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From: Peter Zijlstra <peterz@infradead.org>
To: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	jthierry@redhat.com, tglx@linutronix.de
Subject: Re: [PATCH V2 9/9] x86/speculation: Remove all ANNOTATE_NOSPEC_ALTERNATIVE directives
Date: Tue, 7 Apr 2020 19:26:30 +0200	[thread overview]
Message-ID: <20200407172630.GH20730@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <06605b1c-c9ae-fd18-bcb1-e4a48f2cb60e@oracle.com>

On Tue, Apr 07, 2020 at 07:01:43PM +0200, Alexandre Chartre wrote:

> I think that's the case with smap_save:
> 
> static __always_inline unsigned long smap_save(void)
> {
>         unsigned long flags;
> 
>         asm volatile (ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC,
>                                   X86_FEATURE_SMAP)
>                       : "=rm" (flags) : : "memory", "cc");
> 
>         return flags;
> }
> 
> The alternative does change the stack but objtool won't complain
> because it handles the pushf and pop instruction.

Oh bugger; indeed! That'll wreck unwinding.

  reply	other threads:[~2020-04-07 17:26 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-07  7:31 [PATCH V2 0/9] objtool changes to remove all ANNOTATE_NOSPEC_ALTERNATIVE Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 1/9] objtool: Introduce HINT_RET_OFFSET Alexandre Chartre
2020-04-07 12:53   ` Peter Zijlstra
2020-04-07 13:17     ` Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 2/9] objtool: UNWIND_HINT_RET_OFFSET should not check registers Alexandre Chartre
2020-05-01 18:22   ` [tip: objtool/core] " tip-bot2 for Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 3/9] objtool: is_fentry_call() crashes if call has no destination Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 4/9] objtool: Allow branches within the same alternative Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 5/9] objtool: Add support for intra-function calls Alexandre Chartre
2020-04-07 13:07   ` Peter Zijlstra
2020-04-07 13:28     ` Alexandre Chartre
2020-04-08 14:06       ` Alexandre Chartre
2020-04-08 14:19         ` Julien Thierry
2020-04-08 16:03           ` Alexandre Chartre
2020-04-08 16:04             ` Julien Thierry
2020-04-08 17:06               ` Alexandre Chartre
2020-04-08 17:07                 ` Julien Thierry
2020-04-07  7:31 ` [PATCH V2 6/9] x86/speculation: Change __FILL_RETURN_BUFFER to work with objtool Alexandre Chartre
2020-04-07 13:27   ` Josh Poimboeuf
2020-04-07  7:31 ` [PATCH V2 7/9] x86/speculation: Annotate intra-function calls Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 8/9] x86/speculation: Add unwind hint to trampoline return Alexandre Chartre
2020-04-07  7:31 ` [PATCH V2 9/9] x86/speculation: Remove all ANNOTATE_NOSPEC_ALTERNATIVE directives Alexandre Chartre
2020-04-07 13:28   ` Peter Zijlstra
2020-04-07 13:34     ` Josh Poimboeuf
2020-04-07 14:32       ` Alexandre Chartre
2020-04-07 16:18         ` Alexandre Chartre
2020-04-07 16:28           ` Josh Poimboeuf
2020-04-07 17:01             ` Alexandre Chartre
2020-04-07 17:26               ` Peter Zijlstra [this message]
2020-04-07 17:27             ` Peter Zijlstra
2020-04-08 21:35               ` Peter Zijlstra
2020-04-09  8:18                 ` Alexandre Chartre
2020-04-09 10:34                   ` Peter Zijlstra
2020-04-09 10:40                     ` Peter Zijlstra
2020-04-07 16:41           ` Peter Zijlstra
2020-04-07 17:04             ` Alexandre Chartre
2020-04-07 13:52   ` Peter Zijlstra
2020-04-07 13:59     ` Peter Zijlstra
2020-04-07 13:35 ` [PATCH V2 0/9] objtool changes to remove all ANNOTATE_NOSPEC_ALTERNATIVE Josh Poimboeuf
2020-04-07 14:02   ` Alexandre Chartre

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