[PATCH 07/21] perf/x86/intel/lbr: Use dynamic data structure for task_ctx

kan.liang
2020-06-19T14:08:04Z

The type of task_ctx is hardcoded as struct x86_perf_task_context,
which doesn't apply for Architecture LBR. For example, Architecture LBR
doesn't have the TOS MSR. The number of LBR entries is variable. A new
struct will be introduced for Architecture LBR. Perf has to determine
the type of task_ctx at run time.

The type of task_ctx pointer is changed to 'void *', which will be
determined at run time.

The generic LBR optimization can be shared between Architecture LBR and
model-specific LBR. Both need to access the structure for the generic
LBR optimization. A helper task_context_opt() is introduced to retrieve
the pointer of the structure at run time.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
---
arch/x86/events/intel/lbr.c | 58 ++++++++++++++++++++------------------------
arch/x86/events/perf_event.h | 7 +++++-
2 files changed, 32 insertions(+), 33 deletions(-)

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index f220a4c..1c253ab 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -351,17 +351,17 @@ void intel_pmu_lbr_restore(void *ctx)
wrmsrl(x86_pmu.lbr_tos, tos);
}

-static bool lbr_is_reset_in_cstate(struct x86_perf_task_context *task_ctx)
+static bool lbr_is_reset_in_cstate(void *ctx)
{
- return !rdlbr_from(task_ctx->tos);
+ return !rdlbr_from(((struct x86_perf_task_context *)ctx)->tos);
}

-static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
+static void __intel_pmu_lbr_restore(void *ctx)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

- if (task_ctx->opt.lbr_callstack_users == 0 ||
- task_ctx->opt.lbr_stack_state == LBR_NONE) {
+ if (task_context_opt(ctx)->lbr_callstack_users == 0 ||
+ task_context_opt(ctx)->lbr_stack_state == LBR_NONE) {
intel_pmu_lbr_reset();
return;
}
@@ -371,16 +371,16 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
* - No one else touched them, and
* - Was not cleared in Cstate
*/
- if ((task_ctx == cpuc->last_task_ctx) &&
- (task_ctx->opt.log_id == cpuc->last_log_id) &&
- !lbr_is_reset_in_cstate(task_ctx)) {
- task_ctx->opt.lbr_stack_state = LBR_NONE;
+ if ((ctx == cpuc->last_task_ctx) &&
+ (task_context_opt(ctx)->log_id == cpuc->last_log_id) &&
+ !lbr_is_reset_in_cstate(ctx)) {
+ task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
return;
}

- x86_pmu.lbr_restore(task_ctx);
+ x86_pmu.lbr_restore(ctx);

- task_ctx->opt.lbr_stack_state = LBR_NONE;
+ task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
}

void intel_pmu_lbr_save(void *ctx)
@@ -406,27 +406,27 @@ void intel_pmu_lbr_save(void *ctx)
task_ctx->tos = tos;
}

-static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
+static void __intel_pmu_lbr_save(void *ctx)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

- if (task_ctx->opt.lbr_callstack_users == 0) {
- task_ctx->opt.lbr_stack_state = LBR_NONE;
+ if (task_context_opt(ctx)->lbr_callstack_users == 0) {
+ task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
return;
}

- x86_pmu.lbr_save(task_ctx);
+ x86_pmu.lbr_save(ctx);

- task_ctx->opt.lbr_stack_state = LBR_VALID;
+ task_context_opt(ctx)->lbr_stack_state = LBR_VALID;

- cpuc->last_task_ctx = task_ctx;
- cpuc->last_log_id = ++task_ctx->opt.log_id;
+ cpuc->last_task_ctx = ctx;
+ cpuc->last_log_id = ++task_context_opt(ctx)->log_id;
}

void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
struct perf_event_context *next)
{
- struct x86_perf_task_context *prev_ctx_data, *next_ctx_data;
+ void *prev_ctx_data, *next_ctx_data;

swap(prev->task_ctx_data, next->task_ctx_data);

@@ -442,14 +442,14 @@ void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
if (!prev_ctx_data || !next_ctx_data)
return;

- swap(prev_ctx_data->opt.lbr_callstack_users,
- next_ctx_data->opt.lbr_callstack_users);
+ swap(task_context_opt(prev_ctx_data)->lbr_callstack_users,
+ task_context_opt(next_ctx_data)->lbr_callstack_users);
}

void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
- struct x86_perf_task_context *task_ctx;
+ void *task_ctx;

if (!cpuc->lbr_users)
return;
@@ -486,17 +486,14 @@ static inline bool branch_user_callstack(unsigned br_sel)
void intel_pmu_lbr_add(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
- struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;

cpuc->br_sel = event->hw.branch_reg.reg;

- if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data) {
- task_ctx = event->ctx->task_ctx_data;
- task_ctx->opt.lbr_callstack_users++;
- }
+ if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data)
+ task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users++;

/*
* Request pmu::sched_task() callback, which will fire inside the
@@ -527,16 +524,13 @@ void intel_pmu_lbr_add(struct perf_event *event)
void intel_pmu_lbr_del(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
- struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;

if (branch_user_callstack(cpuc->br_sel) &&
- event->ctx->task_ctx_data) {
- task_ctx = event->ctx->task_ctx_data;
- task_ctx->opt.lbr_callstack_users--;
- }
+ event->ctx->task_ctx_data)
+ task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users--;

if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip > 0)
cpuc->lbr_pebs_users--;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index fd73c6c..e33d348 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -246,7 +246,7 @@ struct cpu_hw_events {
struct perf_branch_entry lbr_entries[MAX_LBR_ENTRIES];
struct er_account *lbr_sel;
u64 br_sel;
- struct x86_perf_task_context *last_task_ctx;
+ void *last_task_ctx;
int last_log_id;

/*
@@ -798,6 +798,11 @@ static struct perf_pmu_events_ht_attr event_attr_##v = { \
struct pmu *x86_get_pmu(void);
extern struct x86_pmu x86_pmu __read_mostly;

+static inline struct x86_perf_task_context_opt *task_context_opt(void *ctx)
+{
+ return &((struct x86_perf_task_context *)ctx)->opt;
+}
+
static inline bool x86_pmu_has_lbr_callstack(void)
{
return x86_pmu.lbr_sel_map &&
--
2.7.4