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Subject[PATCH 3/5] x86/vm86: Move fields from kernel_vm86_struct
Date
Move the non-regs fields to the off-stack data.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
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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