From f1e88e5c9c24f04e49538e960ad3aba8a29abc16 Mon Sep 17 00:00:00 2001
From: Zachary Amsden <zach@vmware.com>
Date: Sat, 3 Sep 2005 15:56:44 -0700
Subject: [PATCH] --- yaml --- r: 6985 b: refs/heads/master c:
 a5201129307f414890f9a4410e38da205f5d7359 h: refs/heads/master i:   6983:
 0026af6e9e681d79ac9532eb28e38066ad1b7549 v: v3

---
 [refs]                             |  2 +-
 trunk/arch/i386/kernel/ioport.c    |  7 ++++---
 trunk/arch/i386/kernel/process.c   |  6 ++++++
 trunk/include/asm-i386/processor.h | 16 ++++++++++++++++
 trunk/include/asm-i386/system.h    |  4 +---
 5 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/[refs] b/[refs]
index fedd70e29021..1f904c8f77cc 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 0998e4228aca046fbd747c3fed909791d52e88eb
+refs/heads/master: a5201129307f414890f9a4410e38da205f5d7359
diff --git a/trunk/arch/i386/kernel/ioport.c b/trunk/arch/i386/kernel/ioport.c
index 8b25160393c1..f2b37654777f 100644
--- a/trunk/arch/i386/kernel/ioport.c
+++ b/trunk/arch/i386/kernel/ioport.c
@@ -132,6 +132,7 @@ asmlinkage long sys_iopl(unsigned long unused)
 	volatile struct pt_regs * regs = (struct pt_regs *) &unused;
 	unsigned int level = regs->ebx;
 	unsigned int old = (regs->eflags >> 12) & 3;
+	struct thread_struct *t = &current->thread;
 
 	if (level > 3)
 		return -EINVAL;
@@ -140,8 +141,8 @@ asmlinkage long sys_iopl(unsigned long unused)
 		if (!capable(CAP_SYS_RAWIO))
 			return -EPERM;
 	}
-	regs->eflags = (regs->eflags &~ 0x3000UL) | (level << 12);
-	/* Make sure we return the long way (not sysenter) */
-	set_thread_flag(TIF_IRET);
+	t->iopl = level << 12;
+	regs->eflags = (regs->eflags & ~X86_EFLAGS_IOPL) | t->iopl;
+	set_iopl_mask(t->iopl);
 	return 0;
 }
diff --git a/trunk/arch/i386/kernel/process.c b/trunk/arch/i386/kernel/process.c
index 660997800393..b45cbf93d439 100644
--- a/trunk/arch/i386/kernel/process.c
+++ b/trunk/arch/i386/kernel/process.c
@@ -711,6 +711,12 @@ struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct tas
 	if (prev->gs | next->gs)
 		loadsegment(gs, next->gs);
 
+	/*
+	 * Restore IOPL if needed.
+	 */
+	if (unlikely(prev->iopl != next->iopl))
+		set_iopl_mask(next->iopl);
+
 	/*
 	 * Now maybe reload the debug registers
 	 */
diff --git a/trunk/include/asm-i386/processor.h b/trunk/include/asm-i386/processor.h
index 992224bff549..37bef8ed7bed 100644
--- a/trunk/include/asm-i386/processor.h
+++ b/trunk/include/asm-i386/processor.h
@@ -455,6 +455,7 @@ struct thread_struct {
 	unsigned int		saved_fs, saved_gs;
 /* IO permissions */
 	unsigned long	*io_bitmap_ptr;
+ 	unsigned long	iopl;
 /* max allowed port in the bitmap, in bytes: */
 	unsigned long	io_bitmap_max;
 };
@@ -511,6 +512,21 @@ static inline void load_esp0(struct tss_struct *tss, struct thread_struct *threa
 			: /* no output */			\
 			:"r" (value))
 
+/*
+ * Set IOPL bits in EFLAGS from given mask
+ */
+static inline void set_iopl_mask(unsigned mask)
+{
+	unsigned int reg;
+	__asm__ __volatile__ ("pushfl;"
+			      "popl %0;"
+			      "andl %1, %0;"
+			      "orl %2, %0;"
+			      "pushl %0;"
+			      "popfl"
+				: "=&r" (reg)
+				: "i" (~X86_EFLAGS_IOPL), "r" (mask));
+}
 
 /* Forward declaration, a strange C thing */
 struct task_struct;
diff --git a/trunk/include/asm-i386/system.h b/trunk/include/asm-i386/system.h
index 37fd2f8c7196..acd5c26b69ba 100644
--- a/trunk/include/asm-i386/system.h
+++ b/trunk/include/asm-i386/system.h
@@ -14,8 +14,7 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc
 
 #define switch_to(prev,next,last) do {					\
 	unsigned long esi,edi;						\
-	asm volatile("pushfl\n\t"					\
-		     "pushl %%ebp\n\t"					\
+	asm volatile("pushl %%ebp\n\t"					\
 		     "movl %%esp,%0\n\t"	/* save ESP */		\
 		     "movl %5,%%esp\n\t"	/* restore ESP */	\
 		     "movl $1f,%1\n\t"		/* save EIP */		\
@@ -23,7 +22,6 @@ extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struc
 		     "jmp __switch_to\n"				\
 		     "1:\t"						\
 		     "popl %%ebp\n\t"					\
-		     "popfl"						\
 		     :"=m" (prev->thread.esp),"=m" (prev->thread.eip),	\
 		      "=a" (last),"=S" (esi),"=D" (edi)			\
 		     :"m" (next->thread.esp),"m" (next->thread.eip),	\