linux-kernel - [PATCH 1/5] x86/vm86: Move userspace accesses to do_sys

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Date:	Sat, 11 Jul 2015 01:09:16 -0400
From:	Brian Gerst <brgerst@...il.com>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 1/5] x86/vm86: Move userspace accesses to do_sys_vm86()

Move the userspace accesses down into the common function in
preparation for the next set of patches.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/kernel/vm86_32.c | 61 +++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 34 deletions(-)

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index fc9db6e..71a8b0a 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -200,7 +200,8 @@ out:
 
 
 static int do_vm86_irq_handling(int subfunction, int irqnumber);
-static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
+static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
+			struct kernel_vm86_struct *info);
 
 SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
 {
@@ -209,21 +210,8 @@ SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
 					 * This remains on the stack until we
 					 * return to 32 bit user space.
 					 */
-	struct task_struct *tsk = current;
-	int tmp;
 
-	if (tsk->thread.saved_sp0)
-		return -EPERM;
-	tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
-				       offsetof(struct kernel_vm86_struct, vm86plus) -
-				       sizeof(info.regs));
-	if (tmp)
-		return -EFAULT;
-	memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
-	info.regs32 = current_pt_regs();
-	tsk->thread.vm86_info = v86;
-	do_sys_vm86(&info, tsk);
-	return 0;	/* we never return here */
+	return do_sys_vm86((struct vm86plus_struct __user *) v86, false, &info);
 }
 
 
@@ -234,11 +222,7 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
 					 * This remains on the stack until we
 					 * return to 32 bit user space.
 					 */
-	struct task_struct *tsk;
-	int tmp;
-	struct vm86plus_struct __user *v86;
 
-	tsk = current;
 	switch (cmd) {
 	case VM86_REQUEST_IRQ:
 	case VM86_FREE_IRQ:
@@ -256,25 +240,34 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
 	}
 
 	/* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
-	if (tsk->thread.saved_sp0)
-		return -EPERM;
-	v86 = (struct vm86plus_struct __user *)arg;
-	tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
-				       offsetof(struct kernel_vm86_struct, regs32) -
-				       sizeof(info.regs));
-	if (tmp)
-		return -EFAULT;
-	info.regs32 = current_pt_regs();
-	info.vm86plus.is_vm86pus = 1;
-	tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
-	do_sys_vm86(&info, tsk);
-	return 0;	/* we never return here */
+	return do_sys_vm86((struct vm86plus_struct __user *) arg, true, &info);
 }
 
 
-static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
+static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
+			struct kernel_vm86_struct *info)
 {
 	struct tss_struct *tss;
+	struct task_struct *tsk = current;
+
+	if (tsk->thread.saved_sp0)
+		return -EPERM;
+	if (plus) {
+		if (copy_vm86_regs_from_user(&info->regs, &v86->regs,
+			offsetof(struct kernel_vm86_struct, regs32) -
+			sizeof(info->regs)))
+			return -EFAULT;
+		info->vm86plus.is_vm86pus = 1;
+	} else {
+		if (copy_vm86_regs_from_user(&info->regs, &v86->regs,
+			offsetof(struct kernel_vm86_struct, vm86plus) -
+			sizeof(info->regs)))
+			return -EFAULT;
+		memset(&info->vm86plus, 0, sizeof(struct vm86plus_info_struct));
+	}
+	info->regs32 = current_pt_regs();
+	tsk->thread.vm86_info = (struct vm86_struct __user *) v86;
+
 /*
  * make sure the vm86() system call doesn't try to do anything silly
  */
@@ -344,7 +337,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
 		"jmp resume_userspace"
 		: /* no outputs */
 		:"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
-	/* we never return here */
+	return 0;	/* we never return here */
 }
 
 static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval)
-- 
2.4.3

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