Re: [PATCH v2] selftests/ftrace: adjust offset for kprobe syntax error test

[Steven Rostedt]

On Tue, 3 Dec 2024 18:01:06 -0700
Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:

> On 12/2/24 12:41, Steven Rostedt wrote:
> > On Sat, 30 Nov 2024 01:56:21 +0530
> > Hari Bathini <hbathini@xxxxxxxxxxxxx> wrote:
> >   
> >> In 'NOFENTRY_ARGS' test case for syntax check, any offset X of
> >> `vfs_read+X` except function entry offset (0) fits the criterion,
> >> even if that offset is not at instruction boundary, as the parser
> >> comes before probing. But with "ENDBR64" instruction on x86, offset
> >> 4 is treated as function entry. So, X can't be 4 as well. Thus, 8
> >> was used as offset for the test case. On 64-bit powerpc though, any
> >> offset <= 16 can be considered function entry depending on build
> >> configuration (see arch_kprobe_on_func_entry() for implementation
> >> details). So, use `vfs_read+20` to accommodate that scenario too.
> >>
> >> Suggested-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> >> Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>  
> > 
> > Acked-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
> > 
> > Shuah,
> > 
> > Can you take this through your tree?  
> 
> Yes I can take it. I do have question about whether this is
> a fix - sounds like it is from the change log.
> 
> Clearly stating that it is a fix will help so it can be picked
> up for stables.

I would say it's a fix, as the test currently fails in certain scenarios
for powerpc.

You can add:

Fixes: 4231f30fcc34a ("selftests/ftrace: Add BTF arguments test cases")

-- Steve