[PATCH -tip v6 1/2] irq: Make irqentry text section unconditional

[PATCH -tip v6 1/2] irq: Make irqentry text section unconditional

[Masami Hiramatsu]

Generate irqentry and softirqentry text sections without
any configs. This will add above extra sections, but
no performace impact.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
---
 arch/arm/include/asm/traps.h      |    7 -------
 arch/arm64/include/asm/traps.h    |    7 -------
 arch/x86/entry/entry_64.S         |    9 ++-------
 include/asm-generic/sections.h    |    4 ++++
 include/asm-generic/vmlinux.lds.h |    8 --------
 include/linux/interrupt.h         |   14 +-------------
 6 files changed, 7 insertions(+), 42 deletions(-)

diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h
index f555bb3664dc..683d9230984a 100644
--- a/arch/arm/include/asm/traps.h
+++ b/arch/arm/include/asm/traps.h
@@ -18,7 +18,6 @@ struct undef_hook {
 void register_undef_hook(struct undef_hook *hook);
 void unregister_undef_hook(struct undef_hook *hook);
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static inline int __in_irqentry_text(unsigned long ptr)
 {
 	extern char __irqentry_text_start[];
@@ -27,12 +26,6 @@ static inline int __in_irqentry_text(unsigned long ptr)
 	return ptr >= (unsigned long)&__irqentry_text_start &&
 	       ptr < (unsigned long)&__irqentry_text_end;
 }
-#else
-static inline int __in_irqentry_text(unsigned long ptr)
-{
-	return 0;
-}
-#endif
 
 static inline int in_exception_text(unsigned long ptr)
 {
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 02e9035b0685..47a9066f7c86 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -37,18 +37,11 @@ void unregister_undef_hook(struct undef_hook *hook);
 
 void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);
 
-#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static inline int __in_irqentry_text(unsigned long ptr)
 {
 	return ptr >= (unsigned long)&__irqentry_text_start &&
 	       ptr < (unsigned long)&__irqentry_text_end;
 }
-#else
-static inline int __in_irqentry_text(unsigned long ptr)
-{
-	return 0;
-}
-#endif
 
 static inline int in_exception_text(unsigned long ptr)
 {
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index aa58155187c5..5e41396efbbf 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -766,13 +766,8 @@ apicinterrupt3 \num trace(\sym) smp_trace(\sym)
 #endif
 
 /* Make sure APIC interrupt handlers end up in the irqentry section: */
-#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
-# define PUSH_SECTION_IRQENTRY	.pushsection .irqentry.text, "ax"
-# define POP_SECTION_IRQENTRY	.popsection
-#else
-# define PUSH_SECTION_IRQENTRY
-# define POP_SECTION_IRQENTRY
-#endif
+#define PUSH_SECTION_IRQENTRY	.pushsection .irqentry.text, "ax"
+#define POP_SECTION_IRQENTRY	.popsection
 
 .macro apicinterrupt num sym do_sym
 PUSH_SECTION_IRQENTRY
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index 532372c6cf15..e5da44eddd2f 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -27,6 +27,8 @@
  *	__kprobes_text_start, __kprobes_text_end
  *	__entry_text_start, __entry_text_end
  *	__ctors_start, __ctors_end
+ *	__irqentry_text_start, __irqentry_text_end
+ *	__softirqentry_text_start, __softirqentry_text_end
  */
 extern char _text[], _stext[], _etext[];
 extern char _data[], _sdata[], _edata[];
@@ -39,6 +41,8 @@ extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
 extern char __kprobes_text_start[], __kprobes_text_end[];
 extern char __entry_text_start[], __entry_text_end[];
 extern char __start_rodata[], __end_rodata[];
+extern char __irqentry_text_start[], __irqentry_text_end[];
+extern char __softirqentry_text_start[], __softirqentry_text_end[];
 
 /* Start and end of .ctors section - used for constructor calls. */
 extern char __ctors_start[], __ctors_end[];
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index fffc9bdae025..438b014c192f 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -483,25 +483,17 @@
 		*(.entry.text)						\
 		VMLINUX_SYMBOL(__entry_text_end) = .;
 
-#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 #define IRQENTRY_TEXT							\
 		ALIGN_FUNCTION();					\
 		VMLINUX_SYMBOL(__irqentry_text_start) = .;		\
 		*(.irqentry.text)					\
 		VMLINUX_SYMBOL(__irqentry_text_end) = .;
-#else
-#define IRQENTRY_TEXT
-#endif
 
-#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 #define SOFTIRQENTRY_TEXT						\
 		ALIGN_FUNCTION();					\
 		VMLINUX_SYMBOL(__softirqentry_text_start) = .;		\
 		*(.softirqentry.text)					\
 		VMLINUX_SYMBOL(__softirqentry_text_end) = .;
-#else
-#define SOFTIRQENTRY_TEXT
-#endif
 
 /* Section used for early init (in .S files) */
 #define HEAD_TEXT  *(.head.text)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index a2fddddb0d60..59ba11661b6e 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -18,6 +18,7 @@
 #include <linux/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/irq.h>
+#include <asm/sections.h>
 
 /*
  * These correspond to the IORESOURCE_IRQ_* defines in
@@ -726,7 +727,6 @@ extern int early_irq_init(void);
 extern int arch_probe_nr_irqs(void);
 extern int arch_early_irq_init(void);
 
-#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
 /*
  * We want to know which function is an entrypoint of a hardirq or a softirq.
  */
@@ -734,16 +734,4 @@ extern int arch_early_irq_init(void);
 #define __softirq_entry  \
 	__attribute__((__section__(".softirqentry.text")))
 
-/* Limits of hardirq entrypoints */
-extern char __irqentry_text_start[];
-extern char __irqentry_text_end[];
-/* Limits of softirq entrypoints */
-extern char __softirqentry_text_start[];
-extern char __softirqentry_text_end[];
-
-#else
-#define __irq_entry
-#define __softirq_entry
-#endif
-
 #endif

[PATCH -tip v6 2/2] [BUGFIX] kprobes/x86: Do not jump-optimize kprobes on irq entry code

[Masami Hiramatsu]

Since the kernel segment registers are not prepared at the
entry of irq-entry code, if a kprobe on such code is
jump-optimized, accessing per-cpu variables may cause
kernel panic.
However, if the kprobe is not optimized, it kicks int3
exception and set segment registers correctly.

This checks probe-address and if it is in irq-entry code,
it prohibits optimizing such kprobes. This means we can
continuously probing such interrupt handlers by kprobes
but it is not optimized anymore.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Tested-by: Francis Deslauriers <francis.deslauriers@efficios.com>
---
 Changes in v6:
  - Update for unconditional irqentry.
---
 arch/x86/kernel/kprobes/opt.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 69ea0bc1cfa3..4f98aad38237 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -39,6 +39,7 @@
 #include <asm/insn.h>
 #include <asm/debugreg.h>
 #include <asm/set_memory.h>
+#include <asm/sections.h>
 
 #include "common.h"
 
@@ -251,10 +252,12 @@ static int can_optimize(unsigned long paddr)
 
 	/*
 	 * Do not optimize in the entry code due to the unstable
-	 * stack handling.
+	 * stack handling and registers setup.
 	 */
-	if ((paddr >= (unsigned long)__entry_text_start) &&
-	    (paddr <  (unsigned long)__entry_text_end))
+	if (((paddr >= (unsigned long)__entry_text_start) &&
+	     (paddr <  (unsigned long)__entry_text_end)) ||
+	    ((paddr >= (unsigned long)__irqentry_text_start) &&
+	     (paddr <  (unsigned long)__irqentry_text_end)))
 		return 0;
 
 	/* Check there is enough space for a relative jump. */

Re: [PATCH -tip v6 1/2] irq: Make irqentry text section unconditional

[Masami Hiramatsu]

On Fri, 28 Jul 2017 21:24:54 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Generate irqentry and softirqentry text sections without
> any configs. This will add above extra sections, but
> no performace impact.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Suggested-by: Ingo Molnar <mingo@kernel.org>
> ---
>  arch/arm/include/asm/traps.h      |    7 -------
>  arch/arm64/include/asm/traps.h    |    7 -------
>  arch/x86/entry/entry_64.S         |    9 ++-------
>  include/asm-generic/sections.h    |    4 ++++
>  include/asm-generic/vmlinux.lds.h |    8 --------
>  include/linux/interrupt.h         |   14 +-------------
>  6 files changed, 7 insertions(+), 42 deletions(-)

Oops, I forgot to fix x86 unwind code.
I'll update this to fix in_entry_code() unconditional.

Thanks,

> 
> diff --git a/arch/arm/include/asm/traps.h b/arch/arm/include/asm/traps.h
> index f555bb3664dc..683d9230984a 100644
> --- a/arch/arm/include/asm/traps.h
> +++ b/arch/arm/include/asm/traps.h
> @@ -18,7 +18,6 @@ struct undef_hook {
>  void register_undef_hook(struct undef_hook *hook);
>  void unregister_undef_hook(struct undef_hook *hook);
>  
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>  static inline int __in_irqentry_text(unsigned long ptr)
>  {
>  	extern char __irqentry_text_start[];
> @@ -27,12 +26,6 @@ static inline int __in_irqentry_text(unsigned long ptr)
>  	return ptr >= (unsigned long)&__irqentry_text_start &&
>  	       ptr < (unsigned long)&__irqentry_text_end;
>  }
> -#else
> -static inline int __in_irqentry_text(unsigned long ptr)
> -{
> -	return 0;
> -}
> -#endif
>  
>  static inline int in_exception_text(unsigned long ptr)
>  {
> diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
> index 02e9035b0685..47a9066f7c86 100644
> --- a/arch/arm64/include/asm/traps.h
> +++ b/arch/arm64/include/asm/traps.h
> @@ -37,18 +37,11 @@ void unregister_undef_hook(struct undef_hook *hook);
>  
>  void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);
>  
> -#ifdef CONFIG_FUNCTION_GRAPH_TRACER
>  static inline int __in_irqentry_text(unsigned long ptr)
>  {
>  	return ptr >= (unsigned long)&__irqentry_text_start &&
>  	       ptr < (unsigned long)&__irqentry_text_end;
>  }
> -#else
> -static inline int __in_irqentry_text(unsigned long ptr)
> -{
> -	return 0;
> -}
> -#endif
>  
>  static inline int in_exception_text(unsigned long ptr)
>  {
> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
> index aa58155187c5..5e41396efbbf 100644
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -766,13 +766,8 @@ apicinterrupt3 \num trace(\sym) smp_trace(\sym)
>  #endif
>  
>  /* Make sure APIC interrupt handlers end up in the irqentry section: */
> -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
> -# define PUSH_SECTION_IRQENTRY	.pushsection .irqentry.text, "ax"
> -# define POP_SECTION_IRQENTRY	.popsection
> -#else
> -# define PUSH_SECTION_IRQENTRY
> -# define POP_SECTION_IRQENTRY
> -#endif
> +#define PUSH_SECTION_IRQENTRY	.pushsection .irqentry.text, "ax"
> +#define POP_SECTION_IRQENTRY	.popsection
>  
>  .macro apicinterrupt num sym do_sym
>  PUSH_SECTION_IRQENTRY
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index 532372c6cf15..e5da44eddd2f 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -27,6 +27,8 @@
>   *	__kprobes_text_start, __kprobes_text_end
>   *	__entry_text_start, __entry_text_end
>   *	__ctors_start, __ctors_end
> + *	__irqentry_text_start, __irqentry_text_end
> + *	__softirqentry_text_start, __softirqentry_text_end
>   */
>  extern char _text[], _stext[], _etext[];
>  extern char _data[], _sdata[], _edata[];
> @@ -39,6 +41,8 @@ extern char __per_cpu_load[], __per_cpu_start[], __per_cpu_end[];
>  extern char __kprobes_text_start[], __kprobes_text_end[];
>  extern char __entry_text_start[], __entry_text_end[];
>  extern char __start_rodata[], __end_rodata[];
> +extern char __irqentry_text_start[], __irqentry_text_end[];
> +extern char __softirqentry_text_start[], __softirqentry_text_end[];
>  
>  /* Start and end of .ctors section - used for constructor calls. */
>  extern char __ctors_start[], __ctors_end[];
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index fffc9bdae025..438b014c192f 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -483,25 +483,17 @@
>  		*(.entry.text)						\
>  		VMLINUX_SYMBOL(__entry_text_end) = .;
>  
> -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
>  #define IRQENTRY_TEXT							\
>  		ALIGN_FUNCTION();					\
>  		VMLINUX_SYMBOL(__irqentry_text_start) = .;		\
>  		*(.irqentry.text)					\
>  		VMLINUX_SYMBOL(__irqentry_text_end) = .;
> -#else
> -#define IRQENTRY_TEXT
> -#endif
>  
> -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
>  #define SOFTIRQENTRY_TEXT						\
>  		ALIGN_FUNCTION();					\
>  		VMLINUX_SYMBOL(__softirqentry_text_start) = .;		\
>  		*(.softirqentry.text)					\
>  		VMLINUX_SYMBOL(__softirqentry_text_end) = .;
> -#else
> -#define SOFTIRQENTRY_TEXT
> -#endif
>  
>  /* Section used for early init (in .S files) */
>  #define HEAD_TEXT  *(.head.text)
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index a2fddddb0d60..59ba11661b6e 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -18,6 +18,7 @@
>  #include <linux/atomic.h>
>  #include <asm/ptrace.h>
>  #include <asm/irq.h>
> +#include <asm/sections.h>
>  
>  /*
>   * These correspond to the IORESOURCE_IRQ_* defines in
> @@ -726,7 +727,6 @@ extern int early_irq_init(void);
>  extern int arch_probe_nr_irqs(void);
>  extern int arch_early_irq_init(void);
>  
> -#if defined(CONFIG_FUNCTION_GRAPH_TRACER) || defined(CONFIG_KASAN)
>  /*
>   * We want to know which function is an entrypoint of a hardirq or a softirq.
>   */
> @@ -734,16 +734,4 @@ extern int arch_early_irq_init(void);
>  #define __softirq_entry  \
>  	__attribute__((__section__(".softirqentry.text")))
>  
> -/* Limits of hardirq entrypoints */
> -extern char __irqentry_text_start[];
> -extern char __irqentry_text_end[];
> -/* Limits of softirq entrypoints */
> -extern char __softirqentry_text_start[];
> -extern char __softirqentry_text_end[];
> -
> -#else
> -#define __irq_entry
> -#define __softirq_entry
> -#endif
> -
>  #endif
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>