Re: [PATCH] arm64: hw_breakpoint: Save privilege of access control via ptrace

[Tiezhu Yang]

On 06/20/2024 05:08 PM, Oleg Nesterov wrote:
> On 06/20, Tiezhu Yang wrote:
> > On 06/19/2024 11:15 PM, Oleg Nesterov wrote:
> > > > --- a/include/uapi/linux/perf_event.h
> > > > +++ b/include/uapi/linux/perf_event.h
> > > > @@ -467,6 +467,7 @@ struct perf_event_attr {
> > > > 		__u32		wakeup_watermark; /* bytes before wakeup   */
> > > > 	};
> > > >
> > > > +	__u8			bp_priv;
> > > > 	__u32			bp_type;
> > >
> > > Is it safe to add the new member in the middle of uapi struct?
> > > This will break userspace...
> >
> > Let me put the new member "bp_priv" at the end of uapi struct
> > perf_event_attr in the next version if you are OK with it.
>
> And add PERF_ATTR_SIZE_VER9 ?

Yes, thank you.

> Well, you can safely ignore me, you should ask the maintainers ;)
>
> But to me the very idea of arm64-specific and "kernel only" member in
> perf_event_attr looks a bit strange.

I noticed that there is a similar arm64-specific change in
commit 09519ec3b19e ("perf: Add perf_event_attr::config3")
according to the commit message, and it will be used for
LoongArch later if this change is accepted.

Thanks,
Tiezhu