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