Messages in this thread | | | Date | Tue, 5 Apr 2022 10:03:35 +0200 | From | Peter Zijlstra <> | Subject | Re: vmlinux.o: warning: objtool: stackleak_erase()+0x35: call to ftrace_likely_update() leaves .noinstr.text section |
| |
On Mon, Apr 04, 2022 at 03:25:02PM -0400, Steven Rostedt wrote: > On Mon, 4 Apr 2022 11:27:47 -0700 > Kees Cook <keescook@chromium.org> wrote: > > > I got CCed on this because of stackleak_erase() triggering, this, but it > > appears to be an existing issue for other callers too. It looks like > > __branch_check__() shouldn't be emitting ftrace_likely_update() calls > > for noinstr functions... > > > > I have no idea how a macro is meant to check for function attributes, > > though... :( > > Ignore it. It's the branch tracer enabled (that is, every "if ()" is being > traced). > > Although I still use the branch profiler, I do not believe anyone uses the > branch tracer. The branch profiler updates an array of counters that tells > when the branch was true or false, the branch tracer actually traces > (records an event) for every branch in the system!
\o/
> I think I'll just send a patch to nuke the tracer. I'm sure Peter Zijlstra > will be happy when I do that. But I still want the profiler, as I find that > useful.
It'll explode the moment Lai's entry rework goes through. That'll make us run C code before we switch to the kernel address space, so your counters will not exist/be-mapped and *BOOM*.
| |