linux-kernel - Re: [PATCH 08/11] objtool/loongarch: Add unwind hints in prepare

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Message-ID: <2e25fe84-f772-5d87-c7a7-bf40055fb4bc@loongson.cn>
Date: Tue, 1 Apr 2025 15:45:55 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Ingo Molnar <mingo@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
 Peter Zijlstra <peterz@...radead.org>, kernel test robot <lkp@...el.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 08/11] objtool/loongarch: Add unwind hints in
 prepare_frametrace()

On 04/01/2025 03:08 PM, Ingo Molnar wrote:
>
> * Josh Poimboeuf <jpoimboe@...nel.org> wrote:
>
>> If 'regs' points to a local stack variable, prepare_frametrace() stores
>> all registers to the stack.  This confuses objtool as it expects them to
>> be restored from the stack later.
>>
>> The stores don't affect stack tracing, so use unwind hints to hide them
>> from objtool.
>>
>> Fixes the following warnings:
>>
>>   arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[22]=-1+0 reg2[22]=-2-160
>>   arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[23]=-1+0 reg2[23]=-2-152
>>
>> Cc: Tiezhu Yang <yangtiezhu@...ngson.cn>
>> Fixes: cb8a2ef0848c ("LoongArch: Add ORC stack unwinder support")
>> Reported-by: kernel test robot <lkp@...el.com>
>> Closes: https://lore.kernel.org/oe-kbuild-all/202503280703.OARM8SrY-lkp@intel.com/
>> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
>
> Note, I skipped this fix from tip:objtool/urgent for the time being,
> because Tiezhu Yang indicated that he'd be reviewing and testing this
> patch.

Tested-by: Tiezhu Yang <yangtiezhu@...ngson.cn>