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>
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@ -951,6 +951,7 @@ bpf_address_lookup(unsigned long addr, unsigned long *size,
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void bpf_prog_kallsyms_add(struct bpf_prog *fp);
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void bpf_prog_kallsyms_del(struct bpf_prog *fp);
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void bpf_get_prog_name(const struct bpf_prog *prog, char *sym);
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#else /* CONFIG_BPF_JIT */
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@ -1006,6 +1007,12 @@ static inline void bpf_prog_kallsyms_add(struct bpf_prog *fp)
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static inline void bpf_prog_kallsyms_del(struct bpf_prog *fp)
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{
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}
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static inline void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
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{
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sym[0] = '\0';
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}
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#endif /* CONFIG_BPF_JIT */
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void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp);
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@ -1125,6 +1125,9 @@ extern void perf_event_mmap(struct vm_area_struct *vma);
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extern void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
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bool unregister, const char *sym);
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extern void perf_event_bpf_event(struct bpf_prog *prog,
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enum perf_bpf_event_type type,
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u16 flags);
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extern struct perf_guest_info_callbacks *perf_guest_cbs;
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extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
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@ -1350,6 +1353,9 @@ static inline void perf_event_mmap(struct vm_area_struct *vma) { }
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typedef int (perf_ksymbol_get_name_f)(char *name, int name_len, void *data);
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static inline void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len,
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bool unregister, const char *sym) { }
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static inline void perf_event_bpf_event(struct bpf_prog *prog,
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enum perf_bpf_event_type type,
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u16 flags) { }
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static inline void perf_event_exec(void) { }
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static inline void perf_event_comm(struct task_struct *tsk, bool exec) { }
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static inline void perf_event_namespaces(struct task_struct *tsk) { }
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@ -373,7 +373,8 @@ struct perf_event_attr {
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write_backward : 1, /* Write ring buffer from end to beginning */
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namespaces : 1, /* include namespaces data */
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ksymbol : 1, /* include ksymbol events */
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__reserved_1 : 34;
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bpf_event : 1, /* include bpf events */
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__reserved_1 : 33;
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union {
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__u32 wakeup_events; /* wakeup every n events */
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@ -979,6 +980,25 @@ enum perf_event_type {
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*/
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PERF_RECORD_KSYMBOL = 17,
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/*
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* Record bpf events:
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* enum perf_bpf_event_type {
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* PERF_BPF_EVENT_UNKNOWN = 0,
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* PERF_BPF_EVENT_PROG_LOAD = 1,
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* PERF_BPF_EVENT_PROG_UNLOAD = 2,
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* };
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*
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* struct {
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* struct perf_event_header header;
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* u16 type;
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* u16 flags;
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* u32 id;
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* u8 tag[BPF_TAG_SIZE];
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* struct sample_id sample_id;
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* };
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*/
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PERF_RECORD_BPF_EVENT = 18,
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PERF_RECORD_MAX, /* non-ABI */
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};
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@ -990,6 +1010,13 @@ enum perf_record_ksymbol_type {
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#define PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER (1 << 0)
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enum perf_bpf_event_type {
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PERF_BPF_EVENT_UNKNOWN = 0,
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PERF_BPF_EVENT_PROG_LOAD = 1,
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PERF_BPF_EVENT_PROG_UNLOAD = 2,
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PERF_BPF_EVENT_MAX, /* non-ABI */
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};
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#define PERF_MAX_STACK_DEPTH 127
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#define PERF_MAX_CONTEXTS_PER_STACK 8
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@ -495,7 +495,7 @@ bpf_get_prog_addr_region(const struct bpf_prog *prog,
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*symbol_end = addr + hdr->pages * PAGE_SIZE;
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}
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static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
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void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
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{
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const char *end = sym + KSYM_NAME_LEN;
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const struct btf_type *type;
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@ -1211,6 +1211,7 @@ static void __bpf_prog_put_rcu(struct rcu_head *rcu)
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static void __bpf_prog_put(struct bpf_prog *prog, bool do_idr_lock)
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{
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if (atomic_dec_and_test(&prog->aux->refcnt)) {
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perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_UNLOAD, 0);
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/* bpf_prog_free_id() must be called first */
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bpf_prog_free_id(prog, do_idr_lock);
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bpf_prog_kallsyms_del_all(prog);
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@ -1554,6 +1555,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
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}
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bpf_prog_kallsyms_add(prog);
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perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_LOAD, 0);
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return err;
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free_used_maps:
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@ -386,6 +386,7 @@ static atomic_t nr_task_events __read_mostly;
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static atomic_t nr_freq_events __read_mostly;
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static atomic_t nr_switch_events __read_mostly;
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static atomic_t nr_ksymbol_events __read_mostly;
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static atomic_t nr_bpf_events __read_mostly;
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static LIST_HEAD(pmus);
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static DEFINE_MUTEX(pmus_lock);
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@ -4308,6 +4309,8 @@ static void unaccount_event(struct perf_event *event)
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dec = true;
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if (event->attr.ksymbol)
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atomic_dec(&nr_ksymbol_events);
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if (event->attr.bpf_event)
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atomic_dec(&nr_bpf_events);
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if (dec) {
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if (!atomic_add_unless(&perf_sched_count, -1, 1))
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@ -7747,6 +7750,116 @@ err:
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WARN_ONCE(1, "%s: Invalid KSYMBOL type 0x%x\n", __func__, ksym_type);
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}
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/*
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* bpf program load/unload tracking
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*/
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struct perf_bpf_event {
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struct bpf_prog *prog;
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struct {
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struct perf_event_header header;
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u16 type;
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u16 flags;
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u32 id;
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u8 tag[BPF_TAG_SIZE];
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} event_id;
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};
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static int perf_event_bpf_match(struct perf_event *event)
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{
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return event->attr.bpf_event;
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}
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static void perf_event_bpf_output(struct perf_event *event, void *data)
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{
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struct perf_bpf_event *bpf_event = data;
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struct perf_output_handle handle;
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struct perf_sample_data sample;
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int ret;
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if (!perf_event_bpf_match(event))
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return;
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perf_event_header__init_id(&bpf_event->event_id.header,
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&sample, event);
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ret = perf_output_begin(&handle, event,
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bpf_event->event_id.header.size);
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if (ret)
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return;
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perf_output_put(&handle, bpf_event->event_id);
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perf_event__output_id_sample(event, &handle, &sample);
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perf_output_end(&handle);
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}
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static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog,
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enum perf_bpf_event_type type)
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{
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bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD;
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char sym[KSYM_NAME_LEN];
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int i;
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if (prog->aux->func_cnt == 0) {
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bpf_get_prog_name(prog, sym);
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perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF,
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(u64)(unsigned long)prog->bpf_func,
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prog->jited_len, unregister, sym);
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} else {
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for (i = 0; i < prog->aux->func_cnt; i++) {
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struct bpf_prog *subprog = prog->aux->func[i];
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bpf_get_prog_name(subprog, sym);
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perf_event_ksymbol(
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PERF_RECORD_KSYMBOL_TYPE_BPF,
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(u64)(unsigned long)subprog->bpf_func,
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subprog->jited_len, unregister, sym);
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}
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}
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}
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void perf_event_bpf_event(struct bpf_prog *prog,
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enum perf_bpf_event_type type,
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u16 flags)
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{
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struct perf_bpf_event bpf_event;
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if (type <= PERF_BPF_EVENT_UNKNOWN ||
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type >= PERF_BPF_EVENT_MAX)
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return;
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switch (type) {
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case PERF_BPF_EVENT_PROG_LOAD:
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case PERF_BPF_EVENT_PROG_UNLOAD:
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if (atomic_read(&nr_ksymbol_events))
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perf_event_bpf_emit_ksymbols(prog, type);
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break;
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default:
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break;
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}
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if (!atomic_read(&nr_bpf_events))
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return;
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bpf_event = (struct perf_bpf_event){
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.prog = prog,
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.event_id = {
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.header = {
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.type = PERF_RECORD_BPF_EVENT,
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.size = sizeof(bpf_event.event_id),
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},
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.type = type,
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.flags = flags,
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.id = prog->aux->id,
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},
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};
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BUILD_BUG_ON(BPF_TAG_SIZE % sizeof(u64));
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memcpy(bpf_event.event_id.tag, prog->tag, BPF_TAG_SIZE);
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perf_iterate_sb(perf_event_bpf_output, &bpf_event, NULL);
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}
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void perf_event_itrace_started(struct perf_event *event)
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{
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event->attach_state |= PERF_ATTACH_ITRACE;
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@ -10008,6 +10121,8 @@ static void account_event(struct perf_event *event)
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inc = true;
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if (event->attr.ksymbol)
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atomic_inc(&nr_ksymbol_events);
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if (event->attr.bpf_event)
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atomic_inc(&nr_bpf_events);
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if (inc) {
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/*
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