linux/arch/unicore32/kernel/traps.c
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   1/*
   2 * linux/arch/unicore32/kernel/traps.c
   3 *
   4 * Code specific to PKUnity SoC and UniCore ISA
   5 *
   6 * Copyright (C) 2001-2010 GUAN Xue-tao
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 *  'traps.c' handles hardware exceptions after we have saved some state.
  13 *  Mostly a debugging aid, but will probably kill the offending process.
  14 */
  15#include <linux/module.h>
  16#include <linux/signal.h>
  17#include <linux/spinlock.h>
  18#include <linux/personality.h>
  19#include <linux/kallsyms.h>
  20#include <linux/kdebug.h>
  21#include <linux/uaccess.h>
  22#include <linux/delay.h>
  23#include <linux/hardirq.h>
  24#include <linux/init.h>
  25#include <linux/atomic.h>
  26#include <linux/unistd.h>
  27
  28#include <asm/cacheflush.h>
  29#include <asm/traps.h>
  30
  31#include "setup.h"
  32
  33static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  34
  35void dump_backtrace_entry(unsigned long where,
  36                unsigned long from, unsigned long frame)
  37{
  38#ifdef CONFIG_KALLSYMS
  39        printk(KERN_DEFAULT "[<%08lx>] (%pS) from [<%08lx>] (%pS)\n",
  40                        where, (void *)where, from, (void *)from);
  41#else
  42        printk(KERN_DEFAULT "Function entered at [<%08lx>] from [<%08lx>]\n",
  43                        where, from);
  44#endif
  45}
  46
  47/*
  48 * Stack pointers should always be within the kernels view of
  49 * physical memory.  If it is not there, then we can't dump
  50 * out any information relating to the stack.
  51 */
  52static int verify_stack(unsigned long sp)
  53{
  54        if (sp < PAGE_OFFSET ||
  55            (sp > (unsigned long)high_memory && high_memory != NULL))
  56                return -EFAULT;
  57
  58        return 0;
  59}
  60
  61/*
  62 * Dump out the contents of some memory nicely...
  63 */
  64static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  65                     unsigned long top)
  66{
  67        unsigned long first;
  68        mm_segment_t fs;
  69        int i;
  70
  71        /*
  72         * We need to switch to kernel mode so that we can use __get_user
  73         * to safely read from kernel space.  Note that we now dump the
  74         * code first, just in case the backtrace kills us.
  75         */
  76        fs = get_fs();
  77        set_fs(KERNEL_DS);
  78
  79        printk(KERN_DEFAULT "%s%s(0x%08lx to 0x%08lx)\n",
  80                        lvl, str, bottom, top);
  81
  82        for (first = bottom & ~31; first < top; first += 32) {
  83                unsigned long p;
  84                char str[sizeof(" 12345678") * 8 + 1];
  85
  86                memset(str, ' ', sizeof(str));
  87                str[sizeof(str) - 1] = '\0';
  88
  89                for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
  90                        if (p >= bottom && p < top) {
  91                                unsigned long val;
  92                                if (__get_user(val, (unsigned long *)p) == 0)
  93                                        sprintf(str + i * 9, " %08lx", val);
  94                                else
  95                                        sprintf(str + i * 9, " ????????");
  96                        }
  97                }
  98                printk(KERN_DEFAULT "%s%04lx:%s\n", lvl, first & 0xffff, str);
  99        }
 100
 101        set_fs(fs);
 102}
 103
 104static void dump_instr(const char *lvl, struct pt_regs *regs)
 105{
 106        unsigned long addr = instruction_pointer(regs);
 107        const int width = 8;
 108        mm_segment_t fs;
 109        char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 110        int i;
 111
 112        /*
 113         * We need to switch to kernel mode so that we can use __get_user
 114         * to safely read from kernel space.  Note that we now dump the
 115         * code first, just in case the backtrace kills us.
 116         */
 117        fs = get_fs();
 118        set_fs(KERNEL_DS);
 119
 120        for (i = -4; i < 1; i++) {
 121                unsigned int val, bad;
 122
 123                bad = __get_user(val, &((u32 *)addr)[i]);
 124
 125                if (!bad)
 126                        p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 127                                        width, val);
 128                else {
 129                        p += sprintf(p, "bad PC value");
 130                        break;
 131                }
 132        }
 133        printk(KERN_DEFAULT "%sCode: %s\n", lvl, str);
 134
 135        set_fs(fs);
 136}
 137
 138static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 139{
 140        unsigned int fp, mode;
 141        int ok = 1;
 142
 143        printk(KERN_DEFAULT "Backtrace: ");
 144
 145        if (!tsk)
 146                tsk = current;
 147
 148        if (regs) {
 149                fp = regs->UCreg_fp;
 150                mode = processor_mode(regs);
 151        } else if (tsk != current) {
 152                fp = thread_saved_fp(tsk);
 153                mode = 0x10;
 154        } else {
 155                asm("mov %0, fp" : "=r" (fp) : : "cc");
 156                mode = 0x10;
 157        }
 158
 159        if (!fp) {
 160                printk("no frame pointer");
 161                ok = 0;
 162        } else if (verify_stack(fp)) {
 163                printk("invalid frame pointer 0x%08x", fp);
 164                ok = 0;
 165        } else if (fp < (unsigned long)end_of_stack(tsk))
 166                printk("frame pointer underflow");
 167        printk("\n");
 168
 169        if (ok)
 170                c_backtrace(fp, mode);
 171}
 172
 173void show_stack(struct task_struct *tsk, unsigned long *sp)
 174{
 175        dump_backtrace(NULL, tsk);
 176        barrier();
 177}
 178
 179static int __die(const char *str, int err, struct thread_info *thread,
 180                struct pt_regs *regs)
 181{
 182        struct task_struct *tsk = thread->task;
 183        static int die_counter;
 184        int ret;
 185
 186        printk(KERN_EMERG "Internal error: %s: %x [#%d]\n",
 187               str, err, ++die_counter);
 188
 189        /* trap and error numbers are mostly meaningless on UniCore */
 190        ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, \
 191                        SIGSEGV);
 192        if (ret == NOTIFY_STOP)
 193                return ret;
 194
 195        print_modules();
 196        __show_regs(regs);
 197        printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
 198                TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 199
 200        if (!user_mode(regs) || in_interrupt()) {
 201                dump_mem(KERN_EMERG, "Stack: ", regs->UCreg_sp,
 202                         THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 203                dump_backtrace(regs, tsk);
 204                dump_instr(KERN_EMERG, regs);
 205        }
 206
 207        return ret;
 208}
 209
 210DEFINE_SPINLOCK(die_lock);
 211
 212/*
 213 * This function is protected against re-entrancy.
 214 */
 215void die(const char *str, struct pt_regs *regs, int err)
 216{
 217        struct thread_info *thread = current_thread_info();
 218        int ret;
 219
 220        oops_enter();
 221
 222        spin_lock_irq(&die_lock);
 223        console_verbose();
 224        bust_spinlocks(1);
 225        ret = __die(str, err, thread, regs);
 226
 227        bust_spinlocks(0);
 228        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 229        spin_unlock_irq(&die_lock);
 230        oops_exit();
 231
 232        if (in_interrupt())
 233                panic("Fatal exception in interrupt");
 234        if (panic_on_oops)
 235                panic("Fatal exception");
 236        if (ret != NOTIFY_STOP)
 237                do_exit(SIGSEGV);
 238}
 239
 240void uc32_notify_die(const char *str, struct pt_regs *regs,
 241                struct siginfo *info, unsigned long err, unsigned long trap)
 242{
 243        if (user_mode(regs)) {
 244                current->thread.error_code = err;
 245                current->thread.trap_no = trap;
 246
 247                force_sig_info(info->si_signo, info, current);
 248        } else
 249                die(str, regs, err);
 250}
 251
 252/*
 253 * bad_mode handles the impossible case in the vectors.  If you see one of
 254 * these, then it's extremely serious, and could mean you have buggy hardware.
 255 * It never returns, and never tries to sync.  We hope that we can at least
 256 * dump out some state information...
 257 */
 258asmlinkage void bad_mode(struct pt_regs *regs, unsigned int reason)
 259{
 260        console_verbose();
 261
 262        printk(KERN_CRIT "Bad mode detected with reason 0x%x\n", reason);
 263
 264        die("Oops - bad mode", regs, 0);
 265        local_irq_disable();
 266        panic("bad mode");
 267}
 268
 269void __pte_error(const char *file, int line, unsigned long val)
 270{
 271        printk(KERN_DEFAULT "%s:%d: bad pte %08lx.\n", file, line, val);
 272}
 273
 274void __pmd_error(const char *file, int line, unsigned long val)
 275{
 276        printk(KERN_DEFAULT "%s:%d: bad pmd %08lx.\n", file, line, val);
 277}
 278
 279void __pgd_error(const char *file, int line, unsigned long val)
 280{
 281        printk(KERN_DEFAULT "%s:%d: bad pgd %08lx.\n", file, line, val);
 282}
 283
 284asmlinkage void __div0(void)
 285{
 286        printk(KERN_DEFAULT "Division by zero in kernel.\n");
 287        dump_stack();
 288}
 289EXPORT_SYMBOL(__div0);
 290
 291void abort(void)
 292{
 293        BUG();
 294
 295        /* if that doesn't kill us, halt */
 296        panic("Oops failed to kill thread");
 297}
 298EXPORT_SYMBOL(abort);
 299
 300void __init trap_init(void)
 301{
 302        return;
 303}
 304
 305void __init early_trap_init(void)
 306{
 307        unsigned long vectors = VECTORS_BASE;
 308
 309        /*
 310         * Copy the vectors, stubs (in entry-unicore.S)
 311         * into the vector page, mapped at 0xffff0000, and ensure these
 312         * are visible to the instruction stream.
 313         */
 314        memcpy((void *)vectors,
 315                        __vectors_start,
 316                        __vectors_end - __vectors_start);
 317        memcpy((void *)vectors + 0x200,
 318                        __stubs_start,
 319                        __stubs_end - __stubs_start);
 320
 321        early_signal_init();
 322
 323        flush_icache_range(vectors, vectors + PAGE_SIZE);
 324}
 325