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authorAlexander Shishkin <alexander.shishkin@linux.intel.com>2017-03-30 18:39:56 +0300
committerIngo Molnar <mingo@kernel.org>2017-08-29 15:09:24 +0200
commit8d4e6c4caa12dafbcba138e5450b7af17b0b2194 (patch)
treea9b6c4f3076bd27f9a87fb67a2907c9a0a3c5cbd
parente0563e049531973e665db853e825a4efed9f881d (diff)
perf/core, pt, bts: Get rid of itrace_started
I just noticed that hw.itrace_started and hw.config are aliased to the same location. Now, the PT driver happens to use both, which works out fine by sheer luck: - STORE(hw.itrace_start) is ordered before STORE(hw.config), in the program order, although there are no compiler barriers to ensure that, - to the perf_log_itrace_start() hw.itrace_start looks set at the same time as when it is intended to be set because both stores happen in the same path, - hw.config is never reset to zero in the PT driver. Now, the use of hw.config by the PT driver makes more sense (it being a HW PMU) than messing around with itrace_started, which is an awkward API to begin with. This patch replaces hw.itrace_started with an attach_state bit and an API call for the PMU drivers to use to communicate the condition. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: vince@deater.net Link: http://lkml.kernel.org/r/20170330153956.25994-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/events/intel/bts.c2
-rw-r--r--arch/x86/events/intel/pt.c5
-rw-r--r--include/linux/perf_event.h5
-rw-r--r--kernel/events/core.c7
4 files changed, 12 insertions, 7 deletions
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index ddd8d3516bfc..16076eb34699 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -268,7 +268,7 @@ static void bts_event_start(struct perf_event *event, int flags)
bts->ds_back.bts_absolute_maximum = cpuc->ds->bts_absolute_maximum;
bts->ds_back.bts_interrupt_threshold = cpuc->ds->bts_interrupt_threshold;
- event->hw.itrace_started = 1;
+ perf_event_itrace_started(event);
event->hw.state = 0;
__bts_event_start(event);
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index ae8324d65e61..81fd41d5a0d9 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -471,8 +471,9 @@ static void pt_config(struct perf_event *event)
struct pt *pt = this_cpu_ptr(&pt_ctx);
u64 reg;
- if (!event->hw.itrace_started) {
- event->hw.itrace_started = 1;
+ /* First round: clear STATUS, in particular the PSB byte counter. */
+ if (!event->hw.config) {
+ perf_event_itrace_started(event);
wrmsrl(MSR_IA32_RTIT_STATUS, 0);
}
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c00cd4b02f32..adda0aaae6c8 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -147,9 +147,6 @@ struct hw_perf_event {
struct list_head cqm_groups_entry;
struct list_head cqm_group_entry;
};
- struct { /* itrace */
- int itrace_started;
- };
struct { /* amd_power */
u64 pwr_acc;
u64 ptsc;
@@ -541,6 +538,7 @@ struct swevent_hlist {
#define PERF_ATTACH_GROUP 0x02
#define PERF_ATTACH_TASK 0x04
#define PERF_ATTACH_TASK_DATA 0x08
+#define PERF_ATTACH_ITRACE 0x10
struct perf_cgroup;
struct ring_buffer;
@@ -864,6 +862,7 @@ extern int perf_aux_output_skip(struct perf_output_handle *handle,
unsigned long size);
extern void *perf_get_aux(struct perf_output_handle *handle);
extern void perf_aux_output_flag(struct perf_output_handle *handle, u64 flags);
+extern void perf_event_itrace_started(struct perf_event *event);
extern int perf_pmu_register(struct pmu *pmu, const char *name, int type);
extern void perf_pmu_unregister(struct pmu *pmu);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e5467e107624..77fd6b11ef22 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7301,6 +7301,11 @@ static void perf_log_throttle(struct perf_event *event, int enable)
perf_output_end(&handle);
}
+void perf_event_itrace_started(struct perf_event *event)
+{
+ event->attach_state |= PERF_ATTACH_ITRACE;
+}
+
static void perf_log_itrace_start(struct perf_event *event)
{
struct perf_output_handle handle;
@@ -7316,7 +7321,7 @@ static void perf_log_itrace_start(struct perf_event *event)
event = event->parent;
if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) ||
- event->hw.itrace_started)
+ event->attach_state & PERF_ATTACH_ITRACE)
return;
rec.header.type = PERF_RECORD_ITRACE_START;