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    Subject[PATCH v4 10/16] perf tools: Introduce bpf-output event
    Date
    Commit a43eec304259a6c637f4014a6d4767159b6a3aa3 (bpf: introduce
    bpf_perf_event_output() helper) add a helper to enable BPF program
    output data to perf ring buffer through a new type of perf event
    PERF_COUNT_SW_BPF_OUTPUT. This patch enable perf to create perf
    event of that type. Now perf user can use following cmdline to
    receive output data from BPF programs:

    # ./perf record -a -e evt=bpf-output/no-inherit/ \
    -e ./test_bpf_output.c/maps:channel.event=evt/ ls /
    # ./perf script
    perf 12927 [004] 355971.129276: 0 evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write
    perf 12927 [004] 355971.129279: 0 evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write
    ...

    Test result:
    # cat ./test_bpf_output.c
    /************************ BEGIN **************************/
    typedef int u32;
    typedef unsigned long long u64;

    enum bpf_map_type {
    BPF_MAP_TYPE_PERF_EVENT_ARRAY = 4,
    };

    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 (*bpf_ktime_get_ns)(void) =
    (void *)5;
    static int (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
    (void *)6;
    static int (*bpf_get_smp_processor_id)(void) =
    (void *)8;
    static int (*bpf_perf_event_output)(void *, struct bpf_map_def *, int, void *, unsigned long) =
    (void *)23;

    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\n";

    output_data.cpuid = bpf_get_smp_processor_id();
    output_data.ktime = bpf_ktime_get_ns();
    int err = bpf_perf_event_output(ctx, &channel, bpf_get_smp_processor_id(),
    &output_data, sizeof(output_data));
    if (err)
    bpf_trace_printk(error_data, sizeof(error_data));
    return 0;
    }
    char _license[] SEC("license") = "GPL";
    int _version SEC("version") = LINUX_VERSION_CODE;
    /************************ END ***************************/

    # ./perf record -a -e evt=bpf-output/no-inherit/ \
    -e ./test_bpf_output.c/maps:channel.event=evt/ ls /
    # ./perf script | grep ls
    ls 4085 [000] 2746114.230215: evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write (/lib/modules/4.3.0-rc4+/build/vmlinux)
    ls 4085 [000] 2746114.230244: evt=bpf-output/no-inherit/: ffffffff811ed5f1 sys_write (/lib/modules/4.3.0-rc4+/build/vmlinux)

    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Zefan Li <lizefan@huawei.com>
    Cc: pi3orama@163.com
    ---
    tools/perf/util/evsel.c | 6 ++++++
    tools/perf/util/parse-events.l | 1 +
    2 files changed, 7 insertions(+)

    diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    index 8e0e6f4..82ece81 100644
    --- a/tools/perf/util/evsel.c
    +++ b/tools/perf/util/evsel.c
    @@ -224,6 +224,12 @@ struct perf_evsel *perf_evsel__new_idx(struct perf_event_attr *attr, int idx)
    if (evsel != NULL)
    perf_evsel__init(evsel, attr, idx);

    + if ((evsel->attr.type == PERF_TYPE_SOFTWARE) &&
    + (evsel->attr.config == PERF_COUNT_SW_BPF_OUTPUT)) {
    + evsel->attr.sample_type |= PERF_SAMPLE_RAW;
    + evsel->attr.sample_period = 1;
    + }
    +
    return evsel;
    }

    diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
    index 8bb3437..27d567f 100644
    --- a/tools/perf/util/parse-events.l
    +++ b/tools/perf/util/parse-events.l
    @@ -249,6 +249,7 @@ cpu-migrations|migrations { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COU
    alignment-faults { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_ALIGNMENT_FAULTS); }
    emulation-faults { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_EMULATION_FAULTS); }
    dummy { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_DUMMY); }
    +bpf-output { return sym(yyscanner, PERF_TYPE_SOFTWARE, PERF_COUNT_SW_BPF_OUTPUT); }

    /*
    * We have to handle the kernel PMU event cycles-ct/cycles-t/mem-loads/mem-stores separately.
    --
    1.8.3.4


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