linux-kernel - Re: [PATCH 1/3] x86_64, entry: Remove a bogus ret_from

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Message-ID: <20150225072328.GB13061@gmail.com>
Date:	Wed, 25 Feb 2015 08:23:28 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 1/3] x86_64, entry: Remove a bogus ret_from_fork
 optimization


* Andy Lutomirski <luto@...capital.net> wrote:

> ret_from_fork checks TIF_IA32 to determine whether pt_regs and the
> related state make sense for ret_from_sys_call.  This is entirely
> the wrong check.  TS_COMPAT would make a little more sense, but
> there's really no point in keeping this optimization at all.
> 
> This fixes a return to the wrong user CS if we came from int 0x80 in
> a 64-bit task.
> 
> Signed-off-by: Andy Lutomirski <luto@...capital.net>

Acked-by: Ingo Molnar <mingo@...nel.org>

Thanks,

	Ingo
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