arch/unicore32/kernel/traps.c

   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/system.h>
  30 #include <asm/traps.h>
  31
  32 #include "setup.h"
  33
  34 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  35
  36 void dump_backtrace_entry(unsigned long where,
  37                 unsigned long from, unsigned long frame)
  38 {
  39 #ifdef CONFIG_KALLSYMS
  40         printk(KERN_DEFAULT "[<%08lx>] (%pS) from [<%08lx>] (%pS)\n",
  41                         where, (void *)where, from, (void *)from);
  42 #else
  43         printk(KERN_DEFAULT "Function entered at [<%08lx>] from [<%08lx>]\n",
  44                         where, from);
  45 #endif
  46 }
  47
  48 /*
  49  * Stack pointers should always be within the kernels view of
  50  * physical memory.  If it is not there, then we can't dump
  51  * out any information relating to the stack.
  52  */
  53 static int verify_stack(unsigned long sp)
  54 {
  55         if (sp < PAGE_OFFSET ||
  56             (sp > (unsigned long)high_memory && high_memory != NULL))
  57                 return -EFAULT;
  58
  59         return 0;
  60 }
  61
  62 /*
  63  * Dump out the contents of some memory nicely...
  64  */
  65 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  66                      unsigned long top)
  67 {
  68         unsigned long first;
  69         mm_segment_t fs;
  70         int i;
  71
  72         /*
  73          * We need to switch to kernel mode so that we can use __get_user
  74          * to safely read from kernel space.  Note that we now dump the
  75          * code first, just in case the backtrace kills us.
  76          */
  77         fs = get_fs();
  78         set_fs(KERNEL_DS);
  79
  80         printk(KERN_DEFAULT "%s%s(0x%08lx to 0x%08lx)\n",
  81                         lvl, str, bottom, top);
  82
  83         for (first = bottom & ~31; first < top; first += 32) {
  84                 unsigned long p;
  85                 char str[sizeof(" 12345678") * 8 + 1];
  86
  87                 memset(str, ' ', sizeof(str));
  88                 str[sizeof(str) - 1] = '\0';
  89
  90                 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
  91                         if (p >= bottom && p < top) {
  92                                 unsigned long val;
  93                                 if (__get_user(val, (unsigned long *)p) == 0)
  94                                         sprintf(str + i * 9, " %08lx", val);
  95                                 else
  96                                         sprintf(str + i * 9, " ????????");
  97                         }
  98                 }
  99                 printk(KERN_DEFAULT "%s%04lx:%s\n", lvl, first & 0xffff, str);
 100         }
 101
 102         set_fs(fs);
 103 }
 104
 105 static void dump_instr(const char *lvl, struct pt_regs *regs)
 106 {
 107         unsigned long addr = instruction_pointer(regs);
 108         const int width = 8;
 109         mm_segment_t fs;
 110         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 111         int i;
 112
 113         /*
 114          * We need to switch to kernel mode so that we can use __get_user
 115          * to safely read from kernel space.  Note that we now dump the
 116          * code first, just in case the backtrace kills us.
 117          */
 118         fs = get_fs();
 119         set_fs(KERNEL_DS);
 120
 121         for (i = -4; i < 1; i++) {
 122                 unsigned int val, bad;
 123
 124                 bad = __get_user(val, &((u32 *)addr)[i]);
 125
 126                 if (!bad)
 127                         p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 128                                         width, val);
 129                 else {
 130                         p += sprintf(p, "bad PC value");
 131                         break;
 132                 }
 133         }
 134         printk(KERN_DEFAULT "%sCode: %s\n", lvl, str);
 135
 136         set_fs(fs);
 137 }
 138
 139 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 140 {
 141         unsigned int fp, mode;
 142         int ok = 1;
 143
 144         printk(KERN_DEFAULT "Backtrace: ");
 145
 146         if (!tsk)
 147                 tsk = current;
 148
 149         if (regs) {
 150                 fp = regs->UCreg_fp;
 151                 mode = processor_mode(regs);
 152         } else if (tsk != current) {
 153                 fp = thread_saved_fp(tsk);
 154                 mode = 0x10;
 155         } else {
 156                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 157                 mode = 0x10;
 158         }
 159
 160         if (!fp) {
 161                 printk("no frame pointer");
 162                 ok = 0;
 163         } else if (verify_stack(fp)) {
 164                 printk("invalid frame pointer 0x%08x", fp);
 165                 ok = 0;
 166         } else if (fp < (unsigned long)end_of_stack(tsk))
 167                 printk("frame pointer underflow");
 168         printk("\n");
 169
 170         if (ok)
 171                 c_backtrace(fp, mode);
 172 }
 173
 174 void dump_stack(void)
 175 {
 176         dump_backtrace(NULL, NULL);
 177 }
 178 EXPORT_SYMBOL(dump_stack);
 179
 180 void show_stack(struct task_struct *tsk, unsigned long *sp)
 181 {
 182         dump_backtrace(NULL, tsk);
 183         barrier();
 184 }
 185
 186 static int __die(const char *str, int err, struct thread_info *thread,
 187                 struct pt_regs *regs)
 188 {
 189         struct task_struct *tsk = thread->task;
 190         static int die_counter;
 191         int ret;
 192
 193         printk(KERN_EMERG "Internal error: %s: %x [#%d]\n",
 194                str, err, ++die_counter);
 195
 196         /* trap and error numbers are mostly meaningless on UniCore */
 197         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, \
 198                         SIGSEGV);
 199         if (ret == NOTIFY_STOP)
 200                 return ret;
 201
 202         print_modules();
 203         __show_regs(regs);
 204         printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
 205                 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 206
 207         if (!user_mode(regs) || in_interrupt()) {
 208                 dump_mem(KERN_EMERG, "Stack: ", regs->UCreg_sp,
 209                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 210                 dump_backtrace(regs, tsk);
 211                 dump_instr(KERN_EMERG, regs);
 212         }
 213
 214         return ret;
 215 }
 216
 217 DEFINE_SPINLOCK(die_lock);
 218
 219 /*
 220  * This function is protected against re-entrancy.
 221  */
 222 void die(const char *str, struct pt_regs *regs, int err)
 223 {
 224         struct thread_info *thread = current_thread_info();
 225         int ret;
 226
 227         oops_enter();
 228
 229         spin_lock_irq(&die_lock);
 230         console_verbose();
 231         bust_spinlocks(1);
 232         ret = __die(str, err, thread, regs);
 233
 234         bust_spinlocks(0);
 235         add_taint(TAINT_DIE);
 236         spin_unlock_irq(&die_lock);
 237         oops_exit();
 238
 239         if (in_interrupt())
 240                 panic("Fatal exception in interrupt");
 241         if (panic_on_oops)
 242                 panic("Fatal exception");
 243         if (ret != NOTIFY_STOP)
 244                 do_exit(SIGSEGV);
 245 }
 246
 247 void uc32_notify_die(const char *str, struct pt_regs *regs,
 248                 struct siginfo *info, unsigned long err, unsigned long trap)
 249 {
 250         if (user_mode(regs)) {
 251                 current->thread.error_code = err;
 252                 current->thread.trap_no = trap;
 253
 254                 force_sig_info(info->si_signo, info, current);
 255         } else
 256                 die(str, regs, err);
 257 }
 258
 259 /*
 260  * bad_mode handles the impossible case in the vectors.  If you see one of
 261  * these, then it's extremely serious, and could mean you have buggy hardware.
 262  * It never returns, and never tries to sync.  We hope that we can at least
 263  * dump out some state information...
 264  */
 265 asmlinkage void bad_mode(struct pt_regs *regs, unsigned int reason)
 266 {
 267         console_verbose();
 268
 269         printk(KERN_CRIT "Bad mode detected with reason 0x%x\n", reason);
 270
 271         die("Oops - bad mode", regs, 0);
 272         local_irq_disable();
 273         panic("bad mode");
 274 }
 275
 276 void __pte_error(const char *file, int line, unsigned long val)
 277 {
 278         printk(KERN_DEFAULT "%s:%d: bad pte %08lx.\n", file, line, val);
 279 }
 280
 281 void __pmd_error(const char *file, int line, unsigned long val)
 282 {
 283         printk(KERN_DEFAULT "%s:%d: bad pmd %08lx.\n", file, line, val);
 284 }
 285
 286 void __pgd_error(const char *file, int line, unsigned long val)
 287 {
 288         printk(KERN_DEFAULT "%s:%d: bad pgd %08lx.\n", file, line, val);
 289 }
 290
 291 asmlinkage void __div0(void)
 292 {
 293         printk(KERN_DEFAULT "Division by zero in kernel.\n");
 294         dump_stack();
 295 }
 296 EXPORT_SYMBOL(__div0);
 297
 298 void abort(void)
 299 {
 300         BUG();
 301
 302         /* if that doesn't kill us, halt */
 303         panic("Oops failed to kill thread");
 304 }
 305 EXPORT_SYMBOL(abort);
 306
 307 void __init trap_init(void)
 308 {
 309         return;
 310 }
 311
 312 void __init early_trap_init(void)
 313 {
 314         unsigned long vectors = VECTORS_BASE;
 315
 316         /*
 317          * Copy the vectors, stubs (in entry-unicore.S)
 318          * into the vector page, mapped at 0xffff0000, and ensure these
 319          * are visible to the instruction stream.
 320          */
 321         memcpy((void *)vectors,
 322                         __vectors_start,
 323                         __vectors_end - __vectors_start);
 324         memcpy((void *)vectors + 0x200,
 325                         __stubs_start,
 326                         __stubs_end - __stubs_start);
 327
 328         early_signal_init();
 329
 330         flush_icache_range(vectors, vectors + PAGE_SIZE);
 331 }