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-rw-r--r--arch/x86/kernel/vm86_32.c832
1 files changed, 832 insertions, 0 deletions
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
new file mode 100644
index 000000000..e9e803a4d
--- /dev/null
+++ b/arch/x86/kernel/vm86_32.c
@@ -0,0 +1,832 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 1994 Linus Torvalds
+ *
+ * 29 dec 2001 - Fixed oopses caused by unchecked access to the vm86
+ * stack - Manfred Spraul <manfred@colorfullife.com>
+ *
+ * 22 mar 2002 - Manfred detected the stackfaults, but didn't handle
+ * them correctly. Now the emulation will be in a
+ * consistent state after stackfaults - Kasper Dupont
+ * <kasperd@daimi.au.dk>
+ *
+ * 22 mar 2002 - Added missing clear_IF in set_vflags_* Kasper Dupont
+ * <kasperd@daimi.au.dk>
+ *
+ * ?? ??? 2002 - Fixed premature returns from handle_vm86_fault
+ * caused by Kasper Dupont's changes - Stas Sergeev
+ *
+ * 4 apr 2002 - Fixed CHECK_IF_IN_TRAP broken by Stas' changes.
+ * Kasper Dupont <kasperd@daimi.au.dk>
+ *
+ * 9 apr 2002 - Changed syntax of macros in handle_vm86_fault.
+ * Kasper Dupont <kasperd@daimi.au.dk>
+ *
+ * 9 apr 2002 - Changed stack access macros to jump to a label
+ * instead of returning to userspace. This simplifies
+ * do_int, and is needed by handle_vm6_fault. Kasper
+ * Dupont <kasperd@daimi.au.dk>
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/capability.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/syscalls.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/audit.h>
+#include <linux/stddef.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+
+#include <linux/uaccess.h>
+#include <asm/io.h>
+#include <asm/tlbflush.h>
+#include <asm/irq.h>
+#include <asm/traps.h>
+#include <asm/vm86.h>
+#include <asm/switch_to.h>
+
+/*
+ * Known problems:
+ *
+ * Interrupt handling is not guaranteed:
+ * - a real x86 will disable all interrupts for one instruction
+ * after a "mov ss,xx" to make stack handling atomic even without
+ * the 'lss' instruction. We can't guarantee this in v86 mode,
+ * as the next instruction might result in a page fault or similar.
+ * - a real x86 will have interrupts disabled for one instruction
+ * past the 'sti' that enables them. We don't bother with all the
+ * details yet.
+ *
+ * Let's hope these problems do not actually matter for anything.
+ */
+
+
+/*
+ * 8- and 16-bit register defines..
+ */
+#define AL(regs) (((unsigned char *)&((regs)->pt.ax))[0])
+#define AH(regs) (((unsigned char *)&((regs)->pt.ax))[1])
+#define IP(regs) (*(unsigned short *)&((regs)->pt.ip))
+#define SP(regs) (*(unsigned short *)&((regs)->pt.sp))
+
+/*
+ * virtual flags (16 and 32-bit versions)
+ */
+#define VFLAGS (*(unsigned short *)&(current->thread.vm86->veflags))
+#define VEFLAGS (current->thread.vm86->veflags)
+
+#define set_flags(X, new, mask) \
+((X) = ((X) & ~(mask)) | ((new) & (mask)))
+
+#define SAFE_MASK (0xDD5)
+#define RETURN_MASK (0xDFF)
+
+void save_v86_state(struct kernel_vm86_regs *regs, int retval)
+{
+ struct task_struct *tsk = current;
+ struct vm86plus_struct __user *user;
+ struct vm86 *vm86 = current->thread.vm86;
+
+ /*
+ * This gets called from entry.S with interrupts disabled, but
+ * from process context. Enable interrupts here, before trying
+ * to access user space.
+ */
+ local_irq_enable();
+
+ BUG_ON(!vm86);
+
+ set_flags(regs->pt.flags, VEFLAGS, X86_EFLAGS_VIF | vm86->veflags_mask);
+ user = vm86->user_vm86;
+
+ if (!user_access_begin(user, vm86->vm86plus.is_vm86pus ?
+ sizeof(struct vm86plus_struct) :
+ sizeof(struct vm86_struct)))
+ goto Efault;
+
+ unsafe_put_user(regs->pt.bx, &user->regs.ebx, Efault_end);
+ unsafe_put_user(regs->pt.cx, &user->regs.ecx, Efault_end);
+ unsafe_put_user(regs->pt.dx, &user->regs.edx, Efault_end);
+ unsafe_put_user(regs->pt.si, &user->regs.esi, Efault_end);
+ unsafe_put_user(regs->pt.di, &user->regs.edi, Efault_end);
+ unsafe_put_user(regs->pt.bp, &user->regs.ebp, Efault_end);
+ unsafe_put_user(regs->pt.ax, &user->regs.eax, Efault_end);
+ unsafe_put_user(regs->pt.ip, &user->regs.eip, Efault_end);
+ unsafe_put_user(regs->pt.cs, &user->regs.cs, Efault_end);
+ unsafe_put_user(regs->pt.flags, &user->regs.eflags, Efault_end);
+ unsafe_put_user(regs->pt.sp, &user->regs.esp, Efault_end);
+ unsafe_put_user(regs->pt.ss, &user->regs.ss, Efault_end);
+ unsafe_put_user(regs->es, &user->regs.es, Efault_end);
+ unsafe_put_user(regs->ds, &user->regs.ds, Efault_end);
+ unsafe_put_user(regs->fs, &user->regs.fs, Efault_end);
+ unsafe_put_user(regs->gs, &user->regs.gs, Efault_end);
+
+ /*
+ * Don't write screen_bitmap in case some user had a value there
+ * and expected it to remain unchanged.
+ */
+
+ user_access_end();
+
+exit_vm86:
+ preempt_disable();
+ tsk->thread.sp0 = vm86->saved_sp0;
+ tsk->thread.sysenter_cs = __KERNEL_CS;
+ update_task_stack(tsk);
+ refresh_sysenter_cs(&tsk->thread);
+ vm86->saved_sp0 = 0;
+ preempt_enable();
+
+ memcpy(&regs->pt, &vm86->regs32, sizeof(struct pt_regs));
+
+ loadsegment(gs, vm86->regs32.gs);
+
+ regs->pt.ax = retval;
+ return;
+
+Efault_end:
+ user_access_end();
+Efault:
+ pr_alert("could not access userspace vm86 info\n");
+ force_exit_sig(SIGSEGV);
+ goto exit_vm86;
+}
+
+static int do_vm86_irq_handling(int subfunction, int irqnumber);
+static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus);
+
+SYSCALL_DEFINE1(vm86old, struct vm86_struct __user *, user_vm86)
+{
+ return do_sys_vm86((struct vm86plus_struct __user *) user_vm86, false);
+}
+
+
+SYSCALL_DEFINE2(vm86, unsigned long, cmd, unsigned long, arg)
+{
+ switch (cmd) {
+ case VM86_REQUEST_IRQ:
+ case VM86_FREE_IRQ:
+ case VM86_GET_IRQ_BITS:
+ case VM86_GET_AND_RESET_IRQ:
+ return do_vm86_irq_handling(cmd, (int)arg);
+ case VM86_PLUS_INSTALL_CHECK:
+ /*
+ * NOTE: on old vm86 stuff this will return the error
+ * from access_ok(), because the subfunction is
+ * interpreted as (invalid) address to vm86_struct.
+ * So the installation check works.
+ */
+ return 0;
+ }
+
+ /* we come here only for functions VM86_ENTER, VM86_ENTER_NO_BYPASS */
+ return do_sys_vm86((struct vm86plus_struct __user *) arg, true);
+}
+
+
+static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
+{
+ struct task_struct *tsk = current;
+ struct vm86 *vm86 = tsk->thread.vm86;
+ struct kernel_vm86_regs vm86regs;
+ struct pt_regs *regs = current_pt_regs();
+ unsigned long err = 0;
+ struct vm86_struct v;
+
+ err = security_mmap_addr(0);
+ if (err) {
+ /*
+ * vm86 cannot virtualize the address space, so vm86 users
+ * need to manage the low 1MB themselves using mmap. Given
+ * that BIOS places important data in the first page, vm86
+ * is essentially useless if mmap_min_addr != 0. DOSEMU,
+ * for example, won't even bother trying to use vm86 if it
+ * can't map a page at virtual address 0.
+ *
+ * To reduce the available kernel attack surface, simply
+ * disallow vm86(old) for users who cannot mmap at va 0.
+ *
+ * The implementation of security_mmap_addr will allow
+ * suitably privileged users to map va 0 even if
+ * vm.mmap_min_addr is set above 0, and we want this
+ * behavior for vm86 as well, as it ensures that legacy
+ * tools like vbetool will not fail just because of
+ * vm.mmap_min_addr.
+ */
+ 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",
+ current->comm, task_pid_nr(current),
+ from_kuid_munged(&init_user_ns, current_uid()));
+ return -EPERM;
+ }
+
+ if (!vm86) {
+ if (!(vm86 = kzalloc(sizeof(*vm86), GFP_KERNEL)))
+ return -ENOMEM;
+ tsk->thread.vm86 = vm86;
+ }
+ if (vm86->saved_sp0)
+ return -EPERM;
+
+ if (copy_from_user(&v, user_vm86,
+ offsetof(struct vm86_struct, int_revectored)))
+ return -EFAULT;
+
+
+ /* VM86_SCREEN_BITMAP had numerous bugs and appears to have no users. */
+ if (v.flags & VM86_SCREEN_BITMAP) {
+ char comm[TASK_COMM_LEN];
+
+ pr_info_once("vm86: '%s' uses VM86_SCREEN_BITMAP, which is no longer supported\n", get_task_comm(comm, current));
+ return -EINVAL;
+ }
+
+ memset(&vm86regs, 0, sizeof(vm86regs));
+
+ vm86regs.pt.bx = v.regs.ebx;
+ vm86regs.pt.cx = v.regs.ecx;
+ vm86regs.pt.dx = v.regs.edx;
+ vm86regs.pt.si = v.regs.esi;
+ vm86regs.pt.di = v.regs.edi;
+ vm86regs.pt.bp = v.regs.ebp;
+ vm86regs.pt.ax = v.regs.eax;
+ vm86regs.pt.ip = v.regs.eip;
+ vm86regs.pt.cs = v.regs.cs;
+ vm86regs.pt.flags = v.regs.eflags;
+ vm86regs.pt.sp = v.regs.esp;
+ vm86regs.pt.ss = v.regs.ss;
+ vm86regs.es = v.regs.es;
+ vm86regs.ds = v.regs.ds;
+ vm86regs.fs = v.regs.fs;
+ vm86regs.gs = v.regs.gs;
+
+ vm86->flags = v.flags;
+ vm86->cpu_type = v.cpu_type;
+
+ if (copy_from_user(&vm86->int_revectored,
+ &user_vm86->int_revectored,
+ sizeof(struct revectored_struct)))
+ return -EFAULT;
+ if (copy_from_user(&vm86->int21_revectored,
+ &user_vm86->int21_revectored,
+ sizeof(struct revectored_struct)))
+ return -EFAULT;
+ if (plus) {
+ if (copy_from_user(&vm86->vm86plus, &user_vm86->vm86plus,
+ sizeof(struct vm86plus_info_struct)))
+ return -EFAULT;
+ vm86->vm86plus.is_vm86pus = 1;
+ } else
+ memset(&vm86->vm86plus, 0,
+ sizeof(struct vm86plus_info_struct));
+
+ memcpy(&vm86->regs32, regs, sizeof(struct pt_regs));
+ vm86->user_vm86 = user_vm86;
+
+/*
+ * The flags register is also special: we cannot trust that the user
+ * has set it up safely, so this makes sure interrupt etc flags are
+ * inherited from protected mode.
+ */
+ VEFLAGS = vm86regs.pt.flags;
+ vm86regs.pt.flags &= SAFE_MASK;
+ vm86regs.pt.flags |= regs->flags & ~SAFE_MASK;
+ vm86regs.pt.flags |= X86_VM_MASK;
+
+ vm86regs.pt.orig_ax = regs->orig_ax;
+
+ switch (vm86->cpu_type) {
+ case CPU_286:
+ vm86->veflags_mask = 0;
+ break;
+ case CPU_386:
+ vm86->veflags_mask = X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+ break;
+ case CPU_486:
+ vm86->veflags_mask = X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+ break;
+ default:
+ vm86->veflags_mask = X86_EFLAGS_ID | X86_EFLAGS_AC | X86_EFLAGS_NT | X86_EFLAGS_IOPL;
+ break;
+ }
+
+/*
+ * Save old state
+ */
+ vm86->saved_sp0 = tsk->thread.sp0;
+ savesegment(gs, vm86->regs32.gs);
+
+ /* make room for real-mode segments */
+ preempt_disable();
+ tsk->thread.sp0 += 16;
+
+ if (boot_cpu_has(X86_FEATURE_SEP)) {
+ tsk->thread.sysenter_cs = 0;
+ refresh_sysenter_cs(&tsk->thread);
+ }
+
+ update_task_stack(tsk);
+ preempt_enable();
+
+ memcpy((struct kernel_vm86_regs *)regs, &vm86regs, sizeof(vm86regs));
+ return regs->ax;
+}
+
+static inline void set_IF(struct kernel_vm86_regs *regs)
+{
+ VEFLAGS |= X86_EFLAGS_VIF;
+}
+
+static inline void clear_IF(struct kernel_vm86_regs *regs)
+{
+ VEFLAGS &= ~X86_EFLAGS_VIF;
+}
+
+static inline void clear_TF(struct kernel_vm86_regs *regs)
+{
+ regs->pt.flags &= ~X86_EFLAGS_TF;
+}
+
+static inline void clear_AC(struct kernel_vm86_regs *regs)
+{
+ regs->pt.flags &= ~X86_EFLAGS_AC;
+}
+
+/*
+ * It is correct to call set_IF(regs) from the set_vflags_*
+ * functions. However someone forgot to call clear_IF(regs)
+ * in the opposite case.
+ * After the command sequence CLI PUSHF STI POPF you should
+ * end up with interrupts disabled, but you ended up with
+ * interrupts enabled.
+ * ( I was testing my own changes, but the only bug I
+ * could find was in a function I had not changed. )
+ * [KD]
+ */
+
+static inline void set_vflags_long(unsigned long flags, struct kernel_vm86_regs *regs)
+{
+ set_flags(VEFLAGS, flags, current->thread.vm86->veflags_mask);
+ set_flags(regs->pt.flags, flags, SAFE_MASK);
+ if (flags & X86_EFLAGS_IF)
+ set_IF(regs);
+ else
+ clear_IF(regs);
+}
+
+static inline void set_vflags_short(unsigned short flags, struct kernel_vm86_regs *regs)
+{
+ set_flags(VFLAGS, flags, current->thread.vm86->veflags_mask);
+ set_flags(regs->pt.flags, flags, SAFE_MASK);
+ if (flags & X86_EFLAGS_IF)
+ set_IF(regs);
+ else
+ clear_IF(regs);
+}
+
+static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
+{
+ unsigned long flags = regs->pt.flags & RETURN_MASK;
+
+ if (VEFLAGS & X86_EFLAGS_VIF)
+ flags |= X86_EFLAGS_IF;
+ flags |= X86_EFLAGS_IOPL;
+ return flags | (VEFLAGS & current->thread.vm86->veflags_mask);
+}
+
+static inline int is_revectored(int nr, struct revectored_struct *bitmap)
+{
+ return test_bit(nr, bitmap->__map);
+}
+
+#define val_byte(val, n) (((__u8 *)&val)[n])
+
+#define pushb(base, ptr, val, err_label) \
+ do { \
+ __u8 __val = val; \
+ ptr--; \
+ if (put_user(__val, base + ptr) < 0) \
+ goto err_label; \
+ } while (0)
+
+#define pushw(base, ptr, val, err_label) \
+ do { \
+ __u16 __val = val; \
+ ptr--; \
+ if (put_user(val_byte(__val, 1), base + ptr) < 0) \
+ goto err_label; \
+ ptr--; \
+ if (put_user(val_byte(__val, 0), base + ptr) < 0) \
+ goto err_label; \
+ } while (0)
+
+#define pushl(base, ptr, val, err_label) \
+ do { \
+ __u32 __val = val; \
+ ptr--; \
+ if (put_user(val_byte(__val, 3), base + ptr) < 0) \
+ goto err_label; \
+ ptr--; \
+ if (put_user(val_byte(__val, 2), base + ptr) < 0) \
+ goto err_label; \
+ ptr--; \
+ if (put_user(val_byte(__val, 1), base + ptr) < 0) \
+ goto err_label; \
+ ptr--; \
+ if (put_user(val_byte(__val, 0), base + ptr) < 0) \
+ goto err_label; \
+ } while (0)
+
+#define popb(base, ptr, err_label) \
+ ({ \
+ __u8 __res; \
+ if (get_user(__res, base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ __res; \
+ })
+
+#define popw(base, ptr, err_label) \
+ ({ \
+ __u16 __res; \
+ if (get_user(val_byte(__res, 0), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ if (get_user(val_byte(__res, 1), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ __res; \
+ })
+
+#define popl(base, ptr, err_label) \
+ ({ \
+ __u32 __res; \
+ if (get_user(val_byte(__res, 0), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ if (get_user(val_byte(__res, 1), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ if (get_user(val_byte(__res, 2), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ if (get_user(val_byte(__res, 3), base + ptr) < 0) \
+ goto err_label; \
+ ptr++; \
+ __res; \
+ })
+
+/* There are so many possible reasons for this function to return
+ * VM86_INTx, so adding another doesn't bother me. We can expect
+ * userspace programs to be able to handle it. (Getting a problem
+ * in userspace is always better than an Oops anyway.) [KD]
+ */
+static void do_int(struct kernel_vm86_regs *regs, int i,
+ unsigned char __user *ssp, unsigned short sp)
+{
+ unsigned long __user *intr_ptr;
+ unsigned long segoffs;
+ struct vm86 *vm86 = current->thread.vm86;
+
+ if (regs->pt.cs == BIOSSEG)
+ goto cannot_handle;
+ if (is_revectored(i, &vm86->int_revectored))
+ goto cannot_handle;
+ if (i == 0x21 && is_revectored(AH(regs), &vm86->int21_revectored))
+ goto cannot_handle;
+ intr_ptr = (unsigned long __user *) (i << 2);
+ if (get_user(segoffs, intr_ptr))
+ goto cannot_handle;
+ if ((segoffs >> 16) == BIOSSEG)
+ goto cannot_handle;
+ pushw(ssp, sp, get_vflags(regs), cannot_handle);
+ pushw(ssp, sp, regs->pt.cs, cannot_handle);
+ pushw(ssp, sp, IP(regs), cannot_handle);
+ regs->pt.cs = segoffs >> 16;
+ SP(regs) -= 6;
+ IP(regs) = segoffs & 0xffff;
+ clear_TF(regs);
+ clear_IF(regs);
+ clear_AC(regs);
+ return;
+
+cannot_handle:
+ save_v86_state(regs, VM86_INTx + (i << 8));
+}
+
+int handle_vm86_trap(struct kernel_vm86_regs *regs, long error_code, int trapno)
+{
+ struct vm86 *vm86 = current->thread.vm86;
+
+ if (vm86->vm86plus.is_vm86pus) {
+ if ((trapno == 3) || (trapno == 1)) {
+ save_v86_state(regs, VM86_TRAP + (trapno << 8));
+ return 0;
+ }
+ do_int(regs, trapno, (unsigned char __user *) (regs->pt.ss << 4), SP(regs));
+ return 0;
+ }
+ if (trapno != 1)
+ return 1; /* we let this handle by the calling routine */
+ current->thread.trap_nr = trapno;
+ current->thread.error_code = error_code;
+ force_sig(SIGTRAP);
+ 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 = &current->thread.vm86->vm86plus;
+
+#define CHECK_IF_IN_TRAP \
+ if (vmpi->vm86dbg_active && vmpi->vm86dbg_TFpendig) \
+ newflags |= X86_EFLAGS_TF
+
+ orig_flags = *(unsigned short *)&regs->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;
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-19 20:38:15 +0000