> On Sep 19, 2018, at 3:39 PM, Alexei Starovoitov <a...@kernel.org> wrote:
>
> 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>
Acked-by: Song Liu <songliubrav...@fb.com>
I guess we should also use this for kernel modules load/unload?
> ---
> 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
>
