[RFC 0/5] mm/bpf/perf: Store build id in file object

Jiri Olsa
2023-02-01T13:58:16Z

hi,
we have a use cases for bpf programs to use binary file's build id.

After some attempts to add helpers/kfuncs [1] [2] Andrii had an idea [3]
to store build id directly in the file object. That would solve our use
case and might be beneficial for other profiling/tracing use cases with
bpf programs.

This RFC patchset adds new config CONFIG_FILE_BUILD_ID option, which adds
build id object pointer to the file object when enabled. The build id is
read/populated when the file is mmap-ed.

I also added bpf and perf changes that would benefit from this.

I'm not sure what's the policy on adding stuff to file object, so apologies
if that's out of line. I'm open to any feedback or suggestions if there's
better place or way to do this.

thanks,
jirka

[1] https://lore.kernel.org/bpf/20221108222027.3409437-1-jolsa@kernel.org/
[2] https://lore.kernel.org/bpf/20221128132915.141211-1-jolsa@kernel.org/
[3] https://lore.kernel.org/bpf/CAEf4BzaZCUoxN_X2ALXwQeFTCwtL17R4P_B_-hUCcidfyO2xyQ@mail.gmail.com/
---
Jiri Olsa (5):
mm: Store build id in file object
bpf: Use file object build id in stackmap
perf: Use file object build id in perf_event_mmap_event
selftests/bpf: Add file_build_id test
selftests/bpf: Add iter_task_vma_buildid test

fs/file_table.c | 3 +++
include/linux/buildid.h | 17 +++++++++++++++++
include/linux/fs.h | 3 +++
kernel/bpf/stackmap.c | 8 ++++++++
kernel/events/core.c | 43 +++++++++++++++++++++++++++++++++++++++----
lib/buildid.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
mm/Kconfig | 7 +++++++
mm/mmap.c | 15 +++++++++++++++
tools/testing/selftests/bpf/prog_tests/bpf_iter.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/prog_tests/file_build_id.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/progs/file_build_id.c | 34 ++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/trace_helpers.c | 35 +++++++++++++++++++++++++++++++++++
tools/testing/selftests/bpf/trace_helpers.h | 1 +
14 files changed, 413 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/file_build_id.c
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
create mode 100644 tools/testing/selftests/bpf/progs/file_build_id.c