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authorLinus Torvalds <torvalds@linux-foundation.org>2022-01-23 17:31:24 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-23 17:31:24 +0200
commit0f9e04221227302d665bf64c69e5308360f4f88a (patch)
tree2813d2877d3ace1cf43be1d953fb58aef2d7505b /kernel
parente783362eb54cd99b2cac8b3a9aeac942e6f6ac07 (diff)
parent8c16dc047b5dd8f7b3bf4584fa75733ea0dde7dc (diff)
Merge tag 'perf_urgent_for_v5.17_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf fixes from Borislav Petkov: - Add support for accessing the general purpose counters on Alder Lake via MMIO - Add new LBR format v7 support which is v5 modulo TSX - Fix counter enumeration on Alder Lake hybrids - Overhaul how context time updates are done and get rid of perf_event::shadow_ctx_time. - The usual amount of fixes: event mask correction, supported event types reporting, etc. * tag 'perf_urgent_for_v5.17_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/perf: Avoid warning for Arch LBR without XSAVE perf/x86/intel/uncore: Add IMC uncore support for ADL perf/x86/intel/lbr: Add static_branch for LBR INFO flags perf/x86/intel/lbr: Support LBR format V7 perf/x86/rapl: fix AMD event handling perf/x86/intel/uncore: Fix CAS_COUNT_WRITE issue for ICX perf/x86/intel: Add a quirk for the calculation of the number of counters on Alder Lake perf: Fix perf_event_read_local() time
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c246
1 files changed, 146 insertions, 100 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index fc18664f49b0..479c9e672ec4 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -674,6 +674,23 @@ perf_event_set_state(struct perf_event *event, enum perf_event_state state)
WRITE_ONCE(event->state, state);
}
+/*
+ * UP store-release, load-acquire
+ */
+
+#define __store_release(ptr, val) \
+do { \
+ barrier(); \
+ WRITE_ONCE(*(ptr), (val)); \
+} while (0)
+
+#define __load_acquire(ptr) \
+({ \
+ __unqual_scalar_typeof(*(ptr)) ___p = READ_ONCE(*(ptr)); \
+ barrier(); \
+ ___p; \
+})
+
#ifdef CONFIG_CGROUP_PERF
static inline bool
@@ -719,34 +736,51 @@ static inline u64 perf_cgroup_event_time(struct perf_event *event)
return t->time;
}
-static inline void __update_cgrp_time(struct perf_cgroup *cgrp)
+static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
{
- struct perf_cgroup_info *info;
- u64 now;
-
- now = perf_clock();
+ struct perf_cgroup_info *t;
- info = this_cpu_ptr(cgrp->info);
+ t = per_cpu_ptr(event->cgrp->info, event->cpu);
+ if (!__load_acquire(&t->active))
+ return t->time;
+ now += READ_ONCE(t->timeoffset);
+ return now;
+}
- info->time += now - info->timestamp;
+static inline void __update_cgrp_time(struct perf_cgroup_info *info, u64 now, bool adv)
+{
+ if (adv)
+ info->time += now - info->timestamp;
info->timestamp = now;
+ /*
+ * see update_context_time()
+ */
+ WRITE_ONCE(info->timeoffset, info->time - info->timestamp);
}
-static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx, bool final)
{
struct perf_cgroup *cgrp = cpuctx->cgrp;
struct cgroup_subsys_state *css;
+ struct perf_cgroup_info *info;
if (cgrp) {
+ u64 now = perf_clock();
+
for (css = &cgrp->css; css; css = css->parent) {
cgrp = container_of(css, struct perf_cgroup, css);
- __update_cgrp_time(cgrp);
+ info = this_cpu_ptr(cgrp->info);
+
+ __update_cgrp_time(info, now, true);
+ if (final)
+ __store_release(&info->active, 0);
}
}
}
static inline void update_cgrp_time_from_event(struct perf_event *event)
{
+ struct perf_cgroup_info *info;
struct perf_cgroup *cgrp;
/*
@@ -760,8 +794,10 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
/*
* Do not update time when cgroup is not active
*/
- if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup))
- __update_cgrp_time(event->cgrp);
+ if (cgroup_is_descendant(cgrp->css.cgroup, event->cgrp->css.cgroup)) {
+ info = this_cpu_ptr(event->cgrp->info);
+ __update_cgrp_time(info, perf_clock(), true);
+ }
}
static inline void
@@ -785,7 +821,8 @@ perf_cgroup_set_timestamp(struct task_struct *task,
for (css = &cgrp->css; css; css = css->parent) {
cgrp = container_of(css, struct perf_cgroup, css);
info = this_cpu_ptr(cgrp->info);
- info->timestamp = ctx->timestamp;
+ __update_cgrp_time(info, ctx->timestamp, false);
+ __store_release(&info->active, 1);
}
}
@@ -982,14 +1019,6 @@ out:
}
static inline void
-perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
-{
- struct perf_cgroup_info *t;
- t = per_cpu_ptr(event->cgrp->info, event->cpu);
- event->shadow_ctx_time = now - t->timestamp;
-}
-
-static inline void
perf_cgroup_event_enable(struct perf_event *event, struct perf_event_context *ctx)
{
struct perf_cpu_context *cpuctx;
@@ -1066,7 +1095,8 @@ static inline void update_cgrp_time_from_event(struct perf_event *event)
{
}
-static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx)
+static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx,
+ bool final)
{
}
@@ -1098,12 +1128,12 @@ perf_cgroup_switch(struct task_struct *task, struct task_struct *next)
{
}
-static inline void
-perf_cgroup_set_shadow_time(struct perf_event *event, u64 now)
+static inline u64 perf_cgroup_event_time(struct perf_event *event)
{
+ return 0;
}
-static inline u64 perf_cgroup_event_time(struct perf_event *event)
+static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
{
return 0;
}
@@ -1525,22 +1555,59 @@ static void perf_unpin_context(struct perf_event_context *ctx)
/*
* Update the record of the current time in a context.
*/
-static void update_context_time(struct perf_event_context *ctx)
+static void __update_context_time(struct perf_event_context *ctx, bool adv)
{
u64 now = perf_clock();
- ctx->time += now - ctx->timestamp;
+ if (adv)
+ ctx->time += now - ctx->timestamp;
ctx->timestamp = now;
+
+ /*
+ * The above: time' = time + (now - timestamp), can be re-arranged
+ * into: time` = now + (time - timestamp), which gives a single value
+ * offset to compute future time without locks on.
+ *
+ * See perf_event_time_now(), which can be used from NMI context where
+ * it's (obviously) not possible to acquire ctx->lock in order to read
+ * both the above values in a consistent manner.
+ */
+ WRITE_ONCE(ctx->timeoffset, ctx->time - ctx->timestamp);
+}
+
+static void update_context_time(struct perf_event_context *ctx)
+{
+ __update_context_time(ctx, true);
}
static u64 perf_event_time(struct perf_event *event)
{
struct perf_event_context *ctx = event->ctx;
+ if (unlikely(!ctx))
+ return 0;
+
if (is_cgroup_event(event))
return perf_cgroup_event_time(event);
- return ctx ? ctx->time : 0;
+ return ctx->time;
+}
+
+static u64 perf_event_time_now(struct perf_event *event, u64 now)
+{
+ struct perf_event_context *ctx = event->ctx;
+
+ if (unlikely(!ctx))
+ return 0;
+
+ if (is_cgroup_event(event))
+ return perf_cgroup_event_time_now(event, now);
+
+ if (!(__load_acquire(&ctx->is_active) & EVENT_TIME))
+ return ctx->time;
+
+ now += READ_ONCE(ctx->timeoffset);
+ return now;
}
static enum event_type_t get_event_type(struct perf_event *event)
@@ -2350,7 +2417,7 @@ __perf_remove_from_context(struct perf_event *event,
if (ctx->is_active & EVENT_TIME) {
update_context_time(ctx);
- update_cgrp_time_from_cpuctx(cpuctx);
+ update_cgrp_time_from_cpuctx(cpuctx, false);
}
event_sched_out(event, cpuctx, ctx);
@@ -2361,6 +2428,9 @@ __perf_remove_from_context(struct perf_event *event,
list_del_event(event, ctx);
if (!ctx->nr_events && ctx->is_active) {
+ if (ctx == &cpuctx->ctx)
+ update_cgrp_time_from_cpuctx(cpuctx, true);
+
ctx->is_active = 0;
ctx->rotate_necessary = 0;
if (ctx->task) {
@@ -2482,40 +2552,6 @@ void perf_event_disable_inatomic(struct perf_event *event)
irq_work_queue(&event->pending);
}
-static void perf_set_shadow_time(struct perf_event *event,
- struct perf_event_context *ctx)
-{
- /*
- * use the correct time source for the time snapshot
- *
- * We could get by without this by leveraging the
- * fact that to get to this function, the caller
- * has most likely already called update_context_time()
- * and update_cgrp_time_xx() and thus both timestamp
- * are identical (or very close). Given that tstamp is,
- * already adjusted for cgroup, we could say that:
- * tstamp - ctx->timestamp
- * is equivalent to
- * tstamp - cgrp->timestamp.
- *
- * Then, in perf_output_read(), the calculation would
- * work with no changes because:
- * - event is guaranteed scheduled in
- * - no scheduled out in between
- * - thus the timestamp would be the same
- *
- * But this is a bit hairy.
- *
- * So instead, we have an explicit cgroup call to remain
- * within the time source all along. We believe it
- * is cleaner and simpler to understand.
- */
- if (is_cgroup_event(event))
- perf_cgroup_set_shadow_time(event, event->tstamp);
- else
- event->shadow_ctx_time = event->tstamp - ctx->timestamp;
-}
-
#define MAX_INTERRUPTS (~0ULL)
static void perf_log_throttle(struct perf_event *event, int enable);
@@ -2556,8 +2592,6 @@ event_sched_in(struct perf_event *event,
perf_pmu_disable(event->pmu);
- perf_set_shadow_time(event, ctx);
-
perf_log_itrace_start(event);
if (event->pmu->add(event, PERF_EF_START)) {
@@ -3251,16 +3285,6 @@ static void ctx_sched_out(struct perf_event_context *ctx,
return;
}
- ctx->is_active &= ~event_type;
- if (!(ctx->is_active & EVENT_ALL))
- ctx->is_active = 0;
-
- if (ctx->task) {
- WARN_ON_ONCE(cpuctx->task_ctx != ctx);
- if (!ctx->is_active)
- cpuctx->task_ctx = NULL;
- }
-
/*
* Always update time if it was set; not only when it changes.
* Otherwise we can 'forget' to update time for any but the last
@@ -3274,7 +3298,22 @@ static void ctx_sched_out(struct perf_event_context *ctx,
if (is_active & EVENT_TIME) {
/* update (and stop) ctx time */
update_context_time(ctx);
- update_cgrp_time_from_cpuctx(cpuctx);
+ update_cgrp_time_from_cpuctx(cpuctx, ctx == &cpuctx->ctx);
+ /*
+ * CPU-release for the below ->is_active store,
+ * see __load_acquire() in perf_event_time_now()
+ */
+ barrier();
+ }
+
+ ctx->is_active &= ~event_type;
+ if (!(ctx->is_active & EVENT_ALL))
+ ctx->is_active = 0;
+
+ if (ctx->task) {
+ WARN_ON_ONCE(cpuctx->task_ctx != ctx);
+ if (!ctx->is_active)
+ cpuctx->task_ctx = NULL;
}
is_active ^= ctx->is_active; /* changed bits */
@@ -3711,13 +3750,19 @@ static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx,
return 0;
}
+/*
+ * Because the userpage is strictly per-event (there is no concept of context,
+ * so there cannot be a context indirection), every userpage must be updated
+ * when context time starts :-(
+ *
+ * IOW, we must not miss EVENT_TIME edges.
+ */
static inline bool event_update_userpage(struct perf_event *event)
{
if (likely(!atomic_read(&event->mmap_count)))
return false;
perf_event_update_time(event);
- perf_set_shadow_time(event, event->ctx);
perf_event_update_userpage(event);
return true;
@@ -3801,13 +3846,23 @@ ctx_sched_in(struct perf_event_context *ctx,
struct task_struct *task)
{
int is_active = ctx->is_active;
- u64 now;
lockdep_assert_held(&ctx->lock);
if (likely(!ctx->nr_events))
return;
+ if (is_active ^ EVENT_TIME) {
+ /* start ctx time */
+ __update_context_time(ctx, false);
+ perf_cgroup_set_timestamp(task, ctx);
+ /*
+ * CPU-release for the below ->is_active store,
+ * see __load_acquire() in perf_event_time_now()
+ */
+ barrier();
+ }
+
ctx->is_active |= (event_type | EVENT_TIME);
if (ctx->task) {
if (!is_active)
@@ -3818,13 +3873,6 @@ ctx_sched_in(struct perf_event_context *ctx,
is_active ^= ctx->is_active; /* changed bits */
- if (is_active & EVENT_TIME) {
- /* start ctx time */
- now = perf_clock();
- ctx->timestamp = now;
- perf_cgroup_set_timestamp(task, ctx);
- }
-
/*
* First go through the list and put on any pinned groups
* in order to give them the best chance of going on.
@@ -4418,6 +4466,18 @@ static inline u64 perf_event_count(struct perf_event *event)
return local64_read(&event->count) + atomic64_read(&event->child_count);
}
+static void calc_timer_values(struct perf_event *event,
+ u64 *now,
+ u64 *enabled,
+ u64 *running)
+{
+ u64 ctx_time;
+
+ *now = perf_clock();
+ ctx_time = perf_event_time_now(event, *now);
+ __perf_update_times(event, ctx_time, enabled, running);
+}
+
/*
* NMI-safe method to read a local event, that is an event that
* is:
@@ -4477,10 +4537,9 @@ int perf_event_read_local(struct perf_event *event, u64 *value,
*value = local64_read(&event->count);
if (enabled || running) {
- u64 now = event->shadow_ctx_time + perf_clock();
- u64 __enabled, __running;
+ u64 __enabled, __running, __now;;
- __perf_update_times(event, now, &__enabled, &__running);
+ calc_timer_values(event, &__now, &__enabled, &__running);
if (enabled)
*enabled = __enabled;
if (running)
@@ -5802,18 +5861,6 @@ static int perf_event_index(struct perf_event *event)
return event->pmu->event_idx(event);
}
-static void calc_timer_values(struct perf_event *event,
- u64 *now,
- u64 *enabled,
- u64 *running)
-{
- u64 ctx_time;
-
- *now = perf_clock();
- ctx_time = event->shadow_ctx_time + *now;
- __perf_update_times(event, ctx_time, enabled, running);
-}
-
static void perf_event_init_userpage(struct perf_event *event)
{
struct perf_event_mmap_page *userpg;
@@ -6353,7 +6400,6 @@ accounting:
ring_buffer_attach(event, rb);
perf_event_update_time(event);
- perf_set_shadow_time(event, event->ctx);
perf_event_init_userpage(event);
perf_event_update_userpage(event);
} else {