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/*

 *  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'. Currently mostly a debugging-aid, will be extended

 * to mainly kill the offending process (probably by giving it a signal,

 * but possibly by killing it outright if necessary).

 */

#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/config.h>

#include <linux/timer.h>

#include <linux/mm.h>

#include <asm/system.h>

#include <asm/segment.h>

#include <asm/io.h>

#include <asm/pgtable.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_kernel(str,regs,error_code); \

}

#define DO_VM86_ERROR(trapnr, signr, str, name, tsk) \

asmlinkage void do_##name(struct pt_regs * regs, long error_code) \

{ \

        if (regs->eflags & VM_MASK) { \

                if (!handle_vm86_trap((struct vm86_regs *) regs, error_code, trapnr)) \

                        return; \

                /* 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); \

}

#define get_seg_byte(seg,addr) ({ \

register unsigned char __res; \

__asm__("push %%fs;mov %%ax,%%fs;movb %%fs:%2,%%al;pop %%fs" \

        :"=a" (__res):"0" (seg),"m" (*(addr))); \

__res;})

#define get_seg_long(seg,addr) ({ \

register unsigned long __res; \

__asm__("push %%fs;mov %%ax,%%fs;movl %%fs:%2,%%eax;pop %%fs" \

        :"=a" (__res):"0" (seg),"m" (*(addr))); \

__res;})

#define _fs() ({ \

register unsigned short __res; \

__asm__("mov %%fs,%%ax":"=a" (__res):); \

__res;})

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 die_if_kernel(const char * str, struct pt_regs * regs, long err)

{

        int i;

        unsigned long esp;

        unsigned short ss;

        unsigned long *stack, addr, module_start, module_end;

        extern char start_kernel, _etext;

        esp = (unsigned long) &regs->esp;

        ss = KERNEL_DS;

        if ((regs->eflags & VM_MASK) || (3 & regs->cs) == 3)

                return;

        if (regs->cs & 3) {

                esp = regs->esp;

                ss = regs->ss;

        }

        console_verbose();

        printk("%s: %04lx\n", str, err & 0xffff);

        printk("CPU:    %d\n", smp_processor_id());

        printk("EIP:    %04x:[<%08lx>]\nEFLAGS: %08lx\n", 0xffff & regs->cs,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   fs: %04x   gs: %04x   ss: %04x\n",

                regs->ds, regs->es, regs->fs, regs->gs, ss);

        store_TR(i);

        if (STACK_MAGIC != *(unsigned long *)current->kernel_stack_page)

                printk("Corrupted stack page\n");

        printk("Process %s (pid: %d, process nr: %d, stackpage=%08lx)\nStack: ",

                current->comm, current->pid, 0xffff & i, current->kernel_stack_page);

        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 ", get_seg_long(ss,stack++));

        }

        printk("\nCall Trace: ");

        stack = (unsigned long *) esp;

        i = 1;

        module_start = ((high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1));

        module_end = module_start + MODULE_RANGE;

        while (((long) stack & 4095) != 0) {

                addr = get_seg_long(ss, 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) &start_kernel) &&

                     (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 ",0xff & get_seg_byte(regs->cs,(i+(char *)regs->eip)));

        printk("\n");

        do_exit(SIGSEGV);

}

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, last_task_used_math)

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)

/* divide_error is after ret_from_sys_call in entry.S */

asmlinkage void ret_from_sys_call(void) __asm__("ret_from_sys_call");

asmlinkage void divide_error(void)      __asm__("divide_error");

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

{

        if (regs->eflags & VM_MASK) {

                handle_vm86_fault((struct vm86_regs *) regs, error_code);

                return;

        }

        /*

         * HACK HACK HACK  :)  Fixing the segment invalid on syscall return

         * barfage for 2.0 has been put into the too-hard basket but having

         * a user producing endless GPFs is unacceptable as well. - Paul G.

         */

        if ((regs->cs & 3) != 3) {

                if (regs->eip >= (unsigned long)ret_from_sys_call &&

                    regs->eip < (unsigned long)divide_error) {

                        static int moancount = 0;

                        if (moancount < 5) {

                                printk(KERN_INFO "Ignoring GPF attempt from program \"%s\" (pid %d).\n",

                                        current->comm, current->pid);

                                moancount++;

                        }

                        do_exit(SIGSEGV);

                }

                else

                        die_if_kernel("general protection",regs,error_code);

        }

        current->tss.error_code = error_code;

        current->tss.trap_no = 13;

        force_sig(SIGSEGV, current);

}

asmlinkage void do_nmi(struct pt_regs * regs, long error_code)

{

#ifdef CONFIG_SMP_NMI_INVAL

        smp_flush_tlb_rcv();

#else

#ifndef CONFIG_IGNORE_NMI

        printk("Uhhuh. NMI received. Dazed and confused, but trying to continue\n");

        printk("You probably have a hardware problem with your RAM chips or a\n");

        printk("power saving mode enabled.\n");

#endif  

#endif

}

asmlinkage void do_debug(struct pt_regs * regs, long error_code)

{

        if (regs->eflags & VM_MASK) {

                handle_vm86_trap((struct vm86_regs *) regs, error_code, 1);

                return;

        }

        force_sig(SIGTRAP, current);

        current->tss.trap_no = 1;

        current->tss.error_code = error_code;

        if ((regs->cs & 3) == 0) {

                /* If this is a kernel mode trap, then reset db7 and allow us to continue */

                __asm__("movl %0,%%db7"

                        : /* no output */

                        : "r" (0));

                return;

        }

        die_if_kernel("debug",regs,error_code);

}

/*

 * Note that we play around with the 'TS' bit to hopefully get

 * the correct behaviour even in the presence of the asynchronous

 * IRQ13 behaviour

 */

void math_error(void)

{

        struct task_struct * task;

        clts();

#ifdef __SMP__

        task = current;

#else

        task = last_task_used_math;

        last_task_used_math = NULL;

        if (!task) {

                __asm__("fnclex");

                return;

        }

#endif

        /*

         *      Save the info for the exception handler

         */

        __asm__ __volatile__("fnsave %0":"=m" (task->tss.i387.hard));

        task->flags&=~PF_USEDFPU;

        stts();

        force_sig(SIGFPE, task);

        task->tss.trap_no = 16;

        task->tss.error_code = 0;

}

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).

 */

#ifndef __SMP__

        if (last_task_used_math == current)

                return;

        if (last_task_used_math)

                __asm__("fnsave %0":"=m" (last_task_used_math->tss.i387));

        else

                __asm__("fnclex");

        last_task_used_math = current;

#endif

        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)

{

  printk("math-emulation not enabled and no coprocessor found.\n");

  printk("killing %s.\n",current->comm);

  force_sig(SIGFPE,current);

  schedule();

}

#endif /* CONFIG_MATH_EMULATION */

struct {

        unsigned short limit;

        unsigned long addr __attribute__((packed));

} idt_descriptor;

void trap_init_f00f_bug(void)

{

        pgd_t * pgd;

        pmd_t * pmd;

        pte_t * pte;

        unsigned long page;

        unsigned long idtpage = (unsigned long)idt;

        struct desc_struct *alias_idt;

        printk("alias mapping IDT readonly ... ");

                /* just to get free address space */

        page = (unsigned long) vmalloc (PAGE_SIZE);

        alias_idt = (void *)(page + (idtpage & ~PAGE_MASK));

        idt_descriptor.limit = 256*8-1;

        idt_descriptor.addr = VMALLOC_VMADDR(alias_idt);

        /*

         * alias map the original idt to the alias page:

         */

        page = VMALLOC_VMADDR(page);

        pgd = pgd_offset(&init_mm, page);

        pmd = pmd_offset(pgd, page);

        pte = pte_offset(pmd, page);

                /* give memory back to the pool, don't need it */

        free_page(pte_page(*pte));

                /* ... and set the readonly alias */

        set_pte(pte, mk_pte(idtpage  & PAGE_MASK, PAGE_KERNEL));

        *pte = pte_wrprotect(*pte);

        flush_tlb_all();

                /* now we have the mapping ok, we can do LIDT */

         __asm__ __volatile__("\tlidt %0": "=m" (idt_descriptor));

        printk(" ... done\n");

}

void trap_init(void)

{

        int i;

        struct desc_struct * p;

        static int smptrap=0;

        if(smptrap)

        {

                __asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");

                load_ldt(0);

                return;

        }

        smptrap++;

        if (strncmp((char*)0x0FFFD9, "EISA", 4) == 0)

                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);

}