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x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
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Move the non-regs fields to the off-stack data.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438148483-11932-3-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Brian Gerst authored and Ingo Molnar committed Jul 31, 2015
1 parent 9fda6a0 commit d4ce0f2
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Showing 2 changed files with 30 additions and 28 deletions.
16 changes: 8 additions & 8 deletions arch/x86/include/asm/vm86.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,7 @@ 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
Expand All @@ -59,10 +53,16 @@ struct kernel_vm86_struct {

struct vm86 {
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
Expand Down
42 changes: 22 additions & 20 deletions arch/x86/kernel/vm86_32.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,6 @@


#define KVM86 ((struct kernel_vm86_struct *)regs)
#define VMPI KVM86->vm86plus


/*
Expand Down Expand Up @@ -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");
Expand Down Expand Up @@ -282,25 +281,27 @@ 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;
Expand All @@ -317,7 +318,7 @@ 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;
Expand Down Expand Up @@ -346,8 +347,7 @@ 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 */
Expand Down Expand Up @@ -539,12 +539,13 @@ 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))
Expand All @@ -568,7 +569,7 @@ static void do_int(struct kernel_vm86_regs *regs, int i,

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
Expand All @@ -595,12 +596,13 @@ 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); \
Expand Down Expand Up @@ -670,8 +672,8 @@ 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);
Expand Down

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