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    SubjectRe: [PATCH 16/26] perf tools: Synthesize modules with mmap3
    On Mon, Sep 14, 2020 at 9:08 AM Arnaldo Carvalho de Melo
    <acme@kernel.org> wrote:
    >
    > Em Sun, Sep 13, 2020 at 11:03:03PM +0200, Jiri Olsa escreveu:
    > > Synthesizing modules with mmap3 events so we can
    > > get build id data for module's maps as well.
    >
    > Ditto as for 15/26
    >
    > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
    > > ---
    > > tools/perf/util/synthetic-events.c | 37 +++++++++++++++++++-----------
    > > 1 file changed, 24 insertions(+), 13 deletions(-)
    > >
    > > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
    > > index bd6e7b84283d..6bd2423ce2f3 100644
    > > --- a/tools/perf/util/synthetic-events.c
    > > +++ b/tools/perf/util/synthetic-events.c
    > > @@ -605,7 +605,7 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
    > > int rc = 0;
    > > struct map *pos;
    > > struct maps *maps = machine__kernel_maps(machine);
    > > - union perf_event *event = zalloc((sizeof(event->mmap) +
    > > + union perf_event *event = zalloc((sizeof(event->mmap3) +
    > > machine->id_hdr_size));
    > > if (event == NULL) {
    > > pr_debug("Not enough memory synthesizing mmap event "
    > > @@ -613,8 +613,6 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
    > > return -1;
    > > }
    > >
    > > - event->header.type = PERF_RECORD_MMAP;
    > > -
    > > /*
    > > * kernel uses 0 for user space maps, see kernel/perf_event.c
    > > * __perf_event_mmap
    > > @@ -631,17 +629,30 @@ int perf_event__synthesize_modules(struct perf_tool *tool, perf_event__handler_t
    > > continue;
    > >
    > > size = PERF_ALIGN(pos->dso->long_name_len + 1, sizeof(u64));
    > > - event->mmap.header.type = PERF_RECORD_MMAP;
    > > - event->mmap.header.size = (sizeof(event->mmap) -
    > > - (sizeof(event->mmap.filename) - size));
    > > - memset(event->mmap.filename + size, 0, machine->id_hdr_size);
    > > - event->mmap.header.size += machine->id_hdr_size;
    > > - event->mmap.start = pos->start;
    > > - event->mmap.len = pos->end - pos->start;
    > > - event->mmap.pid = machine->pid;
    > > -
    > > - memcpy(event->mmap.filename, pos->dso->long_name,
    > > + event->mmap3.header.type = PERF_RECORD_MMAP3;
    > > + event->mmap3.header.size = (sizeof(event->mmap3) -
    > > + (sizeof(event->mmap3.filename) - size));
    > > + memset(event->mmap3.filename + size, 0, machine->id_hdr_size);
    > > + event->mmap3.header.size += machine->id_hdr_size;
    > > + event->mmap3.start = pos->start;
    > > + event->mmap3.len = pos->end - pos->start;
    > > + event->mmap3.pid = machine->pid;
    > > +
    > > + memcpy(event->mmap3.filename, pos->dso->long_name,
    > > pos->dso->long_name_len + 1);
    > > +
    > > + rc = filename__read_build_id(event->mmap3.filename, event->mmap3.buildid,
    > > + BUILD_ID_SIZE);
    > > + if (rc != BUILD_ID_SIZE) {

    IIRC BUILD_ID_SIZE is 20 bytes which is the correct size for SHA-1. A
    build ID may be 128-bits (16 bytes) if md5 or uuid hashes are used.
    Should this test just be "> 0" ?

    Thanks,
    Ian

    > > + if (event->mmap3.filename[0] == '/') {
    > > + pr_debug2("Failed to read build ID for %s\n",
    > > + event->mmap3.filename);
    > > + }
    > > + memset(event->mmap3.buildid, 0x0, sizeof(event->mmap3.buildid));
    > > + }
    > > +
    > > + rc = 0;
    > > +
    > > if (perf_tool__process_synth_event(tool, event, machine, process) != 0) {
    > > rc = -1;
    > > break;
    > > --
    > > 2.26.2
    > >
    >
    > --
    >
    > - Arnaldo

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