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From: Andy Lutomirski <luto@amacapital.net>
To: Jan Beulich <JBeulich@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86-64/entry: add instruction suffix to SYSRET
Date: Tue, 10 Dec 2019 07:29:52 -0800	[thread overview]
Message-ID: <08B92B44-CCA9-4B83-B9CC-F1601D44B73F@amacapital.net> (raw)
In-Reply-To: <cbecab05-9e95-5dec-ef81-499617c153a6@suse.com>



> On Dec 10, 2019, at 2:48 AM, Jan Beulich <JBeulich@suse.com> wrote:
> 
> Omitting suffixes from instructions in AT&T mode is bad practice when
> operand size cannot be determined by the assembler from register
> operands, and is likely going to be warned about by upstream gas in the
> future. Add the missing suffix here.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> 
> --- a/arch/x86/entry/entry_64.S
> +++ b/arch/x86/entry/entry_64.S
> @@ -1728,7 +1728,7 @@ END(nmi)
> SYM_CODE_START(ignore_sysret)
>    UNWIND_HINT_EMPTY
>    mov    $-ENOSYS, %eax
> -    sysret
> +    sysretl

Isn’t the default sysretq?  sysretl looks more correct, but that suggests that your changelog is wrong.

Is this code even reachable?

> SYM_CODE_END(ignore_sysret)
> #endif
> 

  reply	other threads:[~2019-12-10 15:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-10 10:48 [PATCH] x86-64/entry: add instruction suffix to SYSRET Jan Beulich
2019-12-10 15:29 ` Andy Lutomirski [this message]
2019-12-10 15:40   ` Jan Beulich
2019-12-12 21:43     ` Andy Lutomirski
2019-12-13  9:55       ` Jan Beulich
2019-12-13 17:49         ` Andy Lutomirski
2019-12-16 10:11           ` Jan Beulich
2019-12-16 15:23             ` Brian Gerst
2019-12-19  2:39               ` Andy Lutomirski

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