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