Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752765AbZIYW4h (ORCPT ); Fri, 25 Sep 2009 18:56:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752550AbZIYW4g (ORCPT ); Fri, 25 Sep 2009 18:56:36 -0400 Received: from mail-ew0-f211.google.com ([209.85.219.211]:63944 "EHLO mail-ew0-f211.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750992AbZIYW4f convert rfc822-to-8bit (ORCPT ); Fri, 25 Sep 2009 18:56:35 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=T1CQm934sPHxJ43Zb9zAOzctYcyQbJmFgewixmK3AeEy4BxC2b2n7qiUy8lQYWxp9H e+bGH4GNYZ1wfZMTbAoxbDJy8OQfjqj8gj0Vg7PhLJovUFs/JtVCRsa5tXKGF65rdGLS k75e+dLDwjV/qJvntv0uhKv3r+DkL3o4ShstE= MIME-Version: 1.0 In-Reply-To: <4ABD3EC2.1020104@goop.org> References: <4ABD3EC2.1020104@goop.org> Date: Fri, 25 Sep 2009 18:56:38 -0400 Message-ID: <73c1f2160909251556g40f3c5b1o1c29b7f012912873@mail.gmail.com> Subject: Re: [GIT PULL] x86: unify sys_iopl From: Brian Gerst To: Jeremy Fitzhardinge Cc: Ingo Molnar , "the arch/x86 maintainers" , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4660 Lines: 123 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. On Fri, Sep 25, 2009 at 6:05 PM, Jeremy Fitzhardinge wrote: > Hi Ingo, > > The x86-64 implementation of iopl was buggy because it never ended up calling > set_iopl_mask().  This had no effect on native sys_iopl (because set_iopl_mask > is normally no-op on 64-bit), but it ended up never calling the pvop, which caused > iopl to have no effect on 64-bit Xen guests. > > The two functions are needlessly different anyway.  This patch just unifies them > into a single function which is mostly derived from the 32-bit version. > > Thanks, >        J > > The following changes since commit c44c9ec0f38b939b3200436e3aa95c1aa83c41c7: >  Jeremy Fitzhardinge (1): >        x86: split NX setup into separate file to limit unstack-protected code > > are available in the git repository at: > >  git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git bugfix > > Jeremy Fitzhardinge (1): >      x86: unify sys_iopl > >  arch/x86/include/asm/syscalls.h |    8 +++----- >  arch/x86/kernel/ioport.c        |   11 ++--------- >  2 files changed, 5 insertions(+), 14 deletions(-) > > From 8dbb1d168eb8be6bf43d123fdfb3ba3b03762e62 Mon Sep 17 00:00:00 2001 > From: Jeremy Fitzhardinge > Date: Wed, 23 Sep 2009 16:35:24 -0700 > Subject: [PATCH] x86: unify sys_iopl > > The 32 and 64-bit versions of sys_iopl were needlessly different: >  - The 32-bit version ignored its function argument and directly >   fetched the parameter from struct regs, presumably code dating >   from the neolithic era. >  - The 64-bit version never called set_iopl_mask().  Usually this >   is a no-op for 64-bit, but it is also a pvop, which meant that >   that iopl never worked for 64-bit guests under Xen. >  - Both versions use the archaic style of getting pt_regs passed >   to them.  We can get the current pt_regs with task_pt_regs, which >   avoids worrying about the fine details of stack layout. > > We can use the body of the 32-bit function with a few small > adjustments to the function definition. > > Signed-off-by: Jeremy Fitzhardinge > > diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h > index 372b76e..5336ce2 100644 > --- a/arch/x86/include/asm/syscalls.h > +++ b/arch/x86/include/asm/syscalls.h > @@ -33,11 +33,11 @@ long sys_rt_sigreturn(struct pt_regs *); >  asmlinkage int sys_set_thread_area(struct user_desc __user *); >  asmlinkage int sys_get_thread_area(struct user_desc __user *); > > -/* X86_32 only */ > -#ifdef CONFIG_X86_32 >  /* kernel/ioport.c */ > -long sys_iopl(struct pt_regs *); > +asmlinkage long sys_iopl(unsigned int); > > +/* X86_32 only */ > +#ifdef CONFIG_X86_32 >  /* kernel/process_32.c */ >  int sys_clone(struct pt_regs *); >  int sys_execve(struct pt_regs *); > @@ -70,8 +70,6 @@ int sys_vm86(struct pt_regs *); >  #else /* CONFIG_X86_32 */ > >  /* X86_64 only */ > -/* kernel/ioport.c */ > -asmlinkage long sys_iopl(unsigned int, struct pt_regs *); > >  /* kernel/process_64.c */ >  asmlinkage long sys_clone(unsigned long, unsigned long, > diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c > index 99c4d30..bad4f22 100644 > --- a/arch/x86/kernel/ioport.c > +++ b/arch/x86/kernel/ioport.c > @@ -119,11 +119,10 @@ static int do_iopl(unsigned int level, struct pt_regs *regs) >        return 0; >  } > > -#ifdef CONFIG_X86_32 > -long sys_iopl(struct pt_regs *regs) > +asmlinkage long sys_iopl(unsigned int level) >  { > -       unsigned int level = regs->bx; >        struct thread_struct *t = ¤t->thread; > +       struct pt_regs *regs = task_pt_regs(current); >        int rc; > >        rc = do_iopl(level, regs); > @@ -135,9 +134,3 @@ long sys_iopl(struct pt_regs *regs) >  out: >        return rc; >  } > -#else > -asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs) > -{ > -       return do_iopl(level, regs); > -} > -#endif > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at  http://vger.kernel.org/majordomo-info.html > Please read the FAQ at  http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/