[PATCH 3/5] x86/vm86: Move fields from kernel_vm86_struct

[Brian Gerst]

Move the non-regs fields to the off-stack data.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
---
 arch/x86/include/asm/vm86.h | 17 ++++++++--------
 arch/x86/kernel/vm86_32.c   | 48 ++++++++++++++++++++++-----------------------
 2 files changed, 33 insertions(+), 32 deletions(-)

diff --git a/arch/x86/include/asm/vm86.h b/arch/x86/include/asm/vm86.h
index 88f14e3..bc28a40 100644
--- a/arch/x86/include/asm/vm86.h
+++ b/arch/x86/include/asm/vm86.h
@@ -38,13 +38,7 @@ struct kernel_vm86_struct {
  * Therefore, pt_regs in fact points to a complete 'kernel_vm86_struct'
  * in kernelspace, hence we need not reget the data from userspace.
  */
-#define VM86_TSS_ESP0 flags
-	unsigned long flags;
-	unsigned long screen_bitmap;
-	unsigned long cpu_type;
-	struct revectored_struct int_revectored;
-	struct revectored_struct int21_revectored;
-	struct vm86plus_info_struct vm86plus;
+#define VM86_TSS_ESP0 regs32
 	struct pt_regs *regs32;   /* here we save the pointer to the old regs */
 /*
  * The below is not part of the structure, but the stack layout continues
@@ -60,12 +54,19 @@ struct kernel_vm86_struct {
 
 struct kernel_vm86_info {
 	struct vm86_struct __user *vm86_info;
-	unsigned long screen_bitmap;
 	unsigned long v86flags;
 	unsigned long v86mask;
 	unsigned long saved_sp0;
 	unsigned int saved_fs;
 	unsigned int saved_gs;
+
+	/* Must match vm86plus_struct after regs */
+	unsigned long flags;
+	unsigned long screen_bitmap;
+	unsigned long cpu_type;
+	struct revectored_struct int_revectored;
+	struct revectored_struct int21_revectored;
+	struct vm86plus_info_struct vm86plus;
 };
 
 #ifdef CONFIG_VM86
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 8b29c9b..f174602 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -68,7 +68,6 @@
 
 
 #define KVM86	((struct kernel_vm86_struct *)regs)
-#define VMPI	KVM86->vm86plus
 
 
 /*
@@ -111,18 +110,16 @@ static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
 
 /* convert vm86_regs to kernel_vm86_regs */
 static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,
-				    const struct vm86_regs __user *user,
-				    unsigned extra)
+				    const struct vm86_regs __user *user)
 {
 	int ret = 0;
 
 	/* copy ax-fs inclusive */
 	ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax));
-	/* copy orig_ax-__gsh+extra */
+	/* copy orig_ax-__gsh */
 	ret += copy_from_user(&regs->pt.orig_ax, &user->orig_eax,
 			      sizeof(struct kernel_vm86_regs) -
-			      offsetof(struct kernel_vm86_regs, pt.orig_ax) +
-			      extra);
+			      offsetof(struct kernel_vm86_regs, pt.orig_ax));
 	return ret;
 }
 
@@ -261,18 +258,20 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
 	}
 	if (vm86->saved_sp0)
 		return -EPERM;
+	if (copy_vm86_regs_from_user(&info->regs, &v86->regs))
+		return -EFAULT;
 	if (plus) {
-		if (copy_vm86_regs_from_user(&info->regs, &v86->regs,
-			offsetof(struct kernel_vm86_struct, regs32) -
-			sizeof(info->regs)))
+		if (copy_from_user(&vm86->flags, &v86->flags,
+				   sizeof(struct vm86plus_struct) -
+				   offsetof(struct vm86plus_struct, flags)))
 			return -EFAULT;
-		info->vm86plus.is_vm86pus = 1;
+		vm86->vm86plus.is_vm86pus = 1;
 	} else {
-		if (copy_vm86_regs_from_user(&info->regs, &v86->regs,
-			offsetof(struct kernel_vm86_struct, vm86plus) -
-			sizeof(info->regs)))
+		if (copy_from_user(&vm86->flags, &v86->flags,
+				   sizeof(struct vm86_struct) -
+				   offsetof(struct vm86_struct, flags)))
 			return -EFAULT;
-		memset(&info->vm86plus, 0, sizeof(struct vm86plus_info_struct));
+		memset(&vm86->vm86plus, 0, sizeof(struct vm86plus_info_struct));
 	}
 	info->regs32 = current_pt_regs();
 	vm86->vm86_info = (struct vm86_struct __user *) v86;
@@ -297,7 +296,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
 	info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK;
 	info->regs.pt.flags |= X86_VM_MASK;
 
-	switch (info->cpu_type) {
+	switch (vm86->cpu_type) {
 	case CPU_286:
 		vm86->v86mask = 0;
 		break;
@@ -327,8 +326,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
 	load_sp0(tss, &tsk->thread);
 	put_cpu();
 
-	vm86->screen_bitmap = info->screen_bitmap;
-	if (info->flags & VM86_SCREEN_BITMAP)
+	if (vm86->flags & VM86_SCREEN_BITMAP)
 		mark_screen_rdonly(tsk->mm);
 
 	/*call __audit_syscall_exit since we do not exit via the normal paths */
@@ -520,12 +518,13 @@ static void do_int(struct kernel_vm86_regs *regs, int i,
 {
 	unsigned long __user *intr_ptr;
 	unsigned long segoffs;
+	struct kernel_vm86_info *vm86 = current->thread.vm86;
 
 	if (regs->pt.cs == BIOSSEG)
 		goto cannot_handle;
-	if (is_revectored(i, &KVM86->int_revectored))
+	if (is_revectored(i, &vm86->int_revectored))
 		goto cannot_handle;
-	if (i == 0x21 && is_revectored(AH(regs), &KVM86->int21_revectored))
+	if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored))
 		goto cannot_handle;
 	intr_ptr = (unsigned long __user *) (i << 2);
 	if (get_user(segoffs, intr_ptr))
@@ -549,7 +548,7 @@ cannot_handle:
 
 int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
 {
-	if (VMPI.is_vm86pus) {
+	if (current->thread.vm86->vm86plus.is_vm86pus) {
 		if ((trapno == 3) || (trapno == 1)) {
 			KVM86->regs32->ax = VM86_TRAP + (trapno << 8);
 			/* setting this flag forces the code in entry_32.S to
@@ -576,12 +575,13 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
 	unsigned char __user *ssp;
 	unsigned short ip, sp, orig_flags;
 	int data32, pref_done;
+	struct vm86plus_info_struct *vmpi = &current->thread.vm86->vm86plus;
 
 #define CHECK_IF_IN_TRAP \
-	if (VMPI.vm86dbg_active && VMPI.vm86dbg_TFpendig) \
+	if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
 		newflags |= X86_EFLAGS_TF
 #define VM86_FAULT_RETURN do { \
-	if (VMPI.force_return_for_pic  && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \
+	if (vmpi->force_return_for_pic  && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) \
 		return_to_32bit(regs, VM86_PICRETURN); \
 	if (orig_flags & X86_EFLAGS_TF) \
 		handle_vm86_trap(regs, 0, 1); \
@@ -651,8 +651,8 @@ void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
 	case 0xcd: {
 		int intno = popb(csp, ip, simulate_sigsegv);
 		IP(regs) = ip;
-		if (VMPI.vm86dbg_active) {
-			if ((1 << (intno & 7)) & VMPI.vm86dbg_intxxtab[intno >> 3])
+		if (vmpi->vm86dbg_active) {
+			if ((1 << (intno & 7)) & vmpi->vm86dbg_intxxtab[intno >> 3])
 				return_to_32bit(regs, VM86_INTx + (intno << 8));
 		}
 		do_int(regs, intno, ssp, sp);
-- 
2.4.3

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