Re: [PATCH] perf regs x86: Fix arch__intr_reg_mask() for the hybrid platform

Arnaldo Carvalho de Melo
2022-05-20T14:15:14Z

Em Wed, May 18, 2022 at 09:38:20PM -0700, Ian Rogers escreveu:
> On Wed, May 18, 2022 at 7:52 AM <kan.liang@linux.intel.com> wrote:
> >
> > From: Kan Liang <kan.liang@linux.intel.com>
> >
> > The X86 specific arch__intr_reg_mask() is to check whether the kernel
> > and hardware can collect XMM registers. But it doesn't work on some
> > hybrid platform.
> >
> > Without the patch on ADL-N,
> >
> > $perf record -I?
> > available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9 R10
> > R11 R12 R13 R14 R15
> >
> > The config of the test event doesn't contain the PMU information. The
> > kernel may fail to initialize it on the correct hybrid PMU and return
> > the wrong non-supported information.
> >
> > Add the PMU information into the config for the hybrid platform. The
> > same register set is supported among different hybrid PMUs. Checking
> > the first available one is good enough.
> >
> > With the patch on ADL-N,
> >
> > $perf record -I?
> > available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9 R10
> > R11 R12 R13 R14 R15 XMM0 XMM1 XMM2 XMM3 XMM4 XMM5 XMM6 XMM7 XMM8 XMM9
> > XMM10 XMM11 XMM12 XMM13 XMM14 XMM15
> >
> > Fixes: 6466ec14aaf4 ("perf regs x86: Add X86 specific arch__intr_reg_mask()")
> > Reported-by: Ammy Yi <ammy.yi@intel.com>
> > Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>
> Acked-by: Ian Rogers <irogers@google.com>

Thanks, applied.

- Arnaldo

> > ---
> > tools/perf/arch/x86/util/perf_regs.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/tools/perf/arch/x86/util/perf_regs.c b/tools/perf/arch/x86/util/perf_regs.c
> > index 207c56805c55..0ed177991ad0 100644
> > --- a/tools/perf/arch/x86/util/perf_regs.c
> > +++ b/tools/perf/arch/x86/util/perf_regs.c
> > @@ -9,6 +9,8 @@
> > #include "../../../util/perf_regs.h"
> > #include "../../../util/debug.h"
> > #include "../../../util/event.h"
> > +#include "../../../util/pmu.h"
> > +#include "../../../util/pmu-hybrid.h"
> >
> > const struct sample_reg sample_reg_masks[] = {
> > SMPL_REG(AX, PERF_REG_X86_AX),
> > @@ -284,12 +286,22 @@ uint64_t arch__intr_reg_mask(void)
> > .disabled = 1,
> > .exclude_kernel = 1,
> > };
> > + struct perf_pmu *pmu;
>
> nit: this could have smaller scope if just be declared in the if-block.
>
> Thanks,
> Ian
>
> > int fd;
> > /*
> > * In an unnamed union, init it here to build on older gcc versions
> > */
> > attr.sample_period = 1;
> >
> > + if (perf_pmu__has_hybrid()) {
> > + /*
> > + * The same register set is supported among different hybrid PMUs.
> > + * Only check the first available one.
> > + */
> > + pmu = list_first_entry(&perf_pmu__hybrid_pmus, typeof(*pmu), hybrid_list);
> > + attr.config |= (__u64)pmu->type << PERF_PMU_TYPE_SHIFT;
> > + }
> > +
> > event_attr_init(&attr);
> >
> > fd = sys_perf_event_open(&attr, 0, -1, -1, 0);
> > --
> > 2.35.1
> >

--

- Arnaldo