From 0e521efaf36350b8f783984541efa56f560c90b0 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Thu, 3 Jul 2025 13:48:09 -0700 Subject: [PATCH] bpf: Add function to extract program source info Prepare a function for use in future patches that can extract the file info, line info, and the source line number for a given BPF program provided it's program counter. Only the basename of the file path is provided, given it can be excessively long in some cases. This will be used in later patches to print source info to the BPF stream. Reviewed-by: Emil Tsalapatis Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250703204818.925464-4-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- include/linux/bpf.h | 3 +++ kernel/bpf/core.c | 47 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f61aeccb23c3e..c3802af11bac7 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3661,4 +3661,7 @@ static inline bool bpf_is_subprog(const struct bpf_prog *prog) return prog->aux->func_idx != 0; } +int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep, + const char **linep, int *nump); + #endif /* _LINUX_BPF_H */ diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index f0def24573ae9..2dc5b846ae501 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3213,3 +3213,50 @@ EXPORT_SYMBOL(bpf_stats_enabled_key); EXPORT_TRACEPOINT_SYMBOL_GPL(xdp_exception); EXPORT_TRACEPOINT_SYMBOL_GPL(xdp_bulk_tx); + +#ifdef CONFIG_BPF_SYSCALL + +int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep, + const char **linep, int *nump) +{ + int idx = -1, insn_start, insn_end, len; + struct bpf_line_info *linfo; + void **jited_linfo; + struct btf *btf; + + btf = prog->aux->btf; + linfo = prog->aux->linfo; + jited_linfo = prog->aux->jited_linfo; + + if (!btf || !linfo || !jited_linfo) + return -EINVAL; + len = prog->aux->func ? prog->aux->func[prog->aux->func_idx]->len : prog->len; + + linfo = &prog->aux->linfo[prog->aux->linfo_idx]; + jited_linfo = &prog->aux->jited_linfo[prog->aux->linfo_idx]; + + insn_start = linfo[0].insn_off; + insn_end = insn_start + len; + + for (int i = 0; i < prog->aux->nr_linfo && + linfo[i].insn_off >= insn_start && linfo[i].insn_off < insn_end; i++) { + if (jited_linfo[i] >= (void *)ip) + break; + idx = i; + } + + if (idx == -1) + return -ENOENT; + + /* Get base component of the file path. */ + *filep = btf_name_by_offset(btf, linfo[idx].file_name_off); + *filep = kbasename(*filep); + /* Obtain the source line, and strip whitespace in prefix. */ + *linep = btf_name_by_offset(btf, linfo[idx].line_off); + while (isspace(**linep)) + *linep += 1; + *nump = BPF_LINE_INFO_LINE_NUM(linfo[idx].line_col); + return 0; +} + +#endif -- 2.47.2