From e8ca4f0f8c03330bf912daee6aa258f4d33ee724 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 28 Jul 2023 23:19:30 +0900 Subject: [PATCH] perf probe: Show correct error message about @symbol usage for uprobe Since @symbol variable access is not supported by uprobe event, it must be correctly warn user instead of kernel version update. Committer testing: With/without the patch: [root@quaco ~]# perf probe -x ~/bin/perf -L sigtrap_handler 0 sigtrap_handler(int signum __maybe_unused, siginfo_t *info, void *ucontext __maybe_unused) 1 { 2 if (!__atomic_fetch_add(&ctx.signal_count, 1, __ATOMIC_RELAXED)) 3 ctx.first_siginfo = *info; 4 __atomic_fetch_sub(&ctx.tids_want_signal, syscall(SYS_gettid), __ATOMIC_RELAXED); 5 } static void *test_thread(void *arg) { [root@quaco ~]# perf probe -x ~/bin/perf sigtrap_handler:4 "ctx.signal_count" Without the patch: [root@quaco ~]# perf probe -x ~/bin/perf sigtrap_handler:4 "ctx.signal_count" Failed to write event: Invalid argument Please upgrade your kernel to at least 3.14 to have access to feature @ctx Error: Failed to add events. [root@quaco ~]# With the patch: [root@quaco ~]# Failed to write event: Invalid argument @ctx accesses a variable by symbol name, but that is not supported for user application probe. Error: Failed to add events. [root@quaco ~]# Reported-by: Arnaldo Carvalho de Melo Signed-off-by: Masami Hiramatsu Closes: https://lore.kernel.org/all/ZLWDEjvFjrrEJODp@kernel.org/ Tested-by: Arnaldo Carvalho de Melo Link: https://lore.kernel.org/r/169055397023.67089.12693645664676964310.stgit@devnote2 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-event.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 16822a8..2d056f0 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -2800,13 +2800,18 @@ static void warn_uprobe_event_compat(struct probe_trace_event *tev) if (!tev->uprobes || tev->nargs == 0 || !buf) goto out; - for (i = 0; i < tev->nargs; i++) - if (strglobmatch(tev->args[i].value, "[$@+-]*")) { - pr_warning("Please upgrade your kernel to at least " - "3.14 to have access to feature %s\n", + for (i = 0; i < tev->nargs; i++) { + if (strchr(tev->args[i].value, '@')) { + pr_warning("%s accesses a variable by symbol name, but that is not supported for user application probe.\n", + tev->args[i].value); + break; + } + if (strglobmatch(tev->args[i].value, "[$+-]*")) { + pr_warning("Please upgrade your kernel to at least 3.14 to have access to feature %s\n", tev->args[i].value); break; } + } out: free(buf); } -- 2.7.4