On Mon, Nov 1, 2021 at 3:46 PM Dave Marchevsky <davemarchevsky@xxxxxx> wrote: > > bpf_program__get_prog_info_linear is a helper which wraps the > bpf_obj_get_info_by_fd BPF syscall with some niceties that put > all dynamic-length bpf_prog_info in one buffer contiguous with struct > bpf_prog_info, and simplify the selection of which dynamic data to grab. > > The resultant combined struct, bpf_prog_info_linear, is persisted to > file by 'perf' to enable later annotation of BPF prog data. libbpf > includes some vaddr <-> offset conversion helpers for > struct bpf_prog_info_linear to simplify this. > > This functionality is heavily tailored to perf's usecase, so its use as > a general prog info API should be deemphasized in favor of just calling > bpf_obj_get_info_by_fd, which can be more easily fit to purpose. Some > examples from caller migrations in this series: > > * Some callers weren't requesting or using dynamic-sized prog info and > are well served by a simple get_info_by_fd call (e.g. > dump_prog_id_as_func_ptr in bpftool) > * Some callers were requesting all of a specific dynamic info type but > only using the first record, so can avoid unnecessary malloc by > only requesting 1 (e.g. profile_target_name in bpftool) > * bpftool's do_dump saves some malloc/free by growing and reusing its > dynamic prog_info buf as it loops over progs to grab info and dump. > > Perf does need the full functionality of > bpf_program__get_prog_info_linear and its accompanying structs + > helpers, so copy the code to its codebase, migrate all other uses in the > tree, and deprecate the helper in libbpf. > > Since the deprecated symbols continue to be included in perf some > renaming was necessary in perf's copy, otherwise functionality is > unchanged. > > This work was previously discussed in libbpf's issue tracker [0]. > > [0]: https://github.com/libbpf/libbpf/issues/313 > > v2->v3: > * Remove v2's patch 1 ("libbpf: Migrate internal use of > bpf_program__get_prog_info_linear"), which was applied [Andrii] > * Add new patch 1 migrating error checking of libbpf calls to > new scheme [Andrii, Quentin] > * In patch 2, fix != -1 error check of libbpf call, improper realloc > handling, and get rid of confusing macros [Andrii] > * In patch 4, deprecate starting from 0.6 instead of 0.7 [Andrii] LGTM. Quentin, can you please take a look and ack as well? Thanks! > > v1->v2: fix bpftool do_dump changes to clear bpf_prog_info after use and > correctly pass realloc'd ptr back (patch 2) > > Dave Marchevsky (4): > bpftool: Migrate -1 err checks of libbpf fn calls > bpftool: use bpf_obj_get_info_by_fd directly > perf: pull in bpf_program__get_prog_info_linear > libbpf: deprecate bpf_program__get_prog_info_linear > > tools/bpf/bpftool/btf_dumper.c | 42 +-- > tools/bpf/bpftool/prog.c | 158 ++++++++--- > tools/bpf/bpftool/struct_ops.c | 2 +- > tools/lib/bpf/libbpf.h | 3 + > .../Documentation/perf.data-file-format.txt | 2 +- > tools/perf/util/Build | 1 + > tools/perf/util/annotate.c | 3 +- > tools/perf/util/bpf-event.c | 41 ++- > tools/perf/util/bpf-event.h | 2 +- > tools/perf/util/bpf-utils.c | 261 ++++++++++++++++++ > tools/perf/util/bpf-utils.h | 76 +++++ > tools/perf/util/bpf_counter.c | 6 +- > tools/perf/util/dso.c | 1 + > tools/perf/util/env.c | 1 + > tools/perf/util/header.c | 13 +- > 15 files changed, 527 insertions(+), 85 deletions(-) > create mode 100644 tools/perf/util/bpf-utils.c > create mode 100644 tools/perf/util/bpf-utils.h > > -- > 2.30.2 >
