linux-kernel - Re: [PATCH 3/7] objtool: Add support for intra-function calls

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Message-ID: <20200403124107.GO20730@hirez.programming.kicks-ass.net>
Date:   Fri, 3 Apr 2020 14:41:07 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Julien Thierry <jthierry@...hat.com>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de
Subject: Re: [PATCH 3/7] objtool: Add support for intra-function calls

On Fri, Apr 03, 2020 at 09:01:38AM +0100, Julien Thierry wrote:
> 
> Last I found is in qcom_link_stack_sanitization() [2], but that's just a
> workaround for a very specific hardware. In my local tree I just put the
> function as STACK_FRAME_NON_STANDARD. But the code just saves the return
> address, has 16 call instructions that just call the instruction after them,
> restores the return address and lets the C-function return normally (and it
> somehow fixes something for that hardware).
> 
That sounds very much like the RSB flushing we do.