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Date: Wed, 13 Oct 2021 18:25:38 +0100
From: Mark Rutland <mark.rutland@....com>
To: Rob Herring <robh@...nel.org>,
Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
Catalin Marinas <catalin.marinas@....com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>,
Kan Liang <kan.liang@...ux.intel.com>,
Ian Rogers <irogers@...gle.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
honnappa.nagarahalli@....com, Zachary.Leaf@....com,
Raphael Gault <raphael.gault@....com>,
Jonathan Cameron <Jonathan.Cameron@...wei.com>,
Namhyung Kim <namhyung@...nel.org>,
Itaru Kitayama <itaru.kitayama@...il.com>,
Vince Weaver <vincent.weaver@...ne.edu>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>, x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v10 1/5] x86: perf: Move RDPMC event flag to a common
definition
Hi Rob,
On Tue, Sep 14, 2021 at 03:47:56PM -0500, Rob Herring wrote:
> In preparation to enable user counter access on arm64 and to move some
> of the user access handling to perf core, create a common event flag for
> user counter access and convert x86 to use it.
>
> Since the architecture specific flags start at the LSB, starting at the
> MSB for common flags.
Minor comments below (definition rename, and a comment block), but with
those:
Reviewed-by: Mark Rutland <mark.rutland@....com>
Peter, are you happy with this from the x86 side?
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Kan Liang <kan.liang@...ux.intel.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: x86@...nel.org
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: linux-perf-users@...r.kernel.org
> Signed-off-by: Rob Herring <robh@...nel.org>
> ---
> arch/x86/events/core.c | 10 +++++-----
> arch/x86/events/perf_event.h | 2 +-
> include/linux/perf_event.h | 2 ++
> 3 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
> index 2a57dbed4894..2bd50fc061e1 100644
> --- a/arch/x86/events/core.c
> +++ b/arch/x86/events/core.c
> @@ -2469,7 +2469,7 @@ static int x86_pmu_event_init(struct perf_event *event)
>
> if (READ_ONCE(x86_pmu.attr_rdpmc) &&
> !(event->hw.flags & PERF_X86_EVENT_LARGE_PEBS))
> - event->hw.flags |= PERF_X86_EVENT_RDPMC_ALLOWED;
> + event->hw.flags |= PERF_EVENT_FLAG_USER_READ_CNT;
>
> return err;
> }
> @@ -2503,7 +2503,7 @@ void perf_clear_dirty_counters(void)
>
> static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
> {
> - if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
> + if (!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT))
> return;
>
> /*
> @@ -2524,7 +2524,7 @@ static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)
>
> static void x86_pmu_event_unmapped(struct perf_event *event, struct mm_struct *mm)
> {
> - if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
> + if (!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT))
> return;
>
> if (atomic_dec_and_test(&mm->context.perf_rdpmc_allowed))
> @@ -2535,7 +2535,7 @@ static int x86_pmu_event_idx(struct perf_event *event)
> {
> struct hw_perf_event *hwc = &event->hw;
>
> - if (!(hwc->flags & PERF_X86_EVENT_RDPMC_ALLOWED))
> + if (!(hwc->flags & PERF_EVENT_FLAG_USER_READ_CNT))
> return 0;
>
> if (is_metric_idx(hwc->idx))
> @@ -2718,7 +2718,7 @@ void arch_perf_update_userpage(struct perf_event *event,
> userpg->cap_user_time = 0;
> userpg->cap_user_time_zero = 0;
> userpg->cap_user_rdpmc =
> - !!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED);
> + !!(event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT);
> userpg->pmc_width = x86_pmu.cntval_bits;
>
> if (!using_native_sched_clock() || !sched_clock_stable())
> diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
> index e3ac05c97b5e..49f68b15745f 100644
> --- a/arch/x86/events/perf_event.h
> +++ b/arch/x86/events/perf_event.h
> @@ -73,7 +73,7 @@ static inline bool constraint_match(struct event_constraint *c, u64 ecode)
> #define PERF_X86_EVENT_PEBS_NA_HSW 0x0010 /* haswell style datala, unknown */
> #define PERF_X86_EVENT_EXCL 0x0020 /* HT exclusivity on counter */
> #define PERF_X86_EVENT_DYNAMIC 0x0040 /* dynamic alloc'd constraint */
> -#define PERF_X86_EVENT_RDPMC_ALLOWED 0x0080 /* grant rdpmc permission */
> +
> #define PERF_X86_EVENT_EXCL_ACCT 0x0100 /* accounted EXCL event */
> #define PERF_X86_EVENT_AUTO_RELOAD 0x0200 /* use PEBS auto-reload */
> #define PERF_X86_EVENT_LARGE_PEBS 0x0400 /* use large PEBS */
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index fe156a8170aa..12debf008d39 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -142,6 +142,8 @@ struct hw_perf_event {
> int event_base_rdpmc;
> int idx;
> int last_cpu;
> +
> +#define PERF_EVENT_FLAG_USER_READ_CNT 0x80000000
I realise this matches the style of PERF_HES_* and PERF_EF_*. but could
we please arrange this like the PERF_PMU_CAP_* definitions, and move
this immediately before the struct hw_perf_event defintion, with a
comment block, e.g.
/*
* hw_perf_event::flag values
*
* PERF_EVENT_FLAG_ARCH bits are reserved for architecture-specific
* usage.
*/
#define PERF_EVENT_FLAG_ARCH 0x0000ffff
#define PERF_EVENT_FLAG_USER_READ_CNT 0x80000000
Thanks,
Mark.
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