[RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Stian Halseth]

This adds HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP to sparc64, so
that perf record --call-graph dwarf and elfutils' eu-stackprof work
there.

Two things about the user stack dump do not fit in arch code. The
sampled register window's %l/%i registers, which hold the frame pointer
and return address the unwinder starts from, stay in the register file
until a window spills. The kernel already flushes them wherever it
exposes user stack memory (perf_callchain_user(), ptrace), but the stack
dump has no arch entry point where that could happen. And a 64-bit
sparc stack pointer is biased by 2047, so a dump that starts at the
register value begins 2047 bytes below the frame, and is empty when that
page has never been touched.

Patch 1 therefore adds two hooks in the style of perf_arch_misc_flags(),
both no-ops by default. Patch 2 is the sparc64 implementation and their
user. Patch 3 teaches tools/perf the sparc registers and DWARF unwinding
from the dump. The matching elfutils changes are attached to the
tracking issue:

  https://github.com/sparclinux/issues/issues/99

Tested on an UltraSPARC T4-1 on 7.3-rc4: register values check out
against known contents, --call-graph dwarf unwinds correctly for both
cycles and cpu-clock, as does eu-stackprof, and perf stat/record/record
-g are unchanged. Starting the dump at the stack's actual address
matters in practice: with the dump at the biased register value, 94% of
the user samples of xz -T4 had an empty stack dump; with this series,
none do.

Changes since v2:
- Patch 1: add perf_arch_user_stack_pointer(), so an arch can start the
  dump at the stack's actual address (sashiko review).
- Patch 2: drop %g0 from the uapi, as trap entry does not save it; the
  PC takes its slot, as on mips and loongarch (sashiko review).
- Patch 2: start the dump at %sp + 2047 for a 64-bit stack (sashiko
  review).
- Patch 3: follow both, and comment the max_dwarf_reg adjustment (Ian).
  Drop the memcpy() change to memory_read(), which the unbiased dump
  start makes unnecessary.

v2: https://lore.kernel.org/all/20260922201507.1719668-1-stian@itx.no/
v1: https://lore.kernel.org/all/20260922135653.1622301-1-stian@itx.no/

Stian Halseth (3):
  perf/core: Let an arch prepare and locate the user stack dump
  sparc64: Support PERF_SAMPLE_REGS_USER and PERF_SAMPLE_STACK_USER
  perf tools: Support sparc user register samples and dwarf unwinding

 .../features/perf/perf-regs/arch-support.txt  |  2 +-
 .../perf/perf-stackdump/arch-support.txt      |  2 +-
 arch/sparc/Kconfig                            |  2 +
 arch/sparc/include/asm/perf_event.h           |  5 ++
 arch/sparc/include/uapi/asm/perf_regs.h       | 34 +++++++++
 arch/sparc/kernel/Makefile                    |  2 +-
 arch/sparc/kernel/perf_regs.c                 | 74 +++++++++++++++++++
 include/linux/perf_event.h                    | 11 +++
 kernel/events/core.c                          |  2 +
 kernel/events/internal.h                      |  2 +-
 tools/arch/sparc/include/uapi/asm/perf_regs.h | 34 +++++++++
 tools/perf/arch/sparc/include/perf_regs.h     | 18 +++++
 tools/perf/check-headers.sh                   |  1 +
 tools/perf/util/dwarf-regs-arch/Build         |  1 +
 .../util/dwarf-regs-arch/dwarf-regs-sparc.c   | 12 +++
 tools/perf/util/dwarf-regs.c                  |  4 +
 tools/perf/util/include/dwarf-regs.h          |  1 +
 tools/perf/util/perf-regs-arch/Build          |  1 +
 .../util/perf-regs-arch/perf_regs_sparc.c     | 67 +++++++++++++++++
 tools/perf/util/perf_regs.c                   | 18 +++++
 tools/perf/util/perf_regs.h                   |  5 ++
 tools/perf/util/unwind-libdw.c                | 37 ++++++++++
 22 files changed, 331 insertions(+), 4 deletions(-)
 create mode 100644 arch/sparc/include/uapi/asm/perf_regs.h
 create mode 100644 arch/sparc/kernel/perf_regs.c
 create mode 100644 tools/arch/sparc/include/uapi/asm/perf_regs.h
 create mode 100644 tools/perf/arch/sparc/include/perf_regs.h
 create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
 create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_sparc.c

-- 
2.55.0

[RFC PATCH v3 1/3] perf/core: Let an arch prepare and locate the user stack dump

[Stian Halseth]

PERF_SAMPLE_STACK_USER copies the user stack as it is in memory,
starting at the user stack pointer. Two things about sparc64 do not
fit that.

The sampled window's %l and %i registers, including the frame pointer
and return address an unwinder starts from, may still be in the
register file: they only reach the stack when a window spills.
perf_callchain_user() already handles this for the callchain by calling
flushw_user() first; the user stack dump has no equivalent arch entry
point.

And a 64-bit stack pointer is biased by 2047: the stack starts at
%sp + 2047. Starting the dump at the register value spends a quarter of
an 8K dump on memory below the frame, and gives no dump at all when that
page has never been touched, as for a leaf frame at the deepest point a
thread's stack has reached.

Add two hooks in the style of perf_arch_misc_flags():
perf_arch_prepare_ustack(), a no-op by default, called from
perf_prepare_sample() before the dump size is computed, and
perf_arch_user_stack_pointer(), user_stack_pointer() by default, the
address the dump starts at. Flushing in the arch PMU interrupt handler
instead would not do: software events such as cpu-clock reach
perf_event_overflow() without passing through it.

Signed-off-by: Stian Halseth <stian@itx.no>
---
 include/linux/perf_event.h | 11 +++++++++++
 kernel/events/core.c       |  2 ++
 kernel/events/internal.h   |  2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 5842552294c1..49aa22db43c0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1815,6 +1815,17 @@ extern unsigned long perf_instruction_pointer(struct perf_event *event,
 #ifndef perf_arch_bpf_user_pt_regs
 # define perf_arch_bpf_user_pt_regs(regs) regs
 #endif
+/*
+ * Called before the user stack of the current task is dumped, for an arch
+ * that still holds part of the user's stack state in registers.
+ */
+#ifndef perf_arch_prepare_ustack
+static inline void perf_arch_prepare_ustack(void) { }
+#endif
+/* Where the user stack dump starts, for an arch with a biased stack pointer. */
+#ifndef perf_arch_user_stack_pointer
+# define perf_arch_user_stack_pointer(regs)	user_stack_pointer(regs)
+#endif
 
 #ifndef perf_arch_guest_misc_flags
 static inline unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index db7b76d6b68a..90fb35c7d279 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8718,6 +8718,8 @@ void perf_prepare_sample(struct perf_sample_data *data,
 		u16 header_size = perf_sample_data_size(data, event);
 		u16 size = sizeof(u64);
 
+		if (data->regs_user.regs)
+			perf_arch_prepare_ustack();
 		stack_size = perf_sample_ustack_size(stack_size, header_size,
 						     data->regs_user.regs);
 
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index c03c4f2eea57..01b5f53d01d7 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -236,7 +236,7 @@ static inline bool arch_perf_have_user_stack_dump(void)
 	return true;
 }
 
-#define perf_user_stack_pointer(regs) user_stack_pointer(regs)
+#define perf_user_stack_pointer(regs) perf_arch_user_stack_pointer(regs)
 #else
 static inline bool arch_perf_have_user_stack_dump(void)
 {
-- 
2.55.0

[RFC PATCH v3 2/3] sparc64: Support PERF_SAMPLE_REGS_USER and PERF_SAMPLE_STACK_USER

[Stian Halseth]

Select HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP and add the
perf_regs implementation. The exposed registers mirror struct pt_regs:
%g1-%g7, %o0-%o7 (named from the user's point of view; pt_regs calls
them UREG_I*), %tstate, NPC and %y, with the PC in the slot of %g0, as
mips and loongarch do for their hardwired-zero register. Trap entry
does not save %g0, so its pt_regs slot holds stale stack contents for
a trap taken in the kernel and must not be exposed.

%o6 is reported as held in the register, i.e. with the 2047 stack bias
for a 64-bit stack, the same as ptrace and user_stack_pointer(). The
stack dump starts at the stack's actual address instead, %o6 + 2047
when test_thread_64bit_stack() says so, so that it begins at the
sampled frame; the uapi header documents this for consumers.

User-mode values of a 32-bit task are truncated to 32 bits as
genregs32_get() does, since the hardware does not zero-extend them.
Kernel-mode registers, as seen by PERF_SAMPLE_REGS_INTR, are left
alone.

perf_arch_prepare_ustack() flushes the user register windows so the
sampled window's %l and %i registers are in the dumped stack, where a
DWARF unwinder needs them: the CFI of a function after `save` defines
the CFA in terms of %i6.

This makes perf record --call-graph dwarf and eu-stackprof usable on
sparc64.

Signed-off-by: Stian Halseth <stian@itx.no>
---
 .../features/perf/perf-regs/arch-support.txt  |  2 +-
 .../perf/perf-stackdump/arch-support.txt      |  2 +-
 arch/sparc/Kconfig                            |  2 +
 arch/sparc/include/asm/perf_event.h           |  5 ++
 arch/sparc/include/uapi/asm/perf_regs.h       | 34 +++++++++
 arch/sparc/kernel/Makefile                    |  2 +-
 arch/sparc/kernel/perf_regs.c                 | 74 +++++++++++++++++++
 7 files changed, 118 insertions(+), 3 deletions(-)
 create mode 100644 arch/sparc/include/uapi/asm/perf_regs.h
 create mode 100644 arch/sparc/kernel/perf_regs.c

diff --git a/Documentation/features/perf/perf-regs/arch-support.txt b/Documentation/features/perf/perf-regs/arch-support.txt
index 4c9a5a012075..41ab622efa15 100644
--- a/Documentation/features/perf/perf-regs/arch-support.txt
+++ b/Documentation/features/perf/perf-regs/arch-support.txt
@@ -23,7 +23,7 @@
     |       riscv: |  ok  |
     |        s390: |  ok  |
     |          sh: | TODO |
-    |       sparc: | TODO |
+    |       sparc: |  ok  |
     |          um: | TODO |
     |         x86: |  ok  |
     |      xtensa: | TODO |
diff --git a/Documentation/features/perf/perf-stackdump/arch-support.txt b/Documentation/features/perf/perf-stackdump/arch-support.txt
index dd362b5cb638..cafa6fae7704 100644
--- a/Documentation/features/perf/perf-stackdump/arch-support.txt
+++ b/Documentation/features/perf/perf-stackdump/arch-support.txt
@@ -23,7 +23,7 @@
     |       riscv: |  ok  |
     |        s390: |  ok  |
     |          sh: | TODO |
-    |       sparc: | TODO |
+    |       sparc: |  ok  |
     |          um: | TODO |
     |         x86: |  ok  |
     |      xtensa: | TODO |
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index ab77d3f2536e..9d7f575f359d 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -93,6 +93,8 @@ config SPARC64
 	select RTC_DRV_SUN4V
 	select RTC_DRV_STARFIRE
 	select HAVE_PERF_EVENTS
+	select HAVE_PERF_REGS
+	select HAVE_PERF_USER_STACK_DUMP
 	select PERF_USE_VMALLOC
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select HAVE_C_RECORDMCOUNT
diff --git a/arch/sparc/include/asm/perf_event.h b/arch/sparc/include/asm/perf_event.h
index c2aec0c7f4f5..3e70c23e7714 100644
--- a/arch/sparc/include/asm/perf_event.h
+++ b/arch/sparc/include/asm/perf_event.h
@@ -25,6 +25,11 @@ do {							\
 	(regs)->u_regs[UREG_I6] = _fp;			\
 	(regs)->u_regs[UREG_I7] = _i7;			\
 } while (0)
+
+void perf_arch_prepare_ustack(void);
+#define perf_arch_prepare_ustack	perf_arch_prepare_ustack
+unsigned long perf_arch_user_stack_pointer(struct pt_regs *regs);
+#define perf_arch_user_stack_pointer	perf_arch_user_stack_pointer
 #endif
 
 #endif
diff --git a/arch/sparc/include/uapi/asm/perf_regs.h b/arch/sparc/include/uapi/asm/perf_regs.h
new file mode 100644
index 000000000000..0621ffbdafce
--- /dev/null
+++ b/arch/sparc/include/uapi/asm/perf_regs.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_SPARC_PERF_REGS_H
+#define _UAPI_ASM_SPARC_PERF_REGS_H
+
+/*
+ * Mirrors struct pt_regs, with the PC in the slot of the hardwired-zero
+ * %g0.  O6 is %sp as held in the register: for a 64-bit stack (odd O6)
+ * it is biased by 2047, and the PERF_SAMPLE_STACK_USER dump starts at
+ * O6 + 2047.
+ */
+enum perf_event_sparc_regs {
+	PERF_REG_SPARC_PC,
+	PERF_REG_SPARC_G1,
+	PERF_REG_SPARC_G2,
+	PERF_REG_SPARC_G3,
+	PERF_REG_SPARC_G4,
+	PERF_REG_SPARC_G5,
+	PERF_REG_SPARC_G6,
+	PERF_REG_SPARC_G7,
+	PERF_REG_SPARC_O0,
+	PERF_REG_SPARC_O1,
+	PERF_REG_SPARC_O2,
+	PERF_REG_SPARC_O3,
+	PERF_REG_SPARC_O4,
+	PERF_REG_SPARC_O5,
+	PERF_REG_SPARC_O6,
+	PERF_REG_SPARC_O7,
+	PERF_REG_SPARC_TSTATE,
+	PERF_REG_SPARC_NPC,
+	PERF_REG_SPARC_Y,
+	PERF_REG_SPARC_MAX
+};
+
+#endif /* _UAPI_ASM_SPARC_PERF_REGS_H */
diff --git a/arch/sparc/kernel/Makefile b/arch/sparc/kernel/Makefile
index 497b5714fa8f..a3dd92247c3b 100644
--- a/arch/sparc/kernel/Makefile
+++ b/arch/sparc/kernel/Makefile
@@ -113,7 +113,7 @@ obj-$(CONFIG_AUDIT)     += audit.o
 audit--$(CONFIG_AUDIT)  := compat_audit.o
 obj-$(CONFIG_COMPAT)    += $(audit--y)
 
-pc--$(CONFIG_PERF_EVENTS) := perf_event.o
+pc--$(CONFIG_PERF_EVENTS) := perf_event.o perf_regs.o
 obj-$(CONFIG_SPARC64)	+= $(pc--y)
 
 obj-$(CONFIG_UPROBES)	+= uprobes.o
diff --git a/arch/sparc/kernel/perf_regs.c b/arch/sparc/kernel/perf_regs.c
new file mode 100644
index 000000000000..8bcc3421ec19
--- /dev/null
+++ b/arch/sparc/kernel/perf_regs.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/perf_event.h>
+#include <linux/perf_regs.h>
+#include <linux/sched/task_stack.h>
+#include <asm/cacheflush.h>
+#include <asm/ptrace.h>
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	u64 val;
+
+	switch (idx) {
+	case PERF_REG_SPARC_PC:
+		val = regs->tpc;
+		break;
+	case PERF_REG_SPARC_G1 ... PERF_REG_SPARC_O7:
+		val = regs->u_regs[idx];
+		break;
+	case PERF_REG_SPARC_TSTATE:
+		return regs->tstate;
+	case PERF_REG_SPARC_NPC:
+		val = regs->tnpc;
+		break;
+	case PERF_REG_SPARC_Y:
+		return regs->y;
+	default:
+		WARN_ON_ONCE(1);
+		return 0;
+	}
+
+	if (user_mode(regs) && test_thread_flag(TIF_32BIT))
+		val = (u32)val;
+
+	return val;
+}
+
+#define REG_RESERVED (~((1ULL << PERF_REG_SPARC_MAX) - 1))
+
+int perf_reg_validate(u64 mask)
+{
+	if (!mask || mask & REG_RESERVED)
+		return -EINVAL;
+
+	return 0;
+}
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+	if (test_tsk_thread_flag(task, TIF_32BIT))
+		return PERF_SAMPLE_REGS_ABI_32;
+
+	return PERF_SAMPLE_REGS_ABI_64;
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+			struct pt_regs *regs)
+{
+	regs_user->regs = task_pt_regs(current);
+	regs_user->abi = perf_reg_abi(current);
+}
+
+void perf_arch_prepare_ustack(void)
+{
+	flushw_user();
+}
+
+unsigned long perf_arch_user_stack_pointer(struct pt_regs *regs)
+{
+	unsigned long sp = user_stack_pointer(regs);
+
+	if (test_thread_64bit_stack(sp))
+		sp += STACK_BIAS;
+	return sp;
+}
-- 
2.55.0

[RFC PATCH v3 3/3] perf tools: Support sparc user register samples and dwarf unwinding

[Stian Halseth]

Add the sparc perf_regs tables and the EM_SPARC/EM_SPARCV9 dispatch for
register names, masks, ip/sp and the perf-to-DWARF register mapping,
plus the uapi header copy.

For libdw unwinding, seed DWARF registers 16-31 (%l0-%l7, %i0-%i7) from
the register save area at the start of the stack dump: the kernel
flushes the sampled window there, and the CFI after `save` needs %i6
and %i7 to find the first caller. The dump of a 64-bit sparc stack
starts at %sp + 2047, so memory_read() takes its base from there.

Signed-off-by: Stian Halseth <stian@itx.no>
---
 tools/arch/sparc/include/uapi/asm/perf_regs.h | 34 ++++++++++
 tools/perf/arch/sparc/include/perf_regs.h     | 18 +++++
 tools/perf/check-headers.sh                   |  1 +
 tools/perf/util/dwarf-regs-arch/Build         |  1 +
 .../util/dwarf-regs-arch/dwarf-regs-sparc.c   | 12 ++++
 tools/perf/util/dwarf-regs.c                  |  4 ++
 tools/perf/util/include/dwarf-regs.h          |  1 +
 tools/perf/util/perf-regs-arch/Build          |  1 +
 .../util/perf-regs-arch/perf_regs_sparc.c     | 67 +++++++++++++++++++
 tools/perf/util/perf_regs.c                   | 18 +++++
 tools/perf/util/perf_regs.h                   |  5 ++
 tools/perf/util/unwind-libdw.c                | 37 ++++++++++
 12 files changed, 199 insertions(+)
 create mode 100644 tools/arch/sparc/include/uapi/asm/perf_regs.h
 create mode 100644 tools/perf/arch/sparc/include/perf_regs.h
 create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
 create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_sparc.c

diff --git a/tools/arch/sparc/include/uapi/asm/perf_regs.h b/tools/arch/sparc/include/uapi/asm/perf_regs.h
new file mode 100644
index 000000000000..0621ffbdafce
--- /dev/null
+++ b/tools/arch/sparc/include/uapi/asm/perf_regs.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_SPARC_PERF_REGS_H
+#define _UAPI_ASM_SPARC_PERF_REGS_H
+
+/*
+ * Mirrors struct pt_regs, with the PC in the slot of the hardwired-zero
+ * %g0.  O6 is %sp as held in the register: for a 64-bit stack (odd O6)
+ * it is biased by 2047, and the PERF_SAMPLE_STACK_USER dump starts at
+ * O6 + 2047.
+ */
+enum perf_event_sparc_regs {
+	PERF_REG_SPARC_PC,
+	PERF_REG_SPARC_G1,
+	PERF_REG_SPARC_G2,
+	PERF_REG_SPARC_G3,
+	PERF_REG_SPARC_G4,
+	PERF_REG_SPARC_G5,
+	PERF_REG_SPARC_G6,
+	PERF_REG_SPARC_G7,
+	PERF_REG_SPARC_O0,
+	PERF_REG_SPARC_O1,
+	PERF_REG_SPARC_O2,
+	PERF_REG_SPARC_O3,
+	PERF_REG_SPARC_O4,
+	PERF_REG_SPARC_O5,
+	PERF_REG_SPARC_O6,
+	PERF_REG_SPARC_O7,
+	PERF_REG_SPARC_TSTATE,
+	PERF_REG_SPARC_NPC,
+	PERF_REG_SPARC_Y,
+	PERF_REG_SPARC_MAX
+};
+
+#endif /* _UAPI_ASM_SPARC_PERF_REGS_H */
diff --git a/tools/perf/arch/sparc/include/perf_regs.h b/tools/perf/arch/sparc/include/perf_regs.h
new file mode 100644
index 000000000000..493fbff9ea16
--- /dev/null
+++ b/tools/perf/arch/sparc/include/perf_regs.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef ARCH_PERF_REGS_H
+#define ARCH_PERF_REGS_H
+
+#include <stdlib.h>
+#include <linux/types.h>
+#include "../../../../arch/sparc/include/uapi/asm/perf_regs.h"
+
+#define PERF_REGS_MASK	((1ULL << PERF_REG_SPARC_MAX) - 1)
+#define PERF_REGS_MAX	PERF_REG_SPARC_MAX
+
+#ifdef __arch64__
+#define PERF_SAMPLE_REGS_ABI	PERF_SAMPLE_REGS_ABI_64
+#else
+#define PERF_SAMPLE_REGS_ABI	PERF_SAMPLE_REGS_ABI_32
+#endif
+
+#endif /* ARCH_PERF_REGS_H */
diff --git a/tools/perf/check-headers.sh b/tools/perf/check-headers.sh
index 531c0e0e84df..f144590f5082 100755
--- a/tools/perf/check-headers.sh
+++ b/tools/perf/check-headers.sh
@@ -42,6 +42,7 @@ declare -a FILES=(
   "arch/mips/include/uapi/asm/perf_regs.h"
   "arch/powerpc/include/uapi/asm/perf_regs.h"
   "arch/s390/include/uapi/asm/perf_regs.h"
+  "arch/sparc/include/uapi/asm/perf_regs.h"
   "arch/x86/include/uapi/asm/perf_regs.h"
   "arch/x86/include/uapi/asm/kvm.h"
   "arch/x86/include/uapi/asm/svm.h"
diff --git a/tools/perf/util/dwarf-regs-arch/Build b/tools/perf/util/dwarf-regs-arch/Build
index ceb68ae86fd8..bda944029046 100644
--- a/tools/perf/util/dwarf-regs-arch/Build
+++ b/tools/perf/util/dwarf-regs-arch/Build
@@ -6,4 +6,5 @@ perf-util-$(CONFIG_LIBDW) += dwarf-regs-mips.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-powerpc.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-riscv.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-s390.o
+perf-util-$(CONFIG_LIBDW) += dwarf-regs-sparc.o
 perf-util-$(CONFIG_LIBDW) += dwarf-regs-x86.o
diff --git a/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c b/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
new file mode 100644
index 000000000000..a5af1e1d8b8b
--- /dev/null
+++ b/tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <dwarf-regs.h>
+#include "../../../arch/sparc/include/uapi/asm/perf_regs.h"
+
+int __get_dwarf_regnum_for_perf_regnum_sparc(int perf_regnum)
+{
+	if (perf_regnum < PERF_REG_SPARC_G1 || perf_regnum > PERF_REG_SPARC_O7)
+		return -ENOENT;
+
+	return perf_regnum;
+}
diff --git a/tools/perf/util/dwarf-regs.c b/tools/perf/util/dwarf-regs.c
index 797f455eba0d..df9200c31aaa 100644
--- a/tools/perf/util/dwarf-regs.c
+++ b/tools/perf/util/dwarf-regs.c
@@ -217,6 +217,10 @@ int get_dwarf_regnum_for_perf_regnum(int perf_regnum, unsigned int machine,
 	case EM_S390:
 		reg = __get_dwarf_regnum_for_perf_regnum_s390(perf_regnum);
 		break;
+	case EM_SPARC:
+	case EM_SPARCV9:
+		reg = __get_dwarf_regnum_for_perf_regnum_sparc(perf_regnum);
+		break;
 	case EM_LOONGARCH:
 		reg = __get_dwarf_regnum_for_perf_regnum_loongarch(perf_regnum);
 		break;
diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
index 46a764cf322f..4a02f30c5604 100644
--- a/tools/perf/util/include/dwarf-regs.h
+++ b/tools/perf/util/include/dwarf-regs.h
@@ -113,6 +113,7 @@ int __get_dwarf_regnum_for_perf_regnum_loongarch(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_powerpc(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_riscv(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_s390(int perf_regnum);
+int __get_dwarf_regnum_for_perf_regnum_sparc(int perf_regnum);
 int __get_dwarf_regnum_for_perf_regnum_mips(int perf_regnum);
 
 /*
diff --git a/tools/perf/util/perf-regs-arch/Build b/tools/perf/util/perf-regs-arch/Build
index be95402aa540..47220a2f2dae 100644
--- a/tools/perf/util/perf-regs-arch/Build
+++ b/tools/perf/util/perf-regs-arch/Build
@@ -6,4 +6,5 @@ perf-util-y += perf_regs_mips.o
 perf-util-y += perf_regs_powerpc.o
 perf-util-y += perf_regs_riscv.o
 perf-util-y += perf_regs_s390.o
+perf-util-y += perf_regs_sparc.o
 perf-util-y += perf_regs_x86.o
diff --git a/tools/perf/util/perf-regs-arch/perf_regs_sparc.c b/tools/perf/util/perf-regs-arch/perf_regs_sparc.c
new file mode 100644
index 000000000000..9ee8e496ab8c
--- /dev/null
+++ b/tools/perf/util/perf-regs-arch/perf_regs_sparc.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "../perf_regs.h"
+#include "../../arch/sparc/include/perf_regs.h"
+
+uint64_t __perf_reg_mask_sparc(bool intr __maybe_unused)
+{
+	return PERF_REGS_MASK;
+}
+
+const char *__perf_reg_name_sparc(int id)
+{
+	switch (id) {
+	case PERF_REG_SPARC_PC:
+		return "pc";
+	case PERF_REG_SPARC_G1:
+		return "g1";
+	case PERF_REG_SPARC_G2:
+		return "g2";
+	case PERF_REG_SPARC_G3:
+		return "g3";
+	case PERF_REG_SPARC_G4:
+		return "g4";
+	case PERF_REG_SPARC_G5:
+		return "g5";
+	case PERF_REG_SPARC_G6:
+		return "g6";
+	case PERF_REG_SPARC_G7:
+		return "g7";
+	case PERF_REG_SPARC_O0:
+		return "o0";
+	case PERF_REG_SPARC_O1:
+		return "o1";
+	case PERF_REG_SPARC_O2:
+		return "o2";
+	case PERF_REG_SPARC_O3:
+		return "o3";
+	case PERF_REG_SPARC_O4:
+		return "o4";
+	case PERF_REG_SPARC_O5:
+		return "o5";
+	case PERF_REG_SPARC_O6:
+		return "sp";
+	case PERF_REG_SPARC_O7:
+		return "o7";
+	case PERF_REG_SPARC_TSTATE:
+		return "tstate";
+	case PERF_REG_SPARC_NPC:
+		return "npc";
+	case PERF_REG_SPARC_Y:
+		return "y";
+	default:
+		return NULL;
+	}
+
+	return NULL;
+}
+
+uint64_t __perf_reg_ip_sparc(void)
+{
+	return PERF_REG_SPARC_PC;
+}
+
+uint64_t __perf_reg_sp_sparc(void)
+{
+	return PERF_REG_SPARC_O6;
+}
diff --git a/tools/perf/util/perf_regs.c b/tools/perf/util/perf_regs.c
index 558c143abbab..5880b54fd7dc 100644
--- a/tools/perf/util/perf_regs.c
+++ b/tools/perf/util/perf_regs.c
@@ -68,6 +68,10 @@ uint64_t perf_intr_reg_mask(uint16_t e_machine)
 	case EM_S390:
 		mask = __perf_reg_mask_s390(/*intr=*/true);
 		break;
+	case EM_SPARC:
+	case EM_SPARCV9:
+		mask = __perf_reg_mask_sparc(/*intr=*/true);
+		break;
 	case EM_386:
 	case EM_X86_64:
 		mask = __perf_reg_mask_x86(/*intr=*/true);
@@ -111,6 +115,10 @@ uint64_t perf_user_reg_mask(uint16_t e_machine)
 	case EM_S390:
 		mask = __perf_reg_mask_s390(/*intr=*/false);
 		break;
+	case EM_SPARC:
+	case EM_SPARCV9:
+		mask = __perf_reg_mask_sparc(/*intr=*/false);
+		break;
 	case EM_386:
 	case EM_X86_64:
 		mask = __perf_reg_mask_x86(/*intr=*/false);
@@ -154,6 +162,10 @@ const char *perf_reg_name(int id, uint16_t e_machine, uint32_t e_flags)
 	case EM_S390:
 		reg_name = __perf_reg_name_s390(id);
 		break;
+	case EM_SPARC:
+	case EM_SPARCV9:
+		reg_name = __perf_reg_name_sparc(id);
+		break;
 	case EM_386:
 	case EM_X86_64:
 		reg_name = __perf_reg_name_x86(id);
@@ -215,6 +227,9 @@ uint64_t perf_arch_reg_ip(uint16_t e_machine)
 		return __perf_reg_ip_riscv();
 	case EM_S390:
 		return __perf_reg_ip_s390();
+	case EM_SPARC:
+	case EM_SPARCV9:
+		return __perf_reg_ip_sparc();
 	case EM_386:
 	case EM_X86_64:
 		return __perf_reg_ip_x86();
@@ -244,6 +259,9 @@ uint64_t perf_arch_reg_sp(uint16_t e_machine)
 		return __perf_reg_sp_riscv();
 	case EM_S390:
 		return __perf_reg_sp_s390();
+	case EM_SPARC:
+	case EM_SPARCV9:
+		return __perf_reg_sp_sparc();
 	case EM_386:
 	case EM_X86_64:
 		return __perf_reg_sp_x86();
diff --git a/tools/perf/util/perf_regs.h b/tools/perf/util/perf_regs.h
index 79be2b791509..3f453d910aa4 100644
--- a/tools/perf/util/perf_regs.h
+++ b/tools/perf/util/perf_regs.h
@@ -65,6 +65,11 @@ uint64_t __perf_reg_ip_s390(void);
 uint64_t __perf_reg_sp_s390(void);
 int __perf_sdt_arg_parse_op_s390(char *old_op, char **new_op);
 
+uint64_t __perf_reg_mask_sparc(bool intr);
+const char *__perf_reg_name_sparc(int id);
+uint64_t __perf_reg_ip_sparc(void);
+uint64_t __perf_reg_sp_sparc(void);
+
 int __perf_sdt_arg_parse_op_x86(char *old_op, char **new_op);
 uint64_t __perf_reg_mask_x86(bool intr);
 const char *__perf_reg_name_x86(int id);
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index 63a5c2253174..d2adf7f2d8bb 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -4,7 +4,9 @@
 #include <elfutils/libdw.h>
 #include <elfutils/libdwfl.h>
 #include <inttypes.h>
+#include <elf.h>
 #include <errno.h>
+#include <string.h>
 #include "debug.h"
 #include "dso.h"
 #include <dwarf-regs.h>
@@ -225,6 +227,14 @@ static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
 	return -1;
 }
 
+/* A 64-bit sparc stack (odd %sp) is biased; its dump starts past the bias. */
+static u64 stack_dump_start(uint16_t e_machine, u64 sp)
+{
+	if ((e_machine == EM_SPARC || e_machine == EM_SPARCV9) && (sp & 1))
+		return sp + 2047;
+	return sp;
+}
+
 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
 			void *arg)
 {
@@ -243,6 +253,7 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *
 	if (ret)
 		return false;
 
+	start = stack_dump_start(ui->e_machine, start);
 	end = start + stack->size;
 
 	/* Check overflow. */
@@ -267,6 +278,26 @@ static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *
 	return true;
 }
 
+/*
+ * The sampled window's %l and %i registers (DWARF 16-31) are not in the
+ * sample; the kernel flushed them to the register save area at the start
+ * of the dumped stack.
+ */
+static void libdw_set_sparc_window_registers(struct unwind_info *ui,
+					     struct regs_dump *user_regs,
+					     Dwarf_Word *dwarf_regs)
+{
+	struct stack_dump *stack = &ui->sample->user_stack;
+	u64 sp;
+
+	if (perf_reg_value(&sp, user_regs, perf_arch_reg_sp(ui->e_machine)))
+		return;
+	if (!(sp & 1) || 16 * sizeof(u64) > stack->size)
+		return;
+
+	memcpy(&dwarf_regs[16], stack->data, 16 * sizeof(u64));
+}
+
 static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
 {
 	struct dwfl_ui_thread_info *dwfl_ui_ti = arg;
@@ -276,6 +307,7 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
 	int max_dwarf_reg = 0;
 	bool ret;
 	uint16_t e_machine = ui->e_machine;
+	bool is_sparc = e_machine == EM_SPARC || e_machine == EM_SPARCV9;
 	int e_flags = ui->e_flags;
 	uint64_t ip_perf_reg = perf_arch_reg_ip(e_machine);
 	Dwarf_Word val = 0;
@@ -295,6 +327,9 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
 				max_dwarf_reg = dwarf_reg;
 		}
 	}
+	/* libdw_set_sparc_window_registers() fills DWARF 16-31. */
+	if (is_sparc && max_dwarf_reg < 31)
+		max_dwarf_reg = 31;
 
 	dwarf_regs = calloc(max_dwarf_reg + 1, sizeof(*dwarf_regs));
 	if (!dwarf_regs)
@@ -313,6 +348,8 @@ static bool libdw_set_initial_registers(Dwfl_Thread *thread, void *arg)
 			}
 		}
 	}
+	if (is_sparc)
+		libdw_set_sparc_window_registers(ui, user_regs, dwarf_regs);
 	if (perf_reg_value(&val, user_regs, ip_perf_reg) == 0)
 		dwfl_thread_state_register_pc(thread, val);
 
-- 
2.55.0

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Ian Rogers]

On Wed, Sep 23, 2026 at 2:04 AM Stian Halseth <stian@itx.no> wrote:
>
> This adds HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP to sparc64, so
> that perf record --call-graph dwarf and elfutils' eu-stackprof work
> there.
>
> Two things about the user stack dump do not fit in arch code. The
> sampled register window's %l/%i registers, which hold the frame pointer
> and return address the unwinder starts from, stay in the register file
> until a window spills. The kernel already flushes them wherever it
> exposes user stack memory (perf_callchain_user(), ptrace), but the stack
> dump has no arch entry point where that could happen. And a 64-bit
> sparc stack pointer is biased by 2047, so a dump that starts at the
> register value begins 2047 bytes below the frame, and is empty when that
> page has never been touched.
>
> Patch 1 therefore adds two hooks in the style of perf_arch_misc_flags(),
> both no-ops by default. Patch 2 is the sparc64 implementation and their
> user. Patch 3 teaches tools/perf the sparc registers and DWARF unwinding
> from the dump. The matching elfutils changes are attached to the
> tracking issue:
>
>   https://github.com/sparclinux/issues/issues/99
>
> Tested on an UltraSPARC T4-1 on 7.3-rc4: register values check out
> against known contents, --call-graph dwarf unwinds correctly for both
> cycles and cpu-clock, as does eu-stackprof, and perf stat/record/record
> -g are unchanged. Starting the dump at the stack's actual address
> matters in practice: with the dump at the biased register value, 94% of
> the user samples of xz -T4 had an empty stack dump; with this series,
> none do.
>
> Changes since v2:
> - Patch 1: add perf_arch_user_stack_pointer(), so an arch can start the
>   dump at the stack's actual address (sashiko review).
> - Patch 2: drop %g0 from the uapi, as trap entry does not save it; the
>   PC takes its slot, as on mips and loongarch (sashiko review).
> - Patch 2: start the dump at %sp + 2047 for a 64-bit stack (sashiko
>   review).
> - Patch 3: follow both, and comment the max_dwarf_reg adjustment (Ian).
>   Drop the memcpy() change to memory_read(), which the unbiased dump
>   start makes unnecessary.
>
> v2: https://lore.kernel.org/all/20260922201507.1719668-1-stian@itx.no/
> v1: https://lore.kernel.org/all/20260922135653.1622301-1-stian@itx.no/
>
> Stian Halseth (3):
>   perf/core: Let an arch prepare and locate the user stack dump
>   sparc64: Support PERF_SAMPLE_REGS_USER and PERF_SAMPLE_STACK_USER
>   perf tools: Support sparc user register samples and dwarf unwinding

For the series:

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks!
Ian

>  .../features/perf/perf-regs/arch-support.txt  |  2 +-
>  .../perf/perf-stackdump/arch-support.txt      |  2 +-
>  arch/sparc/Kconfig                            |  2 +
>  arch/sparc/include/asm/perf_event.h           |  5 ++
>  arch/sparc/include/uapi/asm/perf_regs.h       | 34 +++++++++
>  arch/sparc/kernel/Makefile                    |  2 +-
>  arch/sparc/kernel/perf_regs.c                 | 74 +++++++++++++++++++
>  include/linux/perf_event.h                    | 11 +++
>  kernel/events/core.c                          |  2 +
>  kernel/events/internal.h                      |  2 +-
>  tools/arch/sparc/include/uapi/asm/perf_regs.h | 34 +++++++++
>  tools/perf/arch/sparc/include/perf_regs.h     | 18 +++++
>  tools/perf/check-headers.sh                   |  1 +
>  tools/perf/util/dwarf-regs-arch/Build         |  1 +
>  .../util/dwarf-regs-arch/dwarf-regs-sparc.c   | 12 +++
>  tools/perf/util/dwarf-regs.c                  |  4 +
>  tools/perf/util/include/dwarf-regs.h          |  1 +
>  tools/perf/util/perf-regs-arch/Build          |  1 +
>  .../util/perf-regs-arch/perf_regs_sparc.c     | 67 +++++++++++++++++
>  tools/perf/util/perf_regs.c                   | 18 +++++
>  tools/perf/util/perf_regs.h                   |  5 ++
>  tools/perf/util/unwind-libdw.c                | 37 ++++++++++
>  22 files changed, 331 insertions(+), 4 deletions(-)
>  create mode 100644 arch/sparc/include/uapi/asm/perf_regs.h
>  create mode 100644 arch/sparc/kernel/perf_regs.c
>  create mode 100644 tools/arch/sparc/include/uapi/asm/perf_regs.h
>  create mode 100644 tools/perf/arch/sparc/include/perf_regs.h
>  create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
>  create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_sparc.c
>
> --
> 2.55.0
>

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Stian Halseth]

[-- Attachment #1: Type: text/plain, Size: 351 bytes --]

Hi Ian,

On Wed, 2026-09-23 at 13:38 -0700, Ian Rogers wrote:
> 
> 
> For the series:
> 
> Reviewed-by: Ian Rogers <irogers@google.com>
> 

Since this series is still marked RFC, should I resend it as a regular
PATCH v4 with your Reviewed-by, or wait for additional maintainer
feedback?

And thank you so much for the reviews!

Stian

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Ian Rogers]

On Wed, Sep 23, 2026 at 1:57 PM Stian Halseth <stian@itx.no> wrote:
>
> Hi Ian,
>
> On Wed, 2026-09-23 at 13:38 -0700, Ian Rogers wrote:
> >
> >
> > For the series:
> >
> > Reviewed-by: Ian Rogers <irogers@google.com>
> >
>
> Since this series is still marked RFC, should I resend it as a regular
> PATCH v4 with your Reviewed-by, or wait for additional maintainer
> feedback?
>
> And thank you so much for the reviews!

I think we have everything we need but the kernel changes are really
up to Peter and Ingo, and the tool changes are up to Arnaldo and
Namhyung.

Thanks,
Ian

> Stian

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Magnus Lindholm]

Hi Stian,

On Wed, Sep 23, 2026 at 11:04 AM Stian Halseth <stian@itx.no> wrote:
>
> This adds HAVE_PERF_REGS and HAVE_PERF_USER_STACK_DUMP to sparc64, so
> that perf record --call-graph dwarf and elfutils' eu-stackprof work
> there.
>
> Two things about the user stack dump do not fit in arch code. The
> sampled register window's %l/%i registers, which hold the frame pointer
> and return address the unwinder starts from, stay in the register file
> until a window spills. The kernel already flushes them wherever it
> exposes user stack memory (perf_callchain_user(), ptrace), but the stack
> dump has no arch entry point where that could happen. And a 64-bit
> sparc stack pointer is biased by 2047, so a dump that starts at the
> register value begins 2047 bytes below the frame, and is empty when that
> page has never been touched.
>
> Patch 1 therefore adds two hooks in the style of perf_arch_misc_flags(),
> both no-ops by default. Patch 2 is the sparc64 implementation and their
> user. Patch 3 teaches tools/perf the sparc registers and DWARF unwinding
> from the dump. The matching elfutils changes are attached to the
> tracking issue:
>
>   https://github.com/sparclinux/issues/issues/99
>
> Tested on an UltraSPARC T4-1 on 7.3-rc4: register values check out
> against known contents, --call-graph dwarf unwinds correctly for both
> cycles and cpu-clock, as does eu-stackprof, and perf stat/record/record
> -g are unchanged. Starting the dump at the stack's actual address
> matters in practice: with the dump at the biased register value, 94% of
> the user samples of xz -T4 had an empty stack dump; with this series,
> none do.
>
> Changes since v2:
> - Patch 1: add perf_arch_user_stack_pointer(), so an arch can start the
>   dump at the stack's actual address (sashiko review).
> - Patch 2: drop %g0 from the uapi, as trap entry does not save it; the
>   PC takes its slot, as on mips and loongarch (sashiko review).
> - Patch 2: start the dump at %sp + 2047 for a 64-bit stack (sashiko
>   review).
> - Patch 3: follow both, and comment the max_dwarf_reg adjustment (Ian).
>   Drop the memcpy() change to memory_read(), which the unbiased dump
>   start makes unnecessary.
>
> v2: https://lore.kernel.org/all/20260922201507.1719668-1-stian@itx.no/
> v1: https://lore.kernel.org/all/20260922135653.1622301-1-stian@itx.no/
>
> Stian Halseth (3):
>   perf/core: Let an arch prepare and locate the user stack dump
>   sparc64: Support PERF_SAMPLE_REGS_USER and PERF_SAMPLE_STACK_USER
>   perf tools: Support sparc user register samples and dwarf unwinding
>
>  .../features/perf/perf-regs/arch-support.txt  |  2 +-
>  .../perf/perf-stackdump/arch-support.txt      |  2 +-
>  arch/sparc/Kconfig                            |  2 +
>  arch/sparc/include/asm/perf_event.h           |  5 ++
>  arch/sparc/include/uapi/asm/perf_regs.h       | 34 +++++++++
>  arch/sparc/kernel/Makefile                    |  2 +-
>  arch/sparc/kernel/perf_regs.c                 | 74 +++++++++++++++++++
>  include/linux/perf_event.h                    | 11 +++
>  kernel/events/core.c                          |  2 +
>  kernel/events/internal.h                      |  2 +-
>  tools/arch/sparc/include/uapi/asm/perf_regs.h | 34 +++++++++
>  tools/perf/arch/sparc/include/perf_regs.h     | 18 +++++
>  tools/perf/check-headers.sh                   |  1 +
>  tools/perf/util/dwarf-regs-arch/Build         |  1 +
>  .../util/dwarf-regs-arch/dwarf-regs-sparc.c   | 12 +++
>  tools/perf/util/dwarf-regs.c                  |  4 +
>  tools/perf/util/include/dwarf-regs.h          |  1 +
>  tools/perf/util/perf-regs-arch/Build          |  1 +
>  .../util/perf-regs-arch/perf_regs_sparc.c     | 67 +++++++++++++++++
>  tools/perf/util/perf_regs.c                   | 18 +++++
>  tools/perf/util/perf_regs.h                   |  5 ++
>  tools/perf/util/unwind-libdw.c                | 37 ++++++++++
>  22 files changed, 331 insertions(+), 4 deletions(-)
>  create mode 100644 arch/sparc/include/uapi/asm/perf_regs.h
>  create mode 100644 arch/sparc/kernel/perf_regs.c
>  create mode 100644 tools/arch/sparc/include/uapi/asm/perf_regs.h
>  create mode 100644 tools/perf/arch/sparc/include/perf_regs.h
>  create mode 100644 tools/perf/util/dwarf-regs-arch/dwarf-regs-sparc.c
>  create mode 100644 tools/perf/util/perf-regs-arch/perf_regs_sparc.c
>
> --
> 2.55.0
>

Hi Stian,

I tested v3 on real hardware. I haven't noticed any regressions.
I built tools/perf from this series and tested the new functionality
with software cpu-clock events.

Basic perf stat/record and the existing frame-pointer callchain mode
worked normally.

PERF_SAMPLE_REGS_USER also worked, with perf successfully recording
and decoding the SPARC register set.

I then tested:

  perf record -e '1:0:u' -F 99 --call-graph dwarf,8192 ...

This recorded 443 samples with PERF_SAMPLE_REGS_USER and
PERF_SAMPLE_STACK_USER, using the full 0x7ffff register mask and an
8192-byte stack dump. perf script and perf report were both able to
unwind the resulting callchains, and no samples were reported lost.

I haven't tested 32-bit compat tasks or hardware-cycle sampling.

Tested-by: Magnus Lindholm <linmag7@gmail.com>

Thanks,
Magnus

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Stian Halseth]

[-- Attachment #1: Type: text/plain, Size: 1026 bytes --]

Hi Magnus,

On Thu, 2026-09-24 at 01:10 +0200, Magnus Lindholm wrote:
> 
> Hi Stian,
> 
> I tested v3 on real hardware. I haven't noticed any regressions.
> I built tools/perf from this series and tested the new functionality
> with software cpu-clock events.
> 
> Basic perf stat/record and the existing frame-pointer callchain mode
> worked normally.
> 
> PERF_SAMPLE_REGS_USER also worked, with perf successfully recording
> and decoding the SPARC register set.
> 
> I then tested:
> 
>   perf record -e '1:0:u' -F 99 --call-graph dwarf,8192 ...
> 
> This recorded 443 samples with PERF_SAMPLE_REGS_USER and
> PERF_SAMPLE_STACK_USER, using the full 0x7ffff register mask and an
> 8192-byte stack dump. perf script and perf report were both able to
> unwind the resulting callchains, and no samples were reported lost.
> 
> I haven't tested 32-bit compat tasks or hardware-cycle sampling.
> 
> Tested-by: Magnus Lindholm <linmag7@gmail.com>
> 
> Thanks,
> Magnus

Thanks for testing,
Stian

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Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Arnaldo Carvalho de Melo]

On Wed, Sep 23, 2026 at 02:16:49PM -0700, Ian Rogers wrote:
> On Wed, Sep 23, 2026 at 1:57 PM Stian Halseth <stian@itx.no> wrote:
> >
> > Hi Ian,
> >
> > On Wed, 2026-09-23 at 13:38 -0700, Ian Rogers wrote:
> > >
> > >
> > > For the series:
> > >
> > > Reviewed-by: Ian Rogers <irogers@google.com>
> > >
> >
> > Since this series is still marked RFC, should I resend it as a regular
> > PATCH v4 with your Reviewed-by, or wait for additional maintainer
> > feedback?
> >
> > And thank you so much for the reviews!
> 
> I think we have everything we need but the kernel changes are really
> up to Peter and Ingo, and the tool changes are up to Arnaldo and
> Namhyung.

Exactly, as soon as the kernel changes land in a path to upstream, I can
do the same for the tooling bits.

Cheers,

- Arnaldo

Re: [RFC PATCH v3 0/3] perf: sparc64 user regs and stack dump, with arch hooks

[Arnaldo Carvalho de Melo]

On Thu, Sep 24, 2026 at 07:09:58PM +0200, Arnaldo Carvalho de Melo wrote:
> On Wed, Sep 23, 2026 at 02:16:49PM -0700, Ian Rogers wrote:
> > On Wed, Sep 23, 2026 at 1:57 PM Stian Halseth <stian@itx.no> wrote:
> > I think we have everything we need but the kernel changes are really
> > up to Peter and Ingo, and the tool changes are up to Arnaldo and
> > Namhyung.
 
> Exactly, as soon as the kernel changes land in a path to upstream, I can
> do the same for the tooling bits.

Once that happens, please resubmit just the tools patches without an RFC
in the subject line.

- Arnaldo