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perf, bpf: Introduce PERF_RECORD_KSYMBOL
For better performance analysis of dynamically JITed and loaded kernel functions, such as BPF programs, this patch introduces PERF_RECORD_KSYMBOL, a new perf_event_type that exposes kernel symbol register/unregister information to user space. The following data structure is used for PERF_RECORD_KSYMBOL. /* * struct { * struct perf_event_header header; * u64 addr; * u32 len; * u16 ksym_type; * u16 flags; * char name[]; * struct sample_id sample_id; * }; */ Signed-off-by: Song Liu <songliubraving@fb.com> Reviewed-by: Arnaldo Carvalho de Melo <acme@redhat.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Alexei Starovoitov <ast@kernel.org> 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/20190117161521.1341602-2-songliubraving@fb.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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parent
5620196951
commit
76193a9452
3 changed files with 130 additions and 2 deletions
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@ -1122,6 +1122,10 @@ static inline void perf_event_task_sched_out(struct task_struct *prev,
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}
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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 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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extern int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
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@ -1342,6 +1346,10 @@ static inline int perf_unregister_guest_info_callbacks
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(struct perf_guest_info_callbacks *callbacks) { return 0; }
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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_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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@ -372,7 +372,8 @@ struct perf_event_attr {
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context_switch : 1, /* context switch data */
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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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__reserved_1 : 35;
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ksymbol : 1, /* include ksymbol events */
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__reserved_1 : 34;
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union {
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__u32 wakeup_events; /* wakeup every n events */
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@ -963,9 +964,32 @@ enum perf_event_type {
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*/
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PERF_RECORD_NAMESPACES = 16,
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/*
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* Record ksymbol register/unregister events:
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*
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* struct {
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* struct perf_event_header header;
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* u64 addr;
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* u32 len;
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* u16 ksym_type;
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* u16 flags;
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* char name[];
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* struct sample_id sample_id;
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* };
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*/
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PERF_RECORD_KSYMBOL = 17,
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PERF_RECORD_MAX, /* non-ABI */
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};
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enum perf_record_ksymbol_type {
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PERF_RECORD_KSYMBOL_TYPE_UNKNOWN = 0,
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PERF_RECORD_KSYMBOL_TYPE_BPF = 1,
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PERF_RECORD_KSYMBOL_TYPE_MAX /* non-ABI */
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};
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#define PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER (1 << 0)
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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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@ -385,6 +385,7 @@ static atomic_t nr_namespaces_events __read_mostly;
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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 LIST_HEAD(pmus);
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static DEFINE_MUTEX(pmus_lock);
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@ -4235,7 +4236,7 @@ static bool is_sb_event(struct perf_event *event)
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if (attr->mmap || attr->mmap_data || attr->mmap2 ||
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attr->comm || attr->comm_exec ||
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attr->task ||
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attr->task || attr->ksymbol ||
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attr->context_switch)
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return true;
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return false;
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@ -4305,6 +4306,8 @@ static void unaccount_event(struct perf_event *event)
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dec = true;
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if (has_branch_stack(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 (dec) {
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if (!atomic_add_unless(&perf_sched_count, -1, 1))
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@ -7653,6 +7656,97 @@ static void perf_log_throttle(struct perf_event *event, int enable)
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perf_output_end(&handle);
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}
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/*
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* ksymbol register/unregister tracking
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*/
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struct perf_ksymbol_event {
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const char *name;
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int name_len;
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struct {
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struct perf_event_header header;
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u64 addr;
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u32 len;
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u16 ksym_type;
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u16 flags;
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} event_id;
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};
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static int perf_event_ksymbol_match(struct perf_event *event)
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{
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return event->attr.ksymbol;
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}
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static void perf_event_ksymbol_output(struct perf_event *event, void *data)
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{
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struct perf_ksymbol_event *ksymbol_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_ksymbol_match(event))
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return;
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perf_event_header__init_id(&ksymbol_event->event_id.header,
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&sample, event);
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ret = perf_output_begin(&handle, event,
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ksymbol_event->event_id.header.size);
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if (ret)
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return;
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perf_output_put(&handle, ksymbol_event->event_id);
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__output_copy(&handle, ksymbol_event->name, ksymbol_event->name_len);
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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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void perf_event_ksymbol(u16 ksym_type, u64 addr, u32 len, bool unregister,
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const char *sym)
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{
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struct perf_ksymbol_event ksymbol_event;
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char name[KSYM_NAME_LEN];
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u16 flags = 0;
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int name_len;
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if (!atomic_read(&nr_ksymbol_events))
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return;
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if (ksym_type >= PERF_RECORD_KSYMBOL_TYPE_MAX ||
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ksym_type == PERF_RECORD_KSYMBOL_TYPE_UNKNOWN)
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goto err;
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strlcpy(name, sym, KSYM_NAME_LEN);
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name_len = strlen(name) + 1;
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while (!IS_ALIGNED(name_len, sizeof(u64)))
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name[name_len++] = '\0';
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BUILD_BUG_ON(KSYM_NAME_LEN % sizeof(u64));
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if (unregister)
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flags |= PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER;
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ksymbol_event = (struct perf_ksymbol_event){
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.name = name,
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.name_len = name_len,
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.event_id = {
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.header = {
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.type = PERF_RECORD_KSYMBOL,
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.size = sizeof(ksymbol_event.event_id) +
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name_len,
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},
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.addr = addr,
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.len = len,
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.ksym_type = ksym_type,
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.flags = flags,
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},
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};
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perf_iterate_sb(perf_event_ksymbol_output, &ksymbol_event, NULL);
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return;
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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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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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@ -9912,6 +10006,8 @@ static void account_event(struct perf_event *event)
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inc = true;
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if (is_cgroup_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 (inc) {
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/*
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