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[PATCH v4] x86: vm86 cleanups

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  [PATCH v4] x86: vm86 cleanups Brian Gerst <brgerst@gmail.com> - 2015-07-29 07:50 +0200
    [PATCH 7/8] x86/vm86: Rename vm86->vm86_info to user_vm86 Brian Gerst <brgerst@gmail.com> - 2015-07-29 07:50 +0200

#1194825 — [PATCH v4] x86: vm86 cleanups

The goal of this set of patches is to change vm86 support to return to
userspace with the normal exit paths instead of leaving data on the kernel
stack and jumping directly into the exit asm routines.  This fixes issues
like ptrace and syscall auditing not working with vm86, and makes possible
cleanups in the syscall exit work code.

Changes from v3:
- Removed patches already accepted
- Renamed some fields per Ingo
- Added patches to allow disabling hardware IRQ support and to fix includes
- Added helper macro for free_vm86 (Note: could not use inline function due
  to header issues)

Changes from v2:
- Use gs slot of regs32 (present but unused in lazy mode)
- Add access_ok() checks before get_user_try/put_user_try

Changes from v1:
- Added first two patches
- Changed userspace access to copy each field explicitly instead of relying
  on the same order of members in the structure.

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#1194826 — [PATCH 7/8] x86/vm86: Rename vm86->vm86_info to user_vm86

Make it clearer that this is the pointer to the userspace vm86 state area.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
 arch/x86/include/asm/vm86.h |  2 +-
 arch/x86/kernel/vm86_32.c   | 70 +++++++++++++++++++++++----------------------
 2 files changed, 37 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/vm86.h b/arch/x86/include/asm/vm86.h
index 05f6394..5c027c5 100644
--- a/arch/x86/include/asm/vm86.h
+++ b/arch/x86/include/asm/vm86.h
@@ -28,7 +28,7 @@ struct kernel_vm86_regs {
 };
 
 struct vm86 {
-	struct vm86plus_struct __user *vm86_info;
+	struct vm86plus_struct __user *user_vm86;
 	struct pt_regs regs32;
 	unsigned long v86flags;
 	unsigned long v86mask;
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 6fce378..aca499d 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -104,17 +104,17 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
 	 */
 	local_irq_enable();
 
-	if (!vm86 || !vm86->vm86_info) {
-		pr_alert("no vm86_info: BAD\n");
+	if (!vm86 || !vm86->user_vm86) {
+		pr_alert("no user_vm86: BAD\n");
 		do_exit(SIGSEGV);
 	}
 	set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->v86mask);
-	user = vm86->vm86_info;
+	user = vm86->user_vm86;
 
 	if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.is_vm86pus ?
 		       sizeof(struct vm86plus_struct) :
 		       sizeof(struct vm86_struct))) {
-		pr_alert("could not access userspace vm86_info\n");
+		pr_alert("could not access userspace vm86 info\n");
 		do_exit(SIGSEGV);
 	}
 
@@ -139,7 +139,7 @@ void save_v86_state(struct kernel_vm86_regs *regs, int retval)
 		put_user_ex(vm86->screen_bitmap, &user->screen_bitmap);
 	} put_user_catch(err);
 	if (err) {
-		pr_alert("could not access userspace vm86_info\n");
+		pr_alert("could not access userspace vm86 info\n");
 		do_exit(SIGSEGV);
 	}
 
@@ -199,11 +199,11 @@ static inline int do_vm86_irq_handling(int subfunction, int irqnumber)
 }
 #endif
 
-static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus);
+static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus);
 
-SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
+SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86)
 {
-	return do_sys_vm86((struct vm86plus_struct __user *) v86, false);
+	return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false);
 }
 
 
@@ -230,7 +230,7 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
 }
 
 
-static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus)
+static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
 {
 	struct tss_struct *tss;
 	struct task_struct *tsk = current;
@@ -247,7 +247,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus)
 	if (vm86->saved_sp0)
 		return -EPERM;
 
-	if (!access_ok(VERIFY_READ, v86, plus ?
+	if (!access_ok(VERIFY_READ, user_vm86, plus ?
 		       sizeof(struct vm86_struct) :
 		       sizeof(struct vm86plus_struct)))
 		return -EFAULT;
@@ -255,40 +255,42 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus)
 	memset(&vm86regs, 0, sizeof(vm86regs));
 	get_user_try {
 		unsigned short seg;
-		get_user_ex(vm86regs.pt.bx, &v86->regs.ebx);
-		get_user_ex(vm86regs.pt.cx, &v86->regs.ecx);
-		get_user_ex(vm86regs.pt.dx, &v86->regs.edx);
-		get_user_ex(vm86regs.pt.si, &v86->regs.esi);
-		get_user_ex(vm86regs.pt.di, &v86->regs.edi);
-		get_user_ex(vm86regs.pt.bp, &v86->regs.ebp);
-		get_user_ex(vm86regs.pt.ax, &v86->regs.eax);
-		get_user_ex(vm86regs.pt.ip, &v86->regs.eip);
-		get_user_ex(seg, &v86->regs.cs);
+		get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx);
+		get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx);
+		get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx);
+		get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi);
+		get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi);
+		get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp);
+		get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax);
+		get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip);
+		get_user_ex(seg, &user_vm86->regs.cs);
 		vm86regs.pt.cs = seg;
-		get_user_ex(vm86regs.pt.flags, &v86->regs.eflags);
-		get_user_ex(vm86regs.pt.sp, &v86->regs.esp);
-		get_user_ex(seg, &v86->regs.ss);
+		get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags);
+		get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp);
+		get_user_ex(seg, &user_vm86->regs.ss);
 		vm86regs.pt.ss = seg;
-		get_user_ex(vm86regs.es, &v86->regs.es);
-		get_user_ex(vm86regs.ds, &v86->regs.ds);
-		get_user_ex(vm86regs.fs, &v86->regs.fs);
-		get_user_ex(vm86regs.gs, &v86->regs.gs);
-
-		get_user_ex(vm86->flags, &v86->flags);
-		get_user_ex(vm86->screen_bitmap, &v86->screen_bitmap);
-		get_user_ex(vm86->cpu_type, &v86->cpu_type);
+		get_user_ex(vm86regs.es, &user_vm86->regs.es);
+		get_user_ex(vm86regs.ds, &user_vm86->regs.ds);
+		get_user_ex(vm86regs.fs, &user_vm86->regs.fs);
+		get_user_ex(vm86regs.gs, &user_vm86->regs.gs);
+
+		get_user_ex(vm86->flags, &user_vm86->flags);
+		get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap);
+		get_user_ex(vm86->cpu_type, &user_vm86->cpu_type);
 	} get_user_catch(err);
 	if (err)
 		return err;
 
-	if (copy_from_user(&vm86->int_revectored, &v86->int_revectored,
+	if (copy_from_user(&vm86->int_revectored,
+			   &user_vm86->int_revectored,
 			   sizeof(struct revectored_struct)))
 		return -EFAULT;
-	if (copy_from_user(&vm86->int21_revectored, &v86->int21_revectored,
+	if (copy_from_user(&vm86->int21_revectored,
+			   &user_vm86->int21_revectored,
 			   sizeof(struct revectored_struct)))
 		return -EFAULT;
 	if (plus) {
-		if (copy_from_user(&vm86->vm86plus, &v86->vm86plus,
+		if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus,
 				   sizeof(struct vm86plus_info_struct)))
 			return -EFAULT;
 		vm86->vm86plus.is_vm86pus = 1;
@@ -297,7 +299,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus)
 		       sizeof(struct vm86plus_info_struct));
 
 	memcpy(&vm86->regs32, regs, sizeof(struct pt_regs));
-	vm86->vm86_info = v86;
+	vm86->user_vm86 = user_vm86;
 
 /*
  * The flags register is also special: we cannot trust that the user
-- 
2.4.3

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