For better performance analysis of BPF programs, this patch introduces
PERF_RECORD_BPF_EVENT, a new perf_event_type that exposes BPF program
load/unload information to user space.
Each BPF program may contain up to BPF_MAX_SUBPROGS (256) sub programs.
The following example shows kernel symbols for a BPF program with 7
sub programs:
ffffffffa0257cf9 t bpf_prog_b07ccb89267cf242_F
ffffffffa02592e1 t bpf_prog_2dcecc18072623fc_F
ffffffffa025b0e9 t bpf_prog_bb7a405ebaec5d5c_F
ffffffffa025dd2c t bpf_prog_a7540d4a39ec1fc7_F
ffffffffa025fcca t bpf_prog_05762d4ade0e3737_F
ffffffffa026108f t bpf_prog_db4bd11e35df90d4_F
ffffffffa0263f00 t bpf_prog_89d64e4abf0f0126_F
ffffffffa0257cf9 t bpf_prog_ae31629322c4b018__dummy_tracepoi
When a bpf program is loaded, PERF_RECORD_KSYMBOL is generated for
each of these sub programs. Therefore, PERF_RECORD_BPF_EVENT is not
needed for simple profiling.
For annotation, user space need to listen to PERF_RECORD_BPF_EVENT
and gather more information about these (sub) programs via sys_bpf.
Signed-off-by: Song Liu <songliubrav...@fb.com>
---
include/linux/filter.h | 7 ++
include/linux/perf_event.h | 3 +
include/uapi/linux/perf_event.h | 29 +++++++-
kernel/bpf/core.c | 2 +-
kernel/bpf/syscall.c | 2 +
kernel/events/core.c | 120 ++++++++++++++++++++++++++++++++
6 files changed, 161 insertions(+), 2 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 537e9e7c6e6f..45d23560f90b 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -955,6 +955,7 @@ bpf_address_lookup(unsigned long addr, unsigned long *size,
void bpf_prog_kallsyms_add(struct bpf_prog *fp);
void bpf_prog_kallsyms_del(struct bpf_prog *fp);
+void bpf_get_prog_name(const struct bpf_prog *prog, char *sym);
#else /* CONFIG_BPF_JIT */
@@ -1010,6 +1011,12 @@ static inline void bpf_prog_kallsyms_add(struct bpf_prog
*fp)
static inline void bpf_prog_kallsyms_del(struct bpf_prog *fp)
{
}
+
+static inline void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
+{
+ sym[0] = '\0';
+}
+
#endif /* CONFIG_BPF_JIT */
void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp);
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 4fd28b16c526..8e752a244ed7 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1118,6 +1118,9 @@ extern void perf_event_mmap(struct vm_area_struct *vma);
typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);
extern void perf_event_ksymbol(int type, u64 addr, u64 len, bool unregister,
perf_ksymbol_get_name_f get_name, void *data);
+extern void perf_event_bpf_event(struct bpf_prog *prog,
+ enum perf_bpf_event_type type,
+ u16 flags);
extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks
*callbacks);
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index 6c9e327e87ed..68db04058408 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -373,7 +373,8 @@ struct perf_event_attr {
write_backward : 1, /* Write ring buffer from
end to beginning */
namespaces : 1, /* include namespaces data
*/
ksymbol : 1, /* include ksymbol events
*/
- __reserved_1 : 34;
+ bpf_event : 1, /* include bpf events */
+ __reserved_1 : 33;
union {
__u32 wakeup_events; /* wakeup every n events */
@@ -986,9 +987,35 @@ enum perf_event_type {
*/
PERF_RECORD_KSYMBOL = 17,
+ /*
+ * Record bpf events:
+ * enum perf_bpf_event_type {
+ * PERF_BPF_EVENT_UNKNOWN = 0,
+ * PERF_BPF_EVENT_PROG_LOAD = 1,
+ * PERF_BPF_EVENT_PROG_UNLOAD = 2,
+ * };
+ *
+ * struct {
+ * struct perf_event_header header;
+ * u16 type;
+ * u16 flags;
+ * u32 id;
+ * u8 tag[BPF_TAG_SIZE];
+ * struct sample_id sample_id;
+ * };
+ */
+ PERF_RECORD_BPF_EVENT = 18,
+
PERF_RECORD_MAX, /* non-ABI */
};
+enum perf_bpf_event_type {
+ PERF_BPF_EVENT_UNKNOWN = 0,
+ PERF_BPF_EVENT_PROG_LOAD = 1,
+ PERF_BPF_EVENT_PROG_UNLOAD = 2,
+ PERF_BPF_EVENT_MAX, /* non-ABI */
+};
+
#define PERF_MAX_STACK_DEPTH 127
#define PERF_MAX_CONTEXTS_PER_STACK 8
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 5cdd8da0e7f2..2a8364294f11 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -496,7 +496,7 @@ bpf_get_prog_addr_region(const struct bpf_prog *prog,
*symbol_end = addr + hdr->pages * PAGE_SIZE;
}
-static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
+void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
{
const char *end = sym + KSYM_NAME_LEN;
const struct btf_type *type;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 6ae062f1cf20..5e9bf04b785e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1211,6 +1211,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
{
if (atomic_dec_and_test(&prog->aux->refcnt)) {
+ perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0);
/* bpf_prog_free_id() must be called first */
bpf_prog_free_id(prog, do_idr_lock);
bpf_prog_kallsyms_del_all(prog);
@@ -1559,6 +1560,7 @@ static int bpf_prog_load(union bpf_attr *attr, union
bpf_attr __user *uattr)
}
bpf_prog_kallsyms_add(prog);
+ perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_LOAD, 0);
return err;
free_used_maps:
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c0ac6dee367c..04feb2b28c46 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -386,6 +386,7 @@ static atomic_t nr_task_events __read_mostly;
static atomic_t nr_freq_events __read_mostly;
static atomic_t nr_switch_events __read_mostly;
static atomic_t nr_ksymbol_events __read_mostly;
+static atomic_t nr_bpf_events __read_mostly;
static LIST_HEAD(pmus);
static DEFINE_MUTEX(pmus_lock);
@@ -4308,6 +4309,8 @@ static void unaccount_event(struct perf_event *event)
dec = true;
if (event->attr.ksymbol)
atomic_dec(&nr_ksymbol_events);
+ if (event->attr.bpf_event)
+ atomic_dec(&nr_bpf_events);
if (dec) {
if (!atomic_add_unless(&perf_sched_count, -1, 1))
@@ -7744,6 +7747,121 @@ void perf_event_ksymbol(int ksym_type, u64 addr, u64
len, bool unregister,
WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
}
+/*
+ * bpf program load/unload tracking
+ */
+
+struct perf_bpf_event {
+ struct bpf_prog *prog;
+ struct {
+ struct perf_event_header header;
+ u16 type;
+ u16 flags;
+ u32 id;
+ u8 tag[BPF_TAG_SIZE];
+ } event_id;
+};
+
+static int perf_event_bpf_match(struct perf_event *event)
+{
+ return event->attr.bpf_event;
+}
+
+static void perf_event_bpf_output(struct perf_event *event, void *data)
+{
+ struct perf_bpf_event *bpf_event = data;
+ struct perf_output_handle handle;
+ struct perf_sample_data sample;
+ int ret;
+
+ if (!perf_event_bpf_match(event))
+ return;
+
+ perf_event_header__init_id(&bpf_event->event_id.header,
+ &sample, event);
+ ret = perf_output_begin(&handle, event,
+ bpf_event->event_id.header.size);
+ if (ret)
+ return;
+
+ perf_output_put(&handle, bpf_event->event_id);
+ perf_event__output_id_sample(event, &handle, &sample);
+
+ perf_output_end(&handle);
+}
+
+static int perf_event_bpf_get_name(char *name, int len, void *data)
+{
+ struct bpf_prog *prog = data;
+
+ bpf_get_prog_name(prog, name);
+ return 0;
+}
+
+static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
+ enum perf_bpf_event_type type)
+{
+ bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
+ int i;
+
+ if (prog->aux->func_cnt == 0) {
+ perf_event_ksymbol(PERF_RECORD_MISC_KSYMBOL_TYPE_BPF,
+ (u64)(unsigned long)prog->bpf_func,
+ prog->jited_len, unregister,
+ perf_event_bpf_get_name, prog);
+ } else {
+ for (i = 0; i < prog->aux->func_cnt; i++) {
+ struct bpf_prog *subprog = prog->aux->func[i];
+
+ perf_event_ksymbol(
+ PERF_RECORD_MISC_KSYMBOL_TYPE_BPF,
+ (u64)(unsigned long)subprog->bpf_func,
+ subprog->jited_len, unregister,
+ perf_event_bpf_get_name, subprog);
+ }
+ }
+}
+
+void perf_event_bpf_event(struct bpf_prog *prog,
+ enum perf_bpf_event_type type,
+ u16 flags)
+{
+ struct perf_bpf_event bpf_event;
+
+ if (type <= PERF_BPF_EVENT_UNKNOWN ||
+ type >= PERF_BPF_EVENT_MAX)
+ return;
+
+ switch (type) {
+ case PERF_BPF_EVENT_PROG_LOAD:
+ case PERF_BPF_EVENT_PROG_UNLOAD:
+ if (atomic_read(&nr_ksymbol_events))
+ perf_event_bpf_emit_ksymbols(prog, type);
+ break;
+ default:
+ break;
+ }
+
+ if (!atomic_read(&nr_bpf_events))
+ return;
+
+ bpf_event = (struct perf_bpf_event){
+ .prog = prog,
+ .event_id = {
+ .header = {
+ .type = PERF_RECORD_BPF_EVENT,
+ .size = sizeof(bpf_event.event_id),
+ },
+ .type = type,
+ .flags = flags,
+ .id = prog->aux->id,
+ },
+ };
+
+ memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
+ perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
+}
+
void perf_event_itrace_started(struct perf_event *event)
{
event->attach_state |= PERF_ATTACH_ITRACE;
@@ -9996,6 +10114,8 @@ static void account_event(struct perf_event *event)
inc = true;
if (event->attr.ksymbol)
atomic_inc(&nr_ksymbol_events);
+ if (event->attr.bpf_event)
+ atomic_inc(&nr_bpf_events);
if (inc) {
/*
--
2.17.1
