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From: "Shi, Yang" <yang.shi@linaro.org>
To: Z Lim <zlim.lnx@gmail.com>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Alexei Starovoitov <ast@kernel.org>,
	daniel@iogearbox.net, Xi Wang <xi.wang@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	linaro-kernel@lists.linaro.org
Subject: Re: [PATCH] arm64: bpf: fix JIT stack setup
Date: Tue, 10 Nov 2015 11:46:42 -0800	[thread overview]
Message-ID: <564249A2.1070903@linaro.org> (raw)
In-Reply-To: <CABg9mcvACuVK2=GBbnur94CsckN2TXRCCiXhX7A8jYQ7arMM+Q@mail.gmail.com>

On 11/9/2015 12:00 PM, Z Lim wrote:
> On Mon, Nov 9, 2015 at 10:08 AM, Shi, Yang <yang.shi@linaro.org> wrote:
>> I added it to stay align with ARMv8 AAPCS to maintain the correct FP during
>> function call. It makes us get correct stack backtrace.
>>
>> I think we'd better to keep compliant with ARMv8 AAPCS in BPF JIT prologue
>> too.
>>
>> If nobody thinks it is necessary, we definitely could remove that change.
>
> Oh no, I don't think anyone will say it's unnecessary!
> I agree the A64_FP-related change is a good idea, so stack unwinding works.
>
> How about splitting this into two patches? One for the BPF-related
> bug, and another for A64 FP-handling.

I'm not sure if this is a good approach or not. IMHO, they are kind of 
atomic. Without A64 FP-handling, that fix looks incomplete and 
introduces another problem (stack backtrace).

Thanks,
Yang

>
> Thanks again for tracking this down and improving things overall for arm64 :)
>
>>
>> Thanks,
>> Yang
>>
>>


WARNING: multiple messages have this Message-ID (diff)
From: yang.shi@linaro.org (Shi, Yang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm64: bpf: fix JIT stack setup
Date: Tue, 10 Nov 2015 11:46:42 -0800	[thread overview]
Message-ID: <564249A2.1070903@linaro.org> (raw)
In-Reply-To: <CABg9mcvACuVK2=GBbnur94CsckN2TXRCCiXhX7A8jYQ7arMM+Q@mail.gmail.com>

On 11/9/2015 12:00 PM, Z Lim wrote:
> On Mon, Nov 9, 2015 at 10:08 AM, Shi, Yang <yang.shi@linaro.org> wrote:
>> I added it to stay align with ARMv8 AAPCS to maintain the correct FP during
>> function call. It makes us get correct stack backtrace.
>>
>> I think we'd better to keep compliant with ARMv8 AAPCS in BPF JIT prologue
>> too.
>>
>> If nobody thinks it is necessary, we definitely could remove that change.
>
> Oh no, I don't think anyone will say it's unnecessary!
> I agree the A64_FP-related change is a good idea, so stack unwinding works.
>
> How about splitting this into two patches? One for the BPF-related
> bug, and another for A64 FP-handling.

I'm not sure if this is a good approach or not. IMHO, they are kind of 
atomic. Without A64 FP-handling, that fix looks incomplete and 
introduces another problem (stack backtrace).

Thanks,
Yang

>
> Thanks again for tracking this down and improving things overall for arm64 :)
>
>>
>> Thanks,
>> Yang
>>
>>

  reply	other threads:[~2015-11-10 19:46 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-07  5:36 [PATCH] arm64: bpf: fix JIT stack setup Yang Shi
2015-11-07  5:36 ` Yang Shi
2015-11-08  2:27 ` Alexei Starovoitov
2015-11-08  2:27   ` Alexei Starovoitov
2015-11-08 22:29   ` Z Lim
2015-11-08 22:29     ` Z Lim
2015-11-08 22:29     ` Z Lim
2015-11-09 18:08     ` Shi, Yang
2015-11-09 18:08       ` Shi, Yang
2015-11-09 18:08       ` Shi, Yang
2015-11-09 20:00       ` Z Lim
2015-11-09 20:00         ` Z Lim
2015-11-09 20:00         ` Z Lim
2015-11-10 19:46         ` Shi, Yang [this message]
2015-11-10 19:46           ` Shi, Yang
2015-11-10 19:46           ` Shi, Yang
2015-11-11  3:11           ` Z Lim
2015-11-11  3:11             ` Z Lim
2015-11-11  3:11             ` Z Lim
  -- strict thread matches above, loose matches on Subject: below --
2015-11-07  5:34 Yang Shi
2015-11-07  5:55 ` Shi, Yang

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