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

Tiezhu Yang
2024-06-20T09:50:55Z

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