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    Subject[PATCH RFC 11/19] perf tools: Synthesize and process mmap events for x86_64 KPTI entry trampolines
    Date
    Like the kernel text, the location of x86_64 KPTI entry trampolines must be
    recorded in the perf.data file. Like the kernel, synthesize a mmap event
    for that, and add processing for it.

    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    ---
    tools/perf/util/event.c | 90 +++++++++++++++++++++++++++++++++++++++++++++--
    tools/perf/util/machine.c | 28 +++++++++++++++
    2 files changed, 115 insertions(+), 3 deletions(-)

    diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
    index aafa9878465f..d810ff8488b1 100644
    --- a/tools/perf/util/event.c
    +++ b/tools/perf/util/event.c
    @@ -888,9 +888,80 @@ int kallsyms__get_function_start(const char *kallsyms_filename,
    return 0;
    }

    -int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
    - perf_event__handler_t process,
    - struct machine *machine)
    +#if defined(__x86_64__)
    +
    +static int perf_event__synthesize_special_kmaps(struct perf_tool *tool,
    + perf_event__handler_t process,
    + struct machine *machine)
    +{
    + int rc = 0;
    + struct map *pos;
    + struct map_groups *kmaps = &machine->kmaps;
    + struct maps *maps = &kmaps->maps;
    + union perf_event *event = zalloc(sizeof(event->mmap) +
    + machine->id_hdr_size);
    +
    + if (!event) {
    + pr_debug("Not enough memory synthesizing mmap event "
    + "for special kernel maps\n");
    + return -1;
    + }
    +
    + for (pos = maps__first(maps); pos; pos = map__next(pos)) {
    + struct kmap *kmap;
    + size_t size;
    +
    + if (!__map__is_special_kernel_map(pos))
    + continue;
    +
    + kmap = map__kmap(pos);
    +
    + size = sizeof(event->mmap) - sizeof(event->mmap.filename) +
    + PERF_ALIGN(strlen(kmap->name) + 1, sizeof(u64)) +
    + machine->id_hdr_size;
    +
    + memset(event, 0, size);
    +
    + event->mmap.header.type = PERF_RECORD_MMAP;
    +
    + /*
    + * kernel uses 0 for user space maps, see kernel/perf_event.c
    + * __perf_event_mmap
    + */
    + if (machine__is_host(machine))
    + event->header.misc = PERF_RECORD_MISC_KERNEL;
    + else
    + event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL;
    +
    + event->mmap.header.size = size;
    +
    + event->mmap.start = pos->start;
    + event->mmap.len = pos->end - pos->start;
    + event->mmap.pgoff = pos->pgoff;
    + event->mmap.pid = machine->pid;
    +
    + strlcpy(event->mmap.filename, kmap->name, PATH_MAX);
    +
    + if (perf_tool__process_synth_event(tool, event, machine,
    + process) != 0) {
    + rc = -1;
    + break;
    + }
    + }
    +
    + free(event);
    + return rc;
    +}
    +
    +#else
    +
    +#define perf_event__synthesize_special_kmaps(t, p, m) 0
    +
    +#endif
    +
    +static int __perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
    + perf_event__handler_t process,
    + struct machine *machine)
    {
    size_t size;
    struct map *map = machine__kernel_map(machine);
    @@ -943,6 +1014,19 @@ int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
    return err;
    }

    +int perf_event__synthesize_kernel_mmap(struct perf_tool *tool,
    + perf_event__handler_t process,
    + struct machine *machine)
    +{
    + int err;
    +
    + err = __perf_event__synthesize_kernel_mmap(tool, process, machine);
    + if (err < 0)
    + return err;
    +
    + return perf_event__synthesize_special_kmaps(tool, process, machine);
    +}
    +
    int perf_event__synthesize_thread_map2(struct perf_tool *tool,
    struct thread_map *threads,
    perf_event__handler_t process,
    diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
    index aa6bb493fcfa..aa938f92d6d1 100644
    --- a/tools/perf/util/machine.c
    +++ b/tools/perf/util/machine.c
    @@ -1493,6 +1493,32 @@ static bool machine__uses_kcore(struct machine *machine)
    return false;
    }

    +static bool perf_event__is_special_kernel_mmap(struct machine *machine,
    + union perf_event *event)
    +{
    + return machine__is(machine, "x86_64") &&
    + is_entry_trampoline(event->mmap.filename);
    +}
    +
    +static int machine__process_special_kernel_map(struct machine *machine,
    + union perf_event *event)
    +{
    + struct map *kernel_map = machine__kernel_map(machine);
    + struct dso *kernel = kernel_map ? kernel_map->dso : NULL;
    + struct special_kernal_map sm = {
    + .start = event->mmap.start,
    + .end = event->mmap.start + event->mmap.len,
    + .pgoff = event->mmap.pgoff,
    + };
    +
    + if (kernel == NULL)
    + return -1;
    +
    + strlcpy(sm.name, event->mmap.filename, KMAP_NAME_LEN);
    +
    + return machine__create_special_kernel_map(machine, kernel, &sm);
    +}
    +
    static int machine__process_kernel_mmap_event(struct machine *machine,
    union perf_event *event)
    {
    @@ -1596,6 +1622,8 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
    */
    dso__load(kernel, machine__kernel_map(machine));
    }
    + } else if (perf_event__is_special_kernel_mmap(machine, event)) {
    + return machine__process_special_kernel_map(machine, event);
    }
    return 0;
    out_problem:
    --
    1.9.1
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