From 876f5ebd58a9ac42f48a7ead3d5b274a314e0ace Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Thu, 3 Jul 2025 13:48:17 -0700 Subject: bpftool: Add support for dumping streams Add support for printing the BPF stream contents of a program in bpftool. The new bpftool prog tracelog command is extended to take stdout and stderr arguments, and then the prog specification. The bpf_prog_stream_read() API added in previous patch is simply reused to grab data and then it is dumped to the respective file. The stdout data is sent to stdout, and stderr is printed to stderr. Cc: Quentin Monnet Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250703204818.925464-12-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/bpf/bpftool/prog.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) (limited to 'tools/bpf/bpftool/prog.c') diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c index deeaa5c1ed7d..9722d841abc0 100644 --- a/tools/bpf/bpftool/prog.c +++ b/tools/bpf/bpftool/prog.c @@ -1113,6 +1113,52 @@ static int do_detach(int argc, char **argv) return 0; } +enum prog_tracelog_mode { + TRACE_STDOUT, + TRACE_STDERR, +}; + +static int +prog_tracelog_stream(int prog_fd, enum prog_tracelog_mode mode) +{ + FILE *file = mode == TRACE_STDOUT ? stdout : stderr; + int stream_id = mode == TRACE_STDOUT ? 1 : 2; + char buf[512]; + int ret; + + ret = 0; + do { + ret = bpf_prog_stream_read(prog_fd, stream_id, buf, sizeof(buf), NULL); + if (ret > 0) + fwrite(buf, sizeof(buf[0]), ret, file); + } while (ret > 0); + + fflush(file); + return ret ? -1 : 0; +} + +static int do_tracelog_any(int argc, char **argv) +{ + enum prog_tracelog_mode mode; + int fd; + + if (argc == 0) + return do_tracelog(argc, argv); + if (!is_prefix(*argv, "stdout") && !is_prefix(*argv, "stderr")) + usage(); + mode = is_prefix(*argv, "stdout") ? TRACE_STDOUT : TRACE_STDERR; + NEXT_ARG(); + + if (!REQ_ARGS(2)) + return -1; + + fd = prog_parse_fd(&argc, &argv); + if (fd < 0) + return -1; + + return prog_tracelog_stream(fd, mode); +} + static int check_single_stdin(char *file_data_in, char *file_ctx_in) { if (file_data_in && file_ctx_in && @@ -2493,6 +2539,7 @@ static int do_help(int argc, char **argv) " [repeat N]\n" " %1$s %2$s profile PROG [duration DURATION] METRICs\n" " %1$s %2$s tracelog\n" + " %1$s %2$s tracelog { stdout | stderr } PROG\n" " %1$s %2$s help\n" "\n" " " HELP_SPEC_MAP "\n" @@ -2532,7 +2579,7 @@ static const struct cmd cmds[] = { { "loadall", do_loadall }, { "attach", do_attach }, { "detach", do_detach }, - { "tracelog", do_tracelog }, + { "tracelog", do_tracelog_any }, { "run", do_run }, { "profile", do_profile }, { 0 } -- cgit v1.2.3