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SubjectRe: [PATCH 2/4] x86/kprobes: Fix frame pointer annotations
On Wed, May 08, 2019 at 09:49:03AM +0200, Peter Zijlstra wrote:
> The kprobe trampolines have a FRAME_POINTER annotation that makes no
> sense. It marks the frame in the middle of pt_regs, at the place of
> saving BP.
>
> Change it to mark the pt_regs frame as per the ENCODE_FRAME_POINTER
> from the respective entry_*.S.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/x86/kernel/kprobes/common.h | 32 +++++++++++++++++++++++---------
> 1 file changed, 23 insertions(+), 9 deletions(-)
>
> --- a/arch/x86/kernel/kprobes/common.h
> +++ b/arch/x86/kernel/kprobes/common.h
> @@ -6,14 +6,15 @@
>
> #include <asm/asm.h>
>
> +#ifdef CONFIG_X86_64
> +
> #ifdef CONFIG_FRAME_POINTER
> -# define SAVE_RBP_STRING " push %" _ASM_BP "\n" \
> - " mov %" _ASM_SP ", %" _ASM_BP "\n"
> +#define ENCODE_FRAME_POINTER \
> + " leaq 1(%rsp), %rbp\n"
> #else
> -# define SAVE_RBP_STRING " push %" _ASM_BP "\n"
> +#define ENCODE_FRAME_POINTER
> #endif

> +#ifdef CONFIG_FRAME_POINTER
> +#define ENCODE_FRAME_POINTER \
> + " movl %esp, %ebp\n" \
> + " andl $0x7fffffff, %ebp\n"
> +#else
> +#define ENCODE_FRAME_POINTER
> +#endif

We should put these macros in a header file somewhere (including
stringified versions).

--
Josh

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