On Fri, Mar 26, 2010 at 05:02:30PM +1100, Paul Mackerras wrote:
> On Fri, Mar 26, 2010 at 02:52:35AM +0100, Frederic Weisbecker wrote:
>
> > The series is not yet mergeable because it would break PowerPc
> > (hot regs snapshot API has been changed, and I don't know how
> > to update PowerPc for that).
> >
> > But if you're fine with the ideas, I can integrate the necessary
> > changes to fix this, and also separate fixes and updates.
>
> The patch below adds the necessary stuff for powerpc. You could fold
> it into your "perf: Move perf_arch_fetch_caller_regs into a macro"
> patch, or keep it as a separate patch in the series (though that would
> make preserving bisectability more difficult).
>
> There is a little difficulty in that you first create a 3-argument
> form of perf_arch_fetch_caller_regs and then remove one argument in a
> later patch, whereas my patch below just creates the 2-argument form.
> I'm sure you can resolve that one way or another.
>
> The patch to add the old-style perf_arch_fetch_caller_regs for powerpc
> is sitting in the tip/perf/urgent branch but hasn't gone anywhere.
> I suppose we need to get Ingo to pull that branch into tip/perf/core
> and then include a revert patch in the series that switches to the new
> interface. Alternatively, if the urgent branch isn't append-only then
> we could disappear it (the urgent branch would need to be rewound by
> one commit).
Thanks a lot, that's axactly what I needed.
I'll sort it out to not break things in the middle :)
>
> Paul.
> ----------
> [PATCH] perf/powerpc: Implement perf_arch_fetch_caller_regs for powerpc
>
> This adds the ability to get a hot register snapshot for powerpc,
> enabling us to get meaningful call chains for tracepoints and context
> switch events.
>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
> ---
> arch/powerpc/include/asm/perf_event.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/perf_event.h b/arch/powerpc/include/asm/perf_event.h
> index e6d4ce6..5c16b89 100644
> --- a/arch/powerpc/include/asm/perf_event.h
> +++ b/arch/powerpc/include/asm/perf_event.h
> @@ -21,3 +21,15 @@
> #ifdef CONFIG_FSL_EMB_PERF_EVENT
> #include <asm/perf_event_fsl_emb.h>
> #endif
> +
> +#ifdef CONFIG_PERF_EVENTS
> +#include <asm/ptrace.h>
> +#include <asm/reg.h>
> +
> +#define perf_arch_fetch_caller_regs(regs, __ip) \
> + do { \
> + (regs)->nip = __ip; \
> + (regs)->gpr[1] = *(unsigned long *)__get_SP(); \
> + asm volatile("mfmsr %0" : "=r" ((regs)->msr)); \
> + } while (0)
> +#endif
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