linux-kernel - Re: [GIT PULL] x86/paravirt for v2.6.33

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Date:	Wed, 09 Dec 2009 10:31:41 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] x86/paravirt for v2.6.33

On 12/08/09 23:36, Ingo Molnar wrote:
> Jeremy, mind sending a patch that updates this code to use the less
> obfuscated 32-bit version, not the 64-bit version? (a delta patch
> against tip:master would be nice, as there's a fair amount of testing in
> the unification change itself already, which we dont want to discard.)
>    

How does this look?

git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git fix-iopl

From: Jeremy Fitzhardinge<jeremy.fitzhardinge@...rix.com>
Date: Wed, 9 Dec 2009 10:26:59 -0800
Subject: [PATCH] x86: Make sys_iopl use passed-in pt_regs

Rather than using task_pt_regs, use the pt_regs * passed into the syscall.
The ABI differences are handled in small 32/64-bit specific functions,
and everything else is handled in the common do_iopl().

Signed-off-by: Jeremy Fitzhardinge<jeremy.fitzhardinge@...rix.com>

diff --git a/arch/x86/include/asm/syscalls.h b/arch/x86/include/asm/syscalls.h
index 5336ce2..70497f0 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 *);

-/* kernel/ioport.c */
-asmlinkage long sys_iopl(unsigned int);
-
  /* X86_32 only */
  #ifdef CONFIG_X86_32
+/* kernel/ioport.c */
+asmlinkage long sys_iopl(struct pt_regs *);
+
  /* kernel/process_32.c */
  int sys_clone(struct pt_regs *);
  int sys_execve(struct pt_regs *);
@@ -71,6 +71,9 @@ int sys_vm86(struct pt_regs *);

  /* 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,
  			  void __user *, void __user *,
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index bad4f22..ac3cf88 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -105,6 +105,7 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
   */
  static int do_iopl(unsigned int level, struct pt_regs *regs)
  {
+	struct thread_struct *t =&current->thread;
  	unsigned int old = (regs->flags>>  12)&  3;

  	if (level>  3)
@@ -116,21 +117,20 @@ static int do_iopl(unsigned int level, struct pt_regs *regs)
  	}
  	regs->flags = (regs->flags&  ~X86_EFLAGS_IOPL) | (level<<  12);

+	t->iopl = level<<  12;
+	set_iopl_mask(t->iopl);
+
  	return 0;
  }

-asmlinkage long sys_iopl(unsigned int level)
+#ifdef CONFIG_X86_64
+asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
  {
-	struct thread_struct *t =&current->thread;
-	struct pt_regs *regs = task_pt_regs(current);
-	int rc;
-
-	rc = do_iopl(level, regs);
-	if (rc<  0)
-		goto out;
-
-	t->iopl = level<<  12;
-	set_iopl_mask(t->iopl);
-out:
-	return rc;
+	return do_iopl(level, regs);
+}
+#else
+asmlinkage long sys_iopl(struct pt_regs *regs)
+{
+	return do_iopl(regs->bx, regs);
  }
+#endif


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