hi, this patchset adds build id object pointer to struct file object. We have several use cases for build id to be used in BPF programs [2][3]. Having build id pointer stored directly in file object allows to get build id reliably regardless of the execution context as described in [3]. Previous iteration [1] stored build id pointer into inode, but it became clear that struct file object is better place, because we read the build id when the file is mmap-ed and as Dave Chinner said [4]: > Yes, the problem being that we can cache hundreds of millions of > inodes in memory, and only a very small subset of them are going to > have open files associated with them. And an even smaller subset are > going to be mmapped. thanks, jirka v3 changes: - moved build id back to file object (discussed in [4]) - drop patch 4, it's not needed [Andrii] - added ack to patch 7 [Andrii] - replaced BUILD_ID_SIZE_MAX macro with enum [Andrii] - few re-formatting fixes [Andrii] v2 changes: - store build id under inode [Matthew Wilcox] - use urandom_read and liburandom_read.so for test [Andrii] - add libelf-based helper to fetch build ID from elf [Andrii] - store build id or error we got when reading it [Andrii] - use full name i_build_id [Andrii] - several tests fixes [Andrii] [1] https://lore.kernel.org/bpf/20230228093206.821563-1-jolsa@xxxxxxxxxx/ [2] https://lore.kernel.org/bpf/CA+khW7juLEcrTOd7iKG3C_WY8L265XKNo0iLzV1fE=o-cyeHcQ@xxxxxxxxxxxxxx/ [3] https://lore.kernel.org/bpf/ZABf26mV0D0LS7r%2F@krava/ [4] https://lore.kernel.org/bpf/20230228220714.GJ2825702@xxxxxxxxxxxxxxxxxxx/ --- Jiri Olsa (9): mm: Store build id in file object perf: Use file object build id in perf_event_mmap_event bpf: Use file object build id in stackmap bpf: Switch BUILD_ID_SIZE_MAX to enum selftests/bpf: Add read_buildid function selftests/bpf: Add err.h header selftests/bpf: Replace extract_build_id with read_build_id selftests/bpf: Add iter_task_vma_buildid test selftests/bpf: Add file_build_id test fs/file_table.c | 3 +++ include/linux/buildid.h | 21 ++++++++++++++++++- include/linux/fs.h | 7 +++++++ kernel/bpf/stackmap.c | 24 +++++++++++++++++++++- kernel/events/core.c | 43 ++++++++++++++++++++++++++++++++++---- lib/buildid.c | 42 +++++++++++++++++++++++++++++++++++++ mm/Kconfig | 9 ++++++++ mm/mmap.c | 18 ++++++++++++++++ tools/testing/selftests/bpf/Makefile | 7 ++++++- tools/testing/selftests/bpf/no_build_id.c | 6 ++++++ tools/testing/selftests/bpf/prog_tests/bpf_iter.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/prog_tests/file_build_id.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c | 19 +++++++---------- tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c | 17 ++++++--------- tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/progs/err.h | 18 ++++++++++++++++ tools/testing/selftests/bpf/progs/file_build_id.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/progs/profiler.inc.h | 3 +-- tools/testing/selftests/bpf/test_progs.c | 25 ---------------------- tools/testing/selftests/bpf/test_progs.h | 11 +++++++++- tools/testing/selftests/bpf/trace_helpers.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ tools/testing/selftests/bpf/trace_helpers.h | 5 +++++ 22 files changed, 608 insertions(+), 58 deletions(-) create mode 100644 tools/testing/selftests/bpf/no_build_id.c 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/err.h create mode 100644 tools/testing/selftests/bpf/progs/file_build_id.c
