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perf, bpf: Introduce PERF_RECORD_BPF_EVENT 

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
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7
include/linux/filter.h
View File

@ -951,6 +951,7 @@ 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 */
@ -1006,6 +1007,12 @@ 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);

6
include/linux/perf_event.h
View File

@ -1125,6 +1125,9 @@ extern void perf_event_mmap(struct vm_area_struct *vma);
extern void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
bool unregister, const char *sym);
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);
@ -1350,6 +1353,9 @@ static inline void perf_event_mmap(struct vm_area_struct *vma) { }
typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);
static inline void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
bool unregister, const char *sym) { }
static inline void perf_event_bpf_event(struct bpf_prog *prog,
enum perf_bpf_event_type type,
u16 flags) { }
static inline void perf_event_exec(void) { }
static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
static inline void perf_event_namespaces(struct task_struct *tsk) { }

29
include/uapi/linux/perf_event.h
View File

@ -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 */
@ -979,6 +980,25 @@ 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 */
};
@ -990,6 +1010,13 @@ enum perf_record_ksymbol_type {
#define PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER (1 << 0)
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

2
kernel/bpf/core.c
View File

@ -495,7 +495,7 @@ 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;

2
kernel/bpf/syscall.c
View File

@ -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);
@ -1554,6 +1555,7 @@ 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:

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) {
/*