linux-kernel - Re: [PATCH] objtool: fix rare switch jump table pattern detection

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Date:   Wed, 26 Oct 2016 18:03:44 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] objtool: fix rare switch jump table pattern detection

On Wednesday, October 26, 2016 10:34:08 AM CEST Josh Poimboeuf wrote:
> The following commit:
> 
>   3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")
> 
> ... improved objtool's ability to detect gcc switch statement jump
> tables for gcc 6.  However the check to allow short jumps with the
> scanned range of instructions wasn't quite right.  The pattern detection
> should allow jumps to the indirect jump instruction itself.
> 
> This fixes the following warning:
> 
>   drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x315: sibling call from callable instruction with changed frame pointer
> 
> Reported-by: Arnd Bergmann <arnd@...db.de>
> Fixes: 3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Tested-by: Arnd Bergmann <arnd@...db.de>

It fixes the mlx4/resource_tracker.o problem, but not the other
one for ttusb-dec/ttusb_dec.o, as you mentioned.

Do you need any more help creating a testcase for that one?

	Arnd