Re: [RFC PATCH 2/9] perf: Add ability to dump user regs

Frederic Weisbecker
2010-10-18T22:36:20Z

On Mon, Oct 18, 2010 at 12:01:18PM +0200, Stephane Eranian wrote:
> On Sun, Oct 17, 2010 at 12:07 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> > On Sat, 2010-10-16 at 00:58 +0200, Frederic Weisbecker wrote:
> >> > Yes, PEBS does not capture the entire state.
> >> >
> >> > Here is what you get on Intel Core:
> >> >         u64 flags, ip;
> >> >         u64 ax, bx, cx, dx;
> >> >         u64 si, di, bp, sp;
> >> >         u64 r8,  r9,  r10, r11;
> >> >         u64 r12, r13, r14, r15;
> >
> >> Ok, that seems to cover most of the state. I guess few people care
> >> about cs, ds, es, fs, gs, most of the time.
> >
> > Yeah, except if you want to profile wine or something like that ;-)
> >
> That means that if you want the segment registers, then you cannot
> use PEBS. I think you could catch that when the event is created.
>
> The other problem here is how to name registers at the API level.
> You would be introducing architecture-specific register names
> in perf_event.h. There is no such a thing today.

That can go into an asm/perf_regs.h or something. It's up to the
arch to name its registers.