sec->fres_end		= fres_end;
+
+	sec->ra_off		= shdr->cfa_fixed_ra_offset;
+	sec->fp_off		= shdr->cfa_fixed_fp_offset;
+
+	return 0;
+}
+
+void __init init_sframe_table(void)
+{
+	kernel_sfsec.sframe_start	= (unsigned long)__start_sframe;
+	kernel_sfsec.sframe_end		= (unsigned long)__end_sframe;
+
+	if (sframe_read_header(&kernel_sfsec)) {
+		pr_warn("invalid vmlinux SFrame header\n");
+		return;
+	}
+
+	sframe_init = true;
+}
diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h
new file mode 100644
index 0000000000000..bf895107c2070
--- /dev/null
+++ b/kernel/unwind/sframe.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * From https://www.sourceware.org/binutils/docs/sframe-spec.html
+ */
+#ifndef _SFRAME_H
+#define _SFRAME_H
+
+#include <linux/types.h>
+
+#define SFRAME_VERSION_1			1
+#define SFRAME_VERSION_2			2
+#define SFRAME_VERSION_3			3
+#define SFRAME_MAGIC				0xdee2
+
+#define SFRAME_F_FDE_SORTED			0x1
+#define SFRAME_F_FRAME_POINTER			0x2
+#define SFRAME_F_FDE_FUNC_START_PCREL		0x4
+
+#define SFRAME_ABI_AARCH64_ENDIAN_BIG		1
+#define SFRAME_ABI_AARCH64_ENDIAN_LITTLE	2
+#define SFRAME_ABI_AMD64_ENDIAN_LITTLE		3
+
+struct sframe_preamble {
+	u16	magic;
+	u8	version;
+	u8	flags;
+} __packed;
+
+struct sframe_header {
+	struct sframe_preamble preamble;
+	u8	abi_arch;
+	s8	cfa_fixed_fp_offset;
+	s8	cfa_fixed_ra_offset;
+	u8	auxhdr_len;
+	u32	num_fdes;
+	u32	num_fres;
+	u32	fre_len;
+	u32	fdes_off;
+	u32	fres_off;
+} __packed;
+
+struct sframe_fde_v3 {
+	s64	func_start_off;
+	u32	func_size;
+	u32	fres_off;
+} __packed;
+
+struct sframe_fda_v3 {
+	u16	fres_num;
+	u8	info;
+	u8	info2;
+	u8	rep_size;
+} __packed;
+
+#define SFRAME_FDE_PCTYPE_INC			0
+#define SFRAME_FDE_PCTYPE_MASK			1
+
+#define SFRAME_AARCH64_PAUTH_KEY_A		0
+#define SFRAME_AARCH64_PAUTH_KEY_B		1
+
+#define SFRAME_V3_FDE_FRE_TYPE(info)		((info) & 0xf)
+#define SFRAME_V3_FDE_PCTYPE(info)		(((info) >> 4) & 0x1)
+#define SFRAME_V3_AARCH64_FDE_PAUTH_KEY(info)	(((info) >> 5) & 0x1)
+
+#define SFRAME_FDE_TYPE_DEFAULT			0
+
+#define SFRAME_V3_FDE_TYPE_MASK			0x1f
+#define SFRAME_V3_FDE_TYPE(info2)		((info2) & SFRAME_V3_FDE_TYPE_MASK)
+
+#define SFRAME_BASE_REG_FP			0
+#define SFRAME_BASE_REG_SP			1
+
+#define SFRAME_V3_FRE_CFA_BASE_REG_ID(info)		((info) & 0x1)
+#define SFRAME_V3_FRE_DATAWORD_COUNT(info)		(((info) >> 1) & 0xf)
+#define SFRAME_V3_FRE_DATAWORD_SIZE(info)		(((info) >> 5) & 0x3)
+#define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info)	(((info) >> 7) & 0x1)
+
+#endif /* _SFRAME_H */
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 03/11] sframe: Add support for reading vmlinux .sframe contents

[Dylan Hatch]

From: Josh Poimboeuf <jpoimboe@kernel.org>

In preparation for using sframe to unwind kernel space stacks, add an
sframe_find() interface for finding the sframe information associated
with a given vmlinux text address.

Treat a RA offset from CFA of zero as indication that the RA is not
saved (on the stack).  For the topmost frame treat it as indication that
the RA is in the link/RA register, such as on arm64 and s390, and obtain
it from there.  For non-topmost frames treat it as error, as the RA must
be saved.

[ Jens Remus: Add initial support for SFrame V3 (limited to regular
FDEs).  Add support for PC-relative FDE function start offset.  Simplify
logic by using an internal FDE representation.  Rename struct sframe_fre
to sframe_fre_internal to align with struct sframe_fde_internal.
Cleanup includes.  Fix checkpatch errors "spaces required around that
':'". ]

[ Dylan Hatch: Adapt for in-kernel unwinding. Squash parts of patches by
Jens Remus <jremus@linux.ibm.com>:
 - "unwind_user: Enable archs that pass RA in a register"
 - "unwind_user: Flexible FP/RA recovery rules"
 - "unwind_user: Flexible CFA recovery rules"
 - "unwind_user/sframe: Add support for outermost frame indication" ]

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Co-developed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Indu Bhagat <ibhagatgnu@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Co-developed-by: Dylan Hatch <dylanbhatch@google.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>

---

Changes since v7:
 - (sashiko) Block tracing and kprobe on the sframe_find code path.
---
 include/linux/sframe.h       |   4 +-
 include/linux/unwind_types.h |  34 ++++
 kernel/unwind/sframe.c       | 351 +++++++++++++++++++++++++++++++++++
 kernel/unwind/sframe.h       |   1 +
 4 files changed, 389 insertions(+), 1 deletion(-)
 create mode 100644 include/linux/unwind_types.h

diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index 54e5cb76cb92c..c1fe8ac7df7b3 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -3,6 +3,7 @@
 #define _LINUX_SFRAME_H
 
 #include <linux/init.h>
+#include <linux/unwind_types.h>
 
 #ifdef CONFIG_UNWIND_SFRAME_LOOKUP
 
@@ -22,11 +23,12 @@ struct sframe_section {
 extern struct sframe_section kernel_sfsec __ro_after_init;
 
 void __init init_sframe_table(void);
+extern int sframe_find(unsigned long ip, struct unwind_frame *frame);
 
 #else /* !CONFIG_UNWIND_SFRAME_LOOKUP */
 
 static inline void __init init_sframe_table(void) {}
-
+static inline int sframe_find(unsigned long ip, struct unwind_frame *frame) { return -EINVAL; }
 #endif /* CONFIG_UNWIND_SFRAME_LOOKUP */
 
 #endif /* _LINUX_SFRAME_H */
diff --git a/include/linux/unwind_types.h b/include/linux/unwind_types.h
new file mode 100644
index 0000000000000..d0e69189af2ab
--- /dev/null
+++ b/include/linux/unwind_types.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UNWIND_TYPES_H
+#define _LINUX_UNWIND_TYPES_H
+
+enum unwind_cfa_rule {
+	UNWIND_CFA_RULE_SP_OFFSET,		/* CFA = SP + offset */
+	UNWIND_CFA_RULE_FP_OFFSET,		/* CFA = FP + offset */
+	/* REG and DEREF variants not implemented -- flex FDEs not supported. */
+};
+
+struct unwind_cfa_rule_data {
+	enum unwind_cfa_rule rule;
+	s32 offset;
+	unsigned int regnum;
+};
+
+enum unwind_rule {
+	UNWIND_RULE_RETAIN,		/* entity = entity */
+	UNWIND_RULE_CFA_OFFSET_DEREF,	/* entity = *(CFA + offset) */
+};
+
+struct unwind_rule_data {
+	enum unwind_rule rule;
+	s32 offset;
+};
+
+struct unwind_frame {
+	struct unwind_cfa_rule_data cfa;
+	struct unwind_rule_data ra;
+	struct unwind_rule_data fp;
+	bool outermost;
+};
+
+#endif /* _LINUX_UNWIND_TYPES_H */
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index d43a3b2367fca..2a188373be857 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -8,6 +8,10 @@
 #include <linux/mm.h>
 #include <linux/string_helpers.h>
 #include <linux/sframe.h>
+#include <linux/unaligned.h>
+#include <linux/unwind_types.h>
+#include <linux/kallsyms.h>
+#include <asm/kprobes.h>
 #include <asm/sections.h>
 
 #include "sframe.h"
@@ -15,6 +19,353 @@
 static bool sframe_init __ro_after_init;
 struct sframe_section kernel_sfsec __ro_after_init;
 
+struct sframe_fde_internal {
+	unsigned long	func_addr;
+	u32		func_size;
+	u32		fda_off;
+	u32		fres_off;
+	u32		fres_num;
+	u8		info;
+	u8		info2;
+	u8		rep_size;
+};
+
+struct sframe_fre_internal {
+	unsigned int	size;
+	u32		ip_off;
+	s32		cfa_off;
+	s32		ra_off;
+	s32		fp_off;
+	u8		info;
+};
+
+static __always_inline unsigned char fre_type_to_size(unsigned char fre_type)
+{
+	if (fre_type > 2)
+		return 0;
+	return 1 << fre_type;
+}
+
+static __always_inline unsigned char dataword_size_enum_to_size(unsigned char dataword_size)
+{
+	if (dataword_size > 2)
+		return 0;
+	return 1 << dataword_size;
+}
+
+static __always_inline int __read_fde(struct sframe_section *sec,
+				      unsigned int fde_num,
+				      struct sframe_fde_internal *fde)
+{
+	unsigned long fde_addr, fda_addr, func_addr;
+	struct sframe_fde_v3 *_fde;
+	struct sframe_fda_v3 *_fda;
+
+	fde_addr = sec->fdes_start + (fde_num * sizeof(struct sframe_fde_v3));
+	_fde = (struct sframe_fde_v3 *)fde_addr;
+
+	func_addr = fde_addr + _fde->func_start_off;
+
+	fda_addr = sec->fres_start + _fde->fres_off;
+	if (fda_addr + sizeof(struct sframe_fda_v3) > sec->fres_end ||
+	    fda_addr + sizeof(struct sframe_fda_v3) < sec->fres_start)
+		return -EINVAL;
+	_fda = (struct sframe_fda_v3 *)fda_addr;
+
+	fde->func_addr	= func_addr;
+	fde->func_size	= _fde->func_size;
+	fde->fda_off	= _fde->fres_off;
+	fde->fres_off	= _fde->fres_off + sizeof(struct sframe_fda_v3);
+	fde->fres_num	= _fda->fres_num;
+	fde->info	= _fda->info;
+	fde->info2	= _fda->info2;
+	fde->rep_size	= _fda->rep_size;
+
+	return 0;
+}
+
+static __always_inline int __find_fde(struct sframe_section *sec,
+				      unsigned long ip,
+				      struct sframe_fde_internal *fde)
+{
+	unsigned long func_addr_low = 0, func_addr_high = ULONG_MAX;
+	struct sframe_fde_v3 *first, *low, *high, *found = NULL;
+	int ret;
+
+	first = (void *)sec->fdes_start;
+	low = first;
+	high = first + sec->num_fdes - 1;
+
+	while (low <= high) {
+		struct sframe_fde_v3 *mid;
+		s64 func_off;
+		unsigned long func_addr;
+
+		mid = low + ((high - low) / 2);
+
+		func_off = get_unaligned((s64 *)mid);
+		func_addr = (unsigned long)mid + func_off;
+
+		if (ip >= func_addr) {
+			if (func_addr < func_addr_low)
+				return -EFAULT;
+
+			func_addr_low = func_addr;
+
+			found = mid;
+			low = mid + 1;
+		} else {
+			if (func_addr > func_addr_high)
+				return -EFAULT;
+
+			func_addr_high = func_addr;
+
+			high = mid - 1;
+		}
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	ret = __read_fde(sec, found - first, fde);
+	if (ret)
+		return ret;
+
+	/* make sure it's not in a gap */
+	if (ip < fde->func_addr || ip >= fde->func_addr + fde->func_size)
+		return -EINVAL;
+
+	return 0;
+}
+
+#define ____GET_AND_INC(to, from, type)					\
+({									\
+	type __to;							\
+	(__to) = get_unaligned((type *)(from));				\
+	from += sizeof(__to);						\
+	to = __to;							\
+})
+
+#define __GET_AND_INC(to, from, size, u_or_s)			\
+({								\
+	switch (size) {						\
+	case 1:							\
+		____GET_AND_INC(to, from, u_or_s##8);		\
+		break;						\
+	case 2:							\
+		____GET_AND_INC(to, from, u_or_s##16);		\
+		break;						\
+	case 4:							\
+		____GET_AND_INC(to, from, u_or_s##32);		\
+		break;						\
+	default:						\
+		return -EFAULT;					\
+	}							\
+})
+
+#define GET_UNSIGNED_AND_INC(to, from, size)			\
+	__GET_AND_INC(to, from, size, u)
+
+#define GET_SIGNED_AND_INC(to, from, size)			\
+	__GET_AND_INC(to, from, size, s)
+
+#define GET_AND_INC(to, from, size)				\
+	_Generic(to,						\
+		 u8 :	GET_UNSIGNED_AND_INC(to, from, size),	\
+		 u16 :	GET_UNSIGNED_AND_INC(to, from, size),	\
+		 u32 :	GET_UNSIGNED_AND_INC(to, from, size),	\
+		 u64 :	GET_UNSIGNED_AND_INC(to, from, size),	\
+		 s8 :	GET_SIGNED_AND_INC(to, from, size),	\
+		 s16 :	GET_SIGNED_AND_INC(to, from, size),	\
+		 s32 :	GET_SIGNED_AND_INC(to, from, size),	\
+		 s64 :	GET_SIGNED_AND_INC(to, from, size))
+
+static __always_inline int __read_fre(struct sframe_section *sec,
+				      struct sframe_fde_internal *fde,
+				      unsigned long fre_addr,
+				      struct sframe_fre_internal *fre)
+{
+	unsigned char fde_type = SFRAME_V3_FDE_TYPE(fde->info2);
+	unsigned char fde_pctype = SFRAME_V3_FDE_PCTYPE(fde->info);
+	unsigned char fre_type = SFRAME_V3_FDE_FRE_TYPE(fde->info);
+	unsigned char dataword_count, dataword_size;
+	s32 cfa_off, ra_off, fp_off;
+	unsigned long cur = fre_addr;
+	unsigned char addr_size;
+	u32 ip_off;
+	u8 info;
+
+	addr_size = fre_type_to_size(fre_type);
+	if (!addr_size)
+		return -EFAULT;
+
+	if (fre_addr + addr_size + 1 > sec->fres_end)
+		return -EFAULT;
+
+	GET_AND_INC(ip_off, cur, addr_size);
+	if (fde_pctype == SFRAME_FDE_PCTYPE_INC && ip_off > fde->func_size)
+		return -EFAULT;
+
+	GET_AND_INC(info, cur, 1);
+	dataword_count = SFRAME_V3_FRE_DATAWORD_COUNT(info);
+	dataword_size  = dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE(info));
+	if (!dataword_size || !dataword_count)
+		return -EFAULT;
+
+	if (cur + (dataword_count * dataword_size) > sec->fres_end)
+		return -EFAULT;
+
+	/* Flexible FDEs not supported */
+	if (fde_type != SFRAME_FDE_TYPE_DEFAULT)
+		return -EFAULT;
+
+	fre->size	= addr_size + 1 + (dataword_count * dataword_size);
+
+	GET_AND_INC(cfa_off, cur, dataword_size);
+	dataword_count--;
+
+	ra_off = sec->ra_off;
+	if (!ra_off && dataword_count) {
+		dataword_count--;
+		GET_AND_INC(ra_off, cur, dataword_size);
+	}
+
+	fp_off = sec->fp_off;
+	if (!fp_off && dataword_count) {
+		dataword_count--;
+		GET_AND_INC(fp_off, cur, dataword_size);
+	}
+
+	if (dataword_count)
+		return -EFAULT;
+
+	fre->ip_off	= ip_off;
+	fre->cfa_off	= cfa_off;
+	fre->ra_off	= ra_off;
+	fre->fp_off	= fp_off;
+	fre->info	= info;
+
+	return 0;
+}
+
+static __always_inline int
+sframe_init_cfa_rule_data(struct unwind_cfa_rule_data *cfa_rule_data,
+			  u8 info, s32 offset)
+{
+	switch (SFRAME_V3_FRE_CFA_BASE_REG_ID(info)) {
+	case SFRAME_BASE_REG_SP:
+		cfa_rule_data->rule = UNWIND_CFA_RULE_SP_OFFSET;
+		break;
+	case SFRAME_BASE_REG_FP:
+		cfa_rule_data->rule = UNWIND_CFA_RULE_FP_OFFSET;
+		break;
+	default:
+		/* Flex FDEs not supported; base can't be another register */
+		return -EINVAL;
+	}
+
+	cfa_rule_data->offset = offset;
+
+	return 0;
+}
+
+static __always_inline void
+sframe_init_rule_data(struct unwind_rule_data *rule_data, s32 offset)
+{
+	if (!offset) {
+		rule_data->rule = UNWIND_RULE_RETAIN;
+		return;
+	}
+	/* Flex FDEs not supported; always deref */
+	rule_data->rule = UNWIND_RULE_CFA_OFFSET_DEREF;
+	rule_data->offset = offset;
+}
+
+static __always_inline int __find_fre(struct sframe_section *sec,
+				      struct sframe_fde_internal *fde,
+				      unsigned long ip,
+				      struct unwind_frame *frame)
+{
+	unsigned char fde_pctype = SFRAME_V3_FDE_PCTYPE(fde->info);
+	struct sframe_fre_internal *fre, *prev_fre = NULL;
+	struct sframe_fre_internal fres[2];
+	unsigned long fre_addr;
+	bool which = false;
+	unsigned int i;
+	u32 ip_off;
+
+	ip_off = ip - fde->func_addr;
+
+	if (fde_pctype == SFRAME_FDE_PCTYPE_MASK) {
+		if (!fde->rep_size)
+			return -EFAULT;
+		ip_off %= fde->rep_size;
+	}
+
+	fre_addr = sec->fres_start + fde->fres_off;
+
+	for (i = 0; i < fde->fres_num; i++) {
+		int ret;
+
+		/*
+		 * Alternate between the two fre_addr[] entries for 'fre' and
+		 * 'prev_fre'.
+		 */
+		fre = which ? fres : fres + 1;
+		which = !which;
+
+		ret = __read_fre(sec, fde, fre_addr, fre);
+		if (ret)
+			return ret;
+
+		fre_addr += fre->size;
+
+		if (prev_fre && fre->ip_off <= prev_fre->ip_off)
+			return -EFAULT;
+
+		if (fre->ip_off > ip_off)
+			break;
+
+		prev_fre = fre;
+	}
+
+	if (!prev_fre)
+		return -EINVAL;
+	fre = prev_fre;
+
+	if (sframe_init_cfa_rule_data(&frame->cfa, fre->info, fre->cfa_off))
+		return -EINVAL;
+
+	sframe_init_rule_data(&frame->ra, fre->ra_off);
+	sframe_init_rule_data(&frame->fp, fre->fp_off);
+	frame->outermost = SFRAME_V3_FRE_RA_UNDEFINED_P(fre->info);
+
+	return 0;
+}
+
+static __always_inline int __sframe_find(struct sframe_section *sec,
+					 unsigned long ip,
+					 struct unwind_frame *frame)
+{
+	struct sframe_fde_internal fde;
+	int ret;
+
+	ret = __find_fde(sec, ip, &fde);
+	if (ret)
+		return ret;
+
+	return __find_fre(sec, &fde, ip, frame);
+}
+
+notrace int sframe_find(unsigned long ip, struct unwind_frame *frame)
+{
+	if (!frame || !sframe_init)
+		return -EINVAL;
+
+	return  __sframe_find(&kernel_sfsec, ip, frame);
+}
+NOKPROBE_SYMBOL(sframe_find);
+
 static int sframe_read_header(struct sframe_section *sec)
 {
 	unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end;
diff --git a/kernel/unwind/sframe.h b/kernel/unwind/sframe.h
index bf895107c2070..17daf68309e61 100644
--- a/kernel/unwind/sframe.h
+++ b/kernel/unwind/sframe.h
@@ -74,5 +74,6 @@ struct sframe_fda_v3 {
 #define SFRAME_V3_FRE_DATAWORD_COUNT(info)		(((info) >> 1) & 0xf)
 #define SFRAME_V3_FRE_DATAWORD_SIZE(info)		(((info) >> 5) & 0x3)
 #define SFRAME_V3_AARCH64_FRE_MANGLED_RA_P(info)	(((info) >> 7) & 0x1)
+#define SFRAME_V3_FRE_RA_UNDEFINED_P(info)		(SFRAME_V3_FRE_DATAWORD_COUNT(info) == 0)
 
 #endif /* _SFRAME_H */
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 04/11] sframe: Separate reading of FRE from reading of FRE data words

[Dylan Hatch]

From: Jens Remus <jremus@linux.ibm.com>

__find_fre() performs linear search for a matching SFrame FRE for a
given IP.  For that purpose it uses __read_fre(), which reads the whole
FRE.  That is the variable-size FRE structure as well as the trailing
variable-length array of variable-size data words.  For the search logic
to skip over the FRE it would be sufficient to read the variable-size
FRE structure only, which includes the count and size of data words.

Add fields to struct sframe_fre_internal to store the FRE data word's
address, count, and size.  Change __read_fre() to read the variable-
size FRE structure only and populate those new fields.  Change
__read_fre_datawords() to use those new fields.  Change __find_fre()
to use __read_fre_datawords() to read the FRE data words only after a
matching FRE has been found.

[ Dylan Hatch: Adapt for in-kernel unwinding without flexible FDEs. ]

Reviewed-by: Indu Bhagat <ibhagatgnu@gmail.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 kernel/unwind/sframe.c | 97 +++++++++++++++++++++++++++++++-----------
 1 file changed, 73 insertions(+), 24 deletions(-)

diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 2a188373be857..ec81110a36796 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -37,6 +37,9 @@ struct sframe_fre_internal {
 	s32		ra_off;
 	s32		fp_off;
 	u8		info;
+	unsigned long	dw_addr;
+	unsigned char	dw_count;
+	unsigned char	dw_size;
 };
 
 static __always_inline unsigned char fre_type_to_size(unsigned char fre_type)
@@ -180,6 +183,67 @@ static __always_inline int __find_fde(struct sframe_section *sec,
 		 s32 :	GET_SIGNED_AND_INC(to, from, size),	\
 		 s64 :	GET_SIGNED_AND_INC(to, from, size))
 
+static __always_inline int
+__read_default_fre_datawords(struct sframe_section *sec,
+			     struct sframe_fde_internal *fde,
+			     struct sframe_fre_internal *fre)
+{
+	unsigned char dataword_count = fre->dw_count;
+	unsigned char dataword_size = fre->dw_size;
+	unsigned long cur = fre->dw_addr;
+	s32 cfa_off, ra_off, fp_off;
+
+	GET_AND_INC(cfa_off, cur, dataword_size);
+	dataword_count--;
+
+	ra_off = sec->ra_off;
+	if (!ra_off && dataword_count) {
+		dataword_count--;
+		GET_AND_INC(ra_off, cur, dataword_size);
+	}
+
+	fp_off = sec->fp_off;
+	if (!fp_off && dataword_count) {
+		dataword_count--;
+		GET_AND_INC(fp_off, cur, dataword_size);
+	}
+
+	if (dataword_count)
+		return -EFAULT;
+
+	fre->cfa_off	= cfa_off;
+	fre->ra_off	= ra_off;
+	fre->fp_off	= fp_off;
+
+	return 0;
+}
+
+static __always_inline int
+__read_fre_datawords(struct sframe_section *sec,
+		     struct sframe_fde_internal *fde,
+		     struct sframe_fre_internal *fre)
+{
+	unsigned char fde_type = SFRAME_V3_FDE_TYPE(fde->info2);
+	unsigned char dataword_count = fre->dw_count;
+
+	if (!dataword_count) {
+		/* A FRE without data words indicates an outermost frame. */
+		fre->cfa_off	= 0;
+		fre->ra_off	= 0;
+		fre->fp_off	= 0;
+
+		return 0;
+	}
+
+	switch (fde_type) {
+	case SFRAME_FDE_TYPE_DEFAULT:
+		return __read_default_fre_datawords(sec, fde, fre);
+	/* Flexible FDEs not supported */
+	default:
+		return -EFAULT;
+	}
+}
+
 static __always_inline int __read_fre(struct sframe_section *sec,
 				      struct sframe_fde_internal *fde,
 				      unsigned long fre_addr,
@@ -189,7 +253,6 @@ static __always_inline int __read_fre(struct sframe_section *sec,
 	unsigned char fde_pctype = SFRAME_V3_FDE_PCTYPE(fde->info);
 	unsigned char fre_type = SFRAME_V3_FDE_FRE_TYPE(fde->info);
 	unsigned char dataword_count, dataword_size;
-	s32 cfa_off, ra_off, fp_off;
 	unsigned long cur = fre_addr;
 	unsigned char addr_size;
 	u32 ip_off;
@@ -209,7 +272,7 @@ static __always_inline int __read_fre(struct sframe_section *sec,
 	GET_AND_INC(info, cur, 1);
 	dataword_count = SFRAME_V3_FRE_DATAWORD_COUNT(info);
 	dataword_size  = dataword_size_enum_to_size(SFRAME_V3_FRE_DATAWORD_SIZE(info));
-	if (!dataword_size || !dataword_count)
+	if (!dataword_size)
 		return -EFAULT;
 
 	if (cur + (dataword_count * dataword_size) > sec->fres_end)
@@ -220,30 +283,11 @@ static __always_inline int __read_fre(struct sframe_section *sec,
 		return -EFAULT;
 
 	fre->size	= addr_size + 1 + (dataword_count * dataword_size);
-
-	GET_AND_INC(cfa_off, cur, dataword_size);
-	dataword_count--;
-
-	ra_off = sec->ra_off;
-	if (!ra_off && dataword_count) {
-		dataword_count--;
-		GET_AND_INC(ra_off, cur, dataword_size);
-	}
-
-	fp_off = sec->fp_off;
-	if (!fp_off && dataword_count) {
-		dataword_count--;
-		GET_AND_INC(fp_off, cur, dataword_size);
-	}
-
-	if (dataword_count)
-		return -EFAULT;
-
 	fre->ip_off	= ip_off;
-	fre->cfa_off	= cfa_off;
-	fre->ra_off	= ra_off;
-	fre->fp_off	= fp_off;
 	fre->info	= info;
+	fre->dw_addr	= cur;
+	fre->dw_count	= dataword_count;
+	fre->dw_size	= dataword_size;
 
 	return 0;
 }
@@ -293,6 +337,7 @@ static __always_inline int __find_fre(struct sframe_section *sec,
 	bool which = false;
 	unsigned int i;
 	u32 ip_off;
+	int ret;
 
 	ip_off = ip - fde->func_addr;
 
@@ -333,6 +378,10 @@ static __always_inline int __find_fre(struct sframe_section *sec,
 		return -EINVAL;
 	fre = prev_fre;
 
+	ret = __read_fre_datawords(sec, fde, fre);
+	if (ret)
+		return ret;
+
 	if (sframe_init_cfa_rule_data(&frame->cfa, fre->info, fre->cfa_off))
 		return -EINVAL;
 
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 05/11] module, sframe: Add sframe support for modules

[Dylan Hatch]

Add sframe table to struct module and support sframe PC lookups when an
.sframe section can be found on incoming modules. SFRAME_F_FDE_SORTED is
not set for module .sframe, so FDEs are sorted right after the sframe
header is read.

Co-developed-by: Weinan Liu <wnliu@google.com>
Signed-off-by: Weinan Liu <wnliu@google.com>
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>

---

Changes since v7:
- (sashiko) Move .sframe module init and sframe section fields to arch
  generic code.
- (sashiko) Make sframe_find() noinstr.
- (sashiko) Add preempt_notrace and instrumentation to
  __sframe_module_find() code path.
---
 arch/arm64/include/asm/module.h |   1 +
 include/linux/module.h          |   5 ++
 include/linux/sframe.h          |   9 +++
 kernel/module/main.c            |  21 ++++++
 kernel/unwind/Makefile          |   4 --
 kernel/unwind/sframe.c          | 118 ++++++++++++++++++++++++++++++--
 6 files changed, 149 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index fb9b88eebeb15..51a8891c24e88 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -6,6 +6,7 @@
 #define __ASM_MODULE_H
 
 #include <asm-generic/module.h>
+#include <linux/sframe.h>
 
 struct mod_plt_sec {
 	int			plt_shndx;
diff --git a/include/linux/module.h b/include/linux/module.h
index 96cc98568eea5..6b3f3d3cb3e8d 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -26,6 +26,7 @@
 #include <linux/rbtree_latch.h>
 #include <linux/error-injection.h>
 #include <linux/tracepoint-defs.h>
+#include <linux/sframe.h>
 #include <linux/srcu.h>
 #include <linux/static_call_types.h>
 #include <linux/dynamic_debug.h>
@@ -577,6 +578,10 @@ struct module {
 #ifdef CONFIG_DYNAMIC_DEBUG_CORE
 	struct _ddebug_info dyndbg_info;
 #endif
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+	struct sframe_section sframe_sec;
+	bool sframe_init;
+#endif
 } ____cacheline_aligned __randomize_layout;
 #ifndef MODULE_ARCH_INIT
 #define MODULE_ARCH_INIT {}
diff --git a/include/linux/sframe.h b/include/linux/sframe.h
index c1fe8ac7df7b3..1aa3e07725f4d 100644
--- a/include/linux/sframe.h
+++ b/include/linux/sframe.h
@@ -2,9 +2,12 @@
 #ifndef _LINUX_SFRAME_H
 #define _LINUX_SFRAME_H
 
+#include <linux/elf.h>
 #include <linux/init.h>
 #include <linux/unwind_types.h>
 
+#include <asm-generic/module.h>
+
 #ifdef CONFIG_UNWIND_SFRAME_LOOKUP
 
 struct sframe_section {
@@ -15,6 +18,7 @@ struct sframe_section {
 	unsigned long	fres_start;
 	unsigned long	fres_end;
 	unsigned int	num_fdes;
+	bool		fdes_sorted;
 
 	signed char	ra_off;
 	signed char	fp_off;
@@ -23,12 +27,17 @@ struct sframe_section {
 extern struct sframe_section kernel_sfsec __ro_after_init;
 
 void __init init_sframe_table(void);
+void sframe_module_init(struct module *mod, void *addr, unsigned int size);
+
 extern int sframe_find(unsigned long ip, struct unwind_frame *frame);
 
 #else /* !CONFIG_UNWIND_SFRAME_LOOKUP */
 
 static inline void __init init_sframe_table(void) {}
+static inline void sframe_module_init(struct module *mod, void *addr, unsigned int size) {}
+
 static inline int sframe_find(unsigned long ip, struct unwind_frame *frame) { return -EINVAL; }
+
 #endif /* CONFIG_UNWIND_SFRAME_LOOKUP */
 
 #endif /* _LINUX_SFRAME_H */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c1b34dc1e89ac..8a4542b7e4a70 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -7,6 +7,7 @@
 
 #define INCLUDE_VERMAGIC
 
+#include <linux/elf.h>
 #include <linux/export.h>
 #include <linux/extable.h>
 #include <linux/moduleloader.h>
@@ -3008,6 +3009,23 @@ static void module_deallocate(struct module *mod, struct load_info *info)
 	free_mod_mem(mod);
 }
 
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+static void setup_sframe(struct module *mod, const struct load_info *info)
+{
+	unsigned int sframe_size;
+	void *sframe = section_objs(info, ".sframe", 1, &sframe_size);
+
+	if (sframe)
+		sframe_module_init(mod, sframe, sframe_size);
+}
+
+#else
+
+static void setup_sframe(struct module *mod, const struct load_info *info) {}
+
+#endif
+
 int __weak module_finalize(const Elf_Ehdr *hdr,
 			   const Elf_Shdr *sechdrs,
 			   struct module *me)
@@ -3027,6 +3045,9 @@ static int post_relocation(struct module *mod, const struct load_info *info)
 	/* Setup kallsyms-specific fields. */
 	add_kallsyms(mod, info);
 
+	/* Initialize sframe metadata. */
+	setup_sframe(mod, info);
+
 	/* Arch-specific module finalizing. */
 	return module_finalize(info->hdr, info->sechdrs, mod);
 }
diff --git a/kernel/unwind/Makefile b/kernel/unwind/Makefile
index c5d953e48fe82..13254e6a7bb6d 100644
--- a/kernel/unwind/Makefile
+++ b/kernel/unwind/Makefile
@@ -1,8 +1,4 @@
  obj-$(CONFIG_UNWIND_USER)		+= user.o deferred.o
 
  KCOV_INSTRUMENT_sframe.o	:= n
- KASAN_SANITIZE_sframe.o	:= n
- KCSAN_SANITIZE_sframe.o	:= n
-
- CFLAGS_REMOVE_sframe.o = $(CC_FLAGS_FTRACE)
  obj-$(CONFIG_UNWIND_SFRAME_LOOKUP)	+= sframe.o
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index ec81110a36796..33883408581da 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -6,8 +6,10 @@
 #define pr_fmt(fmt)	"sframe: " fmt
 
 #include <linux/mm.h>
+#include <linux/rcupdate.h>
 #include <linux/string_helpers.h>
 #include <linux/sframe.h>
+#include <linux/sort.h>
 #include <linux/unaligned.h>
 #include <linux/unwind_types.h>
 #include <linux/kallsyms.h>
@@ -95,6 +97,9 @@ static __always_inline int __find_fde(struct sframe_section *sec,
 	struct sframe_fde_v3 *first, *low, *high, *found = NULL;
 	int ret;
 
+	if (!sec->fdes_sorted)
+		return -EINVAL;
+
 	first = (void *)sec->fdes_start;
 	low = first;
 	high = first + sec->num_fdes - 1;
@@ -406,12 +411,53 @@ static __always_inline int __sframe_find(struct sframe_section *sec,
 	return __find_fre(sec, &fde, ip, frame);
 }
 
-notrace int sframe_find(unsigned long ip, struct unwind_frame *frame)
+#ifdef CONFIG_MODULES
+
+static __always_inline int __sframe_find_module(unsigned long ip,
+						struct unwind_frame *frame)
+{
+	struct module *mod;
+	int ret;
+
+	if (!rcu_is_watching())
+		return -EINVAL;
+
+	instrumentation_begin();
+	scoped_guard(preempt_notrace) {
+		mod = __module_text_address(ip);
+		if (mod && smp_load_acquire(&mod->sframe_init))
+			ret = __sframe_find(&mod->sframe_sec, ip, frame);
+		else
+			ret = -EINVAL;
+	}
+	instrumentation_end();
+
+	return ret;
+}
+
+#else
+
+static __always_inline int __sframe_find_module(unsigned long ip,
+						struct unwind_frame *frame)
+{
+	return -EINVAL;
+}
+
+#endif
+
+noinstr int sframe_find(unsigned long ip, struct unwind_frame *frame)
 {
-	if (!frame || !sframe_init)
+	if (!frame)
 		return -EINVAL;
 
-	return  __sframe_find(&kernel_sfsec, ip, frame);
+	if (__is_kernel_text(ip) || is_kernel_inittext(ip)) {
+		if (!sframe_init)
+			return -EINVAL;
+
+		return __sframe_find(&kernel_sfsec, ip, frame);
+	}
+
+	return  __sframe_find_module(ip, frame);
 }
 NOKPROBE_SYMBOL(sframe_find);
 
@@ -431,7 +477,6 @@ static int sframe_read_header(struct sframe_section *sec)
 
 	if (shdr->preamble.magic != SFRAME_MAGIC ||
 	    shdr->preamble.version != SFRAME_VERSION_3 ||
-	    !(shdr->preamble.flags & SFRAME_F_FDE_SORTED) ||
 	    !(shdr->preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
 	    shdr->auxhdr_len) {
 		pr_debug("bad/unsupported sframe header\n");
@@ -455,6 +500,7 @@ static int sframe_read_header(struct sframe_section *sec)
 		return -EINVAL;
 	}
 
+	sec->fdes_sorted	= shdr->preamble.flags & SFRAME_F_FDE_SORTED;
 	sec->num_fdes		= num_fdes;
 	sec->fdes_start		= fdes_start;
 	sec->fres_start		= fres_start;
@@ -471,10 +517,72 @@ void __init init_sframe_table(void)
 	kernel_sfsec.sframe_start	= (unsigned long)__start_sframe;
 	kernel_sfsec.sframe_end		= (unsigned long)__end_sframe;
 
-	if (sframe_read_header(&kernel_sfsec)) {
+	if (sframe_read_header(&kernel_sfsec) || !kernel_sfsec.fdes_sorted) {
 		pr_warn("invalid vmlinux SFrame header\n");
 		return;
 	}
 
 	sframe_init = true;
 }
+
+#ifdef CONFIG_MODULES
+
+static int sframe_sort_cmp_fde(const void *a, const void *b)
+{
+	const struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+	unsigned long func_start_a, func_start_b;
+
+	func_start_a = (unsigned long)fde_a + fde_a->func_start_off;
+	func_start_b = (unsigned long)fde_b + fde_b->func_start_off;
+
+	return cmp_int(func_start_a, func_start_b);
+}
+
+static void sframe_sort_swap_fde(void *a, void *b, int size)
+{
+	struct sframe_fde_v3 *fde_a = a, *fde_b = b;
+	struct sframe_fde_v3 temp;
+	long delta;
+
+	/* Swap potentially unaligned FDE */
+	memcpy(&temp, fde_a, sizeof(struct sframe_fde_v3));
+	memcpy(fde_a, fde_b, sizeof(struct sframe_fde_v3));
+	memcpy(fde_b, &temp, sizeof(struct sframe_fde_v3));
+
+	/* Adjust FDE function start offset from FDE */
+	delta = (long)((unsigned long)fde_b - (unsigned long)fde_a);
+	fde_a->func_start_off += delta;
+	fde_b->func_start_off -= delta;
+}
+
+static void sframe_sort_fdes(struct sframe_section *sec)
+{
+	void *fdes = (void *)sec->fdes_start;
+	size_t num_fdes = sec->num_fdes;
+
+	if (sec->fdes_sorted)
+		return;
+
+	sort(fdes, num_fdes, sizeof(struct sframe_fde_v3),
+	     sframe_sort_cmp_fde, sframe_sort_swap_fde);
+	sec->fdes_sorted = true;
+}
+
+void sframe_module_init(struct module *mod, void *addr, unsigned int size)
+{
+	struct sframe_section *sec = &mod->sframe_sec;
+
+	sec->sframe_start = (unsigned long)addr;
+	sec->sframe_end   = (unsigned long)addr + size;
+
+	if (sframe_read_header(sec)) {
+		pr_warn("invalid SFrame header in module %s\n", mod->name);
+		return;
+	}
+	sframe_sort_fdes(sec);
+
+	/* Ensure SFrame is initialized when sframe_find() happens */
+	smp_store_release(&mod->sframe_init, true);
+}
+
+#endif
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 06/11] arm64/sframe: Validate IP addresses

[Dylan Hatch]

Validate the given IP and computed function start address against the
known vmlinux and module text address ranges.

This requires arch-specific validation for vmlinux. This is because
arm64 keeps .exit.text (normally discarded) and .rodata.text, both of
both of which lie outside the bounds of .text and .init.text. Note that
.rodata.text contains code that is never executed by the kernel mapping,
but for which the toolchain nonetheless generates sframe data, and needs
to be considered valid at lookup time.

Suggested-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>

---

Changes since v7:
 - (sashiko) Use __always_inline for IP validation helper.
---
 arch/arm64/include/asm/sections.h      |  1 +
 arch/arm64/include/asm/unwind_sframe.h | 32 +++++++++++++++++++
 arch/arm64/kernel/vmlinux.lds.S        |  2 ++
 kernel/unwind/sframe.c                 | 43 +++++++++++++++++++++++++-
 4 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/include/asm/unwind_sframe.h

diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
index 51b0d594239eb..5edb4304f661e 100644
--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -23,6 +23,7 @@ extern char __irqentry_text_start[], __irqentry_text_end[];
 extern char __mmuoff_data_start[], __mmuoff_data_end[];
 extern char __entry_tramp_text_start[], __entry_tramp_text_end[];
 extern char __relocate_new_kernel_start[], __relocate_new_kernel_end[];
+extern char _srodatatext[], _erodatatext[];
 
 static inline size_t entry_tramp_text_size(void)
 {
diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h
new file mode 100644
index 0000000000000..1b45d328c746f
--- /dev/null
+++ b/arch/arm64/include/asm/unwind_sframe.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARM64_UNWIND_SFRAME_H
+#define _ASM_ARM64_UNWIND_SFRAME_H
+
+#include <linux/module.h>
+#include <linux/sframe.h>
+#include <asm/sections.h>
+
+static __always_inline bool sframe_is_kernel_ip_valid(unsigned long ip)
+{
+	if (__is_kernel_text(ip) || is_kernel_inittext(ip))
+		return true;
+
+	/* .exit.text is retained in vmlinux on arm64. */
+	if (ip >= (unsigned long)__exittext_begin &&
+	    ip < (unsigned long)__exittext_end)
+		return true;
+
+	/*
+	 * .rodata.text is never executed from the kernel mapping, but it still
+	 * has sframe data.
+	 */
+	if (ip >= (unsigned long)_srodatatext &&
+	    ip < (unsigned long)_erodatatext)
+		return true;
+
+	return false;
+}
+
+#define sframe_is_kernel_ip_valid sframe_is_kernel_ip_valid
+
+#endif /* _ASM_ARM64_UNWIND_SFRAME_H */
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index eb1f54829503c..82fd20ccb7c43 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -237,12 +237,14 @@ SECTIONS
 
 	/* code sections that are never executed via the kernel mapping */
 	.rodata.text : {
+		_srodatatext = .;
 		TRAMP_TEXT
 		HIBERNATE_TEXT
 		KEXEC_TEXT
 		IDMAP_TEXT
 		. = ALIGN(PAGE_SIZE);
 	}
+	_erodatatext = .;
 
 	idmap_pg_dir = .;
 	. += PAGE_SIZE;
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 33883408581da..c95fcb63e7eaf 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -44,6 +44,45 @@ struct sframe_fre_internal {
 	unsigned char	dw_size;
 };
 
+#ifndef sframe_is_kernel_ip_valid
+
+static __always_inline bool sframe_is_kernel_ip_valid(unsigned long ip)
+{
+	return __is_kernel_text(ip) || is_kernel_inittext(ip);
+}
+
+#endif
+
+#ifdef CONFIG_MODULES
+
+static __always_inline bool sframe_is_sec_module_ip_valid(struct sframe_section *sec,
+							  unsigned long ip)
+{
+	struct module *mod = container_of(sec, struct module, sframe_sec);
+
+	return within_module_mem_type(ip, mod, MOD_TEXT) ||
+		within_module_mem_type(ip, mod, MOD_INIT_TEXT);
+}
+
+#else
+
+static __always_inline bool sframe_is_sec_module_ip_valid(struct sframe_section *sec,
+							  unsigned long ip)
+{
+	return false;
+}
+
+#endif
+
+static __always_inline bool is_sec_ip_valid(struct sframe_section *sec,
+					    unsigned long ip)
+{
+	if (sec == &kernel_sfsec)
+		return sframe_is_kernel_ip_valid(ip);
+
+	return sframe_is_sec_module_ip_valid(sec, ip);
+}
+
 static __always_inline unsigned char fre_type_to_size(unsigned char fre_type)
 {
 	if (fre_type > 2)
@@ -70,6 +109,8 @@ static __always_inline int __read_fde(struct sframe_section *sec,
 	_fde = (struct sframe_fde_v3 *)fde_addr;
 
 	func_addr = fde_addr + _fde->func_start_off;
+	if (!is_sec_ip_valid(sec, func_addr))
+		return -EINVAL;
 
 	fda_addr = sec->fres_start + _fde->fres_off;
 	if (fda_addr + sizeof(struct sframe_fda_v3) > sec->fres_end ||
@@ -450,7 +491,7 @@ noinstr int sframe_find(unsigned long ip, struct unwind_frame *frame)
 	if (!frame)
 		return -EINVAL;
 
-	if (__is_kernel_text(ip) || is_kernel_inittext(ip)) {
+	if (sframe_is_kernel_ip_valid(ip)) {
 		if (!sframe_init)
 			return -EINVAL;
 
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 07/11] sframe: Add debug helpers with object name

[Dylan Hatch]

Include the object name for kernel .sframe sections, indicated with the
format "(<module-name>)" or "(vmlinux)".

Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 kernel/unwind/sframe.c       | 11 +++++++----
 kernel/unwind/sframe_debug.h | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 4 deletions(-)
 create mode 100644 kernel/unwind/sframe_debug.h

diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index c95fcb63e7eaf..2e8ff783de7d8 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -17,6 +17,7 @@
 #include <asm/sections.h>
 
 #include "sframe.h"
+#include "sframe_debug.h"
 
 static bool sframe_init __ro_after_init;
 struct sframe_section kernel_sfsec __ro_after_init;
@@ -510,7 +511,7 @@ static int sframe_read_header(struct sframe_section *sec)
 
 	header_end = sec->sframe_start + sizeof(struct sframe_header);
 	if (header_end >= sec->sframe_end) {
-		pr_debug("header struct doesn't fit in section\n");
+		dbg_sec(sec, "header struct doesn't fit in section\n");
 		return -EINVAL;
 	}
 
@@ -520,12 +521,12 @@ static int sframe_read_header(struct sframe_section *sec)
 	    shdr->preamble.version != SFRAME_VERSION_3 ||
 	    !(shdr->preamble.flags & SFRAME_F_FDE_FUNC_START_PCREL) ||
 	    shdr->auxhdr_len) {
-		pr_debug("bad/unsupported sframe header\n");
+		dbg_sec(sec, "bad/unsupported sframe header\n");
 		return -EINVAL;
 	}
 
 	if (!shdr->num_fdes || !shdr->num_fres) {
-		pr_debug("no fde/fre entries\n");
+		dbg_sec(sec, "no fde/fre entries\n");
 		return -EINVAL;
 	}
 
@@ -537,7 +538,7 @@ static int sframe_read_header(struct sframe_section *sec)
 	fres_end   = fres_start + shdr->fre_len;
 
 	if (fres_start < fdes_end || fres_end > sec->sframe_end || fres_end < sec->sframe_start) {
-		pr_debug("inconsistent fde/fre offsets\n");
+		dbg_sec(sec, "inconsistent fde/fre offsets\n");
 		return -EINVAL;
 	}
 
@@ -564,6 +565,7 @@ void __init init_sframe_table(void)
 	}
 
 	sframe_init = true;
+	dbg_print_header(&kernel_sfsec);
 }
 
 #ifdef CONFIG_MODULES
@@ -624,6 +626,7 @@ void sframe_module_init(struct module *mod, void *addr, unsigned int size)
 
 	/* Ensure SFrame is initialized when sframe_find() happens */
 	smp_store_release(&mod->sframe_init, true);
+	dbg_print_header(sec);
 }
 
 #endif
diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h
new file mode 100644
index 0000000000000..f0bc2136eaad0
--- /dev/null
+++ b/kernel/unwind/sframe_debug.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SFRAME_DEBUG_H
+#define _SFRAME_DEBUG_H
+
+#include <linux/sframe.h>
+#include "sframe.h"
+
+#ifdef CONFIG_MODULES
+
+#define objname(sec) ((sec) == &kernel_sfsec					\
+		     ? "vmlinux"						\
+		     : container_of((sec), struct module, sframe_sec)->name)
+
+#else
+
+#define objname(...) "vmlinux"
+
+#endif
+
+#define dbg_sec(sec, fmt, ...)						\
+	pr_debug("(%s): " fmt, objname(sec), ##__VA_ARGS__)
+
+static __always_inline void dbg_print_header(struct sframe_section *sec)
+{
+	unsigned long fdes_end;
+
+	fdes_end = sec->fdes_start + (sec->num_fdes * sizeof(struct sframe_fde_v3));
+
+	dbg_sec(sec, "SEC:0x%lx-0x%lx fdes:0x%lx-0x%lx fres:0x%lx-0x%lx ra_off:%d fp_off:%d\n",
+		sec->sframe_start, sec->sframe_end, sec->fdes_start, fdes_end, sec->fres_start,
+		sec->fres_end, sec->ra_off, sec->fp_off);
+}
+
+#endif /* _SFRAME_DEBUG_H */
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 08/11] sframe: Add .sframe validation option

[Dylan Hatch]

From: Josh Poimboeuf <jpoimboe@kernel.org>

Add a debug feature to validate all .sframe sections when first loading
the file rather than on demand.

[ Jens Remus: Add support for SFrame V3.  Add support for PC-relative
FDE function start offset.  Adjust to rename of struct sframe_fre to
sframe_fre_internal.  Use %#x/%#lx format specifiers. ]

[ Dylan Hatch: Adapt this patch for in-kernel sframe sections. ]

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Indu Bhagat <ibhagatgnu@gmail.com>
Co-developed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Co-developed-by: Dylan Hatch <dylanbhatch@google.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 arch/Kconfig           | 18 ++++++++++
 kernel/unwind/sframe.c | 78 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 96 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index cc59a5da80915..20aa63c93a0e2 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -538,6 +538,24 @@ config HAVE_UNWIND_KERNEL_SFRAME
 	  practice, this can provide more reliable stacktrace results than
 	  unwinding with frame pointers alone.
 
+config SFRAME_VALIDATION
+	bool "Enable .sframe section debugging"
+	depends on UNWIND_SFRAME_LOOKUP
+	depends on DYNAMIC_DEBUG
+	help
+	  When adding an .sframe section for an object, validate the entire
+	  section immediately rather than on demand.
+
+	  This is a debug feature which is helpful for rooting out .sframe
+	  section issues.  If the .sframe section is corrupt, it will fail to
+	  load immediately, with more information provided in dynamic printks.
+
+	  This has a significant page cache footprint due to its reading of the
+	  entire .sframe section for every loaded module.  Not recommended for
+	  general use.
+
+	  If unsure, say N.
+
 config HAVE_PERF_REGS
 	bool
 	help
diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
index 2e8ff783de7d8..62c22ca70614a 100644
--- a/kernel/unwind/sframe.c
+++ b/kernel/unwind/sframe.c
@@ -15,6 +15,7 @@
 #include <linux/kallsyms.h>
 #include <asm/kprobes.h>
 #include <asm/sections.h>
+#include <asm/unwind_sframe.h>
 
 #include "sframe.h"
 #include "sframe_debug.h"
@@ -503,6 +504,73 @@ noinstr int sframe_find(unsigned long ip, struct unwind_frame *frame)
 }
 NOKPROBE_SYMBOL(sframe_find);
 
+#ifdef CONFIG_SFRAME_VALIDATION
+
+static int sframe_validate_section(struct sframe_section *sec)
+{
+	unsigned long prev_ip = 0;
+	unsigned int i;
+
+	for (i = 0; i < sec->num_fdes; i++) {
+		struct sframe_fre_internal *fre, *prev_fre = NULL;
+		unsigned long ip, fre_addr;
+		struct sframe_fde_internal fde;
+		struct sframe_fre_internal fres[2];
+		bool which = false;
+		unsigned int j;
+		int ret;
+
+		ret = __read_fde(sec, i, &fde);
+		if (ret) {
+			dbg_sec(sec, "__read_fde(%u) failed\n", i);
+			return ret;
+		}
+
+		ip = fde.func_addr;
+		if (ip <= prev_ip) {
+			dbg_sec(sec, "FDE %u not sorted\n", i);
+			return -EFAULT;
+		}
+		prev_ip = ip;
+
+		fre_addr = sec->fres_start + fde.fres_off;
+		for (j = 0; j < fde.fres_num; j++) {
+			int ret;
+
+			fre = which ? fres : fres + 1;
+			which = !which;
+
+			ret = __read_fre(sec, &fde, fre_addr, fre);
+			if (ret) {
+				dbg_sec(sec, "FDE %u: __read_fre(%u) failed\n", i, j);
+				return ret;
+			}
+			ret = __read_fre_datawords(sec, &fde, fre);
+			if (ret) {
+				dbg_sec(sec, "FDE %u: __read_fre_datawords(%u) failed\n", i, j);
+				return ret;
+			}
+
+			fre_addr += fre->size;
+
+			if (prev_fre && fre->ip_off <= prev_fre->ip_off) {
+				dbg_sec(sec, "FDE %u: FRE %u not sorted\n", i, j);
+				return -EFAULT;
+			}
+
+			prev_fre = fre;
+		}
+	}
+
+	return 0;
+}
+
+#else /*  !CONFIG_SFRAME_VALIDATION */
+
+static int sframe_validate_section(struct sframe_section *sec) { return 0; }
+
+#endif /* !CONFIG_SFRAME_VALIDATION */
+
 static int sframe_read_header(struct sframe_section *sec)
 {
 	unsigned long header_end, fdes_start, fdes_end, fres_start, fres_end;
@@ -564,6 +632,11 @@ void __init init_sframe_table(void)
 		return;
 	}
 
+	if (sframe_validate_section(&kernel_sfsec)) {
+		pr_warn("invalid vmlinux SFrame section\n");
+		return;
+	}
+
 	sframe_init = true;
 	dbg_print_header(&kernel_sfsec);
 }
@@ -624,6 +697,11 @@ void sframe_module_init(struct module *mod, void *addr, unsigned int size)
 	}
 	sframe_sort_fdes(sec);
 
+	if (sframe_validate_section(sec)) {
+		pr_warn("invalid SFrame section in module %s\n", mod->name);
+		return;
+	}
+
 	/* Ensure SFrame is initialized when sframe_find() happens */
 	smp_store_release(&mod->sframe_init, true);
 	dbg_print_header(sec);
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 09/11] arm64: entry: add unwind info for call_on_irq_stack()

[Dylan Hatch]

From: Weinan Liu <wnliu@google.com>

DWARF CFI (Call Frame Information) specifies how to recover the return
address and callee-saved registers at each PC in a given function.
Compilers are able to generate the CFI annotations when they compile
the code to assembly language. For handcrafted assembly, we need to
annotate them by hand.

Frame pointers alone are usually sufficient to recover stack frames
(without CFI), except at the exception boundary, where more information
is needed to determine if the LR is live.

Since an exception can be taken from call_on_irq_stack(), annotate it
with CFI. The actual entry assembly functions are left untouched, since
they are not expected to take exceptions themselves.

Signed-off-by: Weinan Liu <wnliu@google.com>
Suggested-by: Jens Remus <jremus@linux.ibm.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 arch/arm64/kernel/entry.S | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index f63049ac32dc6..3703acbeb16a5 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -30,6 +30,12 @@
 #include <asm/asm-uaccess.h>
 #include <asm/unistd.h>
 
+/*
+ * Do not generate .eh_frame.  Only generate .debug_frame and optionally
+ * .sframe (via assembler option --gsframe[-N]).
+ */
+	.cfi_sections .debug_frame
+
 	.macro	clear_gp_regs
 	.irp	n,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
 	mov	x\n, xzr
@@ -866,6 +872,7 @@ NOKPROBE(ret_from_fork)
  * Calls func(regs) using this CPU's irq stack and shadow irq stack.
  */
 SYM_FUNC_START(call_on_irq_stack)
+	.cfi_startproc
 	save_and_disable_daif x9
 #ifdef CONFIG_SHADOW_CALL_STACK
 	get_current_task x16
@@ -876,6 +883,9 @@ SYM_FUNC_START(call_on_irq_stack)
 	/* Create a frame record to save our LR and SP (implicit in FP) */
 	stp	x29, x30, [sp, #-16]!
 	mov	x29, sp
+	.cfi_def_cfa 29, 16
+	.cfi_offset 29, -16
+	.cfi_offset 30, -8
 
 	ldr_this_cpu x16, irq_stack_ptr, x17
 
@@ -891,9 +901,13 @@ SYM_FUNC_START(call_on_irq_stack)
 	 */
 	mov	sp, x29
 	ldp	x29, x30, [sp], #16
+	.cfi_restore 29
+	.cfi_restore 30
+	.cfi_def_cfa 31, 0
 	scs_load_current
 	restore_irq x9
 	ret
+	.cfi_endproc
 SYM_FUNC_END(call_on_irq_stack)
 NOKPROBE(call_on_irq_stack)
 
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 10/11] arm64, crypto/lib: Annotate leaf functions with CFI info

[Dylan Hatch]

DWARF CFI (Call Frame Information) specifies how to recover return
address and callee-saved registers for annotated functions. These
annotations are generated by the compiler, but for assembly, they must
be annotated by hand.

Add simple CFI annotations to assembly leaf functions so that the LR can
be recovered by the unwinder when an exception is taken from one of them.

Signed-off-by: Dylan Hatch <dylanbhatch@google.com>

---

Changes from V7:
 - (sashiko): Put .cfi_startproc right after SYM_START to account for
   potential alignment bytes ahead of the actual function symbol.
---
 arch/arm64/crypto/aes-ce-ccm-core.S    | 12 +++----
 arch/arm64/crypto/aes-neonbs-core.S    | 16 +++++-----
 arch/arm64/crypto/ghash-ce-core.S      | 12 +++----
 arch/arm64/crypto/sm4-ce-ccm-core.S    | 16 +++++-----
 arch/arm64/crypto/sm4-ce-cipher-core.S |  4 +--
 arch/arm64/crypto/sm4-ce-core.S        | 44 +++++++++++++-------------
 arch/arm64/crypto/sm4-ce-gcm-core.S    | 16 +++++-----
 arch/arm64/crypto/sm4-neon-core.S      | 12 +++----
 arch/arm64/include/asm/linkage.h       | 32 +++++++++++++++++++
 arch/arm64/lib/clear_page.S            |  4 +--
 arch/arm64/lib/clear_user.S            |  4 +--
 arch/arm64/lib/copy_from_user.S        |  4 +--
 arch/arm64/lib/copy_page.S             |  4 +--
 arch/arm64/lib/copy_to_user.S          |  4 +--
 arch/arm64/lib/memchr.S                |  4 +--
 arch/arm64/lib/memcmp.S                |  4 +--
 arch/arm64/lib/memcpy.S                |  8 ++---
 arch/arm64/lib/memset.S                |  8 ++---
 arch/arm64/lib/mte.S                   | 28 ++++++++--------
 arch/arm64/lib/strchr.S                |  4 +--
 arch/arm64/lib/strcmp.S                |  4 +--
 arch/arm64/lib/strlen.S                |  4 +--
 arch/arm64/lib/strncmp.S               |  4 +--
 arch/arm64/lib/strnlen.S               |  4 +--
 arch/arm64/lib/tishift.S               | 12 +++----
 25 files changed, 150 insertions(+), 118 deletions(-)

diff --git a/arch/arm64/crypto/aes-ce-ccm-core.S b/arch/arm64/crypto/aes-ce-ccm-core.S
index f2624238fd954..519309c886b99 100644
--- a/arch/arm64/crypto/aes-ce-ccm-core.S
+++ b/arch/arm64/crypto/aes-ce-ccm-core.S
@@ -80,7 +80,7 @@ CPU_LE(	rev	x8, x8			)
 	ret
 	.endm
 
-SYM_FUNC_START_LOCAL(ce_aes_ccm_crypt_tail)
+SYM_LEAF_FUNC_START_LOCAL(ce_aes_ccm_crypt_tail)
 	eor	v0.16b, v0.16b, v5.16b		/* final round mac */
 	eor	v1.16b, v1.16b, v5.16b		/* final round enc */
 
@@ -113,7 +113,7 @@ SYM_INNER_LABEL(ce_aes_ccm_final, SYM_L_LOCAL)
 	eor	v0.16b, v0.16b, v1.16b		/* en-/decrypt the mac */
 0:	st1	{v0.16b}, [x5]			/* store result */
 	ret
-SYM_FUNC_END(ce_aes_ccm_crypt_tail)
+SYM_LEAF_FUNC_END(ce_aes_ccm_crypt_tail)
 
 	/*
 	 * void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
@@ -123,15 +123,15 @@ SYM_FUNC_END(ce_aes_ccm_crypt_tail)
 	 * 			   u8 const rk[], u32 rounds, u8 mac[],
 	 * 			   u8 ctr[], u8 const final_iv[]);
 	 */
-SYM_FUNC_START(ce_aes_ccm_encrypt)
+SYM_LEAF_FUNC_START(ce_aes_ccm_encrypt)
 	movi	v22.16b, #255
 	aes_ccm_do_crypt	1
-SYM_FUNC_END(ce_aes_ccm_encrypt)
+SYM_LEAF_FUNC_END(ce_aes_ccm_encrypt)
 
-SYM_FUNC_START(ce_aes_ccm_decrypt)
+SYM_LEAF_FUNC_START(ce_aes_ccm_decrypt)
 	movi	v22.16b, #0
 	aes_ccm_do_crypt	0
-SYM_FUNC_END(ce_aes_ccm_decrypt)
+SYM_LEAF_FUNC_END(ce_aes_ccm_decrypt)
 
 	.section ".rodata", "a"
 	.align	6
diff --git a/arch/arm64/crypto/aes-neonbs-core.S b/arch/arm64/crypto/aes-neonbs-core.S
index baf450717b24b..01cd6c0aa10ae 100644
--- a/arch/arm64/crypto/aes-neonbs-core.S
+++ b/arch/arm64/crypto/aes-neonbs-core.S
@@ -381,7 +381,7 @@ ISRM0:	.octa		0x0306090c00070a0d01040b0e0205080f
 	/*
 	 * void aesbs_convert_key(u8 out[], u32 const rk[], int rounds)
 	 */
-SYM_FUNC_START(aesbs_convert_key)
+SYM_LEAF_FUNC_START(aesbs_convert_key)
 	ld1		{v7.4s}, [x1], #16		// load round 0 key
 	ld1		{v17.4s}, [x1], #16		// load round 1 key
 
@@ -426,10 +426,10 @@ SYM_FUNC_START(aesbs_convert_key)
 	eor		v17.16b, v17.16b, v7.16b
 	str		q17, [x0]
 	ret
-SYM_FUNC_END(aesbs_convert_key)
+SYM_LEAF_FUNC_END(aesbs_convert_key)
 
 	.align		4
-SYM_FUNC_START_LOCAL(aesbs_encrypt8)
+SYM_LEAF_FUNC_START_LOCAL(aesbs_encrypt8)
 	ldr		q9, [bskey], #16		// round 0 key
 	ldr		q8, M0SR
 	ldr		q24, SR
@@ -489,10 +489,10 @@ SYM_FUNC_START_LOCAL(aesbs_encrypt8)
 	eor		v2.16b, v2.16b, v12.16b
 	eor		v5.16b, v5.16b, v12.16b
 	ret
-SYM_FUNC_END(aesbs_encrypt8)
+SYM_LEAF_FUNC_END(aesbs_encrypt8)
 
 	.align		4
-SYM_FUNC_START_LOCAL(aesbs_decrypt8)
+SYM_LEAF_FUNC_START_LOCAL(aesbs_decrypt8)
 	lsl		x9, rounds, #7
 	add		bskey, bskey, x9
 
@@ -554,7 +554,7 @@ SYM_FUNC_START_LOCAL(aesbs_decrypt8)
 	eor		v3.16b, v3.16b, v12.16b
 	eor		v5.16b, v5.16b, v12.16b
 	ret
-SYM_FUNC_END(aesbs_decrypt8)
+SYM_LEAF_FUNC_END(aesbs_decrypt8)
 
 	/*
 	 * aesbs_ecb_encrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
@@ -735,7 +735,7 @@ SYM_FUNC_END(aesbs_cbc_decrypt)
 	 * aesbs_xts_decrypt(u8 out[], u8 const in[], u8 const rk[], int rounds,
 	 *		     int blocks, u8 iv[])
 	 */
-SYM_FUNC_START_LOCAL(__xts_crypt8)
+SYM_LEAF_FUNC_START_LOCAL(__xts_crypt8)
 	movi		v18.2s, #0x1
 	movi		v19.2s, #0x87
 	uzp1		v18.4s, v18.4s, v19.4s
@@ -766,7 +766,7 @@ SYM_FUNC_START_LOCAL(__xts_crypt8)
 	mov		bskey, x2
 	mov		rounds, x3
 	br		x16
-SYM_FUNC_END(__xts_crypt8)
+SYM_LEAF_FUNC_END(__xts_crypt8)
 
 	.macro		__xts_crypt, do8, o0, o1, o2, o3, o4, o5, o6, o7
 	frame_push	0, 32
diff --git a/arch/arm64/crypto/ghash-ce-core.S b/arch/arm64/crypto/ghash-ce-core.S
index 33772d8fe6b5e..8773678e13df5 100644
--- a/arch/arm64/crypto/ghash-ce-core.S
+++ b/arch/arm64/crypto/ghash-ce-core.S
@@ -66,7 +66,7 @@
 	 * void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
 	 *			       u64 const h[4][2], const char *head)
 	 */
-SYM_FUNC_START(pmull_ghash_update_p64)
+SYM_LEAF_FUNC_START(pmull_ghash_update_p64)
 	ld1		{SHASH.2d}, [x3]
 	ld1		{XL.2d}, [x1]
 
@@ -173,7 +173,7 @@ CPU_LE(	rev64		T1.16b, T1.16b	)
 
 5:	st1		{XL.2d}, [x1]
 	ret
-SYM_FUNC_END(pmull_ghash_update_p64)
+SYM_LEAF_FUNC_END(pmull_ghash_update_p64)
 
 	KS0		.req	v8
 	KS1		.req	v9
@@ -431,7 +431,7 @@ SYM_FUNC_START(pmull_gcm_decrypt)
 	pmull_gcm_do_crypt	0
 SYM_FUNC_END(pmull_gcm_decrypt)
 
-SYM_FUNC_START_LOCAL(pmull_gcm_ghash_4x)
+SYM_LEAF_FUNC_START_LOCAL(pmull_gcm_ghash_4x)
 	movi		MASK.16b, #0xe1
 	shl		MASK.2d, MASK.2d, #57
 
@@ -512,9 +512,9 @@ SYM_FUNC_START_LOCAL(pmull_gcm_ghash_4x)
 	eor		XL.16b, XL.16b, T2.16b
 
 	ret
-SYM_FUNC_END(pmull_gcm_ghash_4x)
+SYM_LEAF_FUNC_END(pmull_gcm_ghash_4x)
 
-SYM_FUNC_START_LOCAL(pmull_gcm_enc_4x)
+SYM_LEAF_FUNC_START_LOCAL(pmull_gcm_enc_4x)
 	ld1		{KS0.16b}, [x5]			// load upper counter
 	sub		w10, w8, #4
 	sub		w11, w8, #3
@@ -577,7 +577,7 @@ SYM_FUNC_START_LOCAL(pmull_gcm_enc_4x)
 	eor		INP3.16b, INP3.16b, KS3.16b
 
 	ret
-SYM_FUNC_END(pmull_gcm_enc_4x)
+SYM_LEAF_FUNC_END(pmull_gcm_enc_4x)
 
 	.section	".rodata", "a"
 	.align		6
diff --git a/arch/arm64/crypto/sm4-ce-ccm-core.S b/arch/arm64/crypto/sm4-ce-ccm-core.S
index fa85856f33cee..20a8853609e04 100644
--- a/arch/arm64/crypto/sm4-ce-ccm-core.S
+++ b/arch/arm64/crypto/sm4-ce-ccm-core.S
@@ -37,7 +37,7 @@
 
 
 .align 3
-SYM_FUNC_START(sm4_ce_cbcmac_update)
+SYM_LEAF_FUNC_START(sm4_ce_cbcmac_update)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: mac
@@ -81,10 +81,10 @@ SYM_FUNC_START(sm4_ce_cbcmac_update)
 .Lcbcmac_end:
 	st1		{RMAC.16b}, [x1]
 	ret
-SYM_FUNC_END(sm4_ce_cbcmac_update)
+SYM_LEAF_FUNC_END(sm4_ce_cbcmac_update)
 
 .align 3
-SYM_FUNC_START(sm4_ce_ccm_final)
+SYM_LEAF_FUNC_START(sm4_ce_ccm_final)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: ctr0 (big endian, 128 bit)
@@ -102,10 +102,10 @@ SYM_FUNC_START(sm4_ce_ccm_final)
 	st1		{RMAC.16b}, [x2]
 
 	ret
-SYM_FUNC_END(sm4_ce_ccm_final)
+SYM_LEAF_FUNC_END(sm4_ce_ccm_final)
 
 .align 3
-SYM_TYPED_FUNC_START(sm4_ce_ccm_enc)
+SYM_TYPED_LEAF_FUNC_START(sm4_ce_ccm_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -214,10 +214,10 @@ SYM_TYPED_FUNC_START(sm4_ce_ccm_enc)
 
 .Lccm_enc_ret:
 	ret
-SYM_FUNC_END(sm4_ce_ccm_enc)
+SYM_LEAF_FUNC_END(sm4_ce_ccm_enc)
 
 .align 3
-SYM_TYPED_FUNC_START(sm4_ce_ccm_dec)
+SYM_TYPED_LEAF_FUNC_START(sm4_ce_ccm_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -326,4 +326,4 @@ SYM_TYPED_FUNC_START(sm4_ce_ccm_dec)
 
 .Lccm_dec_ret:
 	ret
-SYM_FUNC_END(sm4_ce_ccm_dec)
+SYM_LEAF_FUNC_END(sm4_ce_ccm_dec)
diff --git a/arch/arm64/crypto/sm4-ce-cipher-core.S b/arch/arm64/crypto/sm4-ce-cipher-core.S
index 4ac6cfbc57970..7aea346cb14cd 100644
--- a/arch/arm64/crypto/sm4-ce-cipher-core.S
+++ b/arch/arm64/crypto/sm4-ce-cipher-core.S
@@ -15,7 +15,7 @@
 	 * void sm4_ce_do_crypt(const u32 *rk, u32 *out, const u32 *in);
 	 */
 	.text
-SYM_FUNC_START(sm4_ce_do_crypt)
+SYM_LEAF_FUNC_START(sm4_ce_do_crypt)
 	ld1		{v8.4s}, [x2]
 	ld1		{v0.4s-v3.4s}, [x0], #64
 CPU_LE(	rev32		v8.16b, v8.16b		)
@@ -33,4 +33,4 @@ CPU_LE(	rev32		v8.16b, v8.16b		)
 CPU_LE(	rev32		v8.16b, v8.16b		)
 	st1		{v8.4s}, [x1]
 	ret
-SYM_FUNC_END(sm4_ce_do_crypt)
+SYM_LEAF_FUNC_END(sm4_ce_do_crypt)
diff --git a/arch/arm64/crypto/sm4-ce-core.S b/arch/arm64/crypto/sm4-ce-core.S
index 1f3625c2c67e4..6af5b10859b88 100644
--- a/arch/arm64/crypto/sm4-ce-core.S
+++ b/arch/arm64/crypto/sm4-ce-core.S
@@ -40,7 +40,7 @@
 
 
 .align 3
-SYM_FUNC_START(sm4_ce_expand_key)
+SYM_LEAF_FUNC_START(sm4_ce_expand_key)
 	/* input:
 	 *   x0: 128-bit key
 	 *   x1: rkey_enc
@@ -86,10 +86,10 @@ SYM_FUNC_START(sm4_ce_expand_key)
 	st1		{v20.16b-v23.16b}, [x2]
 
 	ret;
-SYM_FUNC_END(sm4_ce_expand_key)
+SYM_LEAF_FUNC_END(sm4_ce_expand_key)
 
 .align 3
-SYM_FUNC_START(sm4_ce_crypt_block)
+SYM_LEAF_FUNC_START(sm4_ce_crypt_block)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -102,10 +102,10 @@ SYM_FUNC_START(sm4_ce_crypt_block)
 	st1		{v0.16b}, [x1];
 
 	ret;
-SYM_FUNC_END(sm4_ce_crypt_block)
+SYM_LEAF_FUNC_END(sm4_ce_crypt_block)
 
 .align 3
-SYM_FUNC_START(sm4_ce_crypt)
+SYM_LEAF_FUNC_START(sm4_ce_crypt)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -153,10 +153,10 @@ SYM_FUNC_START(sm4_ce_crypt)
 
 .Lcrypt_end:
 	ret;
-SYM_FUNC_END(sm4_ce_crypt)
+SYM_LEAF_FUNC_END(sm4_ce_crypt)
 
 .align 3
-SYM_FUNC_START(sm4_ce_cbc_enc)
+SYM_LEAF_FUNC_START(sm4_ce_cbc_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -208,10 +208,10 @@ SYM_FUNC_START(sm4_ce_cbc_enc)
 	st1		{RIV.16b}, [x3]
 
 	ret
-SYM_FUNC_END(sm4_ce_cbc_enc)
+SYM_LEAF_FUNC_END(sm4_ce_cbc_enc)
 
 .align 3
-SYM_FUNC_START(sm4_ce_cbc_dec)
+SYM_LEAF_FUNC_START(sm4_ce_cbc_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -306,10 +306,10 @@ SYM_FUNC_START(sm4_ce_cbc_dec)
 	st1		{RIV.16b}, [x3]
 
 	ret
-SYM_FUNC_END(sm4_ce_cbc_dec)
+SYM_LEAF_FUNC_END(sm4_ce_cbc_dec)
 
 .align 3
-SYM_FUNC_START(sm4_ce_cbc_cts_enc)
+SYM_LEAF_FUNC_START(sm4_ce_cbc_cts_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -354,10 +354,10 @@ SYM_FUNC_START(sm4_ce_cbc_cts_enc)
 	st1		{v1.16b}, [x1]
 
 	ret
-SYM_FUNC_END(sm4_ce_cbc_cts_enc)
+SYM_LEAF_FUNC_END(sm4_ce_cbc_cts_enc)
 
 .align 3
-SYM_FUNC_START(sm4_ce_cbc_cts_dec)
+SYM_LEAF_FUNC_START(sm4_ce_cbc_cts_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -400,10 +400,10 @@ SYM_FUNC_START(sm4_ce_cbc_cts_dec)
 	st1		{v0.16b}, [x1]
 
 	ret
-SYM_FUNC_END(sm4_ce_cbc_cts_dec)
+SYM_LEAF_FUNC_END(sm4_ce_cbc_cts_dec)
 
 .align 3
-SYM_FUNC_START(sm4_ce_ctr_enc)
+SYM_LEAF_FUNC_START(sm4_ce_ctr_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -506,7 +506,7 @@ SYM_FUNC_START(sm4_ce_ctr_enc)
 	stp		x7, x8, [x3]
 
 	ret
-SYM_FUNC_END(sm4_ce_ctr_enc)
+SYM_LEAF_FUNC_END(sm4_ce_ctr_enc)
 
 
 #define tweak_next(vt, vin, RTMP)					\
@@ -517,7 +517,7 @@ SYM_FUNC_END(sm4_ce_ctr_enc)
 		eor		vt.16b, vt.16b, RTMP.16b;
 
 .align 3
-SYM_FUNC_START(sm4_ce_xts_enc)
+SYM_LEAF_FUNC_START(sm4_ce_xts_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -681,10 +681,10 @@ SYM_FUNC_START(sm4_ce_xts_enc)
 
 .Lxts_enc_ret:
 	ret
-SYM_FUNC_END(sm4_ce_xts_enc)
+SYM_LEAF_FUNC_END(sm4_ce_xts_enc)
 
 .align 3
-SYM_FUNC_START(sm4_ce_xts_dec)
+SYM_LEAF_FUNC_START(sm4_ce_xts_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -848,10 +848,10 @@ SYM_FUNC_START(sm4_ce_xts_dec)
 
 .Lxts_dec_ret:
 	ret
-SYM_FUNC_END(sm4_ce_xts_dec)
+SYM_LEAF_FUNC_END(sm4_ce_xts_dec)
 
 .align 3
-SYM_FUNC_START(sm4_ce_mac_update)
+SYM_LEAF_FUNC_START(sm4_ce_mac_update)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: digest
@@ -917,7 +917,7 @@ SYM_FUNC_START(sm4_ce_mac_update)
 .Lmac_ret:
 	st1		{RMAC.16b}, [x1]
 	ret
-SYM_FUNC_END(sm4_ce_mac_update)
+SYM_LEAF_FUNC_END(sm4_ce_mac_update)
 
 
 	.section	".rodata", "a"
diff --git a/arch/arm64/crypto/sm4-ce-gcm-core.S b/arch/arm64/crypto/sm4-ce-gcm-core.S
index 347f25d757279..dac6db8160f28 100644
--- a/arch/arm64/crypto/sm4-ce-gcm-core.S
+++ b/arch/arm64/crypto/sm4-ce-gcm-core.S
@@ -259,7 +259,7 @@
 #define	RH4	v19
 
 .align 3
-SYM_FUNC_START(sm4_ce_pmull_ghash_setup)
+SYM_LEAF_FUNC_START(sm4_ce_pmull_ghash_setup)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: ghash table
@@ -293,10 +293,10 @@ SYM_FUNC_START(sm4_ce_pmull_ghash_setup)
 	st1		{RH1.16b-RH4.16b}, [x1]
 
 	ret
-SYM_FUNC_END(sm4_ce_pmull_ghash_setup)
+SYM_LEAF_FUNC_END(sm4_ce_pmull_ghash_setup)
 
 .align 3
-SYM_FUNC_START(pmull_ghash_update)
+SYM_LEAF_FUNC_START(pmull_ghash_update)
 	/* input:
 	 *   x0: ghash table
 	 *   x1: ghash result
@@ -368,10 +368,10 @@ SYM_FUNC_START(pmull_ghash_update)
 	st1		{RHASH.2d}, [x1]
 
 	ret
-SYM_FUNC_END(pmull_ghash_update)
+SYM_LEAF_FUNC_END(pmull_ghash_update)
 
 .align 3
-SYM_TYPED_FUNC_START(sm4_ce_pmull_gcm_enc)
+SYM_TYPED_LEAF_FUNC_START(sm4_ce_pmull_gcm_enc)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -534,7 +534,7 @@ SYM_TYPED_FUNC_START(sm4_ce_pmull_gcm_enc)
 	st1		{RHASH.2d}, [x5]
 
 	ret
-SYM_FUNC_END(sm4_ce_pmull_gcm_enc)
+SYM_LEAF_FUNC_END(sm4_ce_pmull_gcm_enc)
 
 #undef	RR1
 #undef	RR3
@@ -582,7 +582,7 @@ SYM_FUNC_END(sm4_ce_pmull_gcm_enc)
 #define	RH3	v20
 
 .align 3
-SYM_TYPED_FUNC_START(sm4_ce_pmull_gcm_dec)
+SYM_TYPED_LEAF_FUNC_START(sm4_ce_pmull_gcm_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -726,7 +726,7 @@ SYM_TYPED_FUNC_START(sm4_ce_pmull_gcm_dec)
 	st1		{RHASH.2d}, [x5]
 
 	ret
-SYM_FUNC_END(sm4_ce_pmull_gcm_dec)
+SYM_LEAF_FUNC_END(sm4_ce_pmull_gcm_dec)
 
 	.section	".rodata", "a"
 	.align 4
diff --git a/arch/arm64/crypto/sm4-neon-core.S b/arch/arm64/crypto/sm4-neon-core.S
index 734dc7193610c..d1fe37fce13ad 100644
--- a/arch/arm64/crypto/sm4-neon-core.S
+++ b/arch/arm64/crypto/sm4-neon-core.S
@@ -257,7 +257,7 @@
 
 
 .align 3
-SYM_FUNC_START(sm4_neon_crypt)
+SYM_LEAF_FUNC_START(sm4_neon_crypt)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -318,10 +318,10 @@ SYM_FUNC_START(sm4_neon_crypt)
 
 .Lcrypt_end:
 	ret
-SYM_FUNC_END(sm4_neon_crypt)
+SYM_LEAF_FUNC_END(sm4_neon_crypt)
 
 .align 3
-SYM_FUNC_START(sm4_neon_cbc_dec)
+SYM_LEAF_FUNC_START(sm4_neon_cbc_dec)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -435,10 +435,10 @@ SYM_FUNC_START(sm4_neon_cbc_dec)
 	st1		{RIV.16b}, [x3]
 
 	ret
-SYM_FUNC_END(sm4_neon_cbc_dec)
+SYM_LEAF_FUNC_END(sm4_neon_cbc_dec)
 
 .align 3
-SYM_FUNC_START(sm4_neon_ctr_crypt)
+SYM_LEAF_FUNC_START(sm4_neon_ctr_crypt)
 	/* input:
 	 *   x0: round key array, CTX
 	 *   x1: dst
@@ -563,4 +563,4 @@ SYM_FUNC_START(sm4_neon_ctr_crypt)
 	stp		x7, x8, [x3]
 
 	ret
-SYM_FUNC_END(sm4_neon_ctr_crypt)
+SYM_LEAF_FUNC_END(sm4_neon_ctr_crypt)
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
index d1f7a16729d25..4b898e5bbc463 100644
--- a/arch/arm64/include/asm/linkage.h
+++ b/arch/arm64/include/asm/linkage.h
@@ -3,6 +3,12 @@
 
 #ifdef __ASSEMBLER__
 #include <asm/assembler.h>
+
+/*
+ * Do not generate .eh_frame.  Only generate .debug_frame and optionally
+ * .sframe (via assembler option --gsframe[-N]).
+ */
+	.cfi_sections .debug_frame
 #endif
 
 #define __ALIGN		.balign CONFIG_FUNCTION_ALIGNMENT
@@ -47,4 +53,30 @@
 
 #define __bss_pgtbl __section(".bss..pgtbl") __aligned(PAGE_SIZE)
 
+/*
+ * SYM_[TYPED_]LEAF_FUNC_[START|END] macros add CFI minimal CFI directives
+ * allowing .sframe data to be generated for functions which do not modify the
+ * LR (x30). Unwind data will not be correct if these macros are used on
+ * non-leaf functions, as additional CFI directives would be necessary in such
+ * cases.
+ */
+#define SYM_LEAF_FUNC_START(name)			\
+	SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)	\
+	.cfi_startproc ;				\
+	bti c ;
+
+#define SYM_LEAF_FUNC_END(name)				\
+	.cfi_endproc ;					\
+	SYM_FUNC_END(name)
+
+#define SYM_LEAF_FUNC_START_LOCAL(name)			\
+	SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)	\
+	.cfi_startproc ;				\
+	bti c ;
+
+#define SYM_TYPED_LEAF_FUNC_START(name)				\
+	SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)	\
+	.cfi_startproc ;					\
+	bti c ;
+
 #endif
diff --git a/arch/arm64/lib/clear_page.S b/arch/arm64/lib/clear_page.S
index bd6f7d5eb6eb6..fceb875c35702 100644
--- a/arch/arm64/lib/clear_page.S
+++ b/arch/arm64/lib/clear_page.S
@@ -14,7 +14,7 @@
  * Parameters:
  *	x0 - dest
  */
-SYM_FUNC_START(__pi_clear_page)
+SYM_LEAF_FUNC_START(__pi_clear_page)
 #ifdef CONFIG_AS_HAS_MOPS
 	.arch_extension mops
 alternative_if_not ARM64_HAS_MOPS
@@ -48,6 +48,6 @@ alternative_else_nop_endif
 	tst	x0, #(PAGE_SIZE - 1)
 	b.ne	2b
 	ret
-SYM_FUNC_END(__pi_clear_page)
+SYM_LEAF_FUNC_END(__pi_clear_page)
 SYM_FUNC_ALIAS(clear_page, __pi_clear_page)
 EXPORT_SYMBOL(clear_page)
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index de9a303b6ad0e..cf07c010ca927 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -17,7 +17,7 @@
  * Alignment fixed up by hardware.
  */
 
-SYM_FUNC_START(__arch_clear_user)
+SYM_LEAF_FUNC_START(__arch_clear_user)
 	add	x2, x0, x1
 
 #ifdef CONFIG_AS_HAS_MOPS
@@ -68,5 +68,5 @@ USER(7f, sttrb	wzr, [x2, #-1])
 8:	add	x0, x0, #4	// ...or the second word of the 4-7 byte case
 9:	sub	x0, x2, x0
 	ret
-SYM_FUNC_END(__arch_clear_user)
+SYM_LEAF_FUNC_END(__arch_clear_user)
 EXPORT_SYMBOL(__arch_clear_user)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 400057d607ecd..e9bb9c2dd8e12 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -61,7 +61,7 @@
 
 end	.req	x5
 srcin	.req	x15
-SYM_FUNC_START(__arch_copy_from_user)
+SYM_LEAF_FUNC_START(__arch_copy_from_user)
 	add	end, x0, x2
 	mov	srcin, x1
 #include "copy_template.S"
@@ -79,5 +79,5 @@ USER(9998f, ldtrb tmp1w, [srcin])
 	strb	tmp1w, [dst], #1
 9998:	sub	x0, end, dst			// bytes not copied
 	ret
-SYM_FUNC_END(__arch_copy_from_user)
+SYM_LEAF_FUNC_END(__arch_copy_from_user)
 EXPORT_SYMBOL(__arch_copy_from_user)
diff --git a/arch/arm64/lib/copy_page.S b/arch/arm64/lib/copy_page.S
index e6374e7e55110..b6048d6483064 100644
--- a/arch/arm64/lib/copy_page.S
+++ b/arch/arm64/lib/copy_page.S
@@ -17,7 +17,7 @@
  *	x0 - dest
  *	x1 - src
  */
-SYM_FUNC_START(__pi_copy_page)
+SYM_LEAF_FUNC_START(__pi_copy_page)
 #ifdef CONFIG_AS_HAS_MOPS
 	.arch_extension mops
 alternative_if_not ARM64_HAS_MOPS
@@ -77,6 +77,6 @@ alternative_else_nop_endif
 	stnp	x16, x17, [x0, #112 - 256]
 
 	ret
-SYM_FUNC_END(__pi_copy_page)
+SYM_LEAF_FUNC_END(__pi_copy_page)
 SYM_FUNC_ALIAS(copy_page, __pi_copy_page)
 EXPORT_SYMBOL(copy_page)
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 819f2e3fc7a93..aea10a5b3cbac 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -60,7 +60,7 @@
 
 end	.req	x5
 srcin	.req	x15
-SYM_FUNC_START(__arch_copy_to_user)
+SYM_LEAF_FUNC_START(__arch_copy_to_user)
 	add	end, x0, x2
 	mov	srcin, x1
 #include "copy_template.S"
@@ -79,5 +79,5 @@ USER(9998f, sttrb tmp1w, [dst])
 	add	dst, dst, #1
 9998:	sub	x0, end, dst			// bytes not copied
 	ret
-SYM_FUNC_END(__arch_copy_to_user)
+SYM_LEAF_FUNC_END(__arch_copy_to_user)
 EXPORT_SYMBOL(__arch_copy_to_user)
diff --git a/arch/arm64/lib/memchr.S b/arch/arm64/lib/memchr.S
index 37a9f2a4f7f4b..909599bba5bf7 100644
--- a/arch/arm64/lib/memchr.S
+++ b/arch/arm64/lib/memchr.S
@@ -38,7 +38,7 @@
 
 	.p2align 4
 	nop
-SYM_FUNC_START(__pi_memchr)
+SYM_LEAF_FUNC_START(__pi_memchr)
 	and	chrin, chrin, #0xff
 	lsr	wordcnt, cntin, #3
 	cbz	wordcnt, L(byte_loop)
@@ -71,6 +71,6 @@ CPU_LE(	rev	tmp, tmp)
 L(not_found):
 	mov	result, #0
 	ret
-SYM_FUNC_END(__pi_memchr)
+SYM_LEAF_FUNC_END(__pi_memchr)
 SYM_FUNC_ALIAS_WEAK(memchr, __pi_memchr)
 EXPORT_SYMBOL_NOKASAN(memchr)
diff --git a/arch/arm64/lib/memcmp.S b/arch/arm64/lib/memcmp.S
index a5ccf2c55f911..91ee3a00e6644 100644
--- a/arch/arm64/lib/memcmp.S
+++ b/arch/arm64/lib/memcmp.S
@@ -32,7 +32,7 @@
 #define tmp1		x7
 #define tmp2		x8
 
-SYM_FUNC_START(__pi_memcmp)
+SYM_LEAF_FUNC_START(__pi_memcmp)
 	subs	limit, limit, 8
 	b.lo	L(less8)
 
@@ -134,6 +134,6 @@ L(byte_loop):
 	b.eq	L(byte_loop)
 	sub	result, data1w, data2w
 	ret
-SYM_FUNC_END(__pi_memcmp)
+SYM_LEAF_FUNC_END(__pi_memcmp)
 SYM_FUNC_ALIAS_WEAK(memcmp, __pi_memcmp)
 EXPORT_SYMBOL_NOKASAN(memcmp)
diff --git a/arch/arm64/lib/memcpy.S b/arch/arm64/lib/memcpy.S
index 9b99106fb95f1..90caf402ea7d9 100644
--- a/arch/arm64/lib/memcpy.S
+++ b/arch/arm64/lib/memcpy.S
@@ -57,7 +57,7 @@
    The loop tail is handled by always copying 64 bytes from the end.
 */
 
-SYM_FUNC_START_LOCAL(__pi_memcpy_generic)
+SYM_LEAF_FUNC_START_LOCAL(__pi_memcpy_generic)
 	add	srcend, src, count
 	add	dstend, dstin, count
 	cmp	count, 128
@@ -238,11 +238,11 @@ L(copy64_from_start):
 	stp	B_l, B_h, [dstin, 16]
 	stp	C_l, C_h, [dstin]
 	ret
-SYM_FUNC_END(__pi_memcpy_generic)
+SYM_LEAF_FUNC_END(__pi_memcpy_generic)
 
 #ifdef CONFIG_AS_HAS_MOPS
 	.arch_extension mops
-SYM_FUNC_START(__pi_memcpy)
+SYM_LEAF_FUNC_START(__pi_memcpy)
 alternative_if_not ARM64_HAS_MOPS
 	b	__pi_memcpy_generic
 alternative_else_nop_endif
@@ -252,7 +252,7 @@ alternative_else_nop_endif
 	cpym	[dst]!, [src]!, count!
 	cpye	[dst]!, [src]!, count!
 	ret
-SYM_FUNC_END(__pi_memcpy)
+SYM_LEAF_FUNC_END(__pi_memcpy)
 #else
 SYM_FUNC_ALIAS(__pi_memcpy, __pi_memcpy_generic)
 #endif
diff --git a/arch/arm64/lib/memset.S b/arch/arm64/lib/memset.S
index 97157da65ec6b..8ee307f5891b4 100644
--- a/arch/arm64/lib/memset.S
+++ b/arch/arm64/lib/memset.S
@@ -43,7 +43,7 @@ dst		.req	x8
 tmp3w		.req	w9
 tmp3		.req	x9
 
-SYM_FUNC_START_LOCAL(__pi_memset_generic)
+SYM_LEAF_FUNC_START_LOCAL(__pi_memset_generic)
 	mov	dst, dstin	/* Preserve return value.  */
 	and	A_lw, val, #255
 	orr	A_lw, A_lw, A_lw, lsl #8
@@ -202,11 +202,11 @@ SYM_FUNC_START_LOCAL(__pi_memset_generic)
 	ands	count, count, zva_bits_x
 	b.ne	.Ltail_maybe_long
 	ret
-SYM_FUNC_END(__pi_memset_generic)
+SYM_LEAF_FUNC_END(__pi_memset_generic)
 
 #ifdef CONFIG_AS_HAS_MOPS
 	.arch_extension mops
-SYM_FUNC_START(__pi_memset)
+SYM_LEAF_FUNC_START(__pi_memset)
 alternative_if_not ARM64_HAS_MOPS
 	b	__pi_memset_generic
 alternative_else_nop_endif
@@ -216,7 +216,7 @@ alternative_else_nop_endif
 	setm	[dst]!, count!, val_x
 	sete	[dst]!, count!, val_x
 	ret
-SYM_FUNC_END(__pi_memset)
+SYM_LEAF_FUNC_END(__pi_memset)
 #else
 SYM_FUNC_ALIAS(__pi_memset, __pi_memset_generic)
 #endif
diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S
index 5018ac03b6bf3..442202cd02a32 100644
--- a/arch/arm64/lib/mte.S
+++ b/arch/arm64/lib/mte.S
@@ -27,14 +27,14 @@
  * Clear the tags in a page
  *   x0 - address of the page to be cleared
  */
-SYM_FUNC_START(mte_clear_page_tags)
+SYM_LEAF_FUNC_START(mte_clear_page_tags)
 	multitag_transfer_size x1, x2
 1:	stgm	xzr, [x0]
 	add	x0, x0, x1
 	tst	x0, #(PAGE_SIZE - 1)
 	b.ne	1b
 	ret
-SYM_FUNC_END(mte_clear_page_tags)
+SYM_LEAF_FUNC_END(mte_clear_page_tags)
 
 /*
  * Zero the page and tags at the same time
@@ -42,7 +42,7 @@ SYM_FUNC_END(mte_clear_page_tags)
  * Parameters:
  *	x0 - address to the beginning of the page
  */
-SYM_FUNC_START(mte_zero_clear_page_tags)
+SYM_LEAF_FUNC_START(mte_zero_clear_page_tags)
 	and	x0, x0, #(1 << MTE_TAG_SHIFT) - 1	// clear the tag
 	mrs	x1, dczid_el0
 	tbnz	x1, #4, 2f	// Branch if DC GZVA is prohibited
@@ -60,14 +60,14 @@ SYM_FUNC_START(mte_zero_clear_page_tags)
 	tst	x0, #(PAGE_SIZE - 1)
 	b.ne	2b
 	ret
-SYM_FUNC_END(mte_zero_clear_page_tags)
+SYM_LEAF_FUNC_END(mte_zero_clear_page_tags)
 
 /*
  * Copy the tags from the source page to the destination one
  *   x0 - address of the destination page
  *   x1 - address of the source page
  */
-SYM_FUNC_START(mte_copy_page_tags)
+SYM_LEAF_FUNC_START(mte_copy_page_tags)
 	mov	x2, x0
 	mov	x3, x1
 	multitag_transfer_size x5, x6
@@ -78,7 +78,7 @@ SYM_FUNC_START(mte_copy_page_tags)
 	tst	x2, #(PAGE_SIZE - 1)
 	b.ne	1b
 	ret
-SYM_FUNC_END(mte_copy_page_tags)
+SYM_LEAF_FUNC_END(mte_copy_page_tags)
 
 /*
  * Read tags from a user buffer (one tag per byte) and set the corresponding
@@ -89,7 +89,7 @@ SYM_FUNC_END(mte_copy_page_tags)
  * Returns:
  *   x0 - number of tags read/set
  */
-SYM_FUNC_START(mte_copy_tags_from_user)
+SYM_LEAF_FUNC_START(mte_copy_tags_from_user)
 	mov	x3, x1
 	cbz	x2, 2f
 1:
@@ -103,7 +103,7 @@ USER(2f, ldtrb	w4, [x1])
 	// exception handling and function return
 2:	sub	x0, x1, x3		// update the number of tags set
 	ret
-SYM_FUNC_END(mte_copy_tags_from_user)
+SYM_LEAF_FUNC_END(mte_copy_tags_from_user)
 
 /*
  * Get the tags from a kernel address range and write the tag values to the
@@ -114,7 +114,7 @@ SYM_FUNC_END(mte_copy_tags_from_user)
  * Returns:
  *   x0 - number of tags read/set
  */
-SYM_FUNC_START(mte_copy_tags_to_user)
+SYM_LEAF_FUNC_START(mte_copy_tags_to_user)
 	mov	x3, x0
 	cbz	x2, 2f
 1:
@@ -129,14 +129,14 @@ USER(2f, sttrb	w4, [x0])
 	// exception handling and function return
 2:	sub	x0, x0, x3		// update the number of tags copied
 	ret
-SYM_FUNC_END(mte_copy_tags_to_user)
+SYM_LEAF_FUNC_END(mte_copy_tags_to_user)
 
 /*
  * Save the tags in a page
  *   x0 - page address
  *   x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
  */
-SYM_FUNC_START(mte_save_page_tags)
+SYM_LEAF_FUNC_START(mte_save_page_tags)
 	multitag_transfer_size x7, x5
 1:
 	mov	x2, #0
@@ -153,14 +153,14 @@ SYM_FUNC_START(mte_save_page_tags)
 	b.ne	1b
 
 	ret
-SYM_FUNC_END(mte_save_page_tags)
+SYM_LEAF_FUNC_END(mte_save_page_tags)
 
 /*
  * Restore the tags in a page
  *   x0 - page address
  *   x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
  */
-SYM_FUNC_START(mte_restore_page_tags)
+SYM_LEAF_FUNC_START(mte_restore_page_tags)
 	multitag_transfer_size x7, x5
 1:
 	ldr	x2, [x1], #8
@@ -174,4 +174,4 @@ SYM_FUNC_START(mte_restore_page_tags)
 	b.ne	1b
 
 	ret
-SYM_FUNC_END(mte_restore_page_tags)
+SYM_LEAF_FUNC_END(mte_restore_page_tags)
diff --git a/arch/arm64/lib/strchr.S b/arch/arm64/lib/strchr.S
index 94ee67a6b212c..455582efd07ae 100644
--- a/arch/arm64/lib/strchr.S
+++ b/arch/arm64/lib/strchr.S
@@ -18,7 +18,7 @@
  * Returns:
  *	x0 - address of first occurrence of 'c' or 0
  */
-SYM_FUNC_START(__pi_strchr)
+SYM_LEAF_FUNC_START(__pi_strchr)
 	and	w1, w1, #0xff
 1:	ldrb	w2, [x0], #1
 	cmp	w2, w1
@@ -28,7 +28,7 @@ SYM_FUNC_START(__pi_strchr)
 	cmp	w2, w1
 	csel	x0, x0, xzr, eq
 	ret
-SYM_FUNC_END(__pi_strchr)
+SYM_LEAF_FUNC_END(__pi_strchr)
 
 SYM_FUNC_ALIAS_WEAK(strchr, __pi_strchr)
 EXPORT_SYMBOL_NOKASAN(strchr)
diff --git a/arch/arm64/lib/strcmp.S b/arch/arm64/lib/strcmp.S
index 9b89b45336074..d0ce2040a32b9 100644
--- a/arch/arm64/lib/strcmp.S
+++ b/arch/arm64/lib/strcmp.S
@@ -53,7 +53,7 @@
    NUL too in big-endian, byte-reverse the data before the NUL check.  */
 
 
-SYM_FUNC_START(__pi_strcmp)
+SYM_LEAF_FUNC_START(__pi_strcmp)
 	sub	off2, src2, src1
 	mov	zeroones, REP8_01
 	and	tmp, src1, 7
@@ -185,6 +185,6 @@ L(tail):
 L(done):
 	sub	result, data1, data2
 	ret
-SYM_FUNC_END(__pi_strcmp)
+SYM_LEAF_FUNC_END(__pi_strcmp)
 SYM_FUNC_ALIAS_WEAK(strcmp, __pi_strcmp)
 EXPORT_SYMBOL_NOKASAN(strcmp)
diff --git a/arch/arm64/lib/strlen.S b/arch/arm64/lib/strlen.S
index 4919fe81ae540..a5d4151548b5f 100644
--- a/arch/arm64/lib/strlen.S
+++ b/arch/arm64/lib/strlen.S
@@ -79,7 +79,7 @@
 	   whether the first fetch, which may be misaligned, crosses a page
 	   boundary.  */
 
-SYM_FUNC_START(__pi_strlen)
+SYM_LEAF_FUNC_START(__pi_strlen)
 	and	tmp1, srcin, MIN_PAGE_SIZE - 1
 	mov	zeroones, REP8_01
 	cmp	tmp1, MIN_PAGE_SIZE - 16
@@ -208,6 +208,6 @@ L(page_cross):
 	csel	data1, data1, tmp4, eq
 	csel	data2, data2, tmp2, eq
 	b	L(page_cross_entry)
-SYM_FUNC_END(__pi_strlen)
+SYM_LEAF_FUNC_END(__pi_strlen)
 SYM_FUNC_ALIAS_WEAK(strlen, __pi_strlen)
 EXPORT_SYMBOL_NOKASAN(strlen)
diff --git a/arch/arm64/lib/strncmp.S b/arch/arm64/lib/strncmp.S
index fe7bbc0b42a78..8fd5c5d7dc2ad 100644
--- a/arch/arm64/lib/strncmp.S
+++ b/arch/arm64/lib/strncmp.S
@@ -58,7 +58,7 @@
 #define LS_BK lsl
 #endif
 
-SYM_FUNC_START(__pi_strncmp)
+SYM_LEAF_FUNC_START(__pi_strncmp)
 	cbz	limit, L(ret0)
 	eor	tmp1, src1, src2
 	mov	zeroones, #REP8_01
@@ -305,6 +305,6 @@ L(syndrome_check):
 L(ret0):
 	mov	result, #0
 	ret
-SYM_FUNC_END(__pi_strncmp)
+SYM_LEAF_FUNC_END(__pi_strncmp)
 SYM_FUNC_ALIAS_WEAK(strncmp, __pi_strncmp)
 EXPORT_SYMBOL_NOKASAN(strncmp)
diff --git a/arch/arm64/lib/strnlen.S b/arch/arm64/lib/strnlen.S
index d5ac0e10a01db..9f3f02e3f7e2c 100644
--- a/arch/arm64/lib/strnlen.S
+++ b/arch/arm64/lib/strnlen.S
@@ -47,7 +47,7 @@ limit_wd	.req	x14
 #define REP8_7f 0x7f7f7f7f7f7f7f7f
 #define REP8_80 0x8080808080808080
 
-SYM_FUNC_START(__pi_strnlen)
+SYM_LEAF_FUNC_START(__pi_strnlen)
 	cbz	limit, .Lhit_limit
 	mov	zeroones, #REP8_01
 	bic	src, srcin, #15
@@ -156,7 +156,7 @@ CPU_LE( lsr	tmp2, tmp2, tmp4 )	/* Shift (tmp1 & 63).  */
 .Lhit_limit:
 	mov	len, limit
 	ret
-SYM_FUNC_END(__pi_strnlen)
+SYM_LEAF_FUNC_END(__pi_strnlen)
 
 SYM_FUNC_ALIAS_WEAK(strnlen, __pi_strnlen)
 EXPORT_SYMBOL_NOKASAN(strnlen)
diff --git a/arch/arm64/lib/tishift.S b/arch/arm64/lib/tishift.S
index a88613834fb07..b12d7f6a60031 100644
--- a/arch/arm64/lib/tishift.S
+++ b/arch/arm64/lib/tishift.S
@@ -7,7 +7,7 @@
 
 #include <asm/assembler.h>
 
-SYM_FUNC_START(__ashlti3)
+SYM_LEAF_FUNC_START(__ashlti3)
 	cbz	x2, 1f
 	mov	x3, #64
 	sub	x3, x3, x2
@@ -26,10 +26,10 @@ SYM_FUNC_START(__ashlti3)
 	lsl	x1, x0, x1
 	mov	x0, x2
 	ret
-SYM_FUNC_END(__ashlti3)
+SYM_LEAF_FUNC_END(__ashlti3)
 EXPORT_SYMBOL(__ashlti3)
 
-SYM_FUNC_START(__ashrti3)
+SYM_LEAF_FUNC_START(__ashrti3)
 	cbz	x2, 1f
 	mov	x3, #64
 	sub	x3, x3, x2
@@ -48,10 +48,10 @@ SYM_FUNC_START(__ashrti3)
 	asr	x0, x1, x0
 	mov	x1, x2
 	ret
-SYM_FUNC_END(__ashrti3)
+SYM_LEAF_FUNC_END(__ashrti3)
 EXPORT_SYMBOL(__ashrti3)
 
-SYM_FUNC_START(__lshrti3)
+SYM_LEAF_FUNC_START(__lshrti3)
 	cbz	x2, 1f
 	mov	x3, #64
 	sub	x3, x3, x2
@@ -70,5 +70,5 @@ SYM_FUNC_START(__lshrti3)
 	lsr	x0, x1, x0
 	mov	x1, x2
 	ret
-SYM_FUNC_END(__lshrti3)
+SYM_LEAF_FUNC_END(__lshrti3)
 EXPORT_SYMBOL(__lshrti3)
-- 
2.56.0.360.g66cac248cb-goog

[PATCH v8 11/11] unwind: arm64: Use sframe to unwind interrupt frames

[Dylan Hatch]

Add kunwind_next_regs_sframe() function to unwind by sframe info if
present. Use this method at exception boundaries, falling back to
frame-pointer unwind only on failure. In such failure cases, the
stacktrace is considered unreliable. During normal unwind, prefer frame
pointer unwind (for better performance).

This change restores the LR behavior originally introduced in commit
c2c6b27b5aa14fa2 ("arm64: stacktrace: unwind exception boundaries"),
But later removed in commit 32ed1205682e ("arm64: stacktrace: Skip
reporting LR at exception boundaries")

This can be done because the sframe data can be used to determine
whether the LR is current for the PC value recovered from pt_regs at the
exception boundary.

Co-developed-by: Weinan Liu <wnliu@google.com>
Signed-off-by: Weinan Liu <wnliu@google.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
---
 arch/arm64/kernel/stacktrace.c | 184 +++++++++++++++++++++++++++++++--
 1 file changed, 173 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 3ebcf8c53fb04..67f3f56fd994b 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -13,6 +13,7 @@
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
+#include <linux/sframe.h>
 #include <linux/stacktrace.h>
 
 #include <asm/efi.h>
@@ -26,6 +27,7 @@ enum kunwind_source {
 	KUNWIND_SOURCE_CALLER,
 	KUNWIND_SOURCE_TASK,
 	KUNWIND_SOURCE_REGS_PC,
+	KUNWIND_SOURCE_REGS_LR,
 };
 
 union unwind_flags {
@@ -45,6 +47,7 @@ union unwind_flags {
  * @kr_cur:      When KRETPROBES is selected, holds the kretprobe instance
  *               associated with the most recently encountered replacement lr
  *               value.
+ * @unreliable:  Stacktrace is unreliable.
  */
 struct kunwind_state {
 	struct unwind_state common;
@@ -56,6 +59,7 @@ struct kunwind_state {
 	enum kunwind_source source;
 	union unwind_flags flags;
 	struct pt_regs *regs;
+	bool unreliable;
 };
 
 static __always_inline void
@@ -181,7 +185,6 @@ int kunwind_next_regs_pc(struct kunwind_state *state)
 	state->regs = regs;
 	state->common.pc = regs->pc;
 	state->common.fp = regs->regs[29];
-	state->regs = NULL;
 	state->source = KUNWIND_SOURCE_REGS_PC;
 	return 0;
 }
@@ -244,6 +247,162 @@ kunwind_next_frame_record(struct kunwind_state *state)
 	return 0;
 }
 
+#ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
+
+static __always_inline struct stack_info *
+get_word(struct unwind_state *state, unsigned long *word)
+{
+	unsigned long addr = *word;
+	struct stack_info *info;
+
+	info = unwind_find_stack(state, addr, sizeof(addr));
+	if (!info)
+		return info;
+
+	*word = READ_ONCE(*(unsigned long *)addr);
+
+	return info;
+}
+
+static __always_inline int
+get_consume_word(struct unwind_state *state, unsigned long *word)
+{
+	struct stack_info *info;
+	unsigned long addr = *word;
+
+	info = get_word(state, word);
+	if (!info)
+		return -EINVAL;
+
+	unwind_consume_stack(state, info, addr, sizeof(addr));
+	return 0;
+}
+
+/*
+ * Unwind from a pt_regs according to sframe.
+ */
+static __always_inline int
+kunwind_next_regs_sframe(struct kunwind_state *state)
+{
+	struct unwind_frame frame;
+	unsigned long cfa, fp, ra;
+	enum kunwind_source source = KUNWIND_SOURCE_FRAME;
+	struct pt_regs *regs = state->regs;
+
+	int err;
+
+	if (WARN_ON_ONCE(state->source != KUNWIND_SOURCE_REGS_PC))
+		return -EINVAL;
+	if (WARN_ON_ONCE(!state->regs))
+		return -EINVAL;
+
+	/* FP/SP alignment 8 bytes */
+	if (state->common.fp & 0x7)
+		return -EINVAL;
+
+	err = sframe_find(state->common.pc, &frame);
+	if (err)
+		return -EINVAL;
+
+	/*
+	 * A kernel unwind should always end at a FRAME_META_TYPE_FINAL
+	 * frame. There should be no outermost frames within the kernel.
+	 */
+	if (frame.outermost)
+		return -EINVAL;
+
+	/* Get the Canonical Frame Address (CFA) */
+	switch (frame.cfa.rule) {
+	case UNWIND_CFA_RULE_SP_OFFSET:
+		cfa = state->regs->sp;
+		break;
+	case UNWIND_CFA_RULE_FP_OFFSET:
+		if (state->common.fp < state->regs->sp)
+			return -EINVAL;
+		cfa = state->common.fp;
+		break;
+	/*
+	 * UNWIND_CFA_RULE_REG_OFFSET and UNWIND_CFA_RULE_REG_OFFSET_DEREF not
+	 * implemented -- flexible FDEs are not currently generated by assembler
+	 * for arm64.
+	 */
+	default:
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+	cfa += frame.cfa.offset;
+
+	/* CFA alignment 16 bytes */
+	if (cfa & 0xf)
+		return -EINVAL;
+
+	/*
+	 * Consume RA and FP from the stack. The frame record puts FP at a lower
+	 * address than RA, so we read FP first.
+	 */
+	switch (frame.fp.rule) {
+	case UNWIND_RULE_RETAIN:
+		fp = state->common.fp;
+		break;
+	/*
+	 * UNWIND_RULE_CFA_OFFSET is currently not used for FP
+	 * (e.g. SFrame cannot represent this rule).
+	 */
+	case UNWIND_RULE_CFA_OFFSET_DEREF:
+		fp = cfa + frame.fp.offset;
+		if (!get_word(&state->common, &fp))
+			return -EINVAL;
+		break;
+	/*
+	 * UNWIND_RULE_REG_OFFSET and UNWIND_RULE_REG_OFFSET_DEREF not
+	 * implemented -- flexible FDEs are not currently generated by assembler
+	 * for arm64.
+	 */
+	default:
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+
+	switch (frame.ra.rule) {
+	case UNWIND_RULE_RETAIN:
+		ra = regs->regs[30];
+		source = KUNWIND_SOURCE_REGS_LR;
+		break;
+
+	/*
+	 * UNWIND_RULE_CFA_OFFSET doesn't make sense for RA.
+	 * The return address cannot legitimately be a stack address.
+	 */
+	case UNWIND_RULE_CFA_OFFSET_DEREF:
+		ra = cfa + frame.ra.offset;
+		if (get_consume_word(&state->common, &ra))
+			return -EINVAL;
+		break;
+	/*
+	 * UNWIND_RULE_REG_OFFSET and UNWIND_RULE_REG_OFFSET_DEREF not
+	 * implemented -- flexible FDEs are not currently generated by assembler
+	 * for arm64.
+	 */
+	default:
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+
+	state->common.pc = ra;
+	state->common.fp = fp;
+
+	state->source = source;
+
+	return 0;
+}
+
+#else /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME */
+
+static __always_inline int
+kunwind_next_regs_sframe(struct kunwind_state *state) { return -EINVAL; }
+
+#endif /* !CONFIG_HAVE_UNWIND_KERNEL_SFRAME*/
+
 /*
  * Unwind from one frame record (A) to the next frame record (B).
  *
@@ -259,10 +418,20 @@ kunwind_next(struct kunwind_state *state)
 	state->flags.all = 0;
 
 	switch (state->source) {
+	case KUNWIND_SOURCE_REGS_PC:
+		err = kunwind_next_regs_sframe(state);
+
+		if (err) {
+			/* Fallback to FP based unwinder */
+			err = kunwind_next_frame_record(state);
+			state->unreliable = true;
+		}
+		state->regs = NULL;
+		break;
 	case KUNWIND_SOURCE_FRAME:
 	case KUNWIND_SOURCE_CALLER:
 	case KUNWIND_SOURCE_TASK:
-	case KUNWIND_SOURCE_REGS_PC:
+	case KUNWIND_SOURCE_REGS_LR:
 		err = kunwind_next_frame_record(state);
 		break;
 	default:
@@ -393,15 +562,7 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry,
 static __always_inline bool
 arch_reliable_kunwind_consume_entry(const struct kunwind_state *state, void *cookie)
 {
-	/*
-	 * At an exception boundary we can reliably consume the saved PC. We do
-	 * not know whether the LR was live when the exception was taken, and
-	 * so we cannot perform the next unwind step reliably.
-	 *
-	 * All that matters is whether the *entire* unwind is reliable, so give
-	 * up as soon as we hit an exception boundary.
-	 */
-	if (state->source == KUNWIND_SOURCE_REGS_PC)
+	if (state->unreliable)
 		return false;
 
 	return arch_kunwind_consume_entry(state, cookie);
@@ -452,6 +613,7 @@ static const char *state_source_string(const struct kunwind_state *state)
 	case KUNWIND_SOURCE_CALLER:	return "C";
 	case KUNWIND_SOURCE_TASK:	return "T";
 	case KUNWIND_SOURCE_REGS_PC:	return "P";
+	case KUNWIND_SOURCE_REGS_LR:	return "L";
 	default:			return "U";
 	}
 }
-- 
2.56.0.360.g66cac248cb-goog

Re: [PATCH v8 01/11] arm64, unwind: build kernel with sframe V3 info

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] unwind: missing SFrame unwind information for Rust code
--

commit 531ea7668c66f4aab865a6399bb07911c3617223
Author: Dylan Hatch <dylanbhatch@google.com>

arm64, unwind: build kernel with sframe V3 info

To generate a .sframe section, build with -Wa,--gsframe-3 flags. Also,
add unwind-table options to ensure the necessary CFI directives are
emitted by the compiler, but discard .eh_frame unless
CONFIG_UNWIND_TABLES is explicitly enabled.

> diff --git a/Makefile b/Makefile
> index 7c855e6fe5448..5c2ca98a86786 100644
> --- a/Makefile
> +++ b/Makefile
[ ... ]
> @@ -1197,6 +1197,14 @@ CFLAGS_GCOV	+= $(call try-run,\
>  endif
>  export CFLAGS_GCOV
>  
> +# build with sframe table
> +ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME
> +CC_FLAGS_SFRAME := -Wa,--gsframe-3
> +KBUILD_CFLAGS	+= $(CC_FLAGS_SFRAME)
> +KBUILD_AFLAGS	+= $(CC_FLAGS_SFRAME)

[Severity: Medium]
When CONFIG_HAVE_UNWIND_KERNEL_SFRAME is enabled, the generation flag is
added to C and ASM flags in Makefile, but no equivalent flag is passed to
the Rust compiler.

Because rustc emits object files directly using its LLVM backend and
currently lacks native SFrame emission, does it generate standard .eh_frame
data instead of .sframe?

> +export CC_FLAGS_SFRAME
> +endif
> +
>  # change __FILE__ to the relative path to the source directory
>  ifdef building_out_of_srctree
[ ... ]
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 6b005c8fef706..ae1c23579ad2f 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
[ ... ]
> @@ -55,7 +55,7 @@ KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)
>  KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
>  
>  # Avoid generating .eh_frame* sections.
> -ifneq ($(CONFIG_UNWIND_TABLES),y)
> +ifeq ($(filter y, $(CONFIG_UNWIND_TABLES) $(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)),)
>  KBUILD_CFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
>  KBUILD_AFLAGS	+= -fno-asynchronous-unwind-tables -fno-unwind-tables
>  KBUILD_RUSTFLAGS += -Cforce-unwind-tables=n

[Severity: Medium]
In arch/arm64/Makefile, this change ensures that Rust continues generating
unwind tables when SFrame is enabled. Does this mean Rust will continue to
generate DWARF unwind tables since -Cforce-unwind-tables=n is not applied
when CONFIG_HAVE_UNWIND_KERNEL_SFRAME is enabled and CONFIG_UNWIND_TABLES
is disabled?

[ ... ]
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index af1d720209764..eb1f54829503c 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
[ ... ]
> @@ -145,14 +145,25 @@ jiffies = jiffies_64;
>  #endif
>  
>  #ifdef CONFIG_UNWIND_TABLES
> +
>  #define UNWIND_DATA_SECTIONS				\
>  	.eh_frame : {					\
>  		__pi___eh_frame_start = .;		\
>  		*(.eh_frame)				\
>  		__pi___eh_frame_end = .;		\
>  	}
> +#define SFRAME_DISCARDS
> +
> +#elif defined(CONFIG_HAVE_UNWIND_KERNEL_SFRAME)
> +
> +#define UNWIND_DATA_SECTIONS
> +#define SFRAME_DISCARDS *(.eh_frame)

[Severity: Medium]
When only CONFIG_HAVE_UNWIND_KERNEL_SFRAME is enabled and
CONFIG_UNWIND_TABLES is disabled, the .eh_frame sections are explicitly
discarded here in arch/arm64/kernel/vmlinux.lds.S.

Since Rust code emits .eh_frame data instead of .sframe, does discarding
these sections silently leave all compiled Rust objects without any unwind
information? Could this break reliable stack unwinding across Rust frames?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007114335.440322-1-dylanbhatch@google.com?part=1

Re: [PATCH v8 05/11] module, sframe: Add sframe support for modules

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] unwind: Integer overflow in SFrame header parsing on 32-bit bypasses bounds checks, causing OOB write in sort()
--

commit 37859a60480c542bd986b5fe41b863323e42fd98
Author: Dylan Hatch <dylanbhatch@google.com>

module, sframe: Add sframe support for modules

This commit adds SFrame table support to struct module and enables SFrame
PC lookups for incoming modules. It parses the .sframe section and sorts
the FDEs if they are not already sorted.

> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
> --- a/kernel/unwind/sframe.c
> +++ b/kernel/unwind/sframe.c
[ ... ]
> @@ -471,10 +517,72 @@ void __init init_sframe_table(void)
[ ... ]
> +static void sframe_sort_fdes(struct sframe_section *sec)
> +{
> +	void *fdes = (void *)sec->fdes_start;
> +	size_t num_fdes = sec->num_fdes;
> +
> +	if (sec->fdes_sorted)
> +		return;
> +
> +	sort(fdes, num_fdes, sizeof(struct sframe_fde_v3),
> +	     sframe_sort_cmp_fde, sframe_sort_swap_fde);

[Severity: High]
With module parsing introduced, could this sort() call lead to an
out-of-bounds write if num_fdes is maliciously inflated?

Looking at how sframe_read_header() validates the incoming headers:

    num_fdes   = shdr->num_fdes;
    fdes_start = header_end + shdr->fdes_off;
    fdes_end   = fdes_start + (num_fdes * sizeof(struct sframe_fde_v3));
    
    fres_start = header_end + shdr->fres_off;
    fres_end   = fres_start + shdr->fre_len;
    
    if (fres_start < fdes_end || fres_end > sec->sframe_end || 
        fres_end < sec->sframe_start) {
            pr_debug("inconsistent fde/fre offsets\n");
            return -EINVAL;
    }

On 32-bit architectures, sizeof(struct sframe_fde_v3) evaluates to 16.
If an incoming module sets shdr->num_fdes to a large value like 0x10000000,
the multiplication num_fdes * 16 overflows the 32-bit integer and wraps
around to 0, resulting in fdes_end equaling fdes_start.

If the module also sets shdr->fres_off equal to shdr->fdes_off and
shdr->fre_len to 0, fres_start and fres_end will equal fdes_end. This
evaluates all the bounds checks to false, fully bypassing validation.

When sframe_sort_fdes() is subsequently called on this parsed module data,
it would invoke sort() with the attacker-controlled num_fdes (for example,
268,435,456 elements). Does this need overflow checking (such as size_mul)
to prevent out-of-bounds memory corruption during module load?

Additionally, could fde->fres_off in __find_fre() similarly overflow when
added to sec->fres_start on 32-bit architectures, bypassing bounds checks
and causing out-of-bounds reads during stack unwinding?

> +	sec->fdes_sorted = true;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007114335.440322-1-dylanbhatch@google.com?part=5

Re: [PATCH v8 07/11] sframe: Add debug helpers with object name

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] build: missing <linux/module.h> in sframe_debug.h
--

commit 586ddaf5514eed589ba4352e7a7684af607fdccf
Author: Dylan Hatch <dylanbhatch@google.com>

sframe: Add debug helpers with object name

This commit adds debug helpers that include the object name, formatting
messages with either the module name or vmlinux for kernel SFrame sections.

> diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h
> new file mode 100644
> index 0000000000000..f0bc2136eaad0
> --- /dev/null
> +++ b/kernel/unwind/sframe_debug.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _SFRAME_DEBUG_H
> +#define _SFRAME_DEBUG_H
> +
> +#include <linux/sframe.h>
> +#include "sframe.h"
> +
> +#ifdef CONFIG_MODULES
> +
> +#define objname(sec) ((sec) == &kernel_sfsec					\
> +		     ? "vmlinux"						\
> +		     : container_of((sec), struct module, sframe_sec)->name)

[Severity: Low]
Does this header need to include <linux/module.h> and <linux/stddef.h>?

The objname macro uses container_of and struct module, but the required
headers are not explicitly included. Any future C file including
sframe_debug.h directly without first including <linux/module.h> will fail
to compile.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007114335.440322-1-dylanbhatch@google.com?part=7

Re: [PATCH v8 06/11] arm64/sframe: Validate IP addresses

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] unwind: noinstr violation via static inline callees in sframe_find()
--

commit e12d5712c137b31d5aeba1eafd95262908a336d3
Author: Dylan Hatch <dylanbhatch@google.com>

arm64/sframe: Validate IP addresses

This commit adds validation for instruction pointers during sframe unwinding.
It introduces architecture-specific checks for arm64 to ensure the IPs fall
within valid kernel or module text ranges, handling special sections like
.exit.text and .rodata.text.

[ ... ]
> diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h
> new file mode 100644
> index 0000000000000..1b45d328c746f
> --- /dev/null
> +++ b/arch/arm64/include/asm/unwind_sframe.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_ARM64_UNWIND_SFRAME_H
> +#define _ASM_ARM64_UNWIND_SFRAME_H
> +
> +#include <linux/module.h>
> +#include <linux/sframe.h>
> +#include <asm/sections.h>
> +
> +static __always_inline bool sframe_is_kernel_ip_valid(unsigned long ip)
> +{
> +	if (__is_kernel_text(ip) || is_kernel_inittext(ip))
> +		return true;

[Severity: Low]
Since sframe_find() is marked noinstr and calls this helper, marking
sframe_is_kernel_ip_valid() as __always_inline helps prevent it from being
outlined. However, __is_kernel_text() and is_kernel_inittext() are standard
static inline functions. Could the compiler decide to outline these nested
helpers into the instrumentable .text section?

If that happens, objtool validation might fail during the build, and it could
theoretically result in recursive instrumentation faults (e.g., KASAN) if
called during NMI stack unwinding.

> +
> +	/* .exit.text is retained in vmlinux on arm64. */
> +	if (ip >= (unsigned long)__exittext_begin &&
[ ... ]
> diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c
> index 33883408581da..c95fcb63e7eaf 100644
> --- a/kernel/unwind/sframe.c
> +++ b/kernel/unwind/sframe.c
[ ... ]
> @@ -44,6 +44,45 @@ struct sframe_fre_internal {
[ ... ]
> +#ifdef CONFIG_MODULES
> +
> +static __always_inline bool sframe_is_sec_module_ip_valid(struct sframe_section *sec,
> +							  unsigned long ip)
> +{
> +	struct module *mod = container_of(sec, struct module, sframe_sec);
> +
> +	return within_module_mem_type(ip, mod, MOD_TEXT) ||
> +		within_module_mem_type(ip, mod, MOD_INIT_TEXT);

[Severity: Low]
Similarly, within_module_mem_type() is a regular static inline function
called from the noinstr path. Does this present the same outlining risk
as the kernel text helpers above?

> +}
> +
> +#else

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261007114335.440322-1-dylanbhatch@google.com?part=6