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From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To: Huang Pei <huangpei@loongson.cn>
Cc: ambrosehua@gmail.com, Bibo Mao <maobibo@loongson.cn>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mips@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm@kvack.org, Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Paul Burton <paulburton@kernel.org>,
	Li Xuefeng <lixuefeng@loongson.cn>,
	Yang Tiezhu <yangtiezhu@loongson.cn>,
	Gao Juxin <gaojuxin@loongson.cn>,
	Fuxin Zhang <zhangfx@lemote.com>, Huacai Chen <chenhc@lemote.com>
Subject: Re: [PATCH] MIPS: fix kernel_stack_pointer()
Date: Mon, 1 Feb 2021 13:23:52 +0100	[thread overview]
Message-ID: <20210201122352.GA8095@alpha.franken.de> (raw)
In-Reply-To: <20210129043507.30488-1-huangpei@loongson.cn>

On Fri, Jan 29, 2021 at 12:35:07PM +0800, Huang Pei wrote:
> MIPS always save kernel stack pointer in regs[29]
> 
> Signed-off-by: Huang Pei <huangpei@loongson.cn>
> ---
>  arch/mips/include/asm/ptrace.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/include/asm/ptrace.h b/arch/mips/include/asm/ptrace.h
> index 1e76774b36dd..daf3cf244ea9 100644
> --- a/arch/mips/include/asm/ptrace.h
> +++ b/arch/mips/include/asm/ptrace.h
> @@ -53,7 +53,7 @@ struct pt_regs {
>  
>  static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
>  {
> -	return regs->regs[31];
> +	return regs->regs[29];

hmm, I'm still wondering where the trick is... looks like this is used
for uprobes, so nobody has ever used uprobes or I'm missing something.

How did you find that ?

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]


  reply	other threads:[~2021-02-01 12:24 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-29  4:35 Huang Pei
2021-02-01 12:23 ` Thomas Bogendoerfer [this message]
2021-02-02  1:32   ` Huang Pei
2021-02-03 10:36     ` Thomas Bogendoerfer

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