From f338de22192085a476dd1bc9eac5e074a48f34f9 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Sat, 5 Jun 2021 01:28:23 +0900 Subject: [PATCH] perf probe: Support probes on init functions for offline kernel 'perf probe' internally checks the probe target is in the text area in post-process (after analyzing debuginfo). But it fails if the probe target is in the "inittext". This is a good limitation for the online kernel because such functions have gone after booting. However, for using it for boot-time tracing, user may want to put a probe on init functions. This skips the post checking process if the target is offline kenrel so that user can get the probe definition on the init functions. Without this patch: $ perf probe -k ./build-x86_64/vmlinux -D do_mount_root:10 Probe point 'do_mount_root:10' not found. Error: Failed to add events. With this patch: $ perf probe -k ./build-x86_64/vmlinux -D do_mount_root:10 p:probe/do_mount_root_L10 mount_block_root+300 Signed-off-by: Masami Hiramatsu Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/162282410293.452340.13347006295826431632.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-event.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 0568461b06ea..0fb6ab2b93dc 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -682,8 +682,13 @@ static int post_process_probe_trace_point(struct probe_trace_point *tp, u64 addr = tp->address - offs; sym = map__find_symbol(map, addr); - if (!sym) - return -ENOENT; + if (!sym) { + /* + * If the address is in the inittext section, map can not + * find it. Ignore it if we are probing offline kernel. + */ + return (symbol_conf.ignore_vmlinux_buildid) ? 0 : -ENOENT; + } if (strcmp(sym->name, tp->symbol)) { /* If we have no realname, use symbol for it */ -- 2.20.1