arch/unicore32/kernel/traps.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/arch/unicore32/kernel/traps.c
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  *
   9  *  'traps.c' handles hardware exceptions after we have saved some state.
  10  *  Mostly a debugging aid, but will probably kill the offending process.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/signal.h>
  14 #include <linux/sched/signal.h>
  15 #include <linux/sched/debug.h>
  16 #include <linux/sched/task_stack.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
  33 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  34
  35 void 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  */
  52 static 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  */
  64 static 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
 104 static 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
 138 static 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
 173 void show_stack(struct task_struct *tsk, unsigned long *sp)
 174 {
 175         dump_backtrace(NULL, tsk);
 176         barrier();
 177 }
 178
 179 static 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
 210 DEFINE_SPINLOCK(die_lock);
 211
 212 /*
 213  * This function is protected against re-entrancy.
 214  */
 215 void 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
 240 void uc32_notify_die(const char *str, struct pt_regs *regs,
 241                 int sig, int code, void __user *addr,
 242                 unsigned long err, unsigned long trap)
 243 {
 244         if (user_mode(regs)) {
 245                 current->thread.error_code = err;
 246                 current->thread.trap_no = trap;
 247
 248                 force_sig_fault(sig, code, addr);
 249         } else
 250                 die(str, regs, err);
 251 }
 252
 253 /*
 254  * bad_mode handles the impossible case in the vectors.  If you see one of
 255  * these, then it's extremely serious, and could mean you have buggy hardware.
 256  * It never returns, and never tries to sync.  We hope that we can at least
 257  * dump out some state information...
 258  */
 259 asmlinkage void bad_mode(struct pt_regs *regs, unsigned int reason)
 260 {
 261         console_verbose();
 262
 263         printk(KERN_CRIT "Bad mode detected with reason 0x%x\n", reason);
 264
 265         die("Oops - bad mode", regs, 0);
 266         local_irq_disable();
 267         panic("bad mode");
 268 }
 269
 270 void __pte_error(const char *file, int line, unsigned long val)
 271 {
 272         printk(KERN_DEFAULT "%s:%d: bad pte %08lx.\n", file, line, val);
 273 }
 274
 275 void __pmd_error(const char *file, int line, unsigned long val)
 276 {
 277         printk(KERN_DEFAULT "%s:%d: bad pmd %08lx.\n", file, line, val);
 278 }
 279
 280 void __pgd_error(const char *file, int line, unsigned long val)
 281 {
 282         printk(KERN_DEFAULT "%s:%d: bad pgd %08lx.\n", file, line, val);
 283 }
 284
 285 asmlinkage void __div0(void)
 286 {
 287         printk(KERN_DEFAULT "Division by zero in kernel.\n");
 288         dump_stack();
 289 }
 290 EXPORT_SYMBOL(__div0);
 291
 292 void abort(void)
 293 {
 294         BUG();
 295
 296         /* if that doesn't kill us, halt */
 297         panic("Oops failed to kill thread");
 298 }
 299
 300 void __init trap_init(void)
 301 {
 302         return;
 303 }
 304
 305 void __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 }