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perf, bpf: Introduce PERF_RECORD_BPF_EVENT

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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 <songliubraving@fb.com>
Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradeaed.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel-team@fb.com
Cc: netdev@vger.kernel.org
Link: http://lkml.kernel.org/r/20190117161521.1341602-4-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Song Liu
2019-01-17 08:15:15 -08:00
committed by Arnaldo Carvalho de Melo
parent d764ac6464
commit 6ee52e2a3f
6 changed files with 159 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

115
kernel/events/core.c
View File

@@ -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))
@@ -7747,6 +7750,116 @@ err:
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 void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
enum perf_bpf_event_type type)
{
bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
char sym[KSYM_NAME_LEN];
int i;
if (prog->aux->func_cnt == 0) {
bpf_get_prog_name(prog, sym);
perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
(u64)(unsigned long)prog->bpf_func,
prog->jited_len, unregister, sym);
} else {
for (i = 0; i < prog->aux->func_cnt; i++) {
struct bpf_prog *subprog = prog->aux->func[i];
bpf_get_prog_name(subprog, sym);
perf_event_ksymbol(
PERF_RECORD_KSYMBOL_TYPE_BPF,
(u64)(unsigned long)subprog->bpf_func,
subprog->jited_len, unregister, sym);
}
}
}
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,
},
};
BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
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;
@@ -10008,6 +10121,8 @@ 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) {
/*