From 72c0809856b9174e71eab4e293089f6a114e0d41 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Fri, 8 Apr 2016 15:07:25 +0000 Subject: [PATCH] perf bpf: Automatically create bpf-output event __bpf_stdout__ This patch removes the need to set a bpf-output event in cmdline. By referencing a map named '__bpf_stdout__', perf automatically creates an event for it. For example: # perf record -e ./test_bpf_trace.c usleep 100000 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.012 MB perf.data (2 samples) ] # perf script usleep 4639 [000] 261895.307826: 0 __bpf_stdout__: ffffffff810eb9a1 ... BPF output: 0000: 52 61 69 73 65 20 61 20 Raise a 0008: 42 50 46 20 65 76 65 6e BPF even 0010: 74 21 00 00 t!.. BPF string: "Raise a BPF event!" usleep 4639 [000] 261895.407883: 0 __bpf_stdout__: ffffffff8105d609 ... BPF output: 0000: 52 61 69 73 65 20 61 20 Raise a 0008: 42 50 46 20 65 76 65 6e BPF even 0010: 74 21 00 00 t!.. BPF string: "Raise a BPF event!" perf record -e ./test_bpf_trace.c usleep 100000 equals to: perf record -e bpf-output/no-inherit=1,name=__bpf_stdout__/ \ -e ./test_bpf_trace.c/map:__bpf_stdout__.event=__bpf_stdout__/ \ usleep 100000 Where test_bpf_trace.c is: /************************ BEGIN **************************/ #include struct bpf_map_def { unsigned int type; unsigned int key_size; unsigned int value_size; unsigned int max_entries; }; #define SEC(NAME) __attribute__((section(NAME), used)) static u64 (*ktime_get_ns)(void) = (void *)BPF_FUNC_ktime_get_ns; static int (*trace_printk)(const char *fmt, int fmt_size, ...) = (void *)BPF_FUNC_trace_printk; static int (*get_smp_processor_id)(void) = (void *)BPF_FUNC_get_smp_processor_id; static int (*perf_event_output)(void *, struct bpf_map_def *, int, void *, unsigned long) = (void *)BPF_FUNC_perf_event_output; struct bpf_map_def SEC("maps") __bpf_stdout__ = { .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, .key_size = sizeof(int), .value_size = sizeof(u32), .max_entries = __NR_CPUS__, }; static inline int __attribute__((always_inline)) func(void *ctx, int type) { char output_str[] = "Raise a BPF event!"; char err_str[] = "BAD %d\n"; int err; err = perf_event_output(ctx, &__bpf_stdout__, get_smp_processor_id(), &output_str, sizeof(output_str)); if (err) trace_printk(err_str, sizeof(err_str), err); return 1; } SEC("func_begin=sys_nanosleep") int func_begin(void *ctx) {return func(ctx, 1);} SEC("func_end=sys_nanosleep%return") int func_end(void *ctx) { return func(ctx, 2);} char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; /************************* END ***************************/ Committer note: Testing with 'perf trace': # trace -e nanosleep --ev test_bpf_stdout.c usleep 1 0.007 ( 0.007 ms): usleep/729 nanosleep(rqtp: 0x7ffc5bbc5fe0) ... 0.007 ( ): __bpf_stdout__:Raise a BPF event!..) 0.008 ( ): perf_bpf_probe:func_begin:(ffffffff81112460)) 0.069 ( ): __bpf_stdout__:Raise a BPF event!..) 0.070 ( ): perf_bpf_probe:func_end:(ffffffff81112460 <- ffffffff81003d92)) 0.072 ( 0.072 ms): usleep/729 ... [continued]: nanosleep()) = 0 # Suggested-and-Tested-by: Arnaldo Carvalho de Melo Signed-off-by: Wang Nan Cc: Jiri Olsa Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1460128045-97310-5-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/bpf-loader.c | 37 +++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c index 67f61a902a08..493307d1414c 100644 --- a/tools/perf/util/bpf-loader.c +++ b/tools/perf/util/bpf-loader.c @@ -1483,6 +1483,7 @@ int bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused) { struct bpf_map_priv *tmpl_priv = NULL; struct bpf_object *obj, *tmp; + struct perf_evsel *evsel = NULL; struct bpf_map *map; int err; bool need_init = false; @@ -1507,8 +1508,16 @@ int bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused) if (!need_init) return 0; - if (!tmpl_priv) - return 0; + if (!tmpl_priv) { + err = parse_events(evlist, "bpf-output/no-inherit=1,name=__bpf_stdout__/", + NULL); + if (err) { + pr_debug("ERROR: failed to create bpf-output event\n"); + return -err; + } + + evsel = perf_evlist__last(evlist); + } bpf__for_each_stdout_map(map, obj, tmp) { struct bpf_map_priv *priv; @@ -1519,14 +1528,24 @@ int bpf__setup_stdout(struct perf_evlist *evlist __maybe_unused) if (priv) continue; - priv = bpf_map_priv__clone(tmpl_priv); - if (!priv) - return -ENOMEM; + if (tmpl_priv) { + priv = bpf_map_priv__clone(tmpl_priv); + if (!priv) + return -ENOMEM; - err = bpf_map__set_private(map, priv, bpf_map_priv__clear); - if (err) { - bpf_map_priv__clear(map, priv); - return err; + err = bpf_map__set_private(map, priv, bpf_map_priv__clear); + if (err) { + bpf_map_priv__clear(map, priv); + return err; + } + } else if (evsel) { + struct bpf_map_op *op; + + op = bpf_map__add_newop(map, NULL); + if (IS_ERR(op)) + return PTR_ERR(op); + op->op_type = BPF_MAP_OP_SET_EVSEL; + op->v.evsel = evsel; } } -- 2.20.1