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Subject[PATCH -tip v8 07/26] [BUGFIX] x86: Prohibit probing on thunk functions and restore
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thunk/restore functions are also used for tracing irqoff etc.
and those are involved in kprobe's exception handling.
Prohibit probing on them to avoid kernel crash.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
arch/x86/lib/thunk_32.S | 3 ++-
arch/x86/lib/thunk_64.S | 3 +++
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/lib/thunk_32.S b/arch/x86/lib/thunk_32.S
index 2930ae0..28f85c91 100644
--- a/arch/x86/lib/thunk_32.S
+++ b/arch/x86/lib/thunk_32.S
@@ -4,8 +4,8 @@
* (inspired by Andi Kleen's thunk_64.S)
* Subject to the GNU public license, v.2. No warranty of any kind.
*/
-
#include <linux/linkage.h>
+ #include <asm/asm.h>

#ifdef CONFIG_TRACE_IRQFLAGS
/* put return address in eax (arg1) */
@@ -22,6 +22,7 @@
popl %ecx
popl %eax
ret
+ _ASM_NOKPROBE(\name)
.endm

thunk_ra trace_hardirqs_on_thunk,trace_hardirqs_on_caller
diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S
index a63efd6..92d9fea 100644
--- a/arch/x86/lib/thunk_64.S
+++ b/arch/x86/lib/thunk_64.S
@@ -8,6 +8,7 @@
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/calling.h>
+#include <asm/asm.h>

/* rdi: arg1 ... normal C conventions. rax is saved/restored. */
.macro THUNK name, func, put_ret_addr_in_rdi=0
@@ -25,6 +26,7 @@
call \func
jmp restore
CFI_ENDPROC
+ _ASM_NOKPROBE(\name)
.endm

#ifdef CONFIG_TRACE_IRQFLAGS
@@ -43,3 +45,4 @@ restore:
RESTORE_ARGS
ret
CFI_ENDPROC
+ _ASM_NOKPROBE(restore)



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