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    Subject[RFC PATCH v9 33/50] perf record: Probe at kprobe points
    Date
    In this patch, kprobe points are created using add_perf_probe_events.
    Since all events are already grouped together in an array, calling
    add_perf_probe_events() once creates all of them.

    probe_conf.max_probes is set to MAX_PROBES to support glob matching.

    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    ---
    tools/perf/builtin-record.c | 18 ++++++++++++++++-
    tools/perf/util/bpf-loader.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
    tools/perf/util/bpf-loader.h | 4 ++++
    3 files changed, 69 insertions(+), 1 deletion(-)

    diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
    index de165a1..28ceae8 100644
    --- a/tools/perf/builtin-record.c
    +++ b/tools/perf/builtin-record.c
    @@ -29,6 +29,7 @@
    #include "util/data.h"
    #include "util/auxtrace.h"
    #include "util/parse-branch-options.h"
    +#include "util/bpf-loader.h"

    #include <unistd.h>
    #include <sched.h>
    @@ -1109,7 +1110,21 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
    if (err)
    return err;

    - err = -ENOMEM;
    + /*
    + * bpf__probe must be called before symbol__init() because we
    + * need init_symbol_maps. If called after symbol__init,
    + * symbol_conf.sort_by_name won't take effect.
    + *
    + * bpf__unprobe() is safe even if bpf__probe() failed, and it
    + * also calls symbol__init. Therefore, goto out_symbol_exit
    + * is safe when probe failed.
    + */
    + err = bpf__probe();
    + if (err) {
    + pr_err("Probing at events in BPF object failed.\n");
    + pr_err("Try perf probe -d '*' to remove existing probe events.\n");
    + goto out_symbol_exit;
    + }

    symbol__init(NULL);

    @@ -1170,6 +1185,7 @@ out_symbol_exit:
    perf_evlist__delete(rec->evlist);
    symbol__exit();
    auxtrace_record__free(rec->itr);
    + bpf__unprobe();
    return err;
    }

    diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
    index 1efb4a6..21f2264 100644
    --- a/tools/perf/util/bpf-loader.c
    +++ b/tools/perf/util/bpf-loader.c
    @@ -193,3 +193,51 @@ void bpf__clear(void)
    bpf_object__for_each(obj, tmp)
    bpf_object__close(obj);
    }
    +
    +static bool is_probing;
    +
    +int bpf__unprobe(void)
    +{
    + struct strfilter *delfilter;
    + int ret;
    +
    + if (!is_probing)
    + return 0;
    +
    + delfilter = strfilter__new(PERF_BPF_PROBE_GROUP ":*", NULL);
    + if (!delfilter) {
    + pr_err("Failed to create delfilter when unprobing\n");
    + return -ENOMEM;
    + }
    +
    + ret = del_perf_probe_events(delfilter);
    + strfilter__delete(delfilter);
    + if (ret < 0 && is_probing)
    + pr_err("Error: failed to delete events: %s\n",
    + strerror(-ret));
    + else
    + is_probing = false;
    + return ret < 0 ? ret : 0;
    +}
    +
    +int bpf__probe(void)
    +{
    + int err;
    +
    + if (nr_probe_events <= 0)
    + return 0;
    +
    + probe_conf.max_probes = MAX_PROBES;
    + /* Let add_perf_probe_events keeps probe_trace_event */
    + err = add_perf_probe_events(probe_event_array,
    + nr_probe_events,
    + false);
    +
    + /* add_perf_probe_events return negative when fail */
    + if (err < 0)
    + pr_err("bpf probe: failed to probe events\n");
    + else
    + is_probing = true;
    +
    + return err < 0 ? err : 0;
    +}
    diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
    index 5a3c954..374aec0 100644
    --- a/tools/perf/util/bpf-loader.h
    +++ b/tools/perf/util/bpf-loader.h
    @@ -12,6 +12,8 @@

    #ifdef HAVE_LIBBPF_SUPPORT
    int bpf__prepare_load(const char *filename, bool source);
    +int bpf__probe(void);
    +int bpf__unprobe(void);

    void bpf__clear(void);
    #else
    @@ -22,6 +24,8 @@ static inline int bpf__prepare_load(const char *filename __maybe_unused,
    return -1;
    }

    +static inline int bpf__probe(void) { return 0; }
    +static inline int bpf__unprobe(void) { return 0; }
    static inline void bpf__clear(void) { }
    #endif
    #endif
    --
    1.8.3.4


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