x86: refactor ioport unification

Refactor ioport unification to pull out common code.

Cc: mboton@gmail.com
Cc: Kevin Winchester <kjwinchester@gmail.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NChris Wright <chrisw@sous-sol.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/ioport.c

@@ -113,13 +113,9 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
  * on system-call entry - see also fork() and the signal handling
  * code.
  */
-#ifdef CONFIG_X86_32
-asmlinkage long sys_iopl(unsigned long regsp)
+static int do_iopl(unsigned int level, struct pt_regs *regs)
 {
-	struct pt_regs *regs = (struct pt_regs *)&regsp;
-	unsigned int level = regs->bx;
 	unsigned int old = (regs->flags >> 12) & 3;
-	struct thread_struct *t = &current->thread;
 
 	if (level > 3)
 		return -EINVAL;
@@ -128,25 +124,31 @@ asmlinkage long sys_iopl(unsigned long regsp)
 		if (!capable(CAP_SYS_RAWIO))
 			return -EPERM;
 	}
-	t->iopl = level << 12;
 	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
-	set_iopl_mask(t->iopl);
+
 	return 0;
 }
-#else
-asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
+
+#ifdef CONFIG_X86_32
+asmlinkage long sys_iopl(unsigned long regsp)
 {
-	unsigned int old = (regs->flags >> 12) & 3;
+	struct pt_regs *regs = (struct pt_regs *)&regsp;
+	unsigned int level = regs->bx;
+	struct thread_struct *t = &current->thread;
+	int rc;
 
-	if (level > 3)
-		return -EINVAL;
-	/* Trying to gain more privileges? */
-	if (level > old) {
-		if (!capable(CAP_SYS_RAWIO))
-			return -EPERM;
-	}
-	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
+	rc = do_iopl(level, regs);
+	if (rc < 0)
+		goto out;
 
-	return 0;
+	t->iopl = level << 12;
+	set_iopl_mask(t->iopl);
+out:
+	return rc;
+}
+#else
+asmlinkage long sys_iopl(unsigned int level, struct pt_regs *regs)
+{
+	return do_iopl(level, regs);
 }
 #endif