linux-kernel - Re: [PATCH V2 9/9] x86/speculation: Remove all ANNOTATE_NOSPEC

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Message-ID: <89b10eb8-c030-b954-6be3-8830fc6a8daa@oracle.com>
Date:   Tue, 7 Apr 2020 16:32:32 +0200
From:   Alexandre Chartre <alexandre.chartre@...cle.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, jthierry@...hat.com,
        tglx@...utronix.de
Subject: Re: [PATCH V2 9/9] x86/speculation: Remove all
 ANNOTATE_NOSPEC_ALTERNATIVE directives

On 4/7/20 3:34 PM, Josh Poimboeuf wrote:
> On Tue, Apr 07, 2020 at 03:28:37PM +0200, Peter Zijlstra wrote:
>> Josh, we should probably have objtool verify it doesn't emit ORC entries
>> in alternative ranges.
> 
> Agreed, it might be as simple as checking for insn->alt_group in the
> INSN_STACK check or in update_insn_state().
> 

We could do that only for the "objtool orc generate" command. That way
"objtool check" would still check the alternative, but "objtool orc generate"
will just use the first half of the alternative (like it does today with
ANNOTATE_NOSPEC_ALTERNATIVE). We can even keep all ANNOTATE_NOSPEC_ALTERNATIVE
but only use them for "objtool orc generate".

alex.