Re: [PATCH v2 12/39] x86/ibt,ftrace: Search for __fentry__ location

[Naveen N. Rao]

Peter Zijlstra wrote:
> On Thu, Mar 03, 2022 at 09:34:13AM -0500, Steven Rostedt wrote:
> > On Thu, 3 Mar 2022 14:04:52 +0100
> > Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> >
> > > > @@ -1596,7 +1596,7 @@ static int check_ftrace_location(struct kprobe *p)
> > > > {
> > > > 	unsigned long ftrace_addr;
> > > > 
> > > > -	ftrace_addr = ftrace_location((unsigned long)p->addr);
> > > > +	ftrace_addr = ftrace_location_range((unsigned long)p->addr, (unsigned long)p->addr);  
> > > 
> > > Yes, although perhaps a new helper. I'll go ponder during lunch.
> >
> > Is there more places to add that to make it worth creating a helper?
>
> This is what I ended up with, I've looked at all ftrace_location() sites
> there are, seems to work too, both the built-in boot time ftrace tests
> and the selftests work splat-less.
>
> I should update the Changelog some though.
>
> Naveen also mentioned register_ftrace_direct() could be further cleaned
> up, but I didn't want to do too much in once go.

Not a problem, I can send those as cleanups atop this series.

> ---
>
> Subject: x86/ibt,ftrace: Search for __fentry__ location
> From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Date: Wed Feb 23 10:01:38 CET 2022
>
> Have ftrace_location() search the symbol for the __fentry__ location
> when it isn't at func+0 and use this for {,un}register_ftrace_direct().
>
> This avoids a whole bunch of assumptions about __fentry__ being at
> func+0.
>
> Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> ---

This version looks good to me.
Acked-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>


Thanks,
Naveen