On Wed, Feb 01, 2023 at 02:57:32PM +0100, Jiri Olsa wrote: > 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. hi, Matthew suggested on irc to consider inode for storing build id I tried that and it seems to have better stats wrt allocated build id objects, because inode is being shared among file objects I took /proc/slabinfo output after running bpf tests - build id stored in file: # name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail> build_id 668 775 160 25 1 : tunables 0 0 0 : slabdata 31 31 0 - build id stored in inode: # name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab> : tunables <limit> <batchcount> <sharedfactor> : slabdata <active_slabs> <num_slabs> <sharedavail> build_id 222 225 160 25 1 : tunables 0 0 0 : slabdata 9 9 0 I'm stranger to inode/fs/mm code so I'll spend some time checking on what I possibly broke in there before I send it, but I'd appreciate any early feedback ;-) the code is in here: git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git inode_build_id I'll send another version with inode if there's no objection thanks, jirka > > thanks, > jirka > > > [1] https://lore.kernel.org/bpf/20221108222027.3409437-1-jolsa@xxxxxxxxxx/ > [2] https://lore.kernel.org/bpf/20221128132915.141211-1-jolsa@xxxxxxxxxx/ > [3] https://lore.kernel.org/bpf/CAEf4BzaZCUoxN_X2ALXwQeFTCwtL17R4P_B_-hUCcidfyO2xyQ@xxxxxxxxxxxxxx/ > --- > 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
