Import 2.1.116pre2

[davej-history.git] / arch / i386 / kernel / traps.c

/*
 *  linux/arch/i386/traps.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 * 'Traps.c' handles hardware traps and faults after we have saved some
 * state in 'asm.s'.
 */
#include <linux/config.h>
#include <linux/head.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/smp.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/delay.h>

#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/spinlock.h>
#include <asm/atomic.h>
#include <asm/debugreg.h>

asmlinkage int system_call(void);
asmlinkage void lcall7(void);
struct desc_struct default_ldt = { 0, 0 };

static inline void console_verbose(void)
{
        extern int console_loglevel;
        console_loglevel = 15;
}

#define DO_ERROR(trapnr, signr, str, name, tsk) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
        tsk->tss.error_code = error_code; \
        tsk->tss.trap_no = trapnr; \
        force_sig(signr, tsk); \
        die_if_no_fixup(str,regs,error_code); \
}

#define DO_VM86_ERROR(trapnr, signr, str, name, tsk) \
asmlinkage void do_##name(struct pt_regs * regs, long error_code) \
{ \
        lock_kernel(); \
        if (regs->eflags & VM_MASK) { \
                if (!handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, trapnr)) \
                        goto out; \
                /* else fall through */ \
        } \
        tsk->tss.error_code = error_code; \
        tsk->tss.trap_no = trapnr; \
        force_sig(signr, tsk); \
        die_if_kernel(str,regs,error_code); \
out: \
        unlock_kernel(); \
}

void page_exception(void);

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 reserved(void);
asmlinkage void alignment_check(void);
asmlinkage void spurious_interrupt_bug(void);

int kstack_depth_to_print = 24;

/*
 * These constants are for searching for possible module text
 * segments.  VMALLOC_OFFSET comes from mm/vmalloc.c; MODULE_RANGE is
 * a guess of how much space is likely to be vmalloced.
 */
#define VMALLOC_OFFSET (8*1024*1024)
#define MODULE_RANGE (8*1024*1024)

static void show_registers(struct pt_regs *regs)
{
        int i;
        int in_kernel = 1;
        unsigned long esp;
        unsigned short ss;
        unsigned long *stack, addr, module_start, module_end;
        extern char _stext, _etext;

        esp = (unsigned long) (1+regs);
        ss = __KERNEL_DS;
        if (regs->xcs & 3) {
                in_kernel = 0;
                esp = regs->esp;
                ss = regs->xss & 0xffff;
        }
        printk("CPU:    %d\nEIP:    %04x:[<%08lx>]\nEFLAGS: %08lx\n",
                smp_processor_id(), 0xffff & regs->xcs, regs->eip, regs->eflags);
        printk("eax: %08lx   ebx: %08lx   ecx: %08lx   edx: %08lx\n",
                regs->eax, regs->ebx, regs->ecx, regs->edx);
        printk("esi: %08lx   edi: %08lx   ebp: %08lx   esp: %08lx\n",
                regs->esi, regs->edi, regs->ebp, esp);
        printk("ds: %04x   es: %04x   ss: %04x\n",
                regs->xds & 0xffff, regs->xes & 0xffff, ss);
        store_TR(i);
        printk("Process %s (pid: %d, process nr: %d, stackpage=%08lx)",
                current->comm, current->pid, 0xffff & i, 4096+(unsigned long)current);

        /*
         * When in-kernel, we also print out the stack and code at the
         * time of the fault..
         */
        if (in_kernel) {
                printk("\nStack: ");
                stack = (unsigned long *) esp;
                for(i=0; i < kstack_depth_to_print; i++) {
                        if (((long) stack & 4095) == 0)
                                break;
                        if (i && ((i % 8) == 0))
                                printk("\n       ");
                        printk("%08lx ", *stack++);
                }
                printk("\nCall Trace: ");
                stack = (unsigned long *) esp;
                i = 1;
                module_start = PAGE_OFFSET + (max_mapnr << PAGE_SHIFT);
                module_start = ((module_start + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1));
                module_end = module_start + MODULE_RANGE;
                while (((long) stack & 4095) != 0) {
                        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 (((addr >= (unsigned long) &_stext) &&
                             (addr <= (unsigned long) &_etext)) ||
                            ((addr >= module_start) && (addr <= module_end))) {
                                if (i && ((i % 8) == 0))
                                        printk("\n       ");
                                printk("[<%08lx>] ", addr);
                                i++;
                        }
                }
                printk("\nCode: ");
                for(i=0;i<20;i++)
                        printk("%02x ", ((unsigned char *)regs->eip)[i]);
        }
        printk("\n");
}       

spinlock_t die_lock;

void die(const char * str, struct pt_regs * regs, long err)
{
        console_verbose();
        spin_lock_irq(&die_lock);
        printk("%s: %04lx\n", str, err & 0xffff);
        show_registers(regs);
        spin_unlock_irq(&die_lock);
        do_exit(SIGSEGV);
}

static void die_if_kernel(const char * str, struct pt_regs * regs, long err)
{
        if (!(regs->eflags & VM_MASK) && !(3 & regs->xcs))
                die(str, regs, err);
}

static void die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
{
        if (!(regs->eflags & VM_MASK) && !(3 & regs->xcs))
        {
                unsigned long fixup;
                fixup = search_exception_table(regs->eip);
                if (fixup) {
                        regs->eip = fixup;
                        return;
                }
                die(str, regs, err);
        }
}

DO_VM86_ERROR( 0, SIGFPE,  "divide error", divide_error, current)
DO_VM86_ERROR( 3, SIGTRAP, "int3", int3, current)
DO_VM86_ERROR( 4, SIGSEGV, "overflow", overflow, current)
DO_VM86_ERROR( 5, SIGSEGV, "bounds", bounds, current)
DO_ERROR( 6, SIGILL,  "invalid operand", invalid_op, current)
DO_VM86_ERROR( 7, SIGSEGV, "device not available", device_not_available, current)
DO_ERROR( 8, SIGSEGV, "double fault", double_fault, current)
DO_ERROR( 9, SIGFPE,  "coprocessor segment overrun", coprocessor_segment_overrun, current)
DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS, current)
DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present, current)
DO_ERROR(12, SIGBUS,  "stack segment", stack_segment, current)
DO_ERROR(17, SIGSEGV, "alignment check", alignment_check, current)
DO_ERROR(18, SIGSEGV, "reserved", reserved, current)
/* I don't have documents for this but it does seem to cover the cache
   flush from user space exception some people get. */
DO_ERROR(19, SIGSEGV, "cache flush denied", cache_flush_denied, current)

asmlinkage void cache_flush_denied(struct pt_regs * regs, long error_code)
{
        if (regs->eflags & VM_MASK) {
                handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
                return;
        }
        die_if_kernel("cache flush denied",regs,error_code);
        current->tss.error_code = error_code;
        current->tss.trap_no = 19;
        force_sig(SIGSEGV, current);
}

asmlinkage void do_general_protection(struct pt_regs * regs, long error_code)
{
        if (regs->eflags & VM_MASK)
                goto gp_in_vm86;

        if (!(regs->xcs & 3))
                goto gp_in_kernel;

        current->tss.error_code = error_code;
        current->tss.trap_no = 13;
        force_sig(SIGSEGV, current);
        return;

gp_in_vm86:
        lock_kernel();
        handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
        unlock_kernel();
        return;

gp_in_kernel:
        {
                unsigned long fixup;
                fixup = search_exception_table(regs->eip);
                if (fixup) {
                        regs->eip = fixup;
                        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");
}       

static void io_check_error(unsigned char reason, struct pt_regs * regs)
{
        unsigned long i;

        printk("NMI: IOCK error (debug interrupt?)\n");
        show_registers(regs);

        /* Re-enable the IOCK line, wait for a few seconds */
        reason |= 8;
        outb(reason, 0x61);
        i = 2000;
        while (--i) udelay(1000);
        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 do_nmi(struct pt_regs * regs, long error_code)
{
        unsigned char reason = inb(0x61);
        extern atomic_t nmi_counter;

        atomic_inc(&nmi_counter);
        if (reason & 0x80)
                mem_parity_error(reason, regs);
        if (reason & 0x40)
                io_check_error(reason, regs);
        if (!(reason & 0xc0))
                unknown_nmi_error(reason, regs);
}

/*
 * Careful - we must not do a lock-kernel until we have checked that the
 * debug fault happened in user mode. Getting debug exceptions while
 * in the kernel has to be handled without locking, to avoid deadlocks..
 *
 * 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 - and we don't have to be careful about what values
 * can be written to the debug registers because there are no really
 * bad cases).
 */
asmlinkage void do_debug(struct pt_regs * regs, long error_code)
{
        unsigned int condition;
        struct task_struct *tsk = current;

        if (regs->eflags & VM_MASK)
                goto debug_vm86;

        __asm__ __volatile__("movl %%db6,%0" : "=r" (condition));

        /* Mask out spurious TF errors due to lazy TF clearing */
        if (condition & DR_STEP) {
                if ((tsk->flags & PF_PTRACED) == 0)
                        goto clear_TF;
        }

        /* Mast out spurious debug traps due to lazy DR7 setting */
        if (condition & (DR_TRAP0|DR_TRAP1|DR_TRAP2|DR_TRAP3)) {
                if (!tsk->tss.debugreg[7])
                        goto clear_dr7;
        }

        /* If this is a kernel mode trap, we need to reset db7 to allow us to continue sanely */
        if ((regs->xcs & 3) == 0)
                goto clear_dr7;

        /* Ok, finally something we can handle */
        tsk->tss.trap_no = 1;
        tsk->tss.error_code = error_code;
        force_sig(SIGTRAP, tsk);
        return;

debug_vm86:
        lock_kernel();
        handle_vm86_trap((struct kernel_vm86_regs *) regs, error_code, 1);
        unlock_kernel();
        return;

clear_dr7:
        __asm__("movl %0,%%db7"
                : /* no output */
                : "r" (0));
        return;

clear_TF:
        regs->eflags &= ~TF_MASK;
        return;
}

/*
 * 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)
{
        struct task_struct * task;

        lock_kernel();
        clts();
        task = current;
        /*
         *      Save the info for the exception handler
         */
        __asm__ __volatile__("fnsave %0":"=m" (task->tss.i387.hard));
        task->flags&=~PF_USEDFPU;
        stts();

        task->tss.trap_no = 16;
        task->tss.error_code = 0;
        force_sig(SIGFPE, task);
        unlock_kernel();
}

asmlinkage void do_coprocessor_error(struct pt_regs * regs, long error_code)
{
        ignore_irq13 = 1;
        math_error();
}

asmlinkage void do_spurious_interrupt_bug(struct pt_regs * regs,
                                          long error_code)
{
#if 0
        /* No need to warn about this any longer. */
        printk("Ignoring P6 Local APIC Spurious Interrupt Bug...\n");
#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.
 */
asmlinkage void math_state_restore(void)
{
        __asm__ __volatile__("clts");           /* Allow maths ops (or we recurse) */

/*
 *      SMP is actually simpler than uniprocessor for once. Because
 *      we can't pull the delayed FPU switching trick Linus does
 *      we simply have to do the restore each context switch and
 *      set the flag. switch_to() will always save the state in
 *      case we swap processors. We also don't use the coprocessor
 *      timer - IRQ 13 mode isn't used with SMP machines (thank god).
 */

        if(current->used_math)
                __asm__("frstor %0": :"m" (current->tss.i387));
        else
        {
                /*
                 *      Our first FPU usage, clean the chip.
                 */
                __asm__("fninit");
                current->used_math = 1;
        }
        current->flags|=PF_USEDFPU;             /* So we fnsave on switch_to() */
}

#ifndef CONFIG_MATH_EMULATION

asmlinkage void math_emulate(long arg)
{
        lock_kernel();
        printk("math-emulation not enabled and no coprocessor found.\n");
        printk("killing %s.\n",current->comm);
        force_sig(SIGFPE,current);
        schedule();
        unlock_kernel();
}

#endif /* CONFIG_MATH_EMULATION */

__initfunc(void trap_init_f00f_bug(void))
{
        unsigned long page;
        pgd_t * pgd;
        pmd_t * pmd;
        pte_t * pte;

        /*
         * Allocate a new page in virtual address space, 
         * move the IDT into it and write protect this page.
         */
        page = (unsigned long) vmalloc(PAGE_SIZE);
        memcpy((void *) page, idt_table, 256*8);

        pgd = pgd_offset(&init_mm, page);
        pmd = pmd_offset(pgd, page);
        pte = pte_offset(pmd, page);
        *pte = pte_wrprotect(*pte);
        local_flush_tlb();

        /*
         * "idt" is magic - it overlaps the idt_descr
         * variable so that updating idt will automatically
         * update the idt descriptor..
         */
        idt = (struct desc_struct *)page;
        __asm__ __volatile__("lidt %0": "=m" (idt_descr));
}



void __init trap_init(void)
{
        int i;
        struct desc_struct * p;

        if (readl(0x0FFFD9) == 'E' + ('I'<<8) + ('S'<<16) + ('A'<<24))
                EISA_bus = 1;
        set_call_gate(&default_ldt,lcall7);
        set_trap_gate(0,&divide_error);
        set_trap_gate(1,&debug);
        set_trap_gate(2,&nmi);
        set_system_gate(3,&int3);       /* int3-5 can be called from all */
        set_system_gate(4,&overflow);
        set_system_gate(5,&bounds);
        set_trap_gate(6,&invalid_op);
        set_trap_gate(7,&device_not_available);
        set_trap_gate(8,&double_fault);
        set_trap_gate(9,&coprocessor_segment_overrun);
        set_trap_gate(10,&invalid_TSS);
        set_trap_gate(11,&segment_not_present);
        set_trap_gate(12,&stack_segment);
        set_trap_gate(13,&general_protection);
        set_trap_gate(14,&page_fault);
        set_trap_gate(15,&spurious_interrupt_bug);
        set_trap_gate(16,&coprocessor_error);
        set_trap_gate(17,&alignment_check);
        for (i=18;i<48;i++)
                set_trap_gate(i,&reserved);
        set_system_gate(0x80,&system_call);
/* set up GDT task & ldt entries */
        p = gdt+FIRST_TSS_ENTRY;
        set_tss_desc(p, &init_task.tss);
        p++;
        set_ldt_desc(p, &default_ldt, 1);
        p++;
        for(i=1 ; i<NR_TASKS ; i++) {
                p->a=p->b=0;
                p++;
                p->a=p->b=0;
                p++;
        }
/* Clear NT, so that we won't have troubles with that later on */
        __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
        load_TR(0);
        load_ldt(0);
}