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_XTENSA_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 #ifdef CONFIG_MMU
 108 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 109 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 110 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 111 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 112 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 113 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 114 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 115 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 116 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 117 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 118 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 121 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 122 #endif /* CONFIG_MMU */
 123 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 124 #if XTENSA_HAVE_COPROCESSOR(0)
 125 COPROCESSOR(0),
 126 #endif
 127 #if XTENSA_HAVE_COPROCESSOR(1)
 128 COPROCESSOR(1),
 129 #endif
 130 #if XTENSA_HAVE_COPROCESSOR(2)
 131 COPROCESSOR(2),
 132 #endif
 133 #if XTENSA_HAVE_COPROCESSOR(3)
 134 COPROCESSOR(3),
 135 #endif
 136 #if XTENSA_HAVE_COPROCESSOR(4)
 137 COPROCESSOR(4),
 138 #endif
 139 #if XTENSA_HAVE_COPROCESSOR(5)
 140 COPROCESSOR(5),
 141 #endif
 142 #if XTENSA_HAVE_COPROCESSOR(6)
 143 COPROCESSOR(6),
 144 #endif
 145 #if XTENSA_HAVE_COPROCESSOR(7)
 146 COPROCESSOR(7),
 147 #endif
 148 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 149 { -1, -1, 0 }
 150
 151 };
 152
 153 /* The exception table <exc_table> serves two functions:
 154  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 155  * 2. it is a temporary memory buffer for the exception handlers.
 156  */
 157
 158 unsigned long exc_table[EXC_TABLE_SIZE/4];
 159
 160 void die(const char*, struct pt_regs*, long);
 161
 162 static inline void
 163 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 164 {
 165         if (!user_mode(regs))
 166                 die(str, regs, err);
 167 }
 168
 169 /*
 170  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 171  */
 172
 173 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 174 {
 175         __die_if_kernel("Caught unhandled exception - should not happen",
 176                         regs, SIGKILL);
 177
 178         /* If in user mode, send SIGILL signal to current process */
 179         printk("Caught unhandled exception in '%s' "
 180                "(pid = %d, pc = %#010lx) - should not happen\n"
 181                "\tEXCCAUSE is %ld\n",
 182                current->comm, task_pid_nr(current), regs->pc, exccause);
 183         force_sig(SIGILL, current);
 184 }
 185
 186 /*
 187  * Multi-hit exception. This if fatal!
 188  */
 189
 190 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 191 {
 192         die("Caught multihit exception", regs, SIGKILL);
 193 }
 194
 195 /*
 196  * Level-1 interrupt.
 197  * We currently have no priority encoding.
 198  */
 199
 200 unsigned long ignored_level1_interrupts;
 201 extern void do_IRQ(int, struct pt_regs *);
 202
 203 void do_interrupt (struct pt_regs *regs)
 204 {
 205         unsigned long intread = get_sr (interrupt);
 206         unsigned long intenable = get_sr (intenable);
 207         int i, mask;
 208
 209         /* Handle all interrupts (no priorities).
 210          * (Clear the interrupt before processing, in case it's
 211          *  edge-triggered or software-generated)
 212          */
 213
 214         for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) {
 215                 if (mask & (intread & intenable)) {
 216                         set_sr (mask, intclear);
 217                         do_IRQ (i,regs);
 218                 }
 219         }
 220 }
 221
 222 /*
 223  * Illegal instruction. Fatal if in kernel space.
 224  */
 225
 226 void
 227 do_illegal_instruction(struct pt_regs *regs)
 228 {
 229         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 230
 231         /* If in user mode, send SIGILL signal to current process. */
 232
 233         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 234             current->comm, task_pid_nr(current), regs->pc);
 235         force_sig(SIGILL, current);
 236 }
 237
 238
 239 /*
 240  * Handle unaligned memory accesses from user space. Kill task.
 241  *
 242  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 243  * accesses causes from user space.
 244  */
 245
 246 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 247 #ifndef CONFIG_XTENSA_UNALIGNED_USER
 248 void
 249 do_unaligned_user (struct pt_regs *regs)
 250 {
 251         siginfo_t info;
 252
 253         __die_if_kernel("Unhandled unaligned exception in kernel",
 254                         regs, SIGKILL);
 255
 256         current->thread.bad_vaddr = regs->excvaddr;
 257         current->thread.error_code = -3;
 258         printk("Unaligned memory access to %08lx in '%s' "
 259                "(pid = %d, pc = %#010lx)\n",
 260                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 261         info.si_signo = SIGBUS;
 262         info.si_errno = 0;
 263         info.si_code = BUS_ADRALN;
 264         info.si_addr = (void *) regs->excvaddr;
 265         force_sig_info(SIGSEGV, &info, current);
 266
 267 }
 268 #endif
 269 #endif
 270
 271 void
 272 do_debug(struct pt_regs *regs)
 273 {
 274 #ifdef CONFIG_KGDB
 275         /* If remote debugging is configured AND enabled, we give control to
 276          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 277          * native debugger.
 278          */
 279
 280         if (gdb_enter) {
 281                 extern void gdb_handle_exception(struct pt_regs *);
 282                 gdb_handle_exception(regs);
 283                 return_from_debug_flag = 1;
 284                 return;
 285         }
 286 #endif
 287
 288         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 289
 290         /* If in user mode, send SIGTRAP signal to current process */
 291
 292         force_sig(SIGTRAP, current);
 293 }
 294
 295
 296 /* Set exception C handler - for temporary use when probing exceptions */
 297
 298 void * __init trap_set_handler(int cause, void *handler)
 299 {
 300         unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause];
 301         void *previous = (void *)*entry;
 302         *entry = (unsigned long)handler;
 303         return previous;
 304 }
 305
 306
 307 /*
 308  * Initialize dispatch tables.
 309  *
 310  * The exception vectors are stored compressed the __init section in the
 311  * dispatch_init_table. This function initializes the following three tables
 312  * from that compressed table:
 313  * - fast user          first dispatch table for user exceptions
 314  * - fast kernel        first dispatch table for kernel exceptions
 315  * - default C-handler  C-handler called by the default fast handler.
 316  *
 317  * See vectors.S for more details.
 318  */
 319
 320 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
 321
 322 void __init trap_init(void)
 323 {
 324         int i;
 325
 326         /* Setup default vectors. */
 327
 328         for(i = 0; i < 64; i++) {
 329                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 330                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 331                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 332         }
 333
 334         /* Setup specific handlers. */
 335
 336         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 337
 338                 int fast = dispatch_init_table[i].fast;
 339                 int cause = dispatch_init_table[i].cause;
 340                 void *handler = dispatch_init_table[i].handler;
 341
 342                 if (fast == 0)
 343                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 344                 if (fast && fast & USER)
 345                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 346                 if (fast && fast & KRNL)
 347                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 348         }
 349
 350         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 351
 352         i = (unsigned long)exc_table;
 353         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (i));
 354 }
 355
 356 /*
 357  * This function dumps the current valid window frame and other base registers.
 358  */
 359
 360 void show_regs(struct pt_regs * regs)
 361 {
 362         int i, wmask;
 363
 364         wmask = regs->wmask & ~1;
 365
 366         for (i = 0; i < 16; i++) {
 367                 if ((i % 8) == 0)
 368                         printk(KERN_INFO "a%02d:", i);
 369                 printk(KERN_CONT " %08lx", regs->areg[i]);
 370         }
 371         printk(KERN_CONT "\n");
 372
 373         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 374                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 375         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 376                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 377         if (user_mode(regs))
 378                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 379                        regs->windowbase, regs->windowstart, regs->wmask,
 380                        regs->syscall);
 381 }
 382
 383 static __always_inline unsigned long *stack_pointer(struct task_struct *task)
 384 {
 385         unsigned long *sp;
 386
 387         if (!task || task == current)
 388                 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
 389         else
 390                 sp = (unsigned long *)task->thread.sp;
 391
 392         return sp;
 393 }
 394
 395 static inline void spill_registers(void)
 396 {
 397         unsigned int a0, ps;
 398
 399         __asm__ __volatile__ (
 400                 "movi   a14, " __stringify(PS_EXCM_BIT | 1) "\n\t"
 401                 "mov    a12, a0\n\t"
 402                 "rsr    a13, sar\n\t"
 403                 "xsr    a14, ps\n\t"
 404                 "movi   a0, _spill_registers\n\t"
 405                 "rsync\n\t"
 406                 "callx0 a0\n\t"
 407                 "mov    a0, a12\n\t"
 408                 "wsr    a13, sar\n\t"
 409                 "wsr    a14, ps\n\t"
 410                 :: "a" (&a0), "a" (&ps)
 411                 : "a2", "a3", "a4", "a7", "a11", "a12", "a13", "a14", "a15",
 412                   "memory");
 413 }
 414
 415 void show_trace(struct task_struct *task, unsigned long *sp)
 416 {
 417         unsigned long a0, a1, pc;
 418         unsigned long sp_start, sp_end;
 419
 420         if (sp)
 421                 a1 = (unsigned long)sp;
 422         else
 423                 a1 = (unsigned long)stack_pointer(task);
 424
 425         sp_start = a1 & ~(THREAD_SIZE-1);
 426         sp_end = sp_start + THREAD_SIZE;
 427
 428         printk("Call Trace:");
 429 #ifdef CONFIG_KALLSYMS
 430         printk("\n");
 431 #endif
 432         spill_registers();
 433
 434         while (a1 > sp_start && a1 < sp_end) {
 435                 sp = (unsigned long*)a1;
 436
 437                 a0 = *(sp - 4);
 438                 a1 = *(sp - 3);
 439
 440                 if (a1 <= (unsigned long) sp)
 441                         break;
 442
 443                 pc = MAKE_PC_FROM_RA(a0, a1);
 444
 445                 if (kernel_text_address(pc)) {
 446                         printk(" [<%08lx>] ", pc);
 447                         print_symbol("%s\n", pc);
 448                 }
 449         }
 450         printk("\n");
 451 }
 452
 453 /*
 454  * This routine abuses get_user()/put_user() to reference pointers
 455  * with at least a bit of error checking ...
 456  */
 457
 458 static int kstack_depth_to_print = 24;
 459
 460 void show_stack(struct task_struct *task, unsigned long *sp)
 461 {
 462         int i = 0;
 463         unsigned long *stack;
 464
 465         if (!sp)
 466                 sp = stack_pointer(task);
 467         stack = sp;
 468
 469         printk("\nStack: ");
 470
 471         for (i = 0; i < kstack_depth_to_print; i++) {
 472                 if (kstack_end(sp))
 473                         break;
 474                 if (i && ((i % 8) == 0))
 475                         printk("\n       ");
 476                 printk("%08lx ", *sp++);
 477         }
 478         printk("\n");
 479         show_trace(task, stack);
 480 }
 481
 482 void dump_stack(void)
 483 {
 484         show_stack(current, NULL);
 485 }
 486
 487 EXPORT_SYMBOL(dump_stack);
 488
 489
 490 void show_code(unsigned int *pc)
 491 {
 492         long i;
 493
 494         printk("\nCode:");
 495
 496         for(i = -3 ; i < 6 ; i++) {
 497                 unsigned long insn;
 498                 if (__get_user(insn, pc + i)) {
 499                         printk(" (Bad address in pc)\n");
 500                         break;
 501                 }
 502                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 503         }
 504 }
 505
 506 DEFINE_SPINLOCK(die_lock);
 507
 508 void die(const char * str, struct pt_regs * regs, long err)
 509 {
 510         static int die_counter;
 511         int nl = 0;
 512
 513         console_verbose();
 514         spin_lock_irq(&die_lock);
 515
 516         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 517 #ifdef CONFIG_PREEMPT
 518         printk("PREEMPT ");
 519         nl = 1;
 520 #endif
 521         if (nl)
 522                 printk("\n");
 523         show_regs(regs);
 524         if (!user_mode(regs))
 525                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 526
 527         add_taint(TAINT_DIE);
 528         spin_unlock_irq(&die_lock);
 529
 530         if (in_interrupt())
 531                 panic("Fatal exception in interrupt");
 532
 533         if (panic_on_oops)
 534                 panic("Fatal exception");
 535
 536         do_exit(err);
 537 }