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832 lines
22 KiB
832 lines
22 KiB
// 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 <[email protected]> |
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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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* <[email protected]> |
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* |
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* 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont |
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* <[email protected]> |
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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 <[email protected]> |
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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 <[email protected]> |
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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 <[email protected]> |
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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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/* |
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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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/* |
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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 (!user_access_begin(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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goto Efault; |
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unsafe_put_user(regs->pt.bx, &user->regs.ebx, Efault_end); |
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unsafe_put_user(regs->pt.cx, &user->regs.ecx, Efault_end); |
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unsafe_put_user(regs->pt.dx, &user->regs.edx, Efault_end); |
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unsafe_put_user(regs->pt.si, &user->regs.esi, Efault_end); |
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unsafe_put_user(regs->pt.di, &user->regs.edi, Efault_end); |
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unsafe_put_user(regs->pt.bp, &user->regs.ebp, Efault_end); |
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unsafe_put_user(regs->pt.ax, &user->regs.eax, Efault_end); |
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unsafe_put_user(regs->pt.ip, &user->regs.eip, Efault_end); |
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unsafe_put_user(regs->pt.cs, &user->regs.cs, Efault_end); |
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unsafe_put_user(regs->pt.flags, &user->regs.eflags, Efault_end); |
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unsafe_put_user(regs->pt.sp, &user->regs.esp, Efault_end); |
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unsafe_put_user(regs->pt.ss, &user->regs.ss, Efault_end); |
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unsafe_put_user(regs->es, &user->regs.es, Efault_end); |
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unsafe_put_user(regs->ds, &user->regs.ds, Efault_end); |
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unsafe_put_user(regs->fs, &user->regs.fs, Efault_end); |
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unsafe_put_user(regs->gs, &user->regs.gs, Efault_end); |
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/* |
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* Don't write screen_bitmap in case some user had a value there |
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* and expected it to remain unchanged. |
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*/ |
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user_access_end(); |
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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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return; |
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Efault_end: |
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user_access_end(); |
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Efault: |
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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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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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struct vm86_struct v; |
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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 (copy_from_user(&v, user_vm86, |
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offsetof(struct vm86_struct, int_revectored))) |
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return -EFAULT; |
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/* VM86_SCREEN_BITMAP had numerous bugs and appears to have no users. */ |
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if (v.flags & VM86_SCREEN_BITMAP) { |
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char comm[TASK_COMM_LEN]; |
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pr_info_once("vm86: '%s' uses VM86_SCREEN_BITMAP, which is no longer supported\n", get_task_comm(comm, current)); |
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return -EINVAL; |
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} |
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memset(&vm86regs, 0, sizeof(vm86regs)); |
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vm86regs.pt.bx = v.regs.ebx; |
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vm86regs.pt.cx = v.regs.ecx; |
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vm86regs.pt.dx = v.regs.edx; |
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vm86regs.pt.si = v.regs.esi; |
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vm86regs.pt.di = v.regs.edi; |
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vm86regs.pt.bp = v.regs.ebp; |
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vm86regs.pt.ax = v.regs.eax; |
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vm86regs.pt.ip = v.regs.eip; |
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vm86regs.pt.cs = v.regs.cs; |
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vm86regs.pt.flags = v.regs.eflags; |
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vm86regs.pt.sp = v.regs.esp; |
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vm86regs.pt.ss = v.regs.ss; |
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vm86regs.es = v.regs.es; |
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vm86regs.ds = v.regs.ds; |
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vm86regs.fs = v.regs.fs; |
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vm86regs.gs = v.regs.gs; |
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vm86->flags = v.flags; |
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vm86->cpu_type = v.cpu_type; |
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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 (boot_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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memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs)); |
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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) |
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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) \ |
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({ \ |
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__u16 __res; \ |
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if (get_user(val_byte(__res, 0), base + ptr) < 0) \ |
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goto err_label; \ |
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ptr++; \ |
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if (get_user(val_byte(__res, 1), 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 popl(base, ptr, err_label) \ |
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({ \ |
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__u32 __res; \ |
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if (get_user(val_byte(__res, 0), base + ptr) < 0) \ |
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goto err_label; \ |
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ptr++; \ |
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if (get_user(val_byte(__res, 1), base + ptr) < 0) \ |
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goto err_label; \ |
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ptr++; \ |
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if (get_user(val_byte(__res, 2), base + ptr) < 0) \ |
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goto err_label; \ |
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ptr++; \ |
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if (get_user(val_byte(__res, 3), 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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|
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/* There are so many possible reasons for this function to return |
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* VM86_INTx, so adding another doesn't bother me. We can expect |
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* userspace programs to be able to handle it. (Getting a problem |
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* in userspace is always better than an Oops anyway.) [KD] |
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*/ |
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static void do_int(struct kernel_vm86_regs *regs, int i, |
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unsigned char __user *ssp, unsigned short sp) |
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{ |
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unsigned long __user *intr_ptr; |
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unsigned long segoffs; |
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struct vm86 *vm86 = current->thread.vm86; |
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|
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if (regs->pt.cs == BIOSSEG) |
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goto cannot_handle; |
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if (is_revectored(i, &vm86->int_revectored)) |
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goto cannot_handle; |
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if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored)) |
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goto cannot_handle; |
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intr_ptr = (unsigned long __user *) (i << 2); |
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if (get_user(segoffs, intr_ptr)) |
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goto cannot_handle; |
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if ((segoffs >> 16) == BIOSSEG) |
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goto cannot_handle; |
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pushw(ssp, sp, get_vflags(regs), cannot_handle); |
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pushw(ssp, sp, regs->pt.cs, cannot_handle); |
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pushw(ssp, sp, IP(regs), cannot_handle); |
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regs->pt.cs = segoffs >> 16; |
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SP(regs) -= 6; |
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IP(regs) = segoffs & 0xffff; |
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clear_TF(regs); |
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clear_IF(regs); |
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clear_AC(regs); |
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return; |
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cannot_handle: |
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save_v86_state(regs, VM86_INTx + (i << 8)); |
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} |
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|
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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); |
|
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; |
|
} |
|
|
|
|