Collect begin/end functions from .text section, so they could be executed before/after probes.
Link: http://lkml.kernel.org/n/[email protected] Signed-off-by: Jiri Olsa <[email protected]> --- tools/lib/bpf/libbpf.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 07a6d8f5e5ab..26231e278bb8 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -225,6 +225,10 @@ struct bpf_object { struct bpf_map *maps; size_t nr_maps; + struct bpf_program *text; + struct bpf_insn *insn_begin; + struct bpf_insn *insn_end; + bool loaded; /* @@ -440,6 +444,68 @@ bpf_object__init_prog_names(struct bpf_object *obj) return 0; } +static int +bpf_object__init_text(struct bpf_object *obj) +{ + Elf_Data *symbols = obj->efile.symbols; + struct bpf_program *prog; + size_t pi, si; + + if (obj->efile.text_shndx == -1) + return 0; + + for (pi = 0; pi < obj->nr_programs; pi++) { + prog = &obj->programs[pi]; + if (prog->idx != obj->efile.text_shndx) + continue; + + obj->text = prog; + + for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) { + bool is_end = false, is_begin = false; + struct bpf_insn *insn; + const char *name = NULL; + unsigned int insn_idx; + GElf_Sym sym; + + if (!gelf_getsym(symbols, si, &sym)) + continue; + if (sym.st_shndx != prog->idx) + continue; + if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL) + continue; + + name = elf_strptr(obj->efile.elf, + obj->efile.strtabidx, + sym.st_name); + if (!name) { + pr_warning("failed to get sym name string for prog %s\n", + prog->section_name); + return -LIBBPF_ERRNO__LIBELF; + } + + is_begin = !strcmp(name, "BEGIN"); + is_end = !strcmp(name, "END"); + + if (!is_begin && !is_end) + continue; + + insn_idx = sym.st_value / sizeof(struct bpf_insn); + insn = &prog->insns[insn_idx]; + + pr_debug("set %s to %p\n", name, insn); + + if (is_begin) + obj->insn_begin = insn; + else + obj->insn_end = insn; + } + } + + return 0; +} + + static struct bpf_object *bpf_object__new(const char *path, void *obj_buf, size_t obj_buf_sz) @@ -464,6 +530,7 @@ static struct bpf_object *bpf_object__new(const char *path, obj->efile.obj_buf = obj_buf; obj->efile.obj_buf_sz = obj_buf_sz; obj->efile.maps_shndx = -1; + obj->efile.text_shndx = -1; obj->loaded = false; @@ -890,6 +957,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj) goto out; } err = bpf_object__init_prog_names(obj); + if (err) + goto out; + err = bpf_object__init_text(obj); out: return err; } -- 2.13.6
