traps: x86: finalize unification of traps.c

traps_32.c and traps_64.c are now equal. Move one to traps.c,
delete the other one and change the Makefile

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1071 insertions, 0 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
new file mode 100644
index 000000000000..ffb131f74f78
--- /dev/null
+++ b/arch/x86/kernel/traps.c
@@ -0,0 +1,1071 @@
+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
+ *
+ *  Pentium III FXSR, SSE support
+ *      Gareth Hughes <gareth@valinux.com>, May 2000
+ */
+
+/*
+ * Handle hardware traps and faults.
+ */
+#include <linux/interrupt.h>
+#include <linux/kallsyms.h>
+#include <linux/spinlock.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/utsname.h>
+#include <linux/kdebug.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ptrace.h>
+#include <linux/string.h>
+#include <linux/unwind.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/kexec.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/init.h>
+#include <linux/bug.h>
+#include <linux/nmi.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/io.h>
+
+#ifdef CONFIG_EISA
+#include <linux/ioport.h>
+#include <linux/eisa.h>
+#endif
+
+#ifdef CONFIG_MCA
+#include <linux/mca.h>
+#endif
+
+#if defined(CONFIG_EDAC)
+#include <linux/edac.h>
+#endif
+
+#include <asm/stacktrace.h>
+#include <asm/processor.h>
+#include <asm/debugreg.h>
+#include <asm/atomic.h>
+#include <asm/system.h>
+#include <asm/unwind.h>
+#include <asm/traps.h>
+#include <asm/desc.h>
+#include <asm/i387.h>
+
+#include <mach_traps.h>
+
+#ifdef CONFIG_X86_64
+#include <asm/pgalloc.h>
+#include <asm/proto.h>
+#include <asm/pda.h>
+#else
+#include <asm/processor-flags.h>
+#include <asm/arch_hooks.h>
+#include <asm/nmi.h>
+#include <asm/smp.h>
+#include <asm/io.h>
+#include <asm/traps.h>
+
+#include "cpu/mcheck/mce.h"
+
+DECLARE_BITMAP(used_vectors, NR_VECTORS);
+EXPORT_SYMBOL_GPL(used_vectors);
+
+asmlinkage int system_call(void);
+
+/* Do we ignore FPU interrupts ? */
+char ignore_fpu_irq;
+
+/*
+ * The IDT has to be page-aligned to simplify the Pentium
+ * F0 0F bug workaround.. We have a special link segment
+ * for this.
+ */
+gate_desc idt_table[256]
+        __attribute__((__section__(".data.idt"))) = { { { { 0, 0 } } }, };
+#endif
+
+static int ignore_nmis;
+
+static inline void conditional_sti(struct pt_regs *regs)
+{
+        if (regs->flags & X86_EFLAGS_IF)
+                local_irq_enable();
+}
+
+static inline void preempt_conditional_sti(struct pt_regs *regs)
+{
+        inc_preempt_count();
+        if (regs->flags & X86_EFLAGS_IF)
+                local_irq_enable();
+}
+
+static inline void preempt_conditional_cli(struct pt_regs *regs)
+{
+        if (regs->flags & X86_EFLAGS_IF)
+                local_irq_disable();
+        dec_preempt_count();
+}
+
+#ifdef CONFIG_X86_32
+static inline void
+die_if_kernel(const char *str, struct pt_regs *regs, long err)
+{
+        if (!user_mode_vm(regs))
+                die(str, regs, err);
+}
+
+/*
+ * Perform the lazy TSS's I/O bitmap copy. If the TSS has an
+ * invalid offset set (the LAZY one) and the faulting thread has
+ * a valid I/O bitmap pointer, we copy the I/O bitmap in the TSS,
+ * we set the offset field correctly and return 1.
+ */
+static int lazy_iobitmap_copy(void)
+{
+        struct thread_struct *thread;
+        struct tss_struct *tss;
+        int cpu;
+
+        cpu = get_cpu();
+        tss = &per_cpu(init_tss, cpu);
+        thread = &current->thread;
+
+        if (tss->x86_tss.io_bitmap_base == INVALID_IO_BITMAP_OFFSET_LAZY &&
+            thread->io_bitmap_ptr) {
+                memcpy(tss->io_bitmap, thread->io_bitmap_ptr,
+                       thread->io_bitmap_max);
+                /*
+                 * If the previously set map was extending to higher ports
+                 * than the current one, pad extra space with 0xff (no access).
+                 */
+                if (thread->io_bitmap_max < tss->io_bitmap_max) {
+                        memset((char *) tss->io_bitmap +
+                                thread->io_bitmap_max, 0xff,
+                                tss->io_bitmap_max - thread->io_bitmap_max);
+                }
+                tss->io_bitmap_max = thread->io_bitmap_max;
+                tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
+                tss->io_bitmap_owner = thread;
+                put_cpu();
+
+                return 1;
+        }
+        put_cpu();
+
+        return 0;
+}
+#endif
+
+static void __kprobes
+do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
+        long error_code, siginfo_t *info)
+{
+        struct task_struct *tsk = current;
+
+#ifdef CONFIG_X86_32
+        if (regs->flags & X86_VM_MASK) {
+                /*
+                 * traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
+                 * On nmi (interrupt 2), do_trap should not be called.
+                 */
+                if (trapnr < 6)
+                        goto vm86_trap;
+                goto trap_signal;
+        }
+#endif
+
+        if (!user_mode(regs))
+                goto kernel_trap;
+
+#ifdef CONFIG_X86_32
+trap_signal:
+#endif
+        /*
+         * We want error_code and trap_no set for userspace faults and
+         * kernelspace faults which result in die(), but not
+         * kernelspace faults which are fixed up.  die() gives the
+         * process no chance to handle the signal and notice the
+         * kernel fault information, so that won't result in polluting
+         * the information about previously queued, but not yet
+         * delivered, faults.  See also do_general_protection below.
+         */
+        tsk->thread.error_code = error_code;
+        tsk->thread.trap_no = trapnr;
+
+#ifdef CONFIG_X86_64
+        if (show_unhandled_signals && unhandled_signal(tsk, signr) &&
+            printk_ratelimit()) {
+                printk(KERN_INFO
+                       "%s[%d] trap %s ip:%lx sp:%lx error:%lx",
+                       tsk->comm, tsk->pid, str,
+                       regs->ip, regs->sp, error_code);
+                print_vma_addr(" in ", regs->ip);
+                printk("\n");
+        }
+#endif
+
+        if (info)
+                force_sig_info(signr, info, tsk);
+        else
+                force_sig(signr, tsk);
+        return;
+
+kernel_trap:
+        if (!fixup_exception(regs)) {
+                tsk->thread.error_code = error_code;
+                tsk->thread.trap_no = trapnr;
+                die(str, regs, error_code);
+        }
+        return;
+
+#ifdef CONFIG_X86_32
+vm86_trap:
+        if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
+                                                error_code, trapnr))
+                goto trap_signal;
+        return;
+#endif
+}
+
+#define DO_ERROR(trapnr, signr, str, name)                              \
+dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
+{                                                                       \
+        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
+                                                        == NOTIFY_STOP) \
+                return;                                                 \
+        conditional_sti(regs);                                          \
+        do_trap(trapnr, signr, str, regs, error_code, NULL);            \
+}
+
+#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr)         \
+dotraplinkage void do_##name(struct pt_regs *regs, long error_code)     \
+{                                                                       \
+        siginfo_t info;                                                 \
+        info.si_signo = signr;                                          \
+        info.si_errno = 0;                                              \
+        info.si_code = sicode;                                          \
+        info.si_addr = (void __user *)siaddr;                           \
+        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr)  \
+                                                        == NOTIFY_STOP) \
+                return;                                                 \
+        conditional_sti(regs);                                          \
+        do_trap(trapnr, signr, str, regs, error_code, &info);           \
+}
+
+DO_ERROR_INFO(0, SIGFPE, "divide error", divide_error, FPE_INTDIV, regs->ip)
+DO_ERROR(4, SIGSEGV, "overflow", overflow)
+DO_ERROR(5, SIGSEGV, "bounds", bounds)
+DO_ERROR_INFO(6, SIGILL, "invalid opcode", invalid_op, ILL_ILLOPN, regs->ip)
+DO_ERROR(9, SIGFPE, "coprocessor segment overrun", coprocessor_segment_overrun)
+DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
+DO_ERROR(11, SIGBUS, "segment not present", segment_not_present)
+#ifdef CONFIG_X86_32
+DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
+#endif
+DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
+
+#ifdef CONFIG_X86_64
+/* Runs on IST stack */
+dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
+{
+        if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
+                        12, SIGBUS) == NOTIFY_STOP)
+                return;
+        preempt_conditional_sti(regs);
+        do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
+        preempt_conditional_cli(regs);
+}
+
+dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
+{
+        static const char str[] = "double fault";
+        struct task_struct *tsk = current;
+
+        /* Return not checked because double check cannot be ignored */
+        notify_die(DIE_TRAP, str, regs, error_code, 8, SIGSEGV);
+
+        tsk->thread.error_code = error_code;
+        tsk->thread.trap_no = 8;
+
+        /* This is always a kernel trap and never fixable (and thus must
+           never return). */
+        for (;;)
+                die(str, regs, error_code);
+}
+#endif
+
+dotraplinkage void __kprobes
+do_general_protection(struct pt_regs *regs, long error_code)
+{
+        struct task_struct *tsk;
+
+        conditional_sti(regs);
+
+#ifdef CONFIG_X86_32
+        if (lazy_iobitmap_copy()) {
+                /* restart the faulting instruction */
+                return;
+        }
+
+        if (regs->flags & X86_VM_MASK)
+                goto gp_in_vm86;
+#endif
+
+        tsk = current;
+        if (!user_mode(regs))
+                goto gp_in_kernel;
+
+        tsk->thread.error_code = error_code;
+        tsk->thread.trap_no = 13;
+
+        if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
+                        printk_ratelimit()) {
+                printk(KERN_INFO
+                        "%s[%d] general protection ip:%lx sp:%lx error:%lx",
+                        tsk->comm, task_pid_nr(tsk),
+                        regs->ip, regs->sp, error_code);
+                print_vma_addr(" in ", regs->ip);
+                printk("\n");
+        }
+
+        force_sig(SIGSEGV, tsk);
+        return;
+
+#ifdef CONFIG_X86_32
+gp_in_vm86:
+        local_irq_enable();
+        handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
+        return;
+#endif
+
+gp_in_kernel:
+        if (fixup_exception(regs))
+                return;
+
+        tsk->thread.error_code = error_code;
+        tsk->thread.trap_no = 13;
+        if (notify_die(DIE_GPF, "general protection fault", regs,
+                                error_code, 13, SIGSEGV) == NOTIFY_STOP)
+                return;
+        die("general protection fault", regs, error_code);
+}
+
+static notrace __kprobes void
+mem_parity_error(unsigned char reason, struct pt_regs *regs)
+{
+        printk(KERN_EMERG
+                "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+                        reason, smp_processor_id());
+
+        printk(KERN_EMERG
+                "You have some hardware problem, likely on the PCI bus.\n");
+
+#if defined(CONFIG_EDAC)
+        if (edac_handler_set()) {
+                edac_atomic_assert_error();
+                return;
+        }
+#endif
+
+        if (panic_on_unrecovered_nmi)
+                panic("NMI: Not continuing");
+
+        printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
+
+        /* Clear and disable the memory parity error line. */
+        reason = (reason & 0xf) | 4;
+        outb(reason, 0x61);
+}
+
+static notrace __kprobes void
+io_check_error(unsigned char reason, struct pt_regs *regs)
+{
+        unsigned long i;
+
+        printk(KERN_EMERG "NMI: IOCK error (debug interrupt?)\n");
+        show_registers(regs);
+
+        /* Re-enable the IOCK line, wait for a few seconds */
+        reason = (reason & 0xf) | 8;
+        outb(reason, 0x61);
+
+        i = 2000;
+        while (--i)
+                udelay(1000);
+
+        reason &= ~8;
+        outb(reason, 0x61);
+}
+
+static notrace __kprobes void
+unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
+{
+        if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
+                        NOTIFY_STOP)
+                return;
+#ifdef CONFIG_MCA
+        /*
+         * Might actually be able to figure out what the guilty party
+         * is:
+         */
+        if (MCA_bus) {
+                mca_handle_nmi();
+                return;
+        }
+#endif
+        printk(KERN_EMERG
+                "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+                        reason, smp_processor_id());
+
+        printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
+        if (panic_on_unrecovered_nmi)
+                panic("NMI: Not continuing");
+
+        printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
+}
+
+#ifdef CONFIG_X86_32
+static DEFINE_SPINLOCK(nmi_print_lock);
+
+void notrace __kprobes die_nmi(char *str, struct pt_regs *regs, int do_panic)
+{
+        if (notify_die(DIE_NMIWATCHDOG, str, regs, 0, 2, SIGINT) == NOTIFY_STOP)
+                return;
+
+        spin_lock(&nmi_print_lock);
+        /*
+        * We are in trouble anyway, lets at least try
+        * to get a message out:
+        */
+        bust_spinlocks(1);
+        printk(KERN_EMERG "%s", str);
+        printk(" on CPU%d, ip %08lx, registers:\n",
+                smp_processor_id(), regs->ip);
+        show_registers(regs);
+        if (do_panic)
+                panic("Non maskable interrupt");
+        console_silent();
+        spin_unlock(&nmi_print_lock);
+        bust_spinlocks(0);
+
+        /*
+         * If we are in kernel we are probably nested up pretty bad
+         * and might aswell get out now while we still can:
+         */
+        if (!user_mode_vm(regs)) {
+                current->thread.trap_no = 2;
+                crash_kexec(regs);
+        }
+
+        do_exit(SIGSEGV);
+}
+#endif
+
+static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
+{
+        unsigned char reason = 0;
+        int cpu;
+
+        cpu = smp_processor_id();
+
+        /* Only the BSP gets external NMIs from the system. */
+        if (!cpu)
+                reason = get_nmi_reason();
+
+        if (!(reason & 0xc0)) {
+                if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 2, SIGINT)
+                                                                == NOTIFY_STOP)
+                        return;
+#ifdef CONFIG_X86_LOCAL_APIC
+                /*
+                 * Ok, so this is none of the documented NMI sources,
+                 * so it must be the NMI watchdog.
+                 */
+                if (nmi_watchdog_tick(regs, reason))
+                        return;
+                if (!do_nmi_callback(regs, cpu))
+                        unknown_nmi_error(reason, regs);
+#else
+                unknown_nmi_error(reason, regs);
+#endif
+
+                return;
+        }
+        if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
+                return;
+
+        /* AK: following checks seem to be broken on modern chipsets. FIXME */
+        if (reason & 0x80)
+                mem_parity_error(reason, regs);
+        if (reason & 0x40)
+                io_check_error(reason, regs);
+#ifdef CONFIG_X86_32
+        /*
+         * Reassert NMI in case it became active meanwhile
+         * as it's edge-triggered:
+         */
+        reassert_nmi();
+#endif
+}
+
+dotraplinkage notrace __kprobes void
+do_nmi(struct pt_regs *regs, long error_code)
+{
+        nmi_enter();
+
+#ifdef CONFIG_X86_32
+        { int cpu; cpu = smp_processor_id(); ++nmi_count(cpu); }
+#else
+        add_pda(__nmi_count, 1);
+#endif
+
+        if (!ignore_nmis)
+                default_do_nmi(regs);
+
+        nmi_exit();
+}
+
+void stop_nmi(void)
+{
+        acpi_nmi_disable();
+        ignore_nmis++;
+}
+
+void restart_nmi(void)
+{
+        ignore_nmis--;
+        acpi_nmi_enable();
+}
+
+/* May run on IST stack. */
+dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
+{
+#ifdef CONFIG_KPROBES
+        if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
+                        == NOTIFY_STOP)
+                return;
+#else
+        if (notify_die(DIE_TRAP, "int3", regs, error_code, 3, SIGTRAP)
+                        == NOTIFY_STOP)
+                return;
+#endif
+
+        preempt_conditional_sti(regs);
+        do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
+        preempt_conditional_cli(regs);
+}
+
+#ifdef CONFIG_X86_64
+/* Help handler running on IST stack to switch back to user stack
+   for scheduling or signal handling. The actual stack switch is done in
+   entry.S */
+asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
+{
+        struct pt_regs *regs = eregs;
+        /* Did already sync */
+        if (eregs == (struct pt_regs *)eregs->sp)
+                ;
+        /* Exception from user space */
+        else if (user_mode(eregs))
+                regs = task_pt_regs(current);
+        /* Exception from kernel and interrupts are enabled. Move to
+           kernel process stack. */
+        else if (eregs->flags & X86_EFLAGS_IF)
+                regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
+        if (eregs != regs)
+                *regs = *eregs;
+        return regs;
+}
+#endif
+
+/*
+ * Our handling of the processor debug registers is non-trivial.
+ * We do not clear them on entry and exit from the kernel. Therefore
+ * it is possible to get a watchpoint trap here from inside the kernel.
+ * However, the code in ./ptrace.c has ensured that the user can
+ * only set watchpoints on userspace addresses. Therefore the in-kernel
+ * watchpoint trap can only occur in code which is reading/writing
+ * from user space. Such code must not hold kernel locks (since it
+ * can equally take a page fault), therefore it is safe to call
+ * force_sig_info even though that claims and releases locks.
+ *
+ * Code in ./signal.c ensures that the debug control register
+ * is restored before we deliver any signal, and therefore that
+ * user code runs with the correct debug control register even though
+ * we clear it here.
+ *
+ * Being careful here means that we don't have to be as careful in a
+ * lot of more complicated places (task switching can be a bit lazy
+ * about restoring all the debug state, and ptrace doesn't have to
+ * find every occurrence of the TF bit that could be saved away even
+ * by user code)
+ *
+ * May run on IST stack.
+ */
+dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
+{
+        struct task_struct *tsk = current;
+        unsigned long condition;
+        int si_code;
+
+        get_debugreg(condition, 6);
+
+        /*
+         * The processor cleared BTF, so don't mark that we need it set.
+         */
+        clear_tsk_thread_flag(tsk, TIF_DEBUGCTLMSR);
+        tsk->thread.debugctlmsr = 0;
+
+        if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
+                                                SIGTRAP) == NOTIFY_STOP)
+                return;
+
+        /* It's safe to allow irq's after DR6 has been saved */
+        preempt_conditional_sti(regs);
+
+        /* Mask out spurious debug traps due to lazy DR7 setting */
+        if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
+                if (!tsk->thread.debugreg7)
+                        goto clear_dr7;
+        }
+
+#ifdef CONFIG_X86_32
+        if (regs->flags & X86_VM_MASK)
+                goto debug_vm86;
+#endif
+
+        /* Save debug status register where ptrace can see it */
+        tsk->thread.debugreg6 = condition;
+
+        /*
+         * Single-stepping through TF: make sure we ignore any events in
+         * kernel space (but re-enable TF when returning to user mode).
+         */
+        if (condition & DR_STEP) {
+                if (!user_mode(regs))
+                        goto clear_TF_reenable;
+        }
+
+        si_code = get_si_code(condition);
+        /* Ok, finally something we can handle */
+        send_sigtrap(tsk, regs, error_code, si_code);
+
+        /*
+         * Disable additional traps. They'll be re-enabled when
+         * the signal is delivered.
+         */
+clear_dr7:
+        set_debugreg(0, 7);
+        preempt_conditional_cli(regs);
+        return;
+
+#ifdef CONFIG_X86_32
+debug_vm86:
+        handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
+        preempt_conditional_cli(regs);
+        return;
+#endif
+
+clear_TF_reenable:
+        set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
+        regs->flags &= ~X86_EFLAGS_TF;
+        preempt_conditional_cli(regs);
+        return;
+}
+
+#ifdef CONFIG_X86_64
+static int kernel_math_error(struct pt_regs *regs, const char *str, int trapnr)
+{
+        if (fixup_exception(regs))
+                return 1;
+
+        notify_die(DIE_GPF, str, regs, 0, trapnr, SIGFPE);
+        /* Illegal floating point operation in the kernel */
+        current->thread.trap_no = trapnr;
+        die(str, regs, 0);
+        return 0;
+}
+#endif
+
+/*
+ * Note that we play around with the 'TS' bit in an attempt to get
+ * the correct behaviour even in the presence of the asynchronous
+ * IRQ13 behaviour
+ */
+void math_error(void __user *ip)
+{
+        struct task_struct *task;
+        siginfo_t info;
+        unsigned short cwd, swd;
+
+        /*
+         * Save the info for the exception handler and clear the error.
+         */
+        task = current;
+        save_init_fpu(task);
+        task->thread.trap_no = 16;
+        task->thread.error_code = 0;
+        info.si_signo = SIGFPE;
+        info.si_errno = 0;
+        info.si_code = __SI_FAULT;
+        info.si_addr = ip;
+        /*
+         * (~cwd & swd) will mask out exceptions that are not set to unmasked
+         * status.  0x3f is the exception bits in these regs, 0x200 is the
+         * C1 reg you need in case of a stack fault, 0x040 is the stack
+         * fault bit.  We should only be taking one exception at a time,
+         * so if this combination doesn't produce any single exception,
+         * then we have a bad program that isn't synchronizing its FPU usage
+         * and it will suffer the consequences since we won't be able to
+         * fully reproduce the context of the exception
+         */
+        cwd = get_fpu_cwd(task);
+        swd = get_fpu_swd(task);
+        switch (swd & ~cwd & 0x3f) {
+        case 0x000: /* No unmasked exception */
+#ifdef CONFIG_X86_32
+                return;
+#endif
+        default: /* Multiple exceptions */
+                break;
+        case 0x001: /* Invalid Op */
+                /*
+                 * swd & 0x240 == 0x040: Stack Underflow
+                 * swd & 0x240 == 0x240: Stack Overflow
+                 * User must clear the SF bit (0x40) if set
+                 */
+                info.si_code = FPE_FLTINV;
+                break;
+        case 0x002: /* Denormalize */
+        case 0x010: /* Underflow */
+                info.si_code = FPE_FLTUND;
+                break;
+        case 0x004: /* Zero Divide */
+                info.si_code = FPE_FLTDIV;
+                break;
+        case 0x008: /* Overflow */
+                info.si_code = FPE_FLTOVF;
+                break;
+        case 0x020: /* Precision */
+                info.si_code = FPE_FLTRES;
+                break;
+        }
+        force_sig_info(SIGFPE, &info, task);
+}
+
+dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
+{
+        conditional_sti(regs);
+
+#ifdef CONFIG_X86_32
+        ignore_fpu_irq = 1;
+#else
+        if (!user_mode(regs) &&
+            kernel_math_error(regs, "kernel x87 math error", 16))
+                return;
+#endif
+
+        math_error((void __user *)regs->ip);
+}
+
+static void simd_math_error(void __user *ip)
+{
+        struct task_struct *task;
+        siginfo_t info;
+        unsigned short mxcsr;
+
+        /*
+         * Save the info for the exception handler and clear the error.
+         */
+        task = current;
+        save_init_fpu(task);
+        task->thread.trap_no = 19;
+        task->thread.error_code = 0;
+        info.si_signo = SIGFPE;
+        info.si_errno = 0;
+        info.si_code = __SI_FAULT;
+        info.si_addr = ip;
+        /*
+         * The SIMD FPU exceptions are handled a little differently, as there
+         * is only a single status/control register.  Thus, to determine which
+         * unmasked exception was caught we must mask the exception mask bits
+         * at 0x1f80, and then use these to mask the exception bits at 0x3f.
+         */
+        mxcsr = get_fpu_mxcsr(task);
+        switch (~((mxcsr & 0x1f80) >> 7) & (mxcsr & 0x3f)) {
+        case 0x000:
+        default:
+                break;
+        case 0x001: /* Invalid Op */
+                info.si_code = FPE_FLTINV;
+                break;
+        case 0x002: /* Denormalize */
+        case 0x010: /* Underflow */
+                info.si_code = FPE_FLTUND;
+                break;
+        case 0x004: /* Zero Divide */
+                info.si_code = FPE_FLTDIV;
+                break;
+        case 0x008: /* Overflow */
+                info.si_code = FPE_FLTOVF;
+                break;
+        case 0x020: /* Precision */
+                info.si_code = FPE_FLTRES;
+                break;
+        }
+        force_sig_info(SIGFPE, &info, task);
+}
+
+dotraplinkage void
+do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
+{
+        conditional_sti(regs);
+
+#ifdef CONFIG_X86_32
+        if (cpu_has_xmm) {
+                /* Handle SIMD FPU exceptions on PIII+ processors. */
+                ignore_fpu_irq = 1;
+                simd_math_error((void __user *)regs->ip);
+                return;
+        }
+        /*
+         * Handle strange cache flush from user space exception
+         * in all other cases.  This is undocumented behaviour.
+         */
+        if (regs->flags & X86_VM_MASK) {
+                handle_vm86_fault((struct kernel_vm86_regs *)regs, error_code);
+                return;
+        }
+        current->thread.trap_no = 19;
+        current->thread.error_code = error_code;
+        die_if_kernel("cache flush denied", regs, error_code);
+        force_sig(SIGSEGV, current);
+#else
+        if (!user_mode(regs) &&
+                        kernel_math_error(regs, "kernel simd math error", 19))
+                return;
+        simd_math_error((void __user *)regs->ip);
+#endif
+}
+
+dotraplinkage void
+do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
+{
+        conditional_sti(regs);
+#if 0
+        /* No need to warn about this any longer. */
+        printk(KERN_INFO "Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
+#endif
+}
+
+#ifdef CONFIG_X86_32
+unsigned long patch_espfix_desc(unsigned long uesp, unsigned long kesp)
+{
+        struct desc_struct *gdt = get_cpu_gdt_table(smp_processor_id());
+        unsigned long base = (kesp - uesp) & -THREAD_SIZE;
+        unsigned long new_kesp = kesp - base;
+        unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;
+        __u64 desc = *(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS];
+
+        /* Set up base for espfix segment */
+        desc &= 0x00f0ff0000000000ULL;
+        desc |= ((((__u64)base) << 16) & 0x000000ffffff0000ULL) |
+                ((((__u64)base) << 32) & 0xff00000000000000ULL) |
+                ((((__u64)lim_pages) << 32) & 0x000f000000000000ULL) |
+                (lim_pages & 0xffff);
+        *(__u64 *)&gdt[GDT_ENTRY_ESPFIX_SS] = desc;
+
+        return new_kesp;
+}
+#else
+asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
+{
+}
+
+asmlinkage void __attribute__((weak)) mce_threshold_interrupt(void)
+{
+}
+#endif
+
+/*
+ * 'math_state_restore()' saves the current math information in the
+ * old math state array, and gets the new ones from the current task
+ *
+ * Careful.. There are problems with IBM-designed IRQ13 behaviour.
+ * Don't touch unless you *really* know how it works.
+ *
+ * Must be called with kernel preemption disabled (in this case,
+ * local interrupts are disabled at the call-site in entry.S).
+ */
+asmlinkage void math_state_restore(void)
+{
+        struct thread_info *thread = current_thread_info();
+        struct task_struct *tsk = thread->task;
+
+        if (!tsk_used_math(tsk)) {
+                local_irq_enable();
+                /*
+                 * does a slab alloc which can sleep
+                 */
+                if (init_fpu(tsk)) {
+                        /*
+                         * ran out of memory!
+                         */
+                        do_group_exit(SIGKILL);
+                        return;
+                }
+                local_irq_disable();
+        }
+
+        clts();                         /* Allow maths ops (or we recurse) */
+#ifdef CONFIG_X86_32
+        restore_fpu(tsk);
+#else
+        /*
+         * Paranoid restore. send a SIGSEGV if we fail to restore the state.
+         */
+        if (unlikely(restore_fpu_checking(tsk))) {
+                stts();
+                force_sig(SIGSEGV, tsk);
+                return;
+        }
+#endif
+        thread->status |= TS_USEDFPU;   /* So we fnsave on switch_to() */
+        tsk->fpu_counter++;
+}
+EXPORT_SYMBOL_GPL(math_state_restore);
+
+#ifndef CONFIG_MATH_EMULATION
+asmlinkage void math_emulate(long arg)
+{
+        printk(KERN_EMERG
+                "math-emulation not enabled and no coprocessor found.\n");
+        printk(KERN_EMERG "killing %s.\n", current->comm);
+        force_sig(SIGFPE, current);
+        schedule();
+}
+#endif /* CONFIG_MATH_EMULATION */
+
+dotraplinkage void __kprobes
+do_device_not_available(struct pt_regs *regs, long error)
+{
+#ifdef CONFIG_X86_32
+        if (read_cr0() & X86_CR0_EM) {
+                conditional_sti(regs);
+                math_emulate(0);
+        } else {
+                math_state_restore(); /* interrupts still off */
+                conditional_sti(regs);
+        }
+#else
+        math_state_restore();
+#endif
+}
+
+#ifdef CONFIG_X86_32
+#ifdef CONFIG_X86_MCE
+dotraplinkage void __kprobes do_machine_check(struct pt_regs *regs, long error)
+{
+        conditional_sti(regs);
+        machine_check_vector(regs, error);
+}
+#endif
+
+dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
+{
+        siginfo_t info;
+        local_irq_enable();
+
+        info.si_signo = SIGILL;
+        info.si_errno = 0;
+        info.si_code = ILL_BADSTK;
+        info.si_addr = 0;
+        if (notify_die(DIE_TRAP, "iret exception",
+                        regs, error_code, 32, SIGILL) == NOTIFY_STOP)
+                return;
+        do_trap(32, SIGILL, "iret exception", regs, error_code, &info);
+}
+#endif
+
+void __init trap_init(void)
+{
+#ifdef CONFIG_X86_32
+        int i;
+#endif
+
+#ifdef CONFIG_EISA
+        void __iomem *p = early_ioremap(0x0FFFD9, 4);
+
+        if (readl(p) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
+                EISA_bus = 1;
+        early_iounmap(p, 4);
+#endif
+
+        set_intr_gate(0, &divide_error);
+        set_intr_gate_ist(1, &debug, DEBUG_STACK);
+        set_intr_gate_ist(2, &nmi, NMI_STACK);
+        /* int3 can be called from all */
+        set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
+        /* int4 can be called from all */
+        set_system_intr_gate(4, &overflow);
+        set_intr_gate(5, &bounds);
+        set_intr_gate(6, &invalid_op);
+        set_intr_gate(7, &device_not_available);
+#ifdef CONFIG_X86_32
+        set_task_gate(8, GDT_ENTRY_DOUBLEFAULT_TSS);
+#else
+        set_intr_gate_ist(8, &double_fault, DOUBLEFAULT_STACK);
+#endif
+        set_intr_gate(9, &coprocessor_segment_overrun);
+        set_intr_gate(10, &invalid_TSS);
+        set_intr_gate(11, &segment_not_present);
+        set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
+        set_intr_gate(13, &general_protection);
+        set_intr_gate(14, &page_fault);
+        set_intr_gate(15, &spurious_interrupt_bug);
+        set_intr_gate(16, &coprocessor_error);
+        set_intr_gate(17, &alignment_check);
+#ifdef CONFIG_X86_MCE
+        set_intr_gate_ist(18, &machine_check, MCE_STACK);
+#endif
+        set_intr_gate(19, &simd_coprocessor_error);
+
+#ifdef CONFIG_IA32_EMULATION
+        set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
+#endif
+
+#ifdef CONFIG_X86_32
+        if (cpu_has_fxsr) {
+                printk(KERN_INFO "Enabling fast FPU save and restore... ");
+                set_in_cr4(X86_CR4_OSFXSR);
+                printk("done.\n");
+        }
+        if (cpu_has_xmm) {
+                printk(KERN_INFO
+                        "Enabling unmasked SIMD FPU exception support... ");
+                set_in_cr4(X86_CR4_OSXMMEXCPT);
+                printk("done.\n");
+        }
+
+        set_system_trap_gate(SYSCALL_VECTOR, &system_call);
+
+        /* Reserve all the builtin and the syscall vector: */
+        for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
+                set_bit(i, used_vectors);
+
+        set_bit(SYSCALL_VECTOR, used_vectors);
+#endif
+        /*
+         * Should be a barrier for any external CPU state:
+         */
+        cpu_init();
+
+#ifdef CONFIG_X86_32
+        trap_init_hook();
+#endif
+}