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

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Message-ID: <Z-uQ7NqMzqAShWcH@gmail.com>
Date: Tue, 1 Apr 2025 09:08:28 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	Peter Zijlstra <peterz@...radead.org>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>,
	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()


* 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.

Thanks,

	Ingo