852 lines
22 KiB
C
852 lines
22 KiB
C
/*
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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/sched.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 <asm/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/syscalls.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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#define KVM86 ((struct kernel_vm86_struct *)regs)
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#define VMPI KVM86->vm86plus
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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.v86flags))
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#define VEFLAGS (current->thread.v86flags)
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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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/* 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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/*
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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 (!current->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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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(init_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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put_cpu();
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ret = KVM86->regs32;
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ret->fs = current->thread.saved_fs;
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set_user_gs(ret, current->thread.saved_gs);
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return ret;
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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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pgd_t *pgd;
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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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spinlock_t *ptl;
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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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pud = pud_offset(pgd, 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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split_huge_page_pmd_mm(mm, 0xA0000, pmd);
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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();
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}
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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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int sys_vm86old(struct vm86_struct __user *v86)
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{
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struct kernel_vm86_struct info; /* declare this _on top_,
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* this avoids wasting of stack space.
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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, ret = -EPERM;
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tsk = current;
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if (tsk->thread.saved_sp0)
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goto out;
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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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ret = -EFAULT;
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if (tmp)
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goto out;
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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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ret = 0; /* we never return here */
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out:
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return ret;
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}
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int sys_vm86(unsigned long cmd, unsigned long arg)
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{
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struct kernel_vm86_struct info; /* declare this _on top_,
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* this avoids wasting of stack space.
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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, ret;
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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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case VM86_GET_IRQ_BITS:
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case VM86_GET_AND_RESET_IRQ:
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ret = do_vm86_irq_handling(cmd, (int)arg);
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goto out;
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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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ret = 0;
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goto out;
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}
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/* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
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ret = -EPERM;
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if (tsk->thread.saved_sp0)
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goto out;
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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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ret = -EFAULT;
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if (tmp)
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goto out;
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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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ret = 0; /* we never return here */
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out:
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return ret;
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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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{
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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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/*
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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 = info->regs.pt.flags;
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info->regs.pt.flags &= SAFE_MASK;
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info->regs.pt.flags |= info->regs32->flags & ~SAFE_MASK;
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info->regs.pt.flags |= X86_VM_MASK;
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switch (info->cpu_type) {
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case CPU_286:
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tsk->thread.v86mask = 0;
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break;
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case CPU_386:
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tsk->thread.v86mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
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break;
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case CPU_486:
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tsk->thread.v86mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
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break;
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default:
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tsk->thread.v86mask = 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, set default return value (%ax) to 0 (VM86_SIGNAL)
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*/
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info->regs32->ax = VM86_SIGNAL;
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tsk->thread.saved_sp0 = tsk->thread.sp0;
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tsk->thread.saved_fs = info->regs32->fs;
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tsk->thread.saved_gs = get_user_gs(info->regs32);
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tss = &per_cpu(init_tss, get_cpu());
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tsk->thread.sp0 = (unsigned long) &info->VM86_TSS_ESP0;
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if (cpu_has_sep)
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tsk->thread.sysenter_cs = 0;
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load_sp0(tss, &tsk->thread);
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put_cpu();
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tsk->thread.screen_bitmap = info->screen_bitmap;
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if (info->flags & VM86_SCREEN_BITMAP)
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mark_screen_rdonly(tsk->mm);
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/*call __audit_syscall_exit since we do not exit via the normal paths */
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#ifdef CONFIG_AUDITSYSCALL
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if (unlikely(current->audit_context))
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__audit_syscall_exit(1, 0);
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#endif
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__asm__ __volatile__(
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"movl %0,%%esp\n\t"
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"movl %1,%%ebp\n\t"
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#ifdef CONFIG_X86_32_LAZY_GS
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"mov %2, %%gs\n\t"
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#endif
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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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}
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static inline void return_to_32bit(struct kernel_vm86_regs *regs16, int retval)
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{
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struct pt_regs *regs32;
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regs32 = save_v86_state(regs16);
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regs32->ax = retval;
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__asm__ __volatile__("movl %0,%%esp\n\t"
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"movl %1,%%ebp\n\t"
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"jmp resume_userspace"
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: : "r" (regs32), "r" (current_thread_info()));
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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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if (VEFLAGS & X86_EFLAGS_VIP)
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return_to_32bit(regs, VM86_STI);
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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.v86mask);
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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.v86mask);
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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.v86mask);
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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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__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
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:"=r" (nr)
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:"m" (*bitmap), "r" (nr));
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return nr;
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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)
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#define pushw(base, ptr, val, err_label) \
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do { \
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__u16 __val = val; \
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ptr--; \
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if (put_user(val_byte(__val, 1), base + ptr) < 0) \
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goto err_label; \
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ptr--; \
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if (put_user(val_byte(__val, 0), base + ptr) < 0) \
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goto err_label; \
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} while (0)
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#define pushl(base, ptr, val, err_label) \
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do { \
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__u32 __val = val; \
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ptr--; \
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if (put_user(val_byte(__val, 3), base + ptr) < 0) \
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goto err_label; \
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ptr--; \
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if (put_user(val_byte(__val, 2), base + ptr) < 0) \
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goto err_label; \
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ptr--; \
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if (put_user(val_byte(__val, 1), base + ptr) < 0) \
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goto err_label; \
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ptr--; \
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if (put_user(val_byte(__val, 0), base + ptr) < 0) \
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goto err_label; \
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} while (0)
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#define popb(base, ptr, err_label) \
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({ \
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__u8 __res; \
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if (get_user(__res, base + ptr) < 0) \
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goto err_label; \
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ptr++; \
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__res; \
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})
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#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;
|
|
|
|
if (regs->pt.cs == BIOSSEG)
|
|
goto cannot_handle;
|
|
if (is_revectored(i, &KVM86->int_revectored))
|
|
goto cannot_handle;
|
|
if (i == 0x21 && is_revectored(AH(regs), &KVM86->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:
|
|
return_to_32bit(regs, VM86_INTx + (i << 8));
|
|
}
|
|
|
|
int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
|
|
{
|
|
if (VMPI.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
|
|
the path where we call save_v86_state() and change
|
|
the stack pointer to KVM86->regs32 */
|
|
set_thread_flag(TIF_NOTIFY_RESUME);
|
|
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;
|
|
|
|
#define CHECK_IF_IN_TRAP \
|
|
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))) \
|
|
return_to_32bit(regs, VM86_PICRETURN); \
|
|
if (orig_flags & X86_EFLAGS_TF) \
|
|
handle_vm86_trap(regs, 0, 1); \
|
|
return; } while (0)
|
|
|
|
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;
|
|
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);
|
|
|
|
VM86_FAULT_RETURN;
|
|
}
|
|
|
|
/* 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])
|
|
return_to_32bit(regs, VM86_INTx + (intno << 8));
|
|
}
|
|
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);
|
|
}
|
|
VM86_FAULT_RETURN;
|
|
}
|
|
|
|
/* cli */
|
|
case 0xfa:
|
|
IP(regs) = ip;
|
|
clear_IF(regs);
|
|
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);
|
|
VM86_FAULT_RETURN;
|
|
|
|
default:
|
|
return_to_32bit(regs, VM86_UNKNOWN);
|
|
}
|
|
|
|
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]
|
|
*/
|
|
return_to_32bit(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;
|
|
}
|
|
|