introduce perf_event_mmap_bpf_prog() helper to emit RECORD_MMAP events
into perf ring buffer.
It's used by bpf load/unload logic to notify user space of addresses
and names of JITed bpf programs.
Note that event->mmap.pid == -1 is an existing indicator of kernel event.
In addition use event->mmap.tid == BPF_FS_MAGIC to indicate bpf related
RECORD_MMAP event.
Alternatively it's possible to introduce new 'enum perf_event_type' command
specificially for bpf prog load/unload, but existing RECORD_MMAP
is very close, so the choice made by this patch is to extend it.
Signed-off-by: Alexei Starovoitov <a...@kernel.org>
---
include/linux/perf_event.h | 1 +
kernel/events/core.c | 44 +++++++++++++++++++++++++++++++++-----
2 files changed, 40 insertions(+), 5 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 53c500f0ca79..0e79af83138f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1113,6 +1113,7 @@ static inline void perf_event_task_sched_out(struct
task_struct *prev,
}
extern void perf_event_mmap(struct vm_area_struct *vma);
+void perf_event_mmap_bpf_prog(u64 start, u64 len, char *name, int size);
extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks
*callbacks);
extern int perf_unregister_guest_info_callbacks(struct
perf_guest_info_callbacks *callbacks);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2a62b96600ad..c48244ddf993 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7152,7 +7152,7 @@ static int perf_event_mmap_match(struct perf_event *event,
{
struct perf_mmap_event *mmap_event = data;
struct vm_area_struct *vma = mmap_event->vma;
- int executable = vma->vm_flags & VM_EXEC;
+ int executable = !vma || vma->vm_flags & VM_EXEC;
return (!executable && event->attr.mmap_data) ||
(executable && (event->attr.mmap || event->attr.mmap2));
@@ -7165,12 +7165,13 @@ static void perf_event_mmap_output(struct perf_event
*event,
struct perf_output_handle handle;
struct perf_sample_data sample;
int size = mmap_event->event_id.header.size;
+ bool bpf_event = !mmap_event->vma;
int ret;
if (!perf_event_mmap_match(event, data))
return;
- if (event->attr.mmap2) {
+ if (event->attr.mmap2 && !bpf_event) {
mmap_event->event_id.header.type = PERF_RECORD_MMAP2;
mmap_event->event_id.header.size += sizeof(mmap_event->maj);
mmap_event->event_id.header.size += sizeof(mmap_event->min);
@@ -7186,12 +7187,14 @@ static void perf_event_mmap_output(struct perf_event
*event,
if (ret)
goto out;
- mmap_event->event_id.pid = perf_event_pid(event, current);
- mmap_event->event_id.tid = perf_event_tid(event, current);
+ if (!bpf_event) {
+ mmap_event->event_id.pid = perf_event_pid(event, current);
+ mmap_event->event_id.tid = perf_event_tid(event, current);
+ }
perf_output_put(&handle, mmap_event->event_id);
- if (event->attr.mmap2) {
+ if (event->attr.mmap2 && !bpf_event) {
perf_output_put(&handle, mmap_event->maj);
perf_output_put(&handle, mmap_event->min);
perf_output_put(&handle, mmap_event->ino);
@@ -7448,6 +7451,37 @@ void perf_event_mmap(struct vm_area_struct *vma)
perf_event_mmap_event(&mmap_event);
}
+void perf_event_mmap_bpf_prog(u64 start, u64 len, char *name, int size)
+{
+ struct perf_mmap_event mmap_event;
+
+ if (!atomic_read(&nr_mmap_events))
+ return;
+
+ if (!IS_ALIGNED(size, sizeof(u64))) {
+ WARN_ONCE(1, "size is not aligned\n");
+ return;
+ }
+
+ mmap_event = (struct perf_mmap_event){
+ .file_name = name,
+ .file_size = size,
+ .event_id = {
+ .header = {
+ .type = PERF_RECORD_MMAP,
+ .misc = PERF_RECORD_MISC_KERNEL,
+ .size = sizeof(mmap_event.event_id) + size,
+ },
+ .pid = -1, /* indicates kernel */
+ .tid = BPF_FS_MAGIC, /* bpf mmap event */
+ .start = start,
+ .len = len,
+ .pgoff = start,
+ },
+ };
+ perf_iterate_sb(perf_event_mmap_output, &mmap_event, NULL);
+}
+
void perf_event_aux_event(struct perf_event *event, unsigned long head,
unsigned long size, u64 flags)
{
--
2.17.1
