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perf probe: Show correct error message about @symbol usage for uprobe

Browse source 
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
  <sigtrap_handler@/home/acme/git/perf-tools-next/tools/perf/tests/sigtrap.c:0>
        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 <acme@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Closes: https://lore.kernel.org/all/ZLWDEjvFjrrEJODp@kernel.org/
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/169055397023.67089.12693645664676964310.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Masami Hiramatsu 2023-07-28 23:19:30 +09:00 committed by Arnaldo Carvalho de Melo
parent ed847e30f0
commit e8ca4f0f8c
1 changed files with 9 additions and 4 deletions
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13
tools/perf/util/probe-event.c
View file

@ -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);
}