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/sched/signal.h>
  18 #include <linux/sched/debug.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/personality.h>
  21 #include <linux/kallsyms.h>
  22 #include <linux/kdebug.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/delay.h>
  25 #include <linux/hardirq.h>
  26 #include <linux/init.h>
  27 #include <linux/atomic.h>
  28 #include <linux/unistd.h>
  29
  30 #include <asm/cacheflush.h>
  31 #include <asm/traps.h>
  32
  33 #include "setup.h"
  34
  35 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  36
  37 void dump_backtrace_entry(unsigned long where,
  38                 unsigned long from, unsigned long frame)
  39 {
  40 #ifdef CONFIG_KALLSYMS
  41         printk(KERN_DEFAULT "[<%08lx>] (%pS) from [<%08lx>] (%pS)\n",
  42                         where, (void *)where, from, (void *)from);
  43 #else
  44         printk(KERN_DEFAULT "Function entered at [<%08lx>] from [<%08lx>]\n",
  45                         where, from);
  46 #endif
  47 }
  48
  49 /*
  50  * Stack pointers should always be within the kernels view of
  51  * physical memory.  If it is not there, then we can't dump
  52  * out any information relating to the stack.
  53  */
  54 static int verify_stack(unsigned long sp)
  55 {
  56         if (sp < PAGE_OFFSET ||
  57             (sp > (unsigned long)high_memory && high_memory != NULL))
  58                 return -EFAULT;
  59
  60         return 0;
  61 }
  62
  63 /*
  64  * Dump out the contents of some memory nicely...
  65  */
  66 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  67                      unsigned long top)
  68 {
  69         unsigned long first;
  70         mm_segment_t fs;
  71         int i;
  72
  73         /*
  74          * We need to switch to kernel mode so that we can use __get_user
  75          * to safely read from kernel space.  Note that we now dump the
  76          * code first, just in case the backtrace kills us.
  77          */
  78         fs = get_fs();
  79         set_fs(KERNEL_DS);
  80
  81         printk(KERN_DEFAULT "%s%s(0x%08lx to 0x%08lx)\n",
  82                         lvl, str, bottom, top);
  83
  84         for (first = bottom & ~31; first < top; first += 32) {
  85                 unsigned long p;
  86                 char str[sizeof(" 12345678") * 8 + 1];
  87
  88                 memset(str, ' ', sizeof(str));
  89                 str[sizeof(str) - 1] = '\0';
  90
  91                 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
  92                         if (p >= bottom && p < top) {
  93                                 unsigned long val;
  94                                 if (__get_user(val, (unsigned long *)p) == 0)
  95                                         sprintf(str + i * 9, " %08lx", val);
  96                                 else
  97                                         sprintf(str + i * 9, " ????????");
  98                         }
  99                 }
 100                 printk(KERN_DEFAULT "%s%04lx:%s\n", lvl, first & 0xffff, str);
 101         }
 102
 103         set_fs(fs);
 104 }
 105
 106 static void dump_instr(const char *lvl, struct pt_regs *regs)
 107 {
 108         unsigned long addr = instruction_pointer(regs);
 109         const int width = 8;
 110         mm_segment_t fs;
 111         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 112         int i;
 113
 114         /*
 115          * We need to switch to kernel mode so that we can use __get_user
 116          * to safely read from kernel space.  Note that we now dump the
 117          * code first, just in case the backtrace kills us.
 118          */
 119         fs = get_fs();
 120         set_fs(KERNEL_DS);
 121
 122         for (i = -4; i < 1; i++) {
 123                 unsigned int val, bad;
 124
 125                 bad = __get_user(val, &((u32 *)addr)[i]);
 126
 127                 if (!bad)
 128                         p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 129                                         width, val);
 130                 else {
 131                         p += sprintf(p, "bad PC value");
 132                         break;
 133                 }
 134         }
 135         printk(KERN_DEFAULT "%sCode: %s\n", lvl, str);
 136
 137         set_fs(fs);
 138 }
 139
 140 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 141 {
 142         unsigned int fp, mode;
 143         int ok = 1;
 144
 145         printk(KERN_DEFAULT "Backtrace: ");
 146
 147         if (!tsk)
 148                 tsk = current;
 149
 150         if (regs) {
 151                 fp = regs->UCreg_fp;
 152                 mode = processor_mode(regs);
 153         } else if (tsk != current) {
 154                 fp = thread_saved_fp(tsk);
 155                 mode = 0x10;
 156         } else {
 157                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 158                 mode = 0x10;
 159         }
 160
 161         if (!fp) {
 162                 printk("no frame pointer");
 163                 ok = 0;
 164         } else if (verify_stack(fp)) {
 165                 printk("invalid frame pointer 0x%08x", fp);
 166                 ok = 0;
 167         } else if (fp < (unsigned long)end_of_stack(tsk))
 168                 printk("frame pointer underflow");
 169         printk("\n");
 170
 171         if (ok)
 172                 c_backtrace(fp, mode);
 173 }
 174
 175 void show_stack(struct task_struct *tsk, unsigned long *sp)
 176 {
 177         dump_backtrace(NULL, tsk);
 178         barrier();
 179 }
 180
 181 static int __die(const char *str, int err, struct thread_info *thread,
 182                 struct pt_regs *regs)
 183 {
 184         struct task_struct *tsk = thread->task;
 185         static int die_counter;
 186         int ret;
 187
 188         printk(KERN_EMERG "Internal error: %s: %x [#%d]\n",
 189                str, err, ++die_counter);
 190
 191         /* trap and error numbers are mostly meaningless on UniCore */
 192         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, \
 193                         SIGSEGV);
 194         if (ret == NOTIFY_STOP)
 195                 return ret;
 196
 197         print_modules();
 198         __show_regs(regs);
 199         printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
 200                 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 201
 202         if (!user_mode(regs) || in_interrupt()) {
 203                 dump_mem(KERN_EMERG, "Stack: ", regs->UCreg_sp,
 204                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 205                 dump_backtrace(regs, tsk);
 206                 dump_instr(KERN_EMERG, regs);
 207         }
 208
 209         return ret;
 210 }
 211
 212 DEFINE_SPINLOCK(die_lock);
 213
 214 /*
 215  * This function is protected against re-entrancy.
 216  */
 217 void die(const char *str, struct pt_regs *regs, int err)
 218 {
 219         struct thread_info *thread = current_thread_info();
 220         int ret;
 221
 222         oops_enter();
 223
 224         spin_lock_irq(&die_lock);
 225         console_verbose();
 226         bust_spinlocks(1);
 227         ret = __die(str, err, thread, regs);
 228
 229         bust_spinlocks(0);
 230         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 231         spin_unlock_irq(&die_lock);
 232         oops_exit();
 233
 234         if (in_interrupt())
 235                 panic("Fatal exception in interrupt");
 236         if (panic_on_oops)
 237                 panic("Fatal exception");
 238         if (ret != NOTIFY_STOP)
 239                 do_exit(SIGSEGV);
 240 }
 241
 242 void uc32_notify_die(const char *str, struct pt_regs *regs,
 243                 struct siginfo *info, unsigned long err, unsigned long trap)
 244 {
 245         if (user_mode(regs)) {
 246                 current->thread.error_code = err;
 247                 current->thread.trap_no = trap;
 248
 249                 force_sig_info(info->si_signo, info, current);
 250         } else
 251                 die(str, regs, err);
 252 }
 253
 254 /*
 255  * bad_mode handles the impossible case in the vectors.  If you see one of
 256  * these, then it's extremely serious, and could mean you have buggy hardware.
 257  * It never returns, and never tries to sync.  We hope that we can at least
 258  * dump out some state information...
 259  */
 260 asmlinkage void bad_mode(struct pt_regs *regs, unsigned int reason)
 261 {
 262         console_verbose();
 263
 264         printk(KERN_CRIT "Bad mode detected with reason 0x%x\n", reason);
 265
 266         die("Oops - bad mode", regs, 0);
 267         local_irq_disable();
 268         panic("bad mode");
 269 }
 270
 271 void __pte_error(const char *file, int line, unsigned long val)
 272 {
 273         printk(KERN_DEFAULT "%s:%d: bad pte %08lx.\n", file, line, val);
 274 }
 275
 276 void __pmd_error(const char *file, int line, unsigned long val)
 277 {
 278         printk(KERN_DEFAULT "%s:%d: bad pmd %08lx.\n", file, line, val);
 279 }
 280
 281 void __pgd_error(const char *file, int line, unsigned long val)
 282 {
 283         printk(KERN_DEFAULT "%s:%d: bad pgd %08lx.\n", file, line, val);
 284 }
 285
 286 asmlinkage void __div0(void)
 287 {
 288         printk(KERN_DEFAULT "Division by zero in kernel.\n");
 289         dump_stack();
 290 }
 291 EXPORT_SYMBOL(__div0);
 292
 293 void abort(void)
 294 {
 295         BUG();
 296
 297         /* if that doesn't kill us, halt */
 298         panic("Oops failed to kill thread");
 299 }
 300 EXPORT_SYMBOL(abort);
 301
 302 void __init trap_init(void)
 303 {
 304         return;
 305 }
 306
 307 void __init early_trap_init(void)
 308 {
 309         unsigned long vectors = VECTORS_BASE;
 310
 311         /*
 312          * Copy the vectors, stubs (in entry-unicore.S)
 313          * into the vector page, mapped at 0xffff0000, and ensure these
 314          * are visible to the instruction stream.
 315          */
 316         memcpy((void *)vectors,
 317                         __vectors_start,
 318                         __vectors_end - __vectors_start);
 319         memcpy((void *)vectors + 0x200,
 320                         __stubs_start,
 321                         __stubs_end - __stubs_start);
 322
 323         early_signal_init();
 324
 325         flush_icache_range(vectors, vectors + PAGE_SIZE);
 326 }