/*
 *  linux/arch/x86-64/traps.c
 *
 *  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
 *
 *  $Id: traps.c,v 1.36 2002/03/24 11:09:10 ak Exp $
 */

/*
 * 'Traps.c' handles hardware traps and faults after we have saved some
 * state in 'entry.S'.
 */
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/moduleparam.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/atomic.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/i387.h>
#include <asm/kdebug.h>
#include <asm/processor.h>

#include <asm/smp.h>
#include <asm/pgalloc.h>
#include <asm/pda.h>
#include <asm/proto.h>
#include <asm/nmi.h>

#include <linux/irq.h>


extern struct gate_struct idt_table[256]; 

asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
asmlinkage void overflow(void);
asmlinkage void bounds(void);
asmlinkage void invalid_op(void);
asmlinkage void device_not_available(void);
asmlinkage void double_fault(void);
asmlinkage void coprocessor_segment_overrun(void);
asmlinkage void invalid_TSS(void);
asmlinkage void segment_not_present(void);
asmlinkage void stack_segment(void);
asmlinkage void general_protection(void);
asmlinkage void page_fault(void);
asmlinkage void coprocessor_error(void);
asmlinkage void simd_coprocessor_error(void);
asmlinkage void reserved(void);
asmlinkage void alignment_check(void);
asmlinkage void machine_check(void);
asmlinkage void spurious_interrupt_bug(void);
asmlinkage void call_debug(void);

struct notifier_block *die_chain;
static DEFINE_SPINLOCK(die_notifier_lock);

int register_die_notifier(struct notifier_block *nb)
{
        int err = 0;
        unsigned long flags;
        spin_lock_irqsave(&die_notifier_lock, flags);
        err = notifier_chain_register(&die_chain, nb);
        spin_unlock_irqrestore(&die_notifier_lock, flags);
        return err;
}

static inline void conditional_sti(struct pt_regs *regs)
{
        if (regs->eflags & X86_EFLAGS_IF)
                local_irq_enable();
}

static int kstack_depth_to_print = 10;

#ifdef CONFIG_KALLSYMS
#include <linux/kallsyms.h> 
int printk_address(unsigned long address)
{ 
        unsigned long offset = 0, symsize;
        const char *symname;
        char *modname;
        char *delim = ":"; 
        char namebuf[128];

        symname = kallsyms_lookup(address, &symsize, &offset, &modname, namebuf); 
        if (!symname) 
                return printk("[<%016lx>]", address);
        if (!modname) 
                modname = delim = "";           
        return printk("<%016lx>{%s%s%s%s%+ld}",
                      address,delim,modname,delim,symname,offset); 
} 
#else
int printk_address(unsigned long address)
{ 
        return printk("[<%016lx>]", address);
} 
#endif

unsigned long *in_exception_stack(int cpu, unsigned long stack) 
{ 
        int k;
        for (k = 0; k < N_EXCEPTION_STACKS; k++) {
                struct tss_struct *tss = &per_cpu(init_tss, cpu);
                unsigned long end = tss->ist[k] + EXCEPTION_STKSZ;

                if (stack >= tss->ist[k]  && stack <= end)
                        return (unsigned long *)end;
        }
        return NULL;
} 

/*
 * x86-64 can have upto three kernel stacks: 
 * process stack
 * interrupt stack
 * severe exception (double fault, nmi, stack fault) hardware stack
 * Check and process them in order.
 */

void show_trace(unsigned long *stack)
{
        unsigned long addr;
        unsigned long *irqstack, *irqstack_end, *estack_end;
        const int cpu = safe_smp_processor_id();
        int i;

        printk("\nCall Trace:");
        i = 0; 
        
        estack_end = in_exception_stack(cpu, (unsigned long)stack); 
        if (estack_end) { 
                while (stack < estack_end) { 
                        addr = *stack++; 
                        if (__kernel_text_address(addr)) {
                                i += printk_address(addr);
                                i += printk(" "); 
                                if (i > 50) {
                                        printk("\n"); 
                                        i = 0;
                                }
                        }
                }
                i += printk(" <EOE> "); 
                i += 7;
                stack = (unsigned long *) estack_end[-2]; 
        }  

        irqstack_end = (unsigned long *) (cpu_pda[cpu].irqstackptr);
        irqstack = (unsigned long *) (cpu_pda[cpu].irqstackptr - IRQSTACKSIZE + 64);

        if (stack >= irqstack && stack < irqstack_end) {
                printk("<IRQ> ");  
                while (stack < irqstack_end) {
                        addr = *stack++;
                        /*
                         * If the address is either in the text segment of the
                         * kernel, or in the region which contains vmalloc'ed
                         * memory, it *may* be the address of a calling
                         * routine; if so, print it so that someone tracing
                         * down the cause of the crash will be able to figure
                         * out the call path that was taken.
                         */
                         if (__kernel_text_address(addr)) {
                                 i += printk_address(addr);
                                 i += printk(" "); 
                                 if (i > 50) { 
                                        printk("\n       ");
                                         i = 0;
                                 } 
                        }
                } 
                stack = (unsigned long *) (irqstack_end[-1]);
                printk(" <EOI> ");
                i += 7;
        } 

        while (((long) stack & (THREAD_SIZE-1)) != 0) {
                addr = *stack++;
                if (__kernel_text_address(addr)) {
                        i += printk_address(addr);
                        i += printk(" "); 
                        if (i > 50) { 
                                printk("\n       ");
                                         i = 0;
                        } 
                }
        }
        printk("\n");
}

void show_stack(struct task_struct *tsk, unsigned long * rsp)
{
        unsigned long *stack;
        int i;
        const int cpu = safe_smp_processor_id();
        unsigned long *irqstack_end = (unsigned long *) (cpu_pda[cpu].irqstackptr);
        unsigned long *irqstack = (unsigned long *) (cpu_pda[cpu].irqstackptr - IRQSTACKSIZE);    

        // debugging aid: "show_stack(NULL, NULL);" prints the
        // back trace for this cpu.

        if (rsp == NULL) {
                if (tsk)
                        rsp = (unsigned long *)tsk->thread.rsp;
                else
                        rsp = (unsigned long *)&rsp;
        }

        stack = rsp;
        for(i=0; i < kstack_depth_to_print; i++) {
                if (stack >= irqstack && stack <= irqstack_end) {
                        if (stack == irqstack_end) {
                                stack = (unsigned long *) (irqstack_end[-1]);
                                printk(" <EOI> ");
                        }
                } else {
                if (((long) stack & (THREAD_SIZE-1)) == 0)
                        break;
                }
                if (i && ((i % 4) == 0))
                        printk("\n       ");
                printk("%016lx ", *stack++);
        }
        show_trace((unsigned long *)rsp);
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
        unsigned long dummy;
        show_trace(&dummy);
}

EXPORT_SYMBOL(dump_stack);

void show_registers(struct pt_regs *regs)
{
        int i;
        int in_kernel = (regs->cs & 3) == 0;
        unsigned long rsp;
        const int cpu = safe_smp_processor_id(); 
        struct task_struct *cur = cpu_pda[cpu].pcurrent; 

                rsp = regs->rsp;

        printk("CPU %d ", cpu);
        __show_regs(regs);
        printk("Process %s (pid: %d, threadinfo %p, task %p)\n",
                cur->comm, cur->pid, cur->thread_info, cur);

        /*
         * When in-kernel, we also print out the stack and code at the
         * time of the fault..
         */
        if (in_kernel) {

                printk("Stack: ");
                show_stack(NULL, (unsigned long*)rsp);

                printk("\nCode: ");
                if(regs->rip < PAGE_OFFSET)
                        goto bad;

                for(i=0;i<20;i++)
                {
                        unsigned char c;
                        if(__get_user(c, &((unsigned char*)regs->rip)[i])) {
bad:
                                printk(" Bad RIP value.");
                                break;
                        }
                        printk("%02x ", c);
                }
        }
        printk("\n");
}       

void handle_BUG(struct pt_regs *regs)
{ 
        struct bug_frame f;
        char tmp;

        if (regs->cs & 3)
                return; 
        if (__copy_from_user(&f, (struct bug_frame *) regs->rip, 
                             sizeof(struct bug_frame)))
                return; 
        if ((unsigned long)f.filename < __PAGE_OFFSET || 
            f.ud2[0] != 0x0f || f.ud2[1] != 0x0b) 
                return;
        if (__get_user(tmp, f.filename))
                f.filename = "unmapped filename"; 
        printk("----------- [cut here ] --------- [please bite here ] ---------\n");
        printk(KERN_ALERT "Kernel BUG at %.50s:%d\n", f.filename, f.line);
} 

void out_of_line_bug(void)
{ 
        BUG(); 
} 

static DEFINE_SPINLOCK(die_lock);
static int die_owner = -1;

void oops_begin(void)
{
        int cpu = safe_smp_processor_id(); 
        /* racy, but better than risking deadlock. */ 
        local_irq_disable();
        if (!spin_trylock(&die_lock)) { 
                if (cpu == die_owner) 
                        /* nested oops. should stop eventually */;
                else
                        spin_lock(&die_lock); 
        }
        die_owner = cpu; 
        console_verbose();
        bust_spinlocks(1); 
}

void oops_end(void)
{ 
        die_owner = -1;
        bust_spinlocks(0); 
        spin_unlock(&die_lock); 
        local_irq_enable();     /* make sure back scroll still works */
        if (panic_on_oops)
                panic("Oops"); 
} 

void __die(const char * str, struct pt_regs * regs, long err)
{
        static int die_counter;
        printk(KERN_EMERG "%s: %04lx [%u] ", str, err & 0xffff,++die_counter);
#ifdef CONFIG_PREEMPT
        printk("PREEMPT ");
#endif
#ifdef CONFIG_SMP
        printk("SMP ");
#endif
#ifdef CONFIG_DEBUG_PAGEALLOC
        printk("DEBUG_PAGEALLOC");
#endif
        printk("\n");
        notify_die(DIE_OOPS, (char *)str, regs, err, 255, SIGSEGV);
        show_registers(regs);
        /* Executive summary in case the oops scrolled away */
        printk(KERN_ALERT "RIP ");
        printk_address(regs->rip); 
        printk(" RSP <%016lx>\n", regs->rsp); 
}

void die(const char * str, struct pt_regs * regs, long err)
{
        oops_begin();
        handle_BUG(regs);
        __die(str, regs, err);
        oops_end();
        do_exit(SIGSEGV); 
}
static inline void die_if_kernel(const char * str, struct pt_regs * regs, long err)
{
        if (!(regs->eflags & VM_MASK) && (regs->cs == __KERNEL_CS))
                die(str, regs, err);
}

void die_nmi(char *str, struct pt_regs *regs)
{
        oops_begin();
        /*
         * We are in trouble anyway, lets at least try
         * to get a message out.
         */
        printk(str, safe_smp_processor_id());
        show_registers(regs);
        if (panic_on_timeout || panic_on_oops)
                panic("nmi watchdog");
        printk("console shuts up ...\n");
        oops_end();
        do_exit(SIGSEGV);
}

static void do_trap(int trapnr, int signr, char *str, 
                           struct pt_regs * regs, long error_code, siginfo_t *info)
{
        conditional_sti(regs);

#ifdef CONFIG_CHECKING
       { 
               unsigned long gs; 
               struct x8664_pda *pda = cpu_pda + safe_smp_processor_id(); 
               rdmsrl(MSR_GS_BASE, gs); 
               if (gs != (unsigned long)pda) { 
                       wrmsrl(MSR_GS_BASE, pda); 
                       printk("%s: wrong gs %lx expected %p rip %lx\n", str, gs, pda,
                              regs->rip);
               }
       }
#endif

        if ((regs->cs & 3)  != 0) { 
                struct task_struct *tsk = current;

                if (exception_trace && unhandled_signal(tsk, signr))
                        printk(KERN_INFO
                               "%s[%d] trap %s rip:%lx rsp:%lx error:%lx\n",
                               tsk->comm, tsk->pid, str,
                               regs->rip,regs->rsp,error_code); 

                tsk->thread.error_code = error_code;
                tsk->thread.trap_no = trapnr;
                if (info)
                        force_sig_info(signr, info, tsk);
                else
                        force_sig(signr, tsk);
                return;
        }


        /* kernel trap */ 
        {            
                const struct exception_table_entry *fixup;
                fixup = search_exception_tables(regs->rip);
                if (fixup) {
                        regs->rip = fixup->fixup;
                } else  
                        die(str, regs, error_code);
                return;
        }
}

#define DO_ERROR(trapnr, signr, str, name) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                                        == NOTIFY_STOP) \
                return; \
        do_trap(trapnr, signr, str, regs, error_code, NULL); \
}

#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
asmlinkage 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; \
        do_trap(trapnr, signr, str, regs, error_code, &info); \
}

DO_ERROR_INFO( 0, SIGFPE,  "divide error", divide_error, FPE_INTDIV, regs->rip)
DO_ERROR( 4, SIGSEGV, "overflow", overflow)
DO_ERROR( 5, SIGSEGV, "bounds", bounds)
DO_ERROR_INFO( 6, SIGILL,  "invalid operand", invalid_op, ILL_ILLOPN, regs->rip)
DO_ERROR( 7, SIGSEGV, "device not available", device_not_available)
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)
DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
DO_ERROR(18, SIGSEGV, "reserved", reserved)

#define DO_ERROR_STACK(trapnr, signr, str, name) \
asmlinkage void *do_##name(struct pt_regs * regs, long error_code) \
{ \
        struct pt_regs *pr = ((struct pt_regs *)(current->thread.rsp0))-1; \
        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
                                                        == NOTIFY_STOP) \
                return regs; \
        if (regs->cs & 3) { \
                memcpy(pr, regs, sizeof(struct pt_regs)); \
                regs = pr; \
        } \
        do_trap(trapnr, signr, str, regs, error_code, NULL); \
        return regs;            \
}

DO_ERROR_STACK(12, SIGBUS,  "stack segment", stack_segment)
DO_ERROR_STACK( 8, SIGSEGV, "double fault", double_fault)

asmlinkage void do_general_protection(struct pt_regs * regs, long error_code)
{
        conditional_sti(regs);

#ifdef CONFIG_CHECKING
       { 
               unsigned long gs; 
               struct x8664_pda *pda = cpu_pda + safe_smp_processor_id(); 
               rdmsrl(MSR_GS_BASE, gs); 
               if (gs != (unsigned long)pda) { 
                       wrmsrl(MSR_GS_BASE, pda); 
                       oops_in_progress++;
                       printk("general protection handler: wrong gs %lx expected %p\n", gs, pda);
                       oops_in_progress--;
               }
       }
#endif

        if ((regs->cs & 3)!=0) { 
                struct task_struct *tsk = current;

                if (exception_trace && unhandled_signal(tsk, SIGSEGV))
                        printk(KERN_INFO
                       "%s[%d] general protection rip:%lx rsp:%lx error:%lx\n",
                               tsk->comm, tsk->pid,
                               regs->rip,regs->rsp,error_code); 

                tsk->thread.error_code = error_code;
                tsk->thread.trap_no = 13;
                force_sig(SIGSEGV, tsk);
                return;
        } 

        /* kernel gp */
        {
                const struct exception_table_entry *fixup;
                fixup = search_exception_tables(regs->rip);
                if (fixup) {
                        regs->rip = fixup->fixup;
                        return;
                }
                if (notify_die(DIE_GPF, "general protection fault", regs,
                                        error_code, 13, SIGSEGV) == NOTIFY_STOP)
                        return;
                die("general protection fault", regs, error_code);
        }
}

static void mem_parity_error(unsigned char reason, struct pt_regs * regs)
{
        printk("Uhhuh. NMI received. Dazed and confused, but trying to continue\n");
        printk("You probably have a hardware problem with your RAM chips\n");

        /* Clear and disable the memory parity error line. */
        reason = (reason & 0xf) | 4;
        outb(reason, 0x61);
}

static void io_check_error(unsigned char reason, struct pt_regs * regs)
{
        printk("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);
        mdelay(2000);
        reason &= ~8;
        outb(reason, 0x61);
}

static void unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
{       printk("Uhhuh. NMI received for unknown reason %02x.\n", reason);
        printk("Dazed and confused, but trying to continue\n");
        printk("Do you have a strange power saving mode enabled?\n");
}

asmlinkage void default_do_nmi(struct pt_regs *regs)
{
        unsigned char reason = 0;

        /* Only the BSP gets external NMIs from the system.  */
        if (!smp_processor_id())
                reason = get_nmi_reason();

        if (!(reason & 0xc0)) {
                if (notify_die(DIE_NMI_IPI, "nmi_ipi", regs, reason, 0, 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 > 0) {
                        nmi_watchdog_tick(regs,reason);
                        return;
                }
#endif
                unknown_nmi_error(reason, regs);
                return;
        }
        if (notify_die(DIE_NMI, "nmi", regs, reason, 0, 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);

        /*
         * Reassert NMI in case it became active meanwhile
         * as it's edge-triggered.
         */
        outb(0x8f, 0x70);
        inb(0x71);              /* dummy */
        outb(0x0f, 0x70);
        inb(0x71);              /* dummy */
}

asmlinkage void do_int3(struct pt_regs * regs, long error_code)
{
        if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) == NOTIFY_STOP) {
                return;
        }
        do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
        return;
}

/* runs on IST stack. */
asmlinkage void *do_debug(struct pt_regs * regs, unsigned long error_code)
{
        struct pt_regs *pr;
        unsigned long condition;
        struct task_struct *tsk = current;
        siginfo_t info;

        pr = (struct pt_regs *)(current->thread.rsp0)-1;
        if (regs->cs & 3) {
                memcpy(pr, regs, sizeof(struct pt_regs));
                regs = pr;
        }       

#ifdef CONFIG_CHECKING
       { 
               /* RED-PEN interaction with debugger - could destroy gs */
               unsigned long gs; 
               struct x8664_pda *pda = cpu_pda + safe_smp_processor_id(); 
               rdmsrl(MSR_GS_BASE, gs); 
               if (gs != (unsigned long)pda) { 
                       wrmsrl(MSR_GS_BASE, pda); 
                       printk("debug handler: wrong gs %lx expected %p\n", gs, pda);
               }
       }
#endif

        asm("movq %%db6,%0" : "=r" (condition));

        if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
                                                SIGTRAP) == NOTIFY_STOP) {
                return regs;
        }
        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;
                }
        }

        tsk->thread.debugreg6 = condition;

        /* Mask out spurious TF errors due to lazy TF clearing */
        if ((condition & DR_STEP) &&
            (notify_die(DIE_DEBUGSTEP, "debugstep", regs, condition,
                        1, SIGTRAP) != NOTIFY_STOP)) {
                /*
                 * The TF error should be masked out only if the current
                 * process is not traced and if the TRAP flag has been set
                 * previously by a tracing process (condition detected by
                 * the PT_DTRACE flag); remember that the i386 TRAP flag
                 * can be modified by the process itself in user mode,
                 * allowing programs to debug themselves without the ptrace()
                 * interface.
                 */
                if ((regs->cs & 3) == 0)
                       goto clear_TF_reenable;
                if ((tsk->ptrace & (PT_DTRACE|PT_PTRACED)) == PT_DTRACE)
                        goto clear_TF;
        }

        /* Ok, finally something we can handle */
        tsk->thread.trap_no = 1;
        tsk->thread.error_code = error_code;
        info.si_signo = SIGTRAP;
        info.si_errno = 0;
        info.si_code = TRAP_BRKPT;
        if ((regs->cs & 3) == 0) 
                goto clear_dr7; 

        info.si_addr = (void __user *)regs->rip;
        force_sig_info(SIGTRAP, &info, tsk);    
clear_dr7:
        asm volatile("movq %0,%%db7"::"r"(0UL));
        notify_die(DIE_DEBUG, "debug", regs, condition, 1, SIGTRAP);
        return regs;

clear_TF_reenable:
        set_tsk_thread_flag(tsk, TIF_SINGLESTEP);

clear_TF:
        /* RED-PEN could cause spurious errors */
        if (notify_die(DIE_DEBUG, "debug2", regs, condition, 1, SIGTRAP) 
                                                                != NOTIFY_STOP)
        regs->eflags &= ~TF_MASK;
        return regs;    
}

static int kernel_math_error(struct pt_regs *regs, char *str)
{
        const struct exception_table_entry *fixup;
        fixup = search_exception_tables(regs->rip);
        if (fixup) {
                regs->rip = fixup->fixup;
                return 1;
        }
        notify_die(DIE_GPF, str, regs, 0, 16, SIGFPE);
#if 0
        /* This should be a die, but warn only for now */
        die(str, regs, 0);
#else
        printk(KERN_DEBUG "%s: %s at ", current->comm, str);
        printk_address(regs->rip);
        printk("\n");
#endif
        return 0;
}

/*
 * 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
 */
asmlinkage void do_coprocessor_error(struct pt_regs *regs)
{
        void __user *rip = (void __user *)(regs->rip);
        struct task_struct * task;
        siginfo_t info;
        unsigned short cwd, swd;

        conditional_sti(regs);
        if ((regs->cs & 3) == 0 &&
            kernel_math_error(regs, "kernel x87 math error"))
                return;

        /*
         * 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 = rip;
        /*
         * (~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 (((~cwd) & swd & 0x3f) | (swd & 0x240)) {
                case 0x000:
                default:
                        break;
                case 0x001: /* Invalid Op */
                case 0x041: /* Stack Fault */
                case 0x241: /* Stack Fault | Direction */
                        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);
}

asmlinkage void bad_intr(void)
{
        printk("bad interrupt"); 
}

asmlinkage void do_simd_coprocessor_error(struct pt_regs *regs)
{
        void __user *rip = (void __user *)(regs->rip);
        struct task_struct * task;
        siginfo_t info;
        unsigned short mxcsr;

        conditional_sti(regs);
        if ((regs->cs & 3) == 0 &&
                kernel_math_error(regs, "simd math error"))
                return;

        /*
         * 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 = rip;
        /*
         * 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);
}

asmlinkage void do_spurious_interrupt_bug(struct pt_regs * regs)
{
}

asmlinkage void __attribute__((weak)) smp_thermal_interrupt(void)
{
}

/*
 *  '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.
 */
asmlinkage void math_state_restore(void)
{
        struct task_struct *me = current;
        clts();                 /* Allow maths ops (or we recurse) */

        if (!used_math())
                init_fpu(me);
        restore_fpu_checking(&me->thread.i387.fxsave);
        me->thread_info->status |= TS_USEDFPU;
}

void do_call_debug(struct pt_regs *regs) 
{ 
        notify_die(DIE_CALL, "debug call", regs, 0, 255, SIGINT); 
}

void __init trap_init(void)
{
        set_intr_gate(0,&divide_error);
        set_intr_gate_ist(1,&debug,DEBUG_STACK);
        set_intr_gate_ist(2,&nmi,NMI_STACK);
        set_system_gate(3,&int3);
        set_system_gate(4,&overflow);   /* int4-5 can be called from all */
        set_system_gate(5,&bounds);
        set_intr_gate(6,&invalid_op);
        set_intr_gate(7,&device_not_available);
        set_intr_gate_ist(8,&double_fault, DOUBLEFAULT_STACK);
        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_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
#endif
       
        set_intr_gate(KDB_VECTOR, call_debug);
       
        /*
         * Should be a barrier for any external CPU state.
         */
        cpu_init();
}


/* Actual parsing is done early in setup.c. */
static int __init oops_dummy(char *s)
{ 
        panic_on_oops = 1;
        return -1; 
} 
__setup("oops=", oops_dummy); 

static int __init kstack_setup(char *s)
{
        kstack_depth_to_print = simple_strtoul(s,NULL,0);
        return 0;
}
__setup("kstack=", kstack_setup);