875 lines
23 KiB
C
875 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1994 Linus Torvalds
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*
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* 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
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* stack - Manfred Spraul <manfred@colorfullife.com>
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*
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* 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
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* them correctly. Now the emulation will be in a
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* consistent state after stackfaults - Kasper Dupont
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* <kasperd@daimi.au.dk>
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*
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* 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
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* <kasperd@daimi.au.dk>
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*
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* ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
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* caused by Kasper Dupont's changes - Stas Sergeev
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*
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* 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
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* Kasper Dupont <kasperd@daimi.au.dk>
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*
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* 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
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* Kasper Dupont <kasperd@daimi.au.dk>
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*
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* 9 apr 2002 - Changed stack access macros to jump to a label
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* instead of returning to userspace. This simplifies
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* do_int, and is needed by handle_vm6_fault. Kasper
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* Dupont <kasperd@daimi.au.dk>
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/capability.h>
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#include <linux/errno.h>
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#include <linux/interrupt.h>
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#include <linux/syscalls.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/highmem.h>
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#include <linux/ptrace.h>
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#include <linux/audit.h>
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#include <linux/stddef.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/uaccess.h>
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#include <asm/io.h>
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#include <asm/tlbflush.h>
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#include <asm/irq.h>
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#include <asm/traps.h>
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#include <asm/vm86.h>
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#include <asm/switch_to.h>
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/*
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* Known problems:
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*
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* Interrupt handling is not guaranteed:
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* - a real x86 will disable all interrupts for one instruction
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* after a "mov ss,xx" to make stack handling atomic even without
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* the 'lss' instruction. We can't guarantee this in v86 mode,
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* as the next instruction might result in a page fault or similar.
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* - a real x86 will have interrupts disabled for one instruction
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* past the 'sti' that enables them. We don't bother with all the
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* details yet.
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*
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* Let's hope these problems do not actually matter for anything.
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*/
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/*
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* 8- and 16-bit register defines..
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*/
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#define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
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#define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
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#define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
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#define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
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/*
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* virtual flags (16 and 32-bit versions)
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*/
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#define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags))
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#define VEFLAGS (current->thread.vm86->veflags)
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#define set_flags(X, new, mask) \
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((X) = ((X) & ~(mask)) | ((new) & (mask)))
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#define SAFE_MASK (0xDD5)
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#define RETURN_MASK (0xDFF)
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void save_v86_state(struct kernel_vm86_regs *regs, int retval)
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{
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struct task_struct *tsk = current;
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struct vm86plus_struct __user *user;
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struct vm86 *vm86 = current->thread.vm86;
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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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* from process context. Enable interrupts here, before trying
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* to access user space.
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*/
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local_irq_enable();
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if (!vm86 || !vm86->user_vm86) {
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pr_alert("no user_vm86: 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 | vm86->veflags_mask);
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user = vm86->user_vm86;
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if (!access_ok(VERIFY_WRITE, user, vm86->vm86plus.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(vm86->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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preempt_disable();
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tsk->thread.sp0 = vm86->saved_sp0;
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tsk->thread.sysenter_cs = __KERNEL_CS;
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update_task_stack(tsk);
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refresh_sysenter_cs(&tsk->thread);
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vm86->saved_sp0 = 0;
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preempt_enable();
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memcpy(®s->pt, &vm86->regs32, sizeof(struct pt_regs));
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lazy_load_gs(vm86->regs32.gs);
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regs->pt.ax = retval;
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}
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static void mark_screen_rdonly(struct mm_struct *mm)
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{
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struct vm_area_struct *vma;
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spinlock_t *ptl;
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pgd_t *pgd;
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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int i;
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down_write(&mm->mmap_sem);
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pgd = pgd_offset(mm, 0xA0000);
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if (pgd_none_or_clear_bad(pgd))
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goto out;
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p4d = p4d_offset(pgd, 0xA0000);
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if (p4d_none_or_clear_bad(p4d))
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goto out;
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pud = pud_offset(p4d, 0xA0000);
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if (pud_none_or_clear_bad(pud))
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goto out;
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pmd = pmd_offset(pud, 0xA0000);
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if (pmd_trans_huge(*pmd)) {
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vma = find_vma(mm, 0xA0000);
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split_huge_pmd(vma, pmd, 0xA0000);
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}
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if (pmd_none_or_clear_bad(pmd))
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goto out;
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pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
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for (i = 0; i < 32; i++) {
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if (pte_present(*pte))
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set_pte(pte, pte_wrprotect(*pte));
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pte++;
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}
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pte_unmap_unlock(pte, ptl);
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out:
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up_write(&mm->mmap_sem);
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flush_tlb_mm_range(mm, 0xA0000, 0xA0000 + 32*PAGE_SIZE, 0UL);
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}
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static int do_vm86_irq_handling(int subfunction, int irqnumber);
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static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus);
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SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86)
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{
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return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false);
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}
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SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
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{
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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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case VM86_GET_IRQ_BITS:
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case VM86_GET_AND_RESET_IRQ:
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return do_vm86_irq_handling(cmd, (int)arg);
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case VM86_PLUS_INSTALL_CHECK:
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/*
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* NOTE: on old vm86 stuff this will return the error
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* from access_ok(), because the subfunction is
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* interpreted as (invalid) address to vm86_struct.
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* So the installation check works.
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*/
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return 0;
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}
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/* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
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return do_sys_vm86((struct vm86plus_struct __user *) arg, true);
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}
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static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
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{
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struct task_struct *tsk = current;
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struct vm86 *vm86 = tsk->thread.vm86;
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struct kernel_vm86_regs vm86regs;
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struct pt_regs *regs = current_pt_regs();
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unsigned long err = 0;
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err = security_mmap_addr(0);
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if (err) {
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/*
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* vm86 cannot virtualize the address space, so vm86 users
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* need to manage the low 1MB themselves using mmap. Given
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* that BIOS places important data in the first page, vm86
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* is essentially useless if mmap_min_addr != 0. DOSEMU,
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* for example, won't even bother trying to use vm86 if it
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* can't map a page at virtual address 0.
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*
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* To reduce the available kernel attack surface, simply
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* disallow vm86(old) for users who cannot mmap at va 0.
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*
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* The implementation of security_mmap_addr will allow
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* suitably privileged users to map va 0 even if
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* vm.mmap_min_addr is set above 0, and we want this
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* behavior for vm86 as well, as it ensures that legacy
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* tools like vbetool will not fail just because of
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* vm.mmap_min_addr.
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*/
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pr_info_once("Denied a call to vm86(old) from %s[%d] (uid: %d). Set the vm.mmap_min_addr sysctl to 0 and/or adjust LSM mmap_min_addr policy to enable vm86 if you are using a vm86-based DOS emulator.\n",
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current->comm, task_pid_nr(current),
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from_kuid_munged(&init_user_ns, current_uid()));
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return -EPERM;
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}
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if (!vm86) {
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if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL)))
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return -ENOMEM;
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tsk->thread.vm86 = vm86;
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}
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if (vm86->saved_sp0)
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return -EPERM;
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if (!access_ok(VERIFY_READ, user_vm86, 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(&vm86regs, 0, sizeof(vm86regs));
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get_user_try {
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unsigned short seg;
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get_user_ex(vm86regs.pt.bx, &user_vm86->regs.ebx);
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get_user_ex(vm86regs.pt.cx, &user_vm86->regs.ecx);
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get_user_ex(vm86regs.pt.dx, &user_vm86->regs.edx);
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get_user_ex(vm86regs.pt.si, &user_vm86->regs.esi);
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get_user_ex(vm86regs.pt.di, &user_vm86->regs.edi);
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get_user_ex(vm86regs.pt.bp, &user_vm86->regs.ebp);
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get_user_ex(vm86regs.pt.ax, &user_vm86->regs.eax);
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get_user_ex(vm86regs.pt.ip, &user_vm86->regs.eip);
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get_user_ex(seg, &user_vm86->regs.cs);
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vm86regs.pt.cs = seg;
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get_user_ex(vm86regs.pt.flags, &user_vm86->regs.eflags);
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get_user_ex(vm86regs.pt.sp, &user_vm86->regs.esp);
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get_user_ex(seg, &user_vm86->regs.ss);
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vm86regs.pt.ss = seg;
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get_user_ex(vm86regs.es, &user_vm86->regs.es);
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get_user_ex(vm86regs.ds, &user_vm86->regs.ds);
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get_user_ex(vm86regs.fs, &user_vm86->regs.fs);
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get_user_ex(vm86regs.gs, &user_vm86->regs.gs);
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get_user_ex(vm86->flags, &user_vm86->flags);
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get_user_ex(vm86->screen_bitmap, &user_vm86->screen_bitmap);
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get_user_ex(vm86->cpu_type, &user_vm86->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(&vm86->int_revectored,
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&user_vm86->int_revectored,
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sizeof(struct revectored_struct)))
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return -EFAULT;
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if (copy_from_user(&vm86->int21_revectored,
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&user_vm86->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(&vm86->vm86plus, &user_vm86->vm86plus,
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sizeof(struct vm86plus_info_struct)))
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return -EFAULT;
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vm86->vm86plus.is_vm86pus = 1;
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} else
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memset(&vm86->vm86plus, 0,
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sizeof(struct vm86plus_info_struct));
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memcpy(&vm86->regs32, regs, sizeof(struct pt_regs));
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vm86->user_vm86 = user_vm86;
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/*
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* The flags register is also special: we cannot trust that the user
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* has set it up safely, so this makes sure interrupt etc flags are
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* inherited from protected mode.
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*/
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VEFLAGS = vm86regs.pt.flags;
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vm86regs.pt.flags &= SAFE_MASK;
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vm86regs.pt.flags |= regs->flags & ~SAFE_MASK;
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vm86regs.pt.flags |= X86_VM_MASK;
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vm86regs.pt.orig_ax = regs->orig_ax;
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switch (vm86->cpu_type) {
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case CPU_286:
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vm86->veflags_mask = 0;
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break;
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case CPU_386:
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vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
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break;
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case CPU_486:
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vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
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break;
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default:
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vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
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break;
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}
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/*
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* Save old state
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*/
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vm86->saved_sp0 = tsk->thread.sp0;
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lazy_save_gs(vm86->regs32.gs);
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/* make room for real-mode segments */
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preempt_disable();
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tsk->thread.sp0 += 16;
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if (static_cpu_has(X86_FEATURE_SEP)) {
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tsk->thread.sysenter_cs = 0;
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refresh_sysenter_cs(&tsk->thread);
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}
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update_task_stack(tsk);
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preempt_enable();
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if (vm86->flags & VM86_SCREEN_BITMAP)
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mark_screen_rdonly(tsk->mm);
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memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs));
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force_iret();
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return regs->ax;
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}
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static inline void set_IF(struct kernel_vm86_regs *regs)
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{
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VEFLAGS |= X86_EFLAGS_VIF;
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}
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static inline void clear_IF(struct kernel_vm86_regs *regs)
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{
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VEFLAGS &= ~X86_EFLAGS_VIF;
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}
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static inline void clear_TF(struct kernel_vm86_regs *regs)
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{
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regs->pt.flags &= ~X86_EFLAGS_TF;
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}
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static inline void clear_AC(struct kernel_vm86_regs *regs)
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{
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regs->pt.flags &= ~X86_EFLAGS_AC;
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}
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/*
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* It is correct to call set_IF(regs) from the set_vflags_*
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* functions. However someone forgot to call clear_IF(regs)
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* in the opposite case.
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* After the command sequence CLI PUSHF STI POPF you should
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* end up with interrupts disabled, but you ended up with
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* interrupts enabled.
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* ( I was testing my own changes, but the only bug I
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* could find was in a function I had not changed. )
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* [KD]
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*/
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static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
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{
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set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask);
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set_flags(regs->pt.flags, flags, SAFE_MASK);
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if (flags & X86_EFLAGS_IF)
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set_IF(regs);
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else
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clear_IF(regs);
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}
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static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
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{
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set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask);
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set_flags(regs->pt.flags, flags, SAFE_MASK);
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if (flags & X86_EFLAGS_IF)
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set_IF(regs);
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else
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clear_IF(regs);
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}
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static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
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{
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unsigned long flags = regs->pt.flags & RETURN_MASK;
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if (VEFLAGS & X86_EFLAGS_VIF)
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flags |= X86_EFLAGS_IF;
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flags |= X86_EFLAGS_IOPL;
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return flags | (VEFLAGS & current->thread.vm86->veflags_mask);
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}
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static inline int is_revectored(int nr, struct revectored_struct *bitmap)
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{
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return test_bit(nr, bitmap->__map);
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}
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#define val_byte(val, n) (((__u8 *)&val)[n])
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#define pushb(base, ptr, val, err_label) \
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do { \
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__u8 __val = val; \
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ptr--; \
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if (put_user(__val, base + ptr) < 0) \
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goto err_label; \
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} while (0)
|
|
|
|
#define pushw(base, ptr, val, err_label) \
|
|
do { \
|
|
__u16 __val = val; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 1), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 0), base + ptr) < 0) \
|
|
goto err_label; \
|
|
} while (0)
|
|
|
|
#define pushl(base, ptr, val, err_label) \
|
|
do { \
|
|
__u32 __val = val; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 3), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 2), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 1), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr--; \
|
|
if (put_user(val_byte(__val, 0), base + ptr) < 0) \
|
|
goto err_label; \
|
|
} while (0)
|
|
|
|
#define popb(base, ptr, err_label) \
|
|
({ \
|
|
__u8 __res; \
|
|
if (get_user(__res, base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
__res; \
|
|
})
|
|
|
|
#define popw(base, ptr, err_label) \
|
|
({ \
|
|
__u16 __res; \
|
|
if (get_user(val_byte(__res, 0), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
if (get_user(val_byte(__res, 1), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
__res; \
|
|
})
|
|
|
|
#define popl(base, ptr, err_label) \
|
|
({ \
|
|
__u32 __res; \
|
|
if (get_user(val_byte(__res, 0), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
if (get_user(val_byte(__res, 1), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
if (get_user(val_byte(__res, 2), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
if (get_user(val_byte(__res, 3), base + ptr) < 0) \
|
|
goto err_label; \
|
|
ptr++; \
|
|
__res; \
|
|
})
|
|
|
|
/* There are so many possible reasons for this function to return
|
|
* VM86_INTx, so adding another doesn't bother me. We can expect
|
|
* userspace programs to be able to handle it. (Getting a problem
|
|
* in userspace is always better than an Oops anyway.) [KD]
|
|
*/
|
|
static void do_int(struct kernel_vm86_regs *regs, int i,
|
|
unsigned char __user *ssp, unsigned short sp)
|
|
{
|
|
unsigned long __user *intr_ptr;
|
|
unsigned long segoffs;
|
|
struct vm86 *vm86 = current->thread.vm86;
|
|
|
|
if (regs->pt.cs == BIOSSEG)
|
|
goto cannot_handle;
|
|
if (is_revectored(i, &vm86->int_revectored))
|
|
goto cannot_handle;
|
|
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))
|
|
goto cannot_handle;
|
|
if ((segoffs >> 16) == BIOSSEG)
|
|
goto cannot_handle;
|
|
pushw(ssp, sp, get_vflags(regs), cannot_handle);
|
|
pushw(ssp, sp, regs->pt.cs, cannot_handle);
|
|
pushw(ssp, sp, IP(regs), cannot_handle);
|
|
regs->pt.cs = segoffs >> 16;
|
|
SP(regs) -= 6;
|
|
IP(regs) = segoffs & 0xffff;
|
|
clear_TF(regs);
|
|
clear_IF(regs);
|
|
clear_AC(regs);
|
|
return;
|
|
|
|
cannot_handle:
|
|
save_v86_state(regs, VM86_INTx + (i << 8));
|
|
}
|
|
|
|
int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
|
|
{
|
|
struct vm86 *vm86 = current->thread.vm86;
|
|
|
|
if (vm86->vm86plus.is_vm86pus) {
|
|
if ((trapno == 3) || (trapno == 1)) {
|
|
save_v86_state(regs, VM86_TRAP + (trapno << 8));
|
|
return 0;
|
|
}
|
|
do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
|
|
return 0;
|
|
}
|
|
if (trapno != 1)
|
|
return 1; /* we let this handle by the calling routine */
|
|
current->thread.trap_nr = trapno;
|
|
current->thread.error_code = error_code;
|
|
force_sig(SIGTRAP, current);
|
|
return 0;
|
|
}
|
|
|
|
void handle_vm86_fault(struct kernel_vm86_regs *regs, long error_code)
|
|
{
|
|
unsigned char opcode;
|
|
unsigned char __user *csp;
|
|
unsigned char __user *ssp;
|
|
unsigned short ip, sp, orig_flags;
|
|
int data32, pref_done;
|
|
struct vm86plus_info_struct *vmpi = ¤t->thread.vm86->vm86plus;
|
|
|
|
#define CHECK_IF_IN_TRAP \
|
|
if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
|
|
newflags |= X86_EFLAGS_TF
|
|
|
|
orig_flags = *(unsigned short *)®s->pt.flags;
|
|
|
|
csp = (unsigned char __user *) (regs->pt.cs << 4);
|
|
ssp = (unsigned char __user *) (regs->pt.ss << 4);
|
|
sp = SP(regs);
|
|
ip = IP(regs);
|
|
|
|
data32 = 0;
|
|
pref_done = 0;
|
|
do {
|
|
switch (opcode = popb(csp, ip, simulate_sigsegv)) {
|
|
case 0x66: /* 32-bit data */ data32 = 1; break;
|
|
case 0x67: /* 32-bit address */ break;
|
|
case 0x2e: /* CS */ break;
|
|
case 0x3e: /* DS */ break;
|
|
case 0x26: /* ES */ break;
|
|
case 0x36: /* SS */ break;
|
|
case 0x65: /* GS */ break;
|
|
case 0x64: /* FS */ break;
|
|
case 0xf2: /* repnz */ break;
|
|
case 0xf3: /* rep */ break;
|
|
default: pref_done = 1;
|
|
}
|
|
} while (!pref_done);
|
|
|
|
switch (opcode) {
|
|
|
|
/* pushf */
|
|
case 0x9c:
|
|
if (data32) {
|
|
pushl(ssp, sp, get_vflags(regs), simulate_sigsegv);
|
|
SP(regs) -= 4;
|
|
} else {
|
|
pushw(ssp, sp, get_vflags(regs), simulate_sigsegv);
|
|
SP(regs) -= 2;
|
|
}
|
|
IP(regs) = ip;
|
|
goto vm86_fault_return;
|
|
|
|
/* popf */
|
|
case 0x9d:
|
|
{
|
|
unsigned long newflags;
|
|
if (data32) {
|
|
newflags = popl(ssp, sp, simulate_sigsegv);
|
|
SP(regs) += 4;
|
|
} else {
|
|
newflags = popw(ssp, sp, simulate_sigsegv);
|
|
SP(regs) += 2;
|
|
}
|
|
IP(regs) = ip;
|
|
CHECK_IF_IN_TRAP;
|
|
if (data32)
|
|
set_vflags_long(newflags, regs);
|
|
else
|
|
set_vflags_short(newflags, regs);
|
|
|
|
goto check_vip;
|
|
}
|
|
|
|
/* int xx */
|
|
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]) {
|
|
save_v86_state(regs, VM86_INTx + (intno << 8));
|
|
return;
|
|
}
|
|
}
|
|
do_int(regs, intno, ssp, sp);
|
|
return;
|
|
}
|
|
|
|
/* iret */
|
|
case 0xcf:
|
|
{
|
|
unsigned long newip;
|
|
unsigned long newcs;
|
|
unsigned long newflags;
|
|
if (data32) {
|
|
newip = popl(ssp, sp, simulate_sigsegv);
|
|
newcs = popl(ssp, sp, simulate_sigsegv);
|
|
newflags = popl(ssp, sp, simulate_sigsegv);
|
|
SP(regs) += 12;
|
|
} else {
|
|
newip = popw(ssp, sp, simulate_sigsegv);
|
|
newcs = popw(ssp, sp, simulate_sigsegv);
|
|
newflags = popw(ssp, sp, simulate_sigsegv);
|
|
SP(regs) += 6;
|
|
}
|
|
IP(regs) = newip;
|
|
regs->pt.cs = newcs;
|
|
CHECK_IF_IN_TRAP;
|
|
if (data32) {
|
|
set_vflags_long(newflags, regs);
|
|
} else {
|
|
set_vflags_short(newflags, regs);
|
|
}
|
|
goto check_vip;
|
|
}
|
|
|
|
/* cli */
|
|
case 0xfa:
|
|
IP(regs) = ip;
|
|
clear_IF(regs);
|
|
goto vm86_fault_return;
|
|
|
|
/* sti */
|
|
/*
|
|
* Damn. This is incorrect: the 'sti' instruction should actually
|
|
* enable interrupts after the /next/ instruction. Not good.
|
|
*
|
|
* Probably needs some horsing around with the TF flag. Aiee..
|
|
*/
|
|
case 0xfb:
|
|
IP(regs) = ip;
|
|
set_IF(regs);
|
|
goto check_vip;
|
|
|
|
default:
|
|
save_v86_state(regs, VM86_UNKNOWN);
|
|
}
|
|
|
|
return;
|
|
|
|
check_vip:
|
|
if ((VEFLAGS & (X86_EFLAGS_VIP | X86_EFLAGS_VIF)) ==
|
|
(X86_EFLAGS_VIP | X86_EFLAGS_VIF)) {
|
|
save_v86_state(regs, VM86_STI);
|
|
return;
|
|
}
|
|
|
|
vm86_fault_return:
|
|
if (vmpi->force_return_for_pic && (VEFLAGS & (X86_EFLAGS_IF | X86_EFLAGS_VIF))) {
|
|
save_v86_state(regs, VM86_PICRETURN);
|
|
return;
|
|
}
|
|
if (orig_flags & X86_EFLAGS_TF)
|
|
handle_vm86_trap(regs, 0, X86_TRAP_DB);
|
|
return;
|
|
|
|
simulate_sigsegv:
|
|
/* FIXME: After a long discussion with Stas we finally
|
|
* agreed, that this is wrong. Here we should
|
|
* really send a SIGSEGV to the user program.
|
|
* But how do we create the correct context? We
|
|
* are inside a general protection fault handler
|
|
* and has just returned from a page fault handler.
|
|
* The correct context for the signal handler
|
|
* should be a mixture of the two, but how do we
|
|
* get the information? [KD]
|
|
*/
|
|
save_v86_state(regs, VM86_UNKNOWN);
|
|
}
|
|
|
|
/* ---------------- vm86 special IRQ passing stuff ----------------- */
|
|
|
|
#define VM86_IRQNAME "vm86irq"
|
|
|
|
static struct vm86_irqs {
|
|
struct task_struct *tsk;
|
|
int sig;
|
|
} vm86_irqs[16];
|
|
|
|
static DEFINE_SPINLOCK(irqbits_lock);
|
|
static int irqbits;
|
|
|
|
#define ALLOWED_SIGS (1 /* 0 = don't send a signal */ \
|
|
| (1 << SIGUSR1) | (1 << SIGUSR2) | (1 << SIGIO) | (1 << SIGURG) \
|
|
| (1 << SIGUNUSED))
|
|
|
|
static irqreturn_t irq_handler(int intno, void *dev_id)
|
|
{
|
|
int irq_bit;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&irqbits_lock, flags);
|
|
irq_bit = 1 << intno;
|
|
if ((irqbits & irq_bit) || !vm86_irqs[intno].tsk)
|
|
goto out;
|
|
irqbits |= irq_bit;
|
|
if (vm86_irqs[intno].sig)
|
|
send_sig(vm86_irqs[intno].sig, vm86_irqs[intno].tsk, 1);
|
|
/*
|
|
* IRQ will be re-enabled when user asks for the irq (whether
|
|
* polling or as a result of the signal)
|
|
*/
|
|
disable_irq_nosync(intno);
|
|
spin_unlock_irqrestore(&irqbits_lock, flags);
|
|
return IRQ_HANDLED;
|
|
|
|
out:
|
|
spin_unlock_irqrestore(&irqbits_lock, flags);
|
|
return IRQ_NONE;
|
|
}
|
|
|
|
static inline void free_vm86_irq(int irqnumber)
|
|
{
|
|
unsigned long flags;
|
|
|
|
free_irq(irqnumber, NULL);
|
|
vm86_irqs[irqnumber].tsk = NULL;
|
|
|
|
spin_lock_irqsave(&irqbits_lock, flags);
|
|
irqbits &= ~(1 << irqnumber);
|
|
spin_unlock_irqrestore(&irqbits_lock, flags);
|
|
}
|
|
|
|
void release_vm86_irqs(struct task_struct *task)
|
|
{
|
|
int i;
|
|
for (i = FIRST_VM86_IRQ ; i <= LAST_VM86_IRQ; i++)
|
|
if (vm86_irqs[i].tsk == task)
|
|
free_vm86_irq(i);
|
|
}
|
|
|
|
static inline int get_and_reset_irq(int irqnumber)
|
|
{
|
|
int bit;
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
if (invalid_vm86_irq(irqnumber)) return 0;
|
|
if (vm86_irqs[irqnumber].tsk != current) return 0;
|
|
spin_lock_irqsave(&irqbits_lock, flags);
|
|
bit = irqbits & (1 << irqnumber);
|
|
irqbits &= ~bit;
|
|
if (bit) {
|
|
enable_irq(irqnumber);
|
|
ret = 1;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&irqbits_lock, flags);
|
|
return ret;
|
|
}
|
|
|
|
|
|
static int do_vm86_irq_handling(int subfunction, int irqnumber)
|
|
{
|
|
int ret;
|
|
switch (subfunction) {
|
|
case VM86_GET_AND_RESET_IRQ: {
|
|
return get_and_reset_irq(irqnumber);
|
|
}
|
|
case VM86_GET_IRQ_BITS: {
|
|
return irqbits;
|
|
}
|
|
case VM86_REQUEST_IRQ: {
|
|
int sig = irqnumber >> 8;
|
|
int irq = irqnumber & 255;
|
|
if (!capable(CAP_SYS_ADMIN)) return -EPERM;
|
|
if (!((1 << sig) & ALLOWED_SIGS)) return -EPERM;
|
|
if (invalid_vm86_irq(irq)) return -EPERM;
|
|
if (vm86_irqs[irq].tsk) return -EPERM;
|
|
ret = request_irq(irq, &irq_handler, 0, VM86_IRQNAME, NULL);
|
|
if (ret) return ret;
|
|
vm86_irqs[irq].sig = sig;
|
|
vm86_irqs[irq].tsk = current;
|
|
return irq;
|
|
}
|
|
case VM86_FREE_IRQ: {
|
|
if (invalid_vm86_irq(irqnumber)) return -EPERM;
|
|
if (!vm86_irqs[irqnumber].tsk) return 0;
|
|
if (vm86_irqs[irqnumber].tsk != current) return -EPERM;
|
|
free_vm86_irq(irqnumber);
|
|
return 0;
|
|
}
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
|