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Message-ID: <3ab8410a-6c74-4dc1-997d-7b1a00fba877@arm.com>
Date: Thu, 20 Jun 2024 12:31:36 +0100
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Subject: Re: [PATCH] arm64: hw_breakpoint: Save privilege of access control
 via ptrace
To: Oleg Nesterov <oleg@redhat.com>, Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>,
 Catalin Marinas <catalin.marinas@arm.com>,
 Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
 Arnaldo Carvalho de Melo <acme@kernel.org>,
 Namhyung Kim <namhyung@kernel.org>, linux-arm-kernel@lists.infradead.org,
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References: <20240618071010.11214-1-yangtiezhu@loongson.cn>
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From: James Clark <james.clark@arm.com>
In-Reply-To: <20240620103600.GD30070@redhat.com>
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On 20/06/2024 11:36, Oleg Nesterov wrote:
> Again, I can't really comment, I know almost nothing about perf, but
> 
> On 06/20, Tiezhu Yang wrote:
>>
>> On 06/20/2024 05:08 PM, Oleg Nesterov wrote:
>>>
>>> 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")
> 
> but this is another thing even if I have no idea what .config3 means.
> 
> If nothing else, what do you think, say, tools/perf can do with ->bp_priv?

Yeah, including the tools side change in the same series might help to
explain. It's not obvious what the end goal is from the commit message.

Thanks
James

> 
> What should sys_perf_event_open() do if bp_priv != 0 comes from user space?
> 
> Nevermind, please forget, I leave this to you and maintainers.
> 
> Oleg.
> 
>