linux-kernel - Re: [PATCH] objtool: Fix objtool fallthrough detection with function padding

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Message-ID: <20170821130534.6z4ebqwjjaycu3xk@treble>
Date:   Mon, 21 Aug 2017 08:05:34 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org, Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] objtool: Fix objtool fallthrough detection with function
 padding

On Fri, Aug 11, 2017 at 12:24:15PM -0500, Josh Poimboeuf wrote:
> When GCC adds NOP padding between functions, those NOPs aren't
> associated with a function symbol, which breaks objtool's detection of a
> function falling through to another function.  Instead it shows
> confusing errors like:
> 
>   drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x8b: return with modified stack frame
>   drivers/mtd/chips/cfi_util.o: warning: objtool: cfi_qry_mode_on()+0x0: stack state mismatch: cfa1=-4-32 cfa2=7+8
>   drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: fixup_use_fwh_lock()+0x8: unknown stack-related register move
>   drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: fixup_use_fwh_lock()+0x0: stack state mismatch: cfa1=6+16 cfa2=7+8
>   drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0xa: unsupported stack pointer realignment
>   drivers/mtd/chips/cfi_cmdset_0002.o: warning: objtool: do_otp_write()+0x0: stack state mismatch: cfa1=-4-40 cfa2=7+8
> 
> Reported-by: kbuild test robot <fengguang.wu@...el.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Ping?

-- 
Josh