/*
 *  linux/arch/arm/kernel/traps.c
 *
 *  Copyright (C) 1995, 1996 Russell King
 *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  'traps.c' handles hardware exceptions after we have saved some state in
 *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
 *  kill the offending process.
 */
#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
#include <linux/interrupt.h>
#include <linux/init.h>

#include <asm/atomic.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

#include "ptrace.h"

extern void c_backtrace (unsigned long fp, int pmode);
extern void show_pte(struct mm_struct *mm, unsigned long addr);

const char *processor_modes[]=
{ "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "UK6_32" , "ABT_32" ,
  "UK8_32" , "UK9_32" , "UK10_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
};

static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };

/*
 * Stack pointers should always be within the kernels view of
 * physical memory.  If it is not there, then we can't dump
 * out any information relating to the stack.
 */
static int verify_stack(unsigned long sp)
{
        if (sp < PAGE_OFFSET || sp > (unsigned long)high_memory)
                return -EFAULT;

        return 0;
}

/*
 * Dump out the contents of some memory nicely...
 */
void dump_mem(unsigned long bottom, unsigned long top)
{
        unsigned long p = bottom & ~31;
        int i;

        for (p = bottom & ~31; p < top;) {
                printk("%08lx: ", p);

                for (i = 0; i < 8; i++, p += 4) {
                        unsigned int val;

                        if (p < bottom || p >= top)
                                printk("         ");
                        else {
                                __get_user(val, (unsigned long *)p);
                                printk("%08x ", val);
                        }
                        if (i == 3)
                                printk(" ");
                }
                printk ("\n");
        }
}

/*
 * 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 dump_instr(struct pt_regs *regs)
{
        unsigned long addr = instruction_pointer(regs);
        const int thumb = thumb_mode(regs);
        const int width = thumb ? 4 : 8;
        int i;

        printk("Code: ");
        for (i = -2; i < 3; i++) {
                unsigned int val, bad;

                if (thumb)
                        bad = __get_user(val, &((u16 *)addr)[i]);
                else
                        bad = __get_user(val, &((u32 *)addr)[i]);

                if (!bad)
                        printk(i == 0 ? "(%0*x) " : "%0*x ", width, val);
                else {
                        printk("bad PC value.");
                        break;
                }
        }
        printk("\n");
}

static void dump_stack(struct task_struct *tsk, unsigned long sp)
{
        printk("Stack:\n");
        dump_mem(sp - 16, 8192+(unsigned long)tsk);
}

static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
        unsigned int fp;
        int ok = 1;

        printk("Backtrace: ");
        fp = regs->ARM_fp;
        if (!fp) {
                printk("no frame pointer");
                ok = 0;
        } else if (verify_stack(fp)) {
                printk("invalid frame pointer 0x%08x", fp);
                ok = 0;
        } else if (fp < 4096+(unsigned long)tsk)
                printk("frame pointer underflow");
        printk("\n");

        if (ok)
                c_backtrace(fp, processor_mode(regs));
}

/*
 * This is called from SysRq-T (show_task) to display the current
 * call trace for each process.  Very useful.
 */
void show_trace_task(struct task_struct *tsk)
{
        if (tsk != current) {
                unsigned int fp = tsk->thread.save->fp;
                c_backtrace(fp, 0x10);
        }
}

spinlock_t die_lock = SPIN_LOCK_UNLOCKED;

/*
 * This function is protected against re-entrancy.
 */
NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
{
        struct task_struct *tsk = current;

        console_verbose();
        spin_lock_irq(&die_lock);

        printk("Internal error: %s: %x\n", str, err);
        printk("CPU: %d\n", smp_processor_id());
        show_regs(regs);
        printk("Process %s (pid: %d, stackpage=%08lx)\n",
                current->comm, current->pid, 4096+(unsigned long)tsk);

        if (!user_mode(regs) || in_interrupt()) {
                mm_segment_t fs;

                /*
                 * We need to switch to kernel mode so that we can
                 * use __get_user to safely read from kernel space.
                 * Note that we now dump the code first, just in case
                 * the backtrace kills us.
                 */
                fs = get_fs();
                set_fs(KERNEL_DS);

                dump_stack(tsk, (unsigned long)(regs + 1));
                dump_backtrace(regs, tsk);
                dump_instr(regs);

                set_fs(fs);
        }

        spin_unlock_irq(&die_lock);
        do_exit(SIGSEGV);
}

void die_if_kernel(const char *str, struct pt_regs *regs, int err)
{
        if (user_mode(regs))
                return;

        die(str, regs, err);
}

asmlinkage void do_undefinstr(int address, struct pt_regs *regs, int mode)
{
        unsigned long *pc;
        siginfo_t info;

        /*
         * According to the ARM ARM, PC is 2 or 4 bytes ahead, depending
         * whether we're in Thumb mode or not.
         */
        regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
        pc = (unsigned long *)instruction_pointer(regs);

#ifdef CONFIG_DEBUG_USER
        printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
                current->comm, current->pid, pc);
        dump_instr(regs);
#endif

        current->thread.error_code = 0;
        current->thread.trap_no = 6;

        info.si_signo = SIGILL;
        info.si_errno = 0;
        info.si_code  = ILL_ILLOPC;
        info.si_addr  = pc;

        force_sig_info(SIGILL, &info, current);

        die_if_kernel("Oops - undefined instruction", regs, mode);
}

#ifdef CONFIG_CPU_26
asmlinkage void do_excpt(int address, struct pt_regs *regs, int mode)
{
        siginfo_t info;

#ifdef CONFIG_DEBUG_USER
        printk(KERN_INFO "%s (%d): address exception: pc=%08lx\n",
                current->comm, current->pid, instruction_pointer(regs));
        dump_instr(regs);
#endif

        current->thread.error_code = 0;
        current->thread.trap_no = 11;

        info.si_signo = SIGBUS;
        info.si_errno = 0;
        info.si_code  = BUS_ADRERR;
        info.si_addr  = (void *)address;

        force_sig_info(SIGBUS, &info, current);

        die_if_kernel("Oops - address exception", regs, mode);
}
#endif

asmlinkage void do_unexp_fiq (struct pt_regs *regs)
{
#ifndef CONFIG_IGNORE_FIQ
        printk("Hmm.  Unexpected FIQ received, but trying to continue\n");
        printk("You may have a hardware problem...\n");
#endif
}

/*
 * bad_mode handles the impossible case in the vectors.  If you see one of
 * these, then it's extremely serious, and could mean you have buggy hardware.
 * It never returns, and never tries to sync.  We hope that we can at least
 * dump out some state information...
 */
asmlinkage void bad_mode(struct pt_regs *regs, int reason, int proc_mode)
{
        unsigned int vectors = vectors_base();
        mm_segment_t fs;

        console_verbose();

        printk(KERN_CRIT "Bad mode in %s handler detected: mode %s\n",
                handler[reason], processor_modes[proc_mode]);

        /*
         * We need to switch to kernel mode so that we can
         * use __get_user to safely read from kernel space.
         * Note that we now dump the code first, just in case
         * the backtrace kills us.
         */
        fs = get_fs();
        set_fs(KERNEL_DS);

        /*
         * Dump out the vectors and stub routines.  Maybe a better solution
         * would be to dump them out only if we detect that they are corrupted.
         */
        printk(KERN_CRIT "Vectors:\n");
        dump_mem(vectors, 0x40);
        printk(KERN_CRIT "Stubs:\n");
        dump_mem(vectors + 0x200, 0x4b8);

        set_fs(fs);

        die("Oops", regs, 0);
        cli();
        panic("bad mode");
}

static int bad_syscall(int n, struct pt_regs *regs)
{
        siginfo_t info;

        /* You might think just testing `handler' would be enough, but PER_LINUX
         * points it to no_lcall7 to catch undercover SVr4 binaries.  Gutted.
         */
        if (current->personality != PER_LINUX && current->exec_domain->handler) {
                /* Hand it off to iBCS.  The extra parameter and consequent type 
                 * forcing is necessary because of the weird ARM calling convention.
                 */
                current->exec_domain->handler(n, regs);
                return regs->ARM_r0;
        }

#ifdef CONFIG_DEBUG_USER
        printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
                current->pid, current->comm, n);
        dump_instr(regs);
#endif

        info.si_signo = SIGILL;
        info.si_errno = 0;
        info.si_code  = ILL_ILLTRP;
        info.si_addr  = (void *)instruction_pointer(regs) -
                         (thumb_mode(regs) ? 2 : 4);

        force_sig_info(SIGILL, &info, current);
        die_if_kernel("Oops", regs, n);
        return regs->ARM_r0;
}

/*
 * Handle all unrecognised system calls.
 *  0x9f0000 - 0x9fffff are some more esoteric system calls
 */
#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
asmlinkage int arm_syscall(int no, struct pt_regs *regs)
{
        siginfo_t info;

        if ((no >> 16) != 0x9f)
                return bad_syscall(no, regs);

        switch (no & 0xffff) {
        case 0: /* branch through 0 */
                info.si_signo = SIGSEGV;
                info.si_errno = 0;
                info.si_code  = SEGV_MAPERR;
                info.si_addr  = NULL;

                force_sig_info(SIGSEGV, &info, current);

                die_if_kernel("branch through zero", regs, 0);
                return 0;

        case NR(breakpoint): /* SWI BREAK_POINT */
                /*
                 * The PC is always left pointing at the next
                 * instruction.  Fix this.
                 */
                regs->ARM_pc -= 4;
                __ptrace_cancel_bpt(current);

                info.si_signo = SIGTRAP;
                info.si_errno = 0;
                info.si_code  = TRAP_BRKPT;
                info.si_addr  = (void *)instruction_pointer(regs) -
                                 (thumb_mode(regs) ? 2 : 4);

                force_sig_info(SIGTRAP, &info, current);
                return regs->ARM_r0;

#ifdef CONFIG_CPU_32
        /*
         * Flush a region from virtual address 'r0' to virtual address 'r1'
         * _inclusive_.  There is no alignment requirement on either address;
         * user space does not need to know the hardware cache layout.
         *
         * r2 contains flags.  It should ALWAYS be passed as ZERO until it
         * is defined to be something else.  For now we ignore it, but may
         * the fires of hell burn in your belly if you break this rule. ;)
         *
         * (at a later date, we may want to allow this call to not flush
         * various aspects of the cache.  Passing '0' will guarantee that
         * everything necessary gets flushed to maintain consistency in
         * the specified region).
         */
        case NR(cacheflush):
                cpu_cache_clean_invalidate_range(regs->ARM_r0, regs->ARM_r1, 1);
                return 0;

        case NR(usr26):
                if (!(elf_hwcap & HWCAP_26BIT))
                        break;
                regs->ARM_cpsr &= ~0x10;
                return regs->ARM_r0;

        case NR(usr32):
                if (!(elf_hwcap & HWCAP_26BIT))
                        break;
                regs->ARM_cpsr |= 0x10;
                return regs->ARM_r0;
#else
        case NR(cacheflush):
                return 0;

        case NR(usr26):
        case NR(usr32):
                break;
#endif

        default:
                /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
                   if not implemented, rather than raising SIGILL.  This
                   way the calling program can gracefully determine whether
                   a feature is supported.  */
                if (no <= 0x7ff)
                        return -ENOSYS;
                break;
        }
#ifdef CONFIG_DEBUG_USER
        /*
         * experience shows that these seem to indicate that
         * something catastrophic has happened
         */
        printk("[%d] %s: arm syscall %d\n", current->pid, current->comm, no);
        dump_instr(regs);
        if (user_mode(regs)) {
                show_regs(regs);
                c_backtrace(regs->ARM_fp, processor_mode(regs));
        }
#endif
        info.si_signo = SIGILL;
        info.si_errno = 0;
        info.si_code  = ILL_ILLTRP;
        info.si_addr  = (void *)instruction_pointer(regs) -
                         (thumb_mode(regs) ? 2 : 4);

        force_sig_info(SIGILL, &info, current);
        die_if_kernel("Oops", regs, no);
        return 0;
}

void __bad_xchg(volatile void *ptr, int size)
{
        printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
                __builtin_return_address(0), ptr, size);
        BUG();
}

/*
 * A data abort trap was taken, but we did not handle the instruction.
 * Try to abort the user program, or panic if it was the kernel.
 */
asmlinkage void
baddataabort(int code, unsigned long instr, struct pt_regs *regs)
{
        unsigned long addr = instruction_pointer(regs);
        siginfo_t info;

#ifdef CONFIG_DEBUG_USER
        printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
                current->pid, current->comm, code, instr);
        dump_instr(regs);
        show_pte(current->mm, addr);
#endif

        info.si_signo = SIGILL;
        info.si_errno = 0;
        info.si_code  = ILL_ILLOPC;
        info.si_addr  = (void *)addr;

        force_sig_info(SIGILL, &info, current);
        die_if_kernel("unknown data abort code", regs, instr);
}

void __bug(const char *file, int line, void *data)
{
        printk(KERN_CRIT"kernel BUG at %s:%d!", file, line);
        if (data)
                printk(KERN_CRIT" - extra data = %p", data);
        printk("\n");
        *(int *)0 = 0;
}

void __readwrite_bug(const char *fn)
{
        printk("%s called, but not implemented", fn);
        BUG();
}

void __pte_error(const char *file, int line, unsigned long val)
{
        printk("%s:%d: bad pte %08lx.\n", file, line, val);
}

void __pmd_error(const char *file, int line, unsigned long val)
{
        printk("%s:%d: bad pmd %08lx.\n", file, line, val);
}

void __pgd_error(const char *file, int line, unsigned long val)
{
        printk("%s:%d: bad pgd %08lx.\n", file, line, val);
}

asmlinkage void __div0(void)
{
        printk("Division by zero in kernel.\n");
        __backtrace();
}

void abort(void)
{
        void *lr = __builtin_return_address(0);

        printk(KERN_CRIT "abort() called from %p!  (Please "
               "report to rmk@arm.linux.org.uk)\n", lr);

        BUG();

        /* if that doesn't kill us, halt */
        panic("Oops failed to kill thread");
}

void __init trap_init(void)
{
        extern void __trap_init(void *);

        __trap_init((void *)vectors_base());
        if (vectors_base() != 0)
                printk(KERN_DEBUG "Relocating machine vectors to 0x%08x\n",
                        vectors_base());
#ifdef CONFIG_CPU_32
        modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
#endif
}