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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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x86/entry/vm86: Move userspace accesses to do_sys_vm86()
Move the userspace accesses down into the common function in preparation for the next set of patches. Also change to copying the fields explicitly instead of assuming a fixed order in pt_regs and the kernel data structures. Signed-off-by: Brian Gerst <brgerst@gmail.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Denys Vlasenko <dvlasenk@redhat.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/1437354550-25858-4-git-send-email-brgerst@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Brian Gerst
Ingo Molnar
parent
df1ae9a5dc
commit
ed0b2edb61
@ -405,7 +405,7 @@ struct thread_struct {
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unsigned long error_code;
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#ifdef CONFIG_X86_32
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/* Virtual 86 mode info */
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struct vm86_struct __user *vm86_info;
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struct vm86plus_struct __user *vm86_info;
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unsigned long screen_bitmap;
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unsigned long v86flags;
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unsigned long v86mask;
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@ -90,46 +90,13 @@
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#define SAFE_MASK (0xDD5)
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#define RETURN_MASK (0xDFF)
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/* convert kernel_vm86_regs to vm86_regs */
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static int copy_vm86_regs_to_user(struct vm86_regs __user *user,
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const struct kernel_vm86_regs *regs)
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{
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int ret = 0;
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/*
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* kernel_vm86_regs is missing gs, so copy everything up to
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* (but not including) orig_eax, and then rest including orig_eax.
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*/
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ret += copy_to_user(user, regs, offsetof(struct kernel_vm86_regs, pt.orig_ax));
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ret += copy_to_user(&user->orig_eax, ®s->pt.orig_ax,
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sizeof(struct kernel_vm86_regs) -
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offsetof(struct kernel_vm86_regs, pt.orig_ax));
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return ret;
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}
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/* convert vm86_regs to kernel_vm86_regs */
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static int copy_vm86_regs_from_user(struct kernel_vm86_regs *regs,
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const struct vm86_regs __user *user,
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unsigned extra)
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{
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int ret = 0;
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/* copy ax-fs inclusive */
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ret += copy_from_user(regs, user, offsetof(struct kernel_vm86_regs, pt.orig_ax));
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/* copy orig_ax-__gsh+extra */
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ret += copy_from_user(®s->pt.orig_ax, &user->orig_eax,
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sizeof(struct kernel_vm86_regs) -
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offsetof(struct kernel_vm86_regs, pt.orig_ax) +
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extra);
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return ret;
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}
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struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
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{
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struct tss_struct *tss;
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struct pt_regs *ret;
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unsigned long tmp;
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struct task_struct *tsk = current;
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struct vm86plus_struct __user *user;
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long err = 0;
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/*
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* This gets called from entry.S with interrupts disabled, but
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@ -138,23 +105,50 @@ struct pt_regs *save_v86_state(struct kernel_vm86_regs *regs)
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*/
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local_irq_enable();
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if (!current->thread.vm86_info) {
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if (!tsk->thread.vm86_info) {
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pr_alert("no vm86_info: BAD\n");
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do_exit(SIGSEGV);
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}
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set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | current->thread.v86mask);
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tmp = copy_vm86_regs_to_user(¤t->thread.vm86_info->regs, regs);
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tmp += put_user(current->thread.screen_bitmap, ¤t->thread.vm86_info->screen_bitmap);
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if (tmp) {
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set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | tsk->thread.v86mask);
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user = tsk->thread.vm86_info;
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if (!access_ok(VERIFY_WRITE, user, VMPI.is_vm86pus ?
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sizeof(struct vm86plus_struct) :
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sizeof(struct vm86_struct))) {
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pr_alert("could not access userspace vm86_info\n");
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do_exit(SIGSEGV);
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}
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put_user_try {
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put_user_ex(regs->pt.bx, &user->regs.ebx);
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put_user_ex(regs->pt.cx, &user->regs.ecx);
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put_user_ex(regs->pt.dx, &user->regs.edx);
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put_user_ex(regs->pt.si, &user->regs.esi);
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put_user_ex(regs->pt.di, &user->regs.edi);
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put_user_ex(regs->pt.bp, &user->regs.ebp);
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put_user_ex(regs->pt.ax, &user->regs.eax);
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put_user_ex(regs->pt.ip, &user->regs.eip);
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put_user_ex(regs->pt.cs, &user->regs.cs);
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put_user_ex(regs->pt.flags, &user->regs.eflags);
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put_user_ex(regs->pt.sp, &user->regs.esp);
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put_user_ex(regs->pt.ss, &user->regs.ss);
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put_user_ex(regs->es, &user->regs.es);
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put_user_ex(regs->ds, &user->regs.ds);
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put_user_ex(regs->fs, &user->regs.fs);
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put_user_ex(regs->gs, &user->regs.gs);
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put_user_ex(tsk->thread.screen_bitmap, &user->screen_bitmap);
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} put_user_catch(err);
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if (err) {
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pr_alert("could not access userspace vm86_info\n");
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do_exit(SIGSEGV);
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}
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tss = &per_cpu(cpu_tss, get_cpu());
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current->thread.sp0 = current->thread.saved_sp0;
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current->thread.sysenter_cs = __KERNEL_CS;
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load_sp0(tss, ¤t->thread);
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current->thread.saved_sp0 = 0;
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tsk->thread.sp0 = tsk->thread.saved_sp0;
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tsk->thread.sysenter_cs = __KERNEL_CS;
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load_sp0(tss, &tsk->thread);
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tsk->thread.saved_sp0 = 0;
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put_cpu();
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ret = KVM86->regs32;
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@ -199,7 +193,8 @@ out:
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static int do_vm86_irq_handling(int subfunction, int irqnumber);
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static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk);
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static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
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struct kernel_vm86_struct *info);
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SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
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{
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@ -208,21 +203,8 @@ SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, v86)
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* This remains on the stack until we
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* return to 32 bit user space.
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*/
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struct task_struct *tsk = current;
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int tmp;
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if (tsk->thread.saved_sp0)
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return -EPERM;
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tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
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offsetof(struct kernel_vm86_struct, vm86plus) -
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sizeof(info.regs));
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if (tmp)
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return -EFAULT;
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memset(&info.vm86plus, 0, (int)&info.regs32 - (int)&info.vm86plus);
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info.regs32 = current_pt_regs();
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tsk->thread.vm86_info = v86;
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do_sys_vm86(&info, tsk);
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return 0; /* we never return here */
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return do_sys_vm86((struct vm86plus_struct __user *) v86, false, &info);
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}
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@ -233,11 +215,7 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
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* This remains on the stack until we
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* return to 32 bit user space.
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*/
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struct task_struct *tsk;
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int tmp;
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struct vm86plus_struct __user *v86;
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tsk = current;
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switch (cmd) {
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case VM86_REQUEST_IRQ:
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case VM86_FREE_IRQ:
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@ -255,34 +233,69 @@ SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
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}
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/* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
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if (tsk->thread.saved_sp0)
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return -EPERM;
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v86 = (struct vm86plus_struct __user *)arg;
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tmp = copy_vm86_regs_from_user(&info.regs, &v86->regs,
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offsetof(struct kernel_vm86_struct, regs32) -
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sizeof(info.regs));
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if (tmp)
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return -EFAULT;
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info.regs32 = current_pt_regs();
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info.vm86plus.is_vm86pus = 1;
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tsk->thread.vm86_info = (struct vm86_struct __user *)v86;
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do_sys_vm86(&info, tsk);
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return 0; /* we never return here */
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return do_sys_vm86((struct vm86plus_struct __user *) arg, true, &info);
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}
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static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk)
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static long do_sys_vm86(struct vm86plus_struct __user *v86, bool plus,
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struct kernel_vm86_struct *info)
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{
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struct tss_struct *tss;
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/*
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* make sure the vm86() system call doesn't try to do anything silly
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*/
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info->regs.pt.ds = 0;
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info->regs.pt.es = 0;
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info->regs.pt.fs = 0;
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#ifndef CONFIG_X86_32_LAZY_GS
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info->regs.pt.gs = 0;
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#endif
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struct task_struct *tsk = current;
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unsigned long err = 0;
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if (tsk->thread.saved_sp0)
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return -EPERM;
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if (!access_ok(VERIFY_READ, v86, plus ?
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sizeof(struct vm86_struct) :
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sizeof(struct vm86plus_struct)))
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return -EFAULT;
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memset(info, 0, sizeof(*info));
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get_user_try {
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unsigned short seg;
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get_user_ex(info->regs.pt.bx, &v86->regs.ebx);
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get_user_ex(info->regs.pt.cx, &v86->regs.ecx);
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get_user_ex(info->regs.pt.dx, &v86->regs.edx);
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get_user_ex(info->regs.pt.si, &v86->regs.esi);
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get_user_ex(info->regs.pt.di, &v86->regs.edi);
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get_user_ex(info->regs.pt.bp, &v86->regs.ebp);
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get_user_ex(info->regs.pt.ax, &v86->regs.eax);
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get_user_ex(info->regs.pt.ip, &v86->regs.eip);
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get_user_ex(seg, &v86->regs.cs);
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info->regs.pt.cs = seg;
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get_user_ex(info->regs.pt.flags, &v86->regs.eflags);
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get_user_ex(info->regs.pt.sp, &v86->regs.esp);
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get_user_ex(seg, &v86->regs.ss);
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info->regs.pt.ss = seg;
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get_user_ex(info->regs.es, &v86->regs.es);
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get_user_ex(info->regs.ds, &v86->regs.ds);
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get_user_ex(info->regs.fs, &v86->regs.fs);
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get_user_ex(info->regs.gs, &v86->regs.gs);
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get_user_ex(info->flags, &v86->flags);
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get_user_ex(info->screen_bitmap, &v86->screen_bitmap);
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get_user_ex(info->cpu_type, &v86->cpu_type);
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} get_user_catch(err);
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if (err)
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return err;
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if (copy_from_user(&info->int_revectored, &v86->int_revectored,
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sizeof(struct revectored_struct)))
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return -EFAULT;
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if (copy_from_user(&info->int21_revectored, &v86->int21_revectored,
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sizeof(struct revectored_struct)))
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return -EFAULT;
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if (plus) {
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if (copy_from_user(&info->vm86plus, &v86->vm86plus,
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sizeof(struct vm86plus_info_struct)))
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return -EFAULT;
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info->vm86plus.is_vm86pus = 1;
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}
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info->regs32 = current_pt_regs();
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tsk->thread.vm86_info = v86;
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/*
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* The flags register is also special: we cannot trust that the user
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@ -344,7 +357,7 @@ static void do_sys_vm86(struct kernel_vm86_struct *info, struct task_struct *tsk
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"jmp resume_userspace"
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: /* no outputs */
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:"r" (&info->regs), "r" (task_thread_info(tsk)), "r" (0));
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/* we never return here */
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unreachable(); /* we never return here */
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}
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static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval)
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