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;
 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         else if (tsk != current)
 151                 fp = thread_saved_fp(tsk);
 152         else
 153                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 154
 155         if (!fp) {
 156                 printk("no frame pointer");
 157                 ok = 0;
 158         } else if (verify_stack(fp)) {
 159                 printk("invalid frame pointer 0x%08x", fp);
 160                 ok = 0;
 161         } else if (fp < (unsigned long)end_of_stack(tsk))
 162                 printk("frame pointer underflow");
 163         printk("\n");
 164
 165         if (ok)
 166                 c_backtrace(fp, KERN_DEFAULT);
 167 }
 168
 169 void show_stack(struct task_struct *tsk, unsigned long *sp)
 170 {
 171         dump_backtrace(NULL, tsk);
 172         barrier();
 173 }
 174
 175 static int __die(const char *str, int err, struct thread_info *thread,
 176                 struct pt_regs *regs)
 177 {
 178         struct task_struct *tsk = thread->task;
 179         static int die_counter;
 180         int ret;
 181
 182         printk(KERN_EMERG "Internal error: %s: %x [#%d]\n",
 183                str, err, ++die_counter);
 184
 185         /* trap and error numbers are mostly meaningless on UniCore */
 186         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, \
 187                         SIGSEGV);
 188         if (ret == NOTIFY_STOP)
 189                 return ret;
 190
 191         print_modules();
 192         __show_regs(regs);
 193         printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
 194                 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 195
 196         if (!user_mode(regs) || in_interrupt()) {
 197                 dump_mem(KERN_EMERG, "Stack: ", regs->UCreg_sp,
 198                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 199                 dump_backtrace(regs, tsk);
 200                 dump_instr(KERN_EMERG, regs);
 201         }
 202
 203         return ret;
 204 }
 205
 206 DEFINE_SPINLOCK(die_lock);
 207
 208 /*
 209  * This function is protected against re-entrancy.
 210  */
 211 void die(const char *str, struct pt_regs *regs, int err)
 212 {
 213         struct thread_info *thread = current_thread_info();
 214         int ret;
 215
 216         oops_enter();
 217
 218         spin_lock_irq(&die_lock);
 219         console_verbose();
 220         bust_spinlocks(1);
 221         ret = __die(str, err, thread, regs);
 222
 223         bust_spinlocks(0);
 224         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 225         spin_unlock_irq(&die_lock);
 226         oops_exit();
 227
 228         if (in_interrupt())
 229                 panic("Fatal exception in interrupt");
 230         if (panic_on_oops)
 231                 panic("Fatal exception");
 232         if (ret != NOTIFY_STOP)
 233                 do_exit(SIGSEGV);
 234 }
 235
 236 void uc32_notify_die(const char *str, struct pt_regs *regs,
 237                 int sig, int code, void __user *addr,
 238                 unsigned long err, unsigned long trap)
 239 {
 240         if (user_mode(regs)) {
 241                 current->thread.error_code = err;
 242                 current->thread.trap_no = trap;
 243
 244                 force_sig_fault(sig, code, addr);
 245         } else
 246                 die(str, regs, err);
 247 }
 248
 249 /*
 250  * bad_mode handles the impossible case in the vectors.  If you see one of
 251  * these, then it's extremely serious, and could mean you have buggy hardware.
 252  * It never returns, and never tries to sync.  We hope that we can at least
 253  * dump out some state information...
 254  */
 255 asmlinkage void bad_mode(struct pt_regs *regs, unsigned int reason)
 256 {
 257         console_verbose();
 258
 259         printk(KERN_CRIT "Bad mode detected with reason 0x%x\n", reason);
 260
 261         die("Oops - bad mode", regs, 0);
 262         local_irq_disable();
 263         panic("bad mode");
 264 }
 265
 266 void __pte_error(const char *file, int line, unsigned long val)
 267 {
 268         printk(KERN_DEFAULT "%s:%d: bad pte %08lx.\n", file, line, val);
 269 }
 270
 271 void __pmd_error(const char *file, int line, unsigned long val)
 272 {
 273         printk(KERN_DEFAULT "%s:%d: bad pmd %08lx.\n", file, line, val);
 274 }
 275
 276 void __pgd_error(const char *file, int line, unsigned long val)
 277 {
 278         printk(KERN_DEFAULT "%s:%d: bad pgd %08lx.\n", file, line, val);
 279 }
 280
 281 asmlinkage void __div0(void)
 282 {
 283         printk(KERN_DEFAULT "Division by zero in kernel.\n");
 284         dump_stack();
 285 }
 286 EXPORT_SYMBOL(__div0);
 287
 288 void abort(void)
 289 {
 290         BUG();
 291
 292         /* if that doesn't kill us, halt */
 293         panic("Oops failed to kill thread");
 294 }
 295
 296 void __init trap_init(void)
 297 {
 298         return;
 299 }
 300
 301 void __init early_trap_init(void)
 302 {
 303         unsigned long vectors = VECTORS_BASE;
 304
 305         /*
 306          * Copy the vectors, stubs (in entry-unicore.S)
 307          * into the vector page, mapped at 0xffff0000, and ensure these
 308          * are visible to the instruction stream.
 309          */
 310         memcpy((void *)vectors,
 311                         __vectors_start,
 312                         __vectors_end - __vectors_start);
 313         memcpy((void *)vectors + 0x200,
 314                         __stubs_start,
 315                         __stubs_end - __stubs_start);
 316
 317         early_signal_init();
 318
 319         flush_icache_range(vectors, vectors + PAGE_SIZE);
 320 }