[PATCH 05/21] perf/x86/intel/lbr: Add pointers for LBR save and restore

kan.liang
2020-06-19T14:08:02Z

The MSRs of Architectural LBR are different from previous model-specific
LBR. Perf has to implement different functions to save and restore them.

The function pointers for LBR save and restore are introduced. Perf
should initialize the corresponding functions at boot time.

The generic optimizations, e.g. avoiding restore LBR if no one else
touched them, still apply for Architectural LBRs. The related codes are
not moved to model-specific functions.

Current model-specific LBR functions are set as default.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
arch/x86/events/intel/core.c | 4 +++
arch/x86/events/intel/lbr.c | 71 +++++++++++++++++++++++++++-----------------
arch/x86/events/perf_event.h | 6 ++++
3 files changed, 54 insertions(+), 27 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 03b17d5..b236cff 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3956,6 +3956,8 @@ static __initconst const struct x86_pmu core_pmu = {
.lbr_disable = intel_pmu_lbr_disable,
.lbr_reset = intel_pmu_lbr_reset_64,
.lbr_read = intel_pmu_lbr_read_64,
+ .lbr_save = intel_pmu_lbr_save,
+ .lbr_restore = intel_pmu_lbr_restore,
};

static __initconst const struct x86_pmu intel_pmu = {
@@ -4006,6 +4008,8 @@ static __initconst const struct x86_pmu intel_pmu = {
.lbr_disable = intel_pmu_lbr_disable,
.lbr_reset = intel_pmu_lbr_reset_64,
.lbr_read = intel_pmu_lbr_read_64,
+ .lbr_save = intel_pmu_lbr_save,
+ .lbr_restore = intel_pmu_lbr_restore,
};

static __init void intel_clovertown_quirk(void)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index d762c76..18f9990 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -323,11 +323,37 @@ static inline u64 rdlbr_to(unsigned int idx)
return val;
}

-static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
+void intel_pmu_lbr_restore(void *ctx)
{
- struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct x86_perf_task_context *task_ctx = ctx;
int i;
unsigned lbr_idx, mask;
+ u64 tos = task_ctx->tos;
+
+ mask = x86_pmu.lbr_nr - 1;
+ for (i = 0; i < task_ctx->valid_lbrs; i++) {
+ lbr_idx = (tos - i) & mask;
+ wrlbr_from(lbr_idx, task_ctx->lbr_from[i]);
+ wrlbr_to (lbr_idx, task_ctx->lbr_to[i]);
+
+ if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
+ wrmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
+ }
+
+ for (; i < x86_pmu.lbr_nr; i++) {
+ lbr_idx = (tos - i) & mask;
+ wrlbr_from(lbr_idx, 0);
+ wrlbr_to(lbr_idx, 0);
+ if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
+ wrmsrl(MSR_LBR_INFO_0 + lbr_idx, 0);
+ }
+
+ wrmsrl(x86_pmu.lbr_tos, tos);
+}
+
+static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
u64 tos;

if (task_ctx->lbr_callstack_users == 0 ||
@@ -349,40 +375,18 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
return;
}

- mask = x86_pmu.lbr_nr - 1;
- for (i = 0; i < task_ctx->valid_lbrs; i++) {
- lbr_idx = (tos - i) & mask;
- wrlbr_from(lbr_idx, task_ctx->lbr_from[i]);
- wrlbr_to (lbr_idx, task_ctx->lbr_to[i]);
-
- if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
- wrmsrl(MSR_LBR_INFO_0 + lbr_idx, task_ctx->lbr_info[i]);
- }
-
- for (; i < x86_pmu.lbr_nr; i++) {
- lbr_idx = (tos - i) & mask;
- wrlbr_from(lbr_idx, 0);
- wrlbr_to(lbr_idx, 0);
- if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
- wrmsrl(MSR_LBR_INFO_0 + lbr_idx, 0);
- }
+ x86_pmu.lbr_restore(task_ctx);

- wrmsrl(x86_pmu.lbr_tos, tos);
task_ctx->lbr_stack_state = LBR_NONE;
}

-static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
+void intel_pmu_lbr_save(void *ctx)
{
- struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+ struct x86_perf_task_context *task_ctx = ctx;
unsigned lbr_idx, mask;
u64 tos, from;
int i;

- if (task_ctx->lbr_callstack_users == 0) {
- task_ctx->lbr_stack_state = LBR_NONE;
- return;
- }
-
mask = x86_pmu.lbr_nr - 1;
tos = intel_pmu_lbr_tos();
for (i = 0; i < x86_pmu.lbr_nr; i++) {
@@ -397,6 +401,19 @@ static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
}
task_ctx->valid_lbrs = i;
task_ctx->tos = tos;
+}
+
+static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
+{
+ struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+ if (task_ctx->lbr_callstack_users == 0) {
+ task_ctx->lbr_stack_state = LBR_NONE;
+ return;
+ }
+
+ x86_pmu.lbr_save(task_ctx);
+
task_ctx->lbr_stack_state = LBR_VALID;

cpuc->last_task_ctx = task_ctx;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index e2e086c0..7c67847 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -694,6 +694,8 @@ struct x86_pmu {
void (*lbr_disable)(void);
void (*lbr_reset)(void);
void (*lbr_read)(struct cpu_hw_events *cpuc);
+ void (*lbr_save)(void *ctx);
+ void (*lbr_restore)(void *ctx);

/*
* Intel PT/LBR/BTS are exclusive
@@ -1091,6 +1093,10 @@ void intel_pmu_lbr_read_32(struct cpu_hw_events *cpuc);

void intel_pmu_lbr_read_64(struct cpu_hw_events *cpuc);

+void intel_pmu_lbr_save(void *ctx);
+
+void intel_pmu_lbr_restore(void *ctx);
+
void intel_pmu_lbr_init_core(void);

void intel_pmu_lbr_init_nhm(void);
--
2.7.4