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Date: Fri, 25 Sep 2009 19:54:59 -0400
Message-ID: <73c1f2160909251654v1c9f8eb9k9211f1e0c5e15f67@mail.gmail.com>
Subject: Re: [GIT PULL] x86: unify sys_iopl
From: Brian Gerst <brgerst@gmail.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@redhat.com>,
       "the arch/x86 maintainers" <x86@kernel.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Fri, Sep 25, 2009 at 7:22 PM, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> On 09/25/09 15:56, Brian Gerst wrote:
>> The correct fix is to move set_iopl_mask into do_iopl.  sys_iopl
>> should only be a wrapper around do_iopl to manage the different
>> calling convention used by 32-bit and 64-bit.
>>
>
> The patch eliminates that distinction, so I guess do_iopl should really
> be folded into sys_iopl (though the compiler effectively does that
> anyway by inlining it).

Using task_pt_regs is less effecient than getting the pointer directly
from the syscall entry code.  On 32-bit it probably doesn't matter too
much, but on 64-bit, you still need the special stub code in
entry_64.S to put the full pt_regs struct on the stack.  Changing the
calling conventions should be a seperate patch, and should be done for
all pt_regs-using syscalls.
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