[PATCH RFC 3/5] perf: Use file object build id in perf_event_mmap_event

Jiri Olsa
2023-02-01T13:59:02Z

Use build id from file object when available for perf's MMAP2
event build id data.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/events/core.c | 43 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index d56328e5080e..44001fc7edb7 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8508,6 +8508,9 @@ struct perf_mmap_event {
u32 prot, flags;
u8 build_id[BUILD_ID_SIZE_MAX];
u32 build_id_size;
+#ifdef CONFIG_FILE_BUILD_ID
+ struct build_id *f_bid;
+#endif

struct {
struct perf_event_header header;
@@ -8520,6 +8523,38 @@ struct perf_mmap_event {
} event_id;
};

+#ifdef CONFIG_FILE_BUILD_ID
+static void build_id_read(struct perf_mmap_event *mmap_event)
+{
+ struct vm_area_struct *vma = mmap_event->vma;
+
+ mmap_event->f_bid = vma->vm_file ? vma->vm_file->f_bid : NULL;
+}
+
+static bool has_build_id(struct perf_mmap_event *mmap_event)
+{
+ return mmap_event->f_bid;
+}
+
+#define build_id_data mmap_event->f_bid->data
+#define build_id_size mmap_event->f_bid->sz
+#else
+static void build_id_read(struct perf_mmap_event *mmap_event)
+{
+ struct vm_area_struct *vma = mmap_event->vma;
+
+ build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size);
+}
+
+static bool has_build_id(struct perf_mmap_event *mmap_event)
+{
+ return mmap_event->build_id_size;
+}
+
+#define build_id_data mmap_event->build_id
+#define build_id_size mmap_event->build_id_size
+#endif
+
static int perf_event_mmap_match(struct perf_event *event,
void *data)
{
@@ -8564,7 +8599,7 @@ static void perf_event_mmap_output(struct perf_event *event,
mmap_event->event_id.pid = perf_event_pid(event, current);
mmap_event->event_id.tid = perf_event_tid(event, current);

- use_build_id = event->attr.build_id && mmap_event->build_id_size;
+ use_build_id = event->attr.build_id && has_build_id(mmap_event);

if (event->attr.mmap2 && use_build_id)
mmap_event->event_id.header.misc |= PERF_RECORD_MISC_MMAP_BUILD_ID;
@@ -8573,10 +8608,10 @@ static void perf_event_mmap_output(struct perf_event *event,

if (event->attr.mmap2) {
if (use_build_id) {
- u8 size[4] = { (u8) mmap_event->build_id_size, 0, 0, 0 };
+ u8 size[4] = { (u8) build_id_size, 0, 0, 0 };

__output_copy(&handle, size, 4);
- __output_copy(&handle, mmap_event->build_id, BUILD_ID_SIZE_MAX);
+ __output_copy(&handle, build_id_data, BUILD_ID_SIZE_MAX);
} else {
perf_output_put(&handle, mmap_event->maj);
perf_output_put(&handle, mmap_event->min);
@@ -8708,7 +8743,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size;

if (atomic_read(&nr_build_id_events))
- build_id_parse(vma, mmap_event->build_id, &mmap_event->build_id_size);
+ build_id_read(mmap_event);

perf_iterate_sb(perf_event_mmap_output,
mmap_event,
--
2.39.1