Messages in this thread | | | Date | Thu, 9 Feb 2023 23:23:05 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [PATCH] tracing/selftests: Ignore __pfx_ symbols in kprobe test |
| |
On Wed, 8 Feb 2023 19:05:08 +0100 Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Feb 07, 2023 at 01:54:02PM -0500, Steven Rostedt wrote: > > On Tue, 7 Feb 2023 13:51:47 -0500 > > Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > > > > > The kprobe probepoint.tc test started failing because of the added __pfx_ > > > symbols that were added because of -fpatchable-function-entry=X,Y causing > > > unwinders to see them as part of the previous functions. But kprobes can > > > not be added on top of them. The selftest looks for tracefs_create_dir and > > > picks it and the previous and following functions to add at their address. > > > This caused it to include __pfx_tracefs_create_dir which is invalid to > > > attach a kprobe to and caused the test to fail. > > > > > > Fixes: 9f2899fe36a62 ("objtool: Add option to generate prefix symbols") > > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > > > > This is assuming that kprobes can not be added on top of these. But another > > solution could be to have kprobes just pick the function the __pfx_ is for. > > Would that be a better solution? > > Simply refusing them is simplest. I don't see a compelling reason to > make this complicated.
Yeah, and __pfx_ symbols has some "range", that means it is hard to translate the probe address if user specify __pfx_*+offset.
BTW, currently kprobe event rejects this __pfx_ symbols because it is notrace symbols, thus we can trace it if CONFIG_KPROBE_EVENTS_ON_NOTRACE=y. But I guess it should not probe that place always because it should never executed right?
Thank you,
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
| |