[PATCH v13 1/5] x86: perf: Move RDPMC event flag to a common definition

Rob Herring
2021-12-08T20:13:27Z

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.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-perf-users@vger.kernel.org
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rob Herring <robh@kernel.org>
---
v11:
- Move PERF_EVENT_FLAG_USER_READ_CNT definition above struct
---
arch/x86/events/core.c | 10 +++++-----
arch/x86/events/perf_event.h | 2 +-
include/linux/perf_event.h | 9 +++++++++
3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 38b2c779146f..68dea7ce6a22 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2476,7 +2476,7 @@ 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;
}
@@ -2510,7 +2510,7 @@ 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;

/*
@@ -2531,7 +2531,7 @@ 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))
@@ -2542,7 +2542,7 @@ 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))
@@ -2725,7 +2725,7 @@ 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 5480db242083..9d376e528dfc 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -74,7 +74,7 @@ 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 0dcfd265beed..ba9467972c09 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -129,6 +129,15 @@ struct hw_perf_event_extra {
int idx; /* index in shared_regs->regs[] */
};

+/**
+ * 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
+
/**
* struct hw_perf_event - performance event hardware details:
*/