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Subject[PATCH 5/7] 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 | 16 ++++++++--------
arch/x86/kernel/vm86_32.c | 42 ++++++++++++++++++++++--------------------
2 files changed, 30 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/vm86.h b/arch/x86/include/asm/vm86.h
index a02967d..ff64c27 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
@@ -60,10 +54,16 @@ struct kernel_vm86_struct {

struct kernel_vm86_info {
struct vm86plus_struct __user *vm86_info;
- unsigned long screen_bitmap;
unsigned long v86flags;
unsigned long v86mask;
unsigned long saved_sp0;
+
+ 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 dce0a1c..bfaa59b 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


/*
@@ -114,7 +113,7 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->v86mask);
user = vm86->vm86_info;

- if (!access_ok(VERIFY_WRITE, user, VMPI.is_vm86pus ?
+ 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");
@@ -283,25 +282,27 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
get_user_ex(info->regs.fs, &v86->regs.fs);
get_user_ex(info->regs.gs, &v86->regs.gs);

- get_user_ex(info->flags, &v86->flags);
- get_user_ex(info->screen_bitmap, &v86->screen_bitmap);
- get_user_ex(info->cpu_type, &v86->cpu_type);
+ 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_catch(err);
if (err)
return err;

- if (copy_from_user(&info->int_revectored, &v86->int_revectored,
+ if (copy_from_user(&vm86->int_revectored, &v86->int_revectored,
sizeof(struct revectored_struct)))
return -EFAULT;
- if (copy_from_user(&info->int21_revectored, &v86->int21_revectored,
+ if (copy_from_user(&vm86->int21_revectored, &v86->int21_revectored,
sizeof(struct revectored_struct)))
return -EFAULT;
if (plus) {
- if (copy_from_user(&info->vm86plus, &v86->vm86plus,
+ if (copy_from_user(&vm86->vm86plus, &v86->vm86plus,
sizeof(struct vm86plus_info_struct)))
return -EFAULT;
- info->vm86plus.is_vm86pus = 1;
- }
+ vm86->vm86plus.is_vm86pus = 1;
+ } else
+ memset(&vm86->vm86plus, 0,
+ sizeof(struct vm86plus_info_struct));

info->regs32 = current_pt_regs();
vm86->vm86_info = v86;
@@ -318,7 +319,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,

info->regs.pt.orig_ax = info->regs32->orig_ax;

- switch (info->cpu_type) {
+ switch (vm86->cpu_type) {
case CPU_286:
vm86->v86mask = 0;
break;
@@ -347,8 +348,7 @@ 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 */
@@ -540,12 +540,13 @@ 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))
@@ -569,7 +570,7 @@ 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
@@ -596,12 +597,13 @@ 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); \
@@ -671,8 +673,8 @@ 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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