On 06.04.2018 18:31, Andi Kleen wrote:
>> diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
>> index e47b2dbbdef3..9284048cf5b0 100644
>> --- a/arch/x86/kernel/perf_regs.c
>> +++ b/arch/x86/kernel/perf_regs.c
>> @@ -157,6 +157,15 @@ void perf_get_regs_user(struct perf_regs *regs_user,
>> */
>> regs_user_copy->bx = -1;
>> regs_user_copy->bp = -1;
>> + if (user_64bit_mode(user_regs)) {
>
> Why is it 64bit only? Should work on 32bit too.
bp register is a part of i386 syscall ABI
(http://man7.org/linux/man-pages/man2/syscall.2.html)
so not sure if it will make any sense for 32bit processes.
-Alexey
>
> -Andi
>
>> + /*
>> + * Store user space frame-pointer value on sample
>> + * to facilitate stack unwinding for cases when
>> + * user space x86_64 executable code has such
>> + * support enabled at compile time;
>> + */
>> + regs_user_copy->bp = user_regs->bp;
>> + }
>> regs_user_copy->r12 = -1;
>> regs_user_copy->r13 = -1;
>> regs_user_copy->r14 = -1;
>
