linux-kernel - Re: [PATCH] objtool: Fix infinite loop in find_jump

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Date:   Wed, 29 Apr 2020 00:40:35 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Miroslav Benes <mbenes@...e.cz>,
        Julien Thierry <jthierry@...hat.com>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>
Subject: Re: [PATCH] objtool: Fix infinite loop in find_jump_table()

On Tue, Apr 28, 2020 at 04:45:16PM -0500, Josh Poimboeuf wrote:
> Kristen found a hang in objtool when building with -ffunction-sections.
> 
> It was caused by evergreen_pcie_gen2_enable.cold() being laid out
> immediately before evergreen_pcie_gen2_enable().  Since their "pfunc" is
> always the same, find_jump_table() got into an infinite loop because it
> didn't recognize the boundary between the two functions.
> 
> Fix that with a new prev_insn_same_sym() helper, which doesn't cross
> subfunction boundaries.
> 
> Reported-by: Kristen Carlson Accardi <kristen@...ux.intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>