Re: [RFC][PATCH 07/11] perf: Provide PERF_SAMPLE_REGS

Stephane Eranian
2010-03-03T17:49:40Z

On Wed, Mar 3, 2010 at 9:39 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, 2010-03-03 at 09:30 -0800, Stephane Eranian wrote:
>> This assumes struct pt_regs is somehow exported to userland.
>> Is that the case?
>
> I seems to have understood they were, and asm/ptrace.h seems to agree
> with that, it has !__KERNEL__ definitions for struct pt_regs.
>
Seems to be the case, indeed.

>> I would clearly spell out that the REGS are the interrupted REGS,
>> not the overflow REGS. Maybe PERF_SAMPLE_IREGS.
>
> They can be both, for PEBS they are the overflow trap (until PEBS does
> fault) regs.

You're saying without PEBS= interrupted state, with PEBS=overflow state.
That precludes requesting both interrupted + overflow state when PEBS is
enabled. That may be interesting to look at differences, distances (in the IP).