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    Subject[PATCH 62/79] libperf: Add perf_evsel__open function
    Date
    Adding perf_evsel__open function into libperf.

    It's a simplified version of evsel__open without fallback
    stuff. We can try to merge it in the future to libperf,
    but it has many glitches.

    Link: http://lkml.kernel.org/n/tip-l21dawds9vj61pbtqhcnacqc@git.kernel.org
    Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    ---
    tools/perf/lib/evsel.c | 65 +++++++++++++++++++++++++++++
    tools/perf/lib/include/perf/evsel.h | 4 ++
    tools/perf/lib/libperf.map | 1 +
    3 files changed, 70 insertions(+)

    diff --git a/tools/perf/lib/evsel.c b/tools/perf/lib/evsel.c
    index 027f1edb4e8e..7027dacb50f6 100644
    --- a/tools/perf/lib/evsel.c
    +++ b/tools/perf/lib/evsel.c
    @@ -1,11 +1,17 @@
    // SPDX-License-Identifier: GPL-2.0
    #include <errno.h>
    +#include <unistd.h>
    +#include <sys/syscall.h>
    #include <perf/evsel.h>
    +#include <perf/cpumap.h>
    +#include <perf/threadmap.h>
    #include <linux/list.h>
    #include <internal/evsel.h>
    #include <linux/zalloc.h>
    #include <stdlib.h>
    #include <internal/xyarray.h>
    +#include <internal/cpumap.h>
    +#include <internal/threadmap.h>
    #include <linux/string.h>

    void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr)
    @@ -46,3 +52,62 @@ int perf_evsel__alloc_fd(struct perf_evsel *evsel, int ncpus, int nthreads)

    return evsel->fd != NULL ? 0 : -ENOMEM;
    }
    +
    +static int
    +sys_perf_event_open(struct perf_event_attr *attr,
    + pid_t pid, int cpu, int group_fd,
    + unsigned long flags)
    +{
    + return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
    +}
    +
    +int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
    + struct perf_thread_map *threads)
    +{
    + int cpu, thread, err = 0;
    +
    + if (cpus == NULL) {
    + static struct perf_cpu_map *empty_cpu_map;
    +
    + if (empty_cpu_map == NULL) {
    + empty_cpu_map = perf_cpu_map__dummy_new();
    + if (empty_cpu_map == NULL)
    + return -ENOMEM;
    + }
    +
    + cpus = empty_cpu_map;
    + }
    +
    + if (threads == NULL) {
    + static struct perf_thread_map *empty_thread_map;
    +
    + if (empty_thread_map == NULL) {
    + empty_thread_map = perf_thread_map__new_dummy();
    + if (empty_thread_map == NULL)
    + return -ENOMEM;
    + }
    +
    + threads = empty_thread_map;
    + }
    +
    + if (evsel->fd == NULL &&
    + perf_evsel__alloc_fd(evsel, cpus->nr, threads->nr) < 0)
    + return -ENOMEM;
    +
    + for (cpu = 0; cpu < cpus->nr; cpu++) {
    + for (thread = 0; thread < threads->nr; thread++) {
    + int fd;
    +
    + fd = sys_perf_event_open(&evsel->attr,
    + threads->map[thread].pid,
    + cpus->map[cpu], -1, 0);
    +
    + if (fd < 0)
    + return -errno;
    +
    + FD(evsel, cpu, thread) = fd;
    + }
    + }
    +
    + return err;
    +}
    diff --git a/tools/perf/lib/include/perf/evsel.h b/tools/perf/lib/include/perf/evsel.h
    index c01de0752e4d..adda02f00369 100644
    --- a/tools/perf/lib/include/perf/evsel.h
    +++ b/tools/perf/lib/include/perf/evsel.h
    @@ -6,10 +6,14 @@
    #include <perf/core.h>

    struct perf_evsel;
    +struct perf_cpu_map;
    +struct perf_thread_map;

    LIBPERF_API void perf_evsel__init(struct perf_evsel *evsel,
    struct perf_event_attr *attr);
    LIBPERF_API struct perf_evsel *perf_evsel__new(struct perf_event_attr *attr);
    LIBPERF_API void perf_evsel__delete(struct perf_evsel *evsel);
    +LIBPERF_API int perf_evsel__open(struct perf_evsel *evsel, struct perf_cpu_map *cpus,
    + struct perf_thread_map *threads);

    #endif /* __LIBPERF_EVSEL_H */
    diff --git a/tools/perf/lib/libperf.map b/tools/perf/lib/libperf.map
    index 9b6e8f165014..7594d3d89c5f 100644
    --- a/tools/perf/lib/libperf.map
    +++ b/tools/perf/lib/libperf.map
    @@ -14,6 +14,7 @@ LIBPERF_0.0.1 {
    perf_evsel__new;
    perf_evsel__delete;
    perf_evsel__init;
    + perf_evsel__open;
    perf_evlist__new;
    perf_evlist__delete;
    perf_evlist__init;
    --
    2.21.0
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