1. 24 Feb, 2016 28 commits
  2. 23 Feb, 2016 11 commits
  3. 22 Feb, 2016 1 commit
    • Wang Nan's avatar
      perf tools: Introduce bpf-output event · 03e0a7df
      Wang Nan authored
      Commit a43eec30 ("bpf: introduce bpf_perf_event_output() helper")
      adds a helper to enable a BPF program to output data to a perf ring
      buffer through a new type of perf event, PERF_COUNT_SW_BPF_OUTPUT. This
      patch enables perf to create events of that type. Now a perf user can
      use the following cmdline to receive output data from BPF programs:
      
        # perf record -a -e bpf-output/no-inherit,name=evt/ \
                          -e ./test_bpf_output.c/map:channel.event=evt/ ls /
        # perf script
           perf 1560 [004] 347747.086295:  evt: ffffffff811fd201 sys_write ...
           perf 1560 [004] 347747.086300:  evt: ffffffff811fd201 sys_write ...
           perf 1560 [004] 347747.086315:  evt: ffffffff811fd201 sys_write ...
                  ...
      
      Test result:
      
        # cat test_bpf_output.c
        /************************ BEGIN **************************/
        #include <uapi/linux/bpf.h>
        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") channel = {
       	.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
       	.key_size = sizeof(int),
       	.value_size = sizeof(u32),
       	.max_entries = __NR_CPUS__,
        };
      
        SEC("func_write=sys_write")
        int func_write(void *ctx)
        {
       	struct {
       		u64 ktime;
       		int cpuid;
       	} __attribute__((packed)) output_data;
       	char error_data[] = "Error: failed to output: %d\n";
      
       	output_data.cpuid = get_smp_processor_id();
       	output_data.ktime = ktime_get_ns();
       	int err = perf_event_output(ctx, &channel, get_smp_processor_id(),
       				    &output_data, sizeof(output_data));
       	if (err)
       		trace_printk(error_data, sizeof(error_data), err);
       	return 0;
        }
        char _license[] SEC("license") = "GPL";
        int _version SEC("version") = LINUX_VERSION_CODE;
        /************************ END ***************************/
      
        # perf record -a -e bpf-output/no-inherit,name=evt/ \
                          -e ./test_bpf_output.c/map:channel.event=evt/ ls /
        # perf script | grep ls
           ls  2242 [003] 347851.557563:   evt: ffffffff811fd201 sys_write ...
           ls  2242 [003] 347851.557571:   evt: ffffffff811fd201 sys_write ...
      Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
      Cc: Adrian Hunter <adrian.hunter@intel.com>
      Cc: Alexei Starovoitov <ast@kernel.org>
      Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
      Cc: Cody P Schafer <dev@codyps.com>
      Cc: He Kuang <hekuang@huawei.com>
      Cc: Jeremie Galarneau <jeremie.galarneau@efficios.com>
      Cc: Jiri Olsa <jolsa@kernel.org>
      Cc: Kirill Smelkov <kirr@nexedi.com>
      Cc: Li Zefan <lizefan@huawei.com>
      Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
      Cc: Namhyung Kim <namhyung@kernel.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Zefan Li <lizefan@huawei.com>
      Cc: pi3orama@163.com
      Link: http://lkml.kernel.org/r/1456132275-98875-11-git-send-email-wangnan0@huawei.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
      03e0a7df