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Subject[PATCH 1/2] perf: Add persistent events
Date
From: Borislav Petkov <bp@alien8.de>

Register and enable events marked as persistent right after perf events
has initialized.

Not-yet-signed-off-by: Borislav Petkov <bp@alien8.de>
---
include/linux/ftrace_event.h | 10 +++++++
include/linux/perf_event.h | 1 +
kernel/perf_event.c | 59 +++++++++++++++++++++++++++++++++++++----
kernel/trace/trace.h | 1 -
4 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index c0f4b36..b40d637 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -13,6 +13,8 @@ struct dentry;

DECLARE_PER_CPU(struct trace_seq, ftrace_event_seq);

+extern struct list_head ftrace_events;
+
struct trace_print_flags {
unsigned long mask;
const char *name;
@@ -134,6 +136,7 @@ struct ftrace_event_call {
int perf_refcount;
int (*perf_event_enable)(struct ftrace_event_call *);
void (*perf_event_disable)(struct ftrace_event_call *);
+ unsigned int type;
};

#define PERF_MAX_TRACE_SIZE 2048
@@ -155,6 +158,13 @@ enum {
FILTER_PTR_STRING,
};

+enum event_type_t {
+ EVENT_FLEXIBLE = 0x1,
+ EVENT_PINNED = 0x2,
+ EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
+ EVENT_PERSISTENT = 0x3,
+};
+
extern int trace_event_raw_init(struct ftrace_event_call *call);
extern int trace_define_field(struct ftrace_event_call *call, const char *type,
const char *name, int offset, int size,
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c8e3754..aa62c97 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -579,6 +579,7 @@ struct perf_event {
struct list_head group_entry;
struct list_head event_entry;
struct list_head sibling_list;
+ struct list_head pevent_entry;
int nr_siblings;
int group_flags;
struct perf_event *group_leader;
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 3d1552d..84f2f36 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -72,6 +72,11 @@ static atomic64_t perf_event_id;
static DEFINE_SPINLOCK(perf_resource_lock);

/*
+ * persistent events which are always on
+ */
+DEFINE_PER_CPU(struct list_head, persistent_events);
+
+/*
* Architecture provided APIs - weak aliases:
*/
extern __weak const struct pmu *hw_perf_event_init(struct perf_event *event)
@@ -1017,12 +1022,6 @@ static int perf_event_refresh(struct perf_event *event, int refresh)
return 0;
}

-enum event_type_t {
- EVENT_FLEXIBLE = 0x1,
- EVENT_PINNED = 0x2,
- EVENT_ALL = EVENT_FLEXIBLE | EVENT_PINNED,
-};
-
static void ctx_sched_out(struct perf_event_context *ctx,
struct perf_cpu_context *cpuctx,
enum event_type_t event_type)
@@ -5385,6 +5384,8 @@ static void __init perf_event_init_all_cpus(void)
for_each_possible_cpu(cpu) {
cpuctx = &per_cpu(perf_cpu_context, cpu);
__perf_event_init_context(&cpuctx->ctx, NULL);
+
+ INIT_LIST_HEAD(&per_cpu(persistent_events, cpu));
}
}

@@ -5405,12 +5406,16 @@ static void __perf_event_exit_cpu(void *info)
struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
struct perf_event_context *ctx = &cpuctx->ctx;
struct perf_event *event, *tmp;
+ struct list_head *pers_events_list = &__get_cpu_var(persistent_events);

list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
__perf_event_remove_from_context(event);
list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
__perf_event_remove_from_context(event);
+ list_for_each_entry_safe(event, tmp, pers_events_list, pevent_entry)
+ __perf_event_remove_from_context(event);
}
+
static void perf_event_exit_cpu(int cpu)
{
struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu);
@@ -5456,6 +5461,46 @@ static struct notifier_block __cpuinitdata perf_cpu_nb = {
.priority = 20,
};

+static void __init perf_init_persistent_events(void)
+{
+
+ struct ftrace_event_call *call;
+ struct perf_event_attr attr;
+ struct perf_event *event;
+ int cpu;
+
+ list_for_each_entry(call, &ftrace_events, list) {
+
+ if (call->type != EVENT_PERSISTENT)
+ continue;
+
+ attr.type = PERF_TYPE_TRACEPOINT,
+ attr.config = call->id,
+ attr.size = sizeof(attr),
+
+ get_online_cpus();
+
+ for_each_online_cpu(cpu) {
+ struct list_head *list;
+
+ event = perf_event_create_kernel_counter(&attr, cpu, -1, NULL);
+ if (IS_ERR(event)) {
+ printk(KERN_ERR "Error initializing persistent "
+ "event %s on cpu %d\n",
+ call->name, cpu);
+ break;
+ }
+
+ list = &per_cpu(persistent_events, cpu);
+ list_add(&event->pevent_entry, list);
+
+ perf_event_enable(event);
+
+ }
+ put_online_cpus();
+ }
+}
+
void __init perf_event_init(void)
{
perf_event_init_all_cpus();
@@ -5464,6 +5509,8 @@ void __init perf_event_init(void)
perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
(void *)(long)smp_processor_id());
register_cpu_notifier(&perf_cpu_nb);
+
+ perf_init_persistent_events();
}

static ssize_t perf_show_reserve_percpu(struct sysdev_class *class,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2825ef2..95f5611 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -786,7 +786,6 @@ filter_check_discard(struct ftrace_event_call *call, void *rec,
}

extern struct mutex event_mutex;
-extern struct list_head ftrace_events;

extern const char *__start___trace_bprintk_fmt[];
extern const char *__stop___trace_bprintk_fmt[];
--
1.7.1


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