arch/xtensa/kernel/traps.c

   1 /*
   2  * arch/xtensa/kernel/traps.c
   3  *
   4  * Exception handling.
   5  *
   6  * Derived from code with the following copyrights:
   7  * Copyright (C) 1994 - 1999 by Ralf Baechle
   8  * Modified for R3000 by Paul M. Antoine, 1995, 1996
   9  * Complete output from die() by Ulf Carlsson, 1998
  10  * Copyright (C) 1999 Silicon Graphics, Inc.
  11  *
  12  * Essentially rewritten for the Xtensa architecture port.
  13  *
  14  * Copyright (C) 2001 - 2005 Tensilica Inc.
  15  *
  16  * Joe Taylor   <joe@tensilica.com, joetylr@yahoo.com>
  17  * Chris Zankel <chris@zankel.net>
  18  * Marc Gauthier<marc@tensilica.com, marc@alumni.uwaterloo.ca>
  19  * Kevin Chea
  20  *
  21  * This file is subject to the terms and conditions of the GNU General Public
  22  * License.  See the file "COPYING" in the main directory of this archive
  23  * for more details.
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/sched.h>
  28 #include <linux/init.h>
  29 #include <linux/module.h>
  30 #include <linux/stringify.h>
  31 #include <linux/kallsyms.h>
  32 #include <linux/delay.h>
  33
  34 #include <asm/ptrace.h>
  35 #include <asm/timex.h>
  36 #include <asm/uaccess.h>
  37 #include <asm/pgtable.h>
  38 #include <asm/processor.h>
  39
  40 #ifdef CONFIG_KGDB
  41 extern int gdb_enter;
  42 extern int return_from_debug_flag;
  43 #endif
  44
  45 /*
  46  * Machine specific interrupt handlers
  47  */
  48
  49 extern void kernel_exception(void);
  50 extern void user_exception(void);
  51
  52 extern void fast_syscall_kernel(void);
  53 extern void fast_syscall_user(void);
  54 extern void fast_alloca(void);
  55 extern void fast_unaligned(void);
  56 extern void fast_second_level_miss(void);
  57 extern void fast_store_prohibited(void);
  58 extern void fast_coprocessor(void);
  59
  60 extern void do_illegal_instruction (struct pt_regs*);
  61 extern void do_interrupt (struct pt_regs*);
  62 extern void do_unaligned_user (struct pt_regs*);
  63 extern void do_multihit (struct pt_regs*, unsigned long);
  64 extern void do_page_fault (struct pt_regs*, unsigned long);
  65 extern void do_debug (struct pt_regs*);
  66 extern void system_call (struct pt_regs*);
  67
  68 /*
  69  * The vector table must be preceded by a save area (which
  70  * implies it must be in RAM, unless one places RAM immediately
  71  * before a ROM and puts the vector at the start of the ROM (!))
  72  */
  73
  74 #define KRNL            0x01
  75 #define USER            0x02
  76
  77 #define COPROCESSOR(x)                                                  \
  78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
  79
  80 typedef struct {
  81         int cause;
  82         int fast;
  83         void* handler;
  84 } dispatch_init_table_t;
  85
  86 dispatch_init_table_t __init dispatch_init_table[] = {
  87
  88 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  89 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
  90 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  91 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  92 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  93 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  94 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
  95 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
  96 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
  97 /* EXCCAUSE_PRIVILEGED unhandled */
  98 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
  99 #ifdef CONFIG_UNALIGNED_USER
 100 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 101 #else
 102 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 103 #endif
 104 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 105 #endif
 106 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 107 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 108 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 109 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 110 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 111 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 112 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 113 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 114 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 115 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 116 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 117 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 119 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 120 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 121 #if (XCHAL_CP_MASK & 1)
 122 COPROCESSOR(0),
 123 #endif
 124 #if (XCHAL_CP_MASK & 2)
 125 COPROCESSOR(1),
 126 #endif
 127 #if (XCHAL_CP_MASK & 4)
 128 COPROCESSOR(2),
 129 #endif
 130 #if (XCHAL_CP_MASK & 8)
 131 COPROCESSOR(3),
 132 #endif
 133 #if (XCHAL_CP_MASK & 16)
 134 COPROCESSOR(4),
 135 #endif
 136 #if (XCHAL_CP_MASK & 32)
 137 COPROCESSOR(5),
 138 #endif
 139 #if (XCHAL_CP_MASK & 64)
 140 COPROCESSOR(6),
 141 #endif
 142 #if (XCHAL_CP_MASK & 128)
 143 COPROCESSOR(7),
 144 #endif
 145 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 146 { -1, -1, 0 }
 147
 148 };
 149
 150 /* The exception table <exc_table> serves two functions:
 151  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 152  * 2. it is a temporary memory buffer for the exception handlers.
 153  */
 154
 155 unsigned long exc_table[EXC_TABLE_SIZE/4];
 156
 157 void die(const char*, struct pt_regs*, long);
 158
 159 static inline void
 160 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 161 {
 162         if (!user_mode(regs))
 163                 die(str, regs, err);
 164 }
 165
 166 /*
 167  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 168  */
 169
 170 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 171 {
 172         __die_if_kernel("Caught unhandled exception - should not happen",
 173                         regs, SIGKILL);
 174
 175         /* If in user mode, send SIGILL signal to current process */
 176         printk("Caught unhandled exception in '%s' "
 177                "(pid = %d, pc = %#010lx) - should not happen\n"
 178                "\tEXCCAUSE is %ld\n",
 179                current->comm, current->pid, regs->pc, exccause);
 180         force_sig(SIGILL, current);
 181 }
 182
 183 /*
 184  * Multi-hit exception. This if fatal!
 185  */
 186
 187 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 188 {
 189         die("Caught multihit exception", regs, SIGKILL);
 190 }
 191
 192 /*
 193  * Level-1 interrupt.
 194  * We currently have no priority encoding.
 195  */
 196
 197 unsigned long ignored_level1_interrupts;
 198 extern void do_IRQ(int, struct pt_regs *);
 199
 200 void do_interrupt (struct pt_regs *regs)
 201 {
 202         unsigned long intread = get_sr (INTREAD);
 203         unsigned long intenable = get_sr (INTENABLE);
 204         int i, mask;
 205
 206         /* Handle all interrupts (no priorities).
 207          * (Clear the interrupt before processing, in case it's
 208          *  edge-triggered or software-generated)
 209          */
 210
 211         for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) {
 212                 if (mask & (intread & intenable)) {
 213                         set_sr (mask, INTCLEAR);
 214                         do_IRQ (i,regs);
 215                 }
 216         }
 217 }
 218
 219 /*
 220  * Illegal instruction. Fatal if in kernel space.
 221  */
 222
 223 void
 224 do_illegal_instruction(struct pt_regs *regs)
 225 {
 226         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 227
 228         /* If in user mode, send SIGILL signal to current process. */
 229
 230         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 231             current->comm, current->pid, regs->pc);
 232         force_sig(SIGILL, current);
 233 }
 234
 235
 236 /*
 237  * Handle unaligned memory accesses from user space. Kill task.
 238  *
 239  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 240  * accesses causes from user space.
 241  */
 242
 243 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 244 #ifndef CONFIG_UNALIGNED_USER
 245 void
 246 do_unaligned_user (struct pt_regs *regs)
 247 {
 248         siginfo_t info;
 249
 250         __die_if_kernel("Unhandled unaligned exception in kernel",
 251                         regs, SIGKILL);
 252
 253         current->thread.bad_vaddr = regs->excvaddr;
 254         current->thread.error_code = -3;
 255         printk("Unaligned memory access to %08lx in '%s' "
 256                "(pid = %d, pc = %#010lx)\n",
 257                regs->excvaddr, current->comm, current->pid, regs->pc);
 258         info.si_signo = SIGBUS;
 259         info.si_errno = 0;
 260         info.si_code = BUS_ADRALN;
 261         info.si_addr = (void *) regs->excvaddr;
 262         force_sig_info(SIGSEGV, &info, current);
 263
 264 }
 265 #endif
 266 #endif
 267
 268 void
 269 do_debug(struct pt_regs *regs)
 270 {
 271 #ifdef CONFIG_KGDB
 272         /* If remote debugging is configured AND enabled, we give control to
 273          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 274          * native debugger.
 275          */
 276
 277         if (gdb_enter) {
 278                 extern void gdb_handle_exception(struct pt_regs *);
 279                 gdb_handle_exception(regs);
 280                 return_from_debug_flag = 1;
 281                 return;
 282         }
 283 #endif
 284
 285         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 286
 287         /* If in user mode, send SIGTRAP signal to current process */
 288
 289         force_sig(SIGTRAP, current);
 290 }
 291
 292
 293 /*
 294  * Initialize dispatch tables.
 295  *
 296  * The exception vectors are stored compressed the __init section in the
 297  * dispatch_init_table. This function initializes the following three tables
 298  * from that compressed table:
 299  * - fast user          first dispatch table for user exceptions
 300  * - fast kernel        first dispatch table for kernel exceptions
 301  * - default C-handler  C-handler called by the default fast handler.
 302  *
 303  * See vectors.S for more details.
 304  */
 305
 306 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
 307
 308 void trap_init(void)
 309 {
 310         int i;
 311
 312         /* Setup default vectors. */
 313
 314         for(i = 0; i < 64; i++) {
 315                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 316                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 317                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 318         }
 319
 320         /* Setup specific handlers. */
 321
 322         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 323
 324                 int fast = dispatch_init_table[i].fast;
 325                 int cause = dispatch_init_table[i].cause;
 326                 void *handler = dispatch_init_table[i].handler;
 327
 328                 if (fast == 0)
 329                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 330                 if (fast && fast & USER)
 331                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 332                 if (fast && fast & KRNL)
 333                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 334         }
 335
 336         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 337
 338         i = (unsigned long)exc_table;
 339         __asm__ __volatile__("wsr  %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i));
 340 }
 341
 342 /*
 343  * This function dumps the current valid window frame and other base registers.
 344  */
 345
 346 void show_regs(struct pt_regs * regs)
 347 {
 348         int i, wmask;
 349
 350         wmask = regs->wmask & ~1;
 351
 352         for (i = 0; i < 32; i++) {
 353                 if (wmask & (1 << (i / 4)))
 354                         break;
 355                 if ((i % 8) == 0)
 356                         printk ("\n" KERN_INFO "a%02d: ", i);
 357                 printk("%08lx ", regs->areg[i]);
 358         }
 359         printk("\n");
 360
 361         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 362                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 363         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 364                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 365         if (user_mode(regs))
 366                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 367                        regs->windowbase, regs->windowstart, regs->wmask,
 368                        regs->syscall);
 369 }
 370
 371 void show_trace(struct task_struct *task, unsigned long *sp)
 372 {
 373         unsigned long a0, a1, pc;
 374         unsigned long sp_start, sp_end;
 375
 376         a1 = (unsigned long)sp;
 377
 378         if (a1 == 0)
 379                 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(a1));
 380
 381
 382         sp_start = a1 & ~(THREAD_SIZE-1);
 383         sp_end = sp_start + THREAD_SIZE;
 384
 385         printk("Call Trace:");
 386 #ifdef CONFIG_KALLSYMS
 387         printk("\n");
 388 #endif
 389         spill_registers();
 390
 391         while (a1 > sp_start && a1 < sp_end) {
 392                 sp = (unsigned long*)a1;
 393
 394                 a0 = *(sp - 4);
 395                 a1 = *(sp - 3);
 396
 397                 if (a1 <= (unsigned long) sp)
 398                         break;
 399
 400                 pc = MAKE_PC_FROM_RA(a0, a1);
 401
 402                 if (kernel_text_address(pc)) {
 403                         printk(" [<%08lx>] ", pc);
 404                         print_symbol("%s\n", pc);
 405                 }
 406         }
 407         printk("\n");
 408 }
 409
 410 /*
 411  * This routine abuses get_user()/put_user() to reference pointers
 412  * with at least a bit of error checking ...
 413  */
 414
 415 static int kstack_depth_to_print = 24;
 416
 417 void show_stack(struct task_struct *task, unsigned long *sp)
 418 {
 419         int i = 0;
 420         unsigned long *stack;
 421
 422         if (sp == 0)
 423                 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
 424
 425         stack = sp;
 426
 427         printk("\nStack: ");
 428
 429         for (i = 0; i < kstack_depth_to_print; i++) {
 430                 if (kstack_end(sp))
 431                         break;
 432                 if (i && ((i % 8) == 0))
 433                         printk("\n       ");
 434                 printk("%08lx ", *sp++);
 435         }
 436         printk("\n");
 437         show_trace(task, stack);
 438 }
 439
 440 void dump_stack(void)
 441 {
 442         show_stack(current, NULL);
 443 }
 444
 445 EXPORT_SYMBOL(dump_stack);
 446
 447
 448 void show_code(unsigned int *pc)
 449 {
 450         long i;
 451
 452         printk("\nCode:");
 453
 454         for(i = -3 ; i < 6 ; i++) {
 455                 unsigned long insn;
 456                 if (__get_user(insn, pc + i)) {
 457                         printk(" (Bad address in pc)\n");
 458                         break;
 459                 }
 460                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 461         }
 462 }
 463
 464 DEFINE_SPINLOCK(die_lock);
 465
 466 void die(const char * str, struct pt_regs * regs, long err)
 467 {
 468         static int die_counter;
 469         int nl = 0;
 470
 471         console_verbose();
 472         spin_lock_irq(&die_lock);
 473
 474         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 475 #ifdef CONFIG_PREEMPT
 476         printk("PREEMPT ");
 477         nl = 1;
 478 #endif
 479         if (nl)
 480                 printk("\n");
 481         show_regs(regs);
 482         if (!user_mode(regs))
 483                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 484
 485         spin_unlock_irq(&die_lock);
 486
 487         if (in_interrupt())
 488                 panic("Fatal exception in interrupt");
 489
 490         if (panic_on_oops)
 491                 panic("Fatal exception");
 492
 493         do_exit(err);
 494 }
 495
 496