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 #include <asm/traps.h>
  41
  42 #ifdef CONFIG_KGDB
  43 extern int gdb_enter;
  44 extern int return_from_debug_flag;
  45 #endif
  46
  47 /*
  48  * Machine specific interrupt handlers
  49  */
  50
  51 extern void kernel_exception(void);
  52 extern void user_exception(void);
  53
  54 extern void fast_syscall_kernel(void);
  55 extern void fast_syscall_user(void);
  56 extern void fast_alloca(void);
  57 extern void fast_unaligned(void);
  58 extern void fast_second_level_miss(void);
  59 extern void fast_store_prohibited(void);
  60 extern void fast_coprocessor(void);
  61
  62 extern void do_illegal_instruction (struct pt_regs*);
  63 extern void do_interrupt (struct pt_regs*);
  64 extern void do_unaligned_user (struct pt_regs*);
  65 extern void do_multihit (struct pt_regs*, unsigned long);
  66 extern void do_page_fault (struct pt_regs*, unsigned long);
  67 extern void do_debug (struct pt_regs*);
  68 extern void system_call (struct pt_regs*);
  69
  70 /*
  71  * The vector table must be preceded by a save area (which
  72  * implies it must be in RAM, unless one places RAM immediately
  73  * before a ROM and puts the vector at the start of the ROM (!))
  74  */
  75
  76 #define KRNL            0x01
  77 #define USER            0x02
  78
  79 #define COPROCESSOR(x)                                                  \
  80 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
  81
  82 typedef struct {
  83         int cause;
  84         int fast;
  85         void* handler;
  86 } dispatch_init_table_t;
  87
  88 static dispatch_init_table_t __initdata dispatch_init_table[] = {
  89
  90 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  91 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
  92 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  93 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  94 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  95 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  96 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
  97 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
  98 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
  99 /* EXCCAUSE_PRIVILEGED unhandled */
 100 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 101 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 102 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 103 #else
 104 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 105 #endif
 106 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 107 #endif
 108 #ifdef CONFIG_MMU
 109 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 110 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 111 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 112 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 113 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 114 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 115 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 116 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 117 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 118 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 119 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 122 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 123 #endif /* CONFIG_MMU */
 124 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 125 #if XTENSA_HAVE_COPROCESSOR(0)
 126 COPROCESSOR(0),
 127 #endif
 128 #if XTENSA_HAVE_COPROCESSOR(1)
 129 COPROCESSOR(1),
 130 #endif
 131 #if XTENSA_HAVE_COPROCESSOR(2)
 132 COPROCESSOR(2),
 133 #endif
 134 #if XTENSA_HAVE_COPROCESSOR(3)
 135 COPROCESSOR(3),
 136 #endif
 137 #if XTENSA_HAVE_COPROCESSOR(4)
 138 COPROCESSOR(4),
 139 #endif
 140 #if XTENSA_HAVE_COPROCESSOR(5)
 141 COPROCESSOR(5),
 142 #endif
 143 #if XTENSA_HAVE_COPROCESSOR(6)
 144 COPROCESSOR(6),
 145 #endif
 146 #if XTENSA_HAVE_COPROCESSOR(7)
 147 COPROCESSOR(7),
 148 #endif
 149 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 150 { -1, -1, 0 }
 151
 152 };
 153
 154 /* The exception table <exc_table> serves two functions:
 155  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 156  * 2. it is a temporary memory buffer for the exception handlers.
 157  */
 158
 159 unsigned long exc_table[EXC_TABLE_SIZE/4];
 160
 161 void die(const char*, struct pt_regs*, long);
 162
 163 static inline void
 164 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 165 {
 166         if (!user_mode(regs))
 167                 die(str, regs, err);
 168 }
 169
 170 /*
 171  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 172  */
 173
 174 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 175 {
 176         __die_if_kernel("Caught unhandled exception - should not happen",
 177                         regs, SIGKILL);
 178
 179         /* If in user mode, send SIGILL signal to current process */
 180         printk("Caught unhandled exception in '%s' "
 181                "(pid = %d, pc = %#010lx) - should not happen\n"
 182                "\tEXCCAUSE is %ld\n",
 183                current->comm, task_pid_nr(current), regs->pc, exccause);
 184         force_sig(SIGILL, current);
 185 }
 186
 187 /*
 188  * Multi-hit exception. This if fatal!
 189  */
 190
 191 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 192 {
 193         die("Caught multihit exception", regs, SIGKILL);
 194 }
 195
 196 /*
 197  * IRQ handler.
 198  * PS.INTLEVEL is the current IRQ priority level.
 199  */
 200
 201 extern void do_IRQ(int, struct pt_regs *);
 202
 203 void do_interrupt(struct pt_regs *regs)
 204 {
 205         static const unsigned int_level_mask[] = {
 206                 0,
 207                 XCHAL_INTLEVEL1_MASK,
 208                 XCHAL_INTLEVEL2_MASK,
 209                 XCHAL_INTLEVEL3_MASK,
 210                 XCHAL_INTLEVEL4_MASK,
 211                 XCHAL_INTLEVEL5_MASK,
 212                 XCHAL_INTLEVEL6_MASK,
 213                 XCHAL_INTLEVEL7_MASK,
 214         };
 215         unsigned level = get_sr(ps) & PS_INTLEVEL_MASK;
 216
 217         if (WARN_ON_ONCE(level >= ARRAY_SIZE(int_level_mask)))
 218                 return;
 219
 220         for (;;) {
 221                 unsigned intread = get_sr(interrupt);
 222                 unsigned intenable = get_sr(intenable);
 223                 unsigned int_at_level = intread & intenable &
 224                         int_level_mask[level];
 225
 226                 if (!int_at_level)
 227                         return;
 228
 229                 /*
 230                  * Clear the interrupt before processing, in case it's
 231                  *  edge-triggered or software-generated
 232                  */
 233                 while (int_at_level) {
 234                         unsigned i = __ffs(int_at_level);
 235                         unsigned mask = 1 << i;
 236
 237                         int_at_level ^= mask;
 238                         set_sr(mask, intclear);
 239                         do_IRQ(i, regs);
 240                 }
 241         }
 242 }
 243
 244 /*
 245  * Illegal instruction. Fatal if in kernel space.
 246  */
 247
 248 void
 249 do_illegal_instruction(struct pt_regs *regs)
 250 {
 251         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 252
 253         /* If in user mode, send SIGILL signal to current process. */
 254
 255         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 256             current->comm, task_pid_nr(current), regs->pc);
 257         force_sig(SIGILL, current);
 258 }
 259
 260
 261 /*
 262  * Handle unaligned memory accesses from user space. Kill task.
 263  *
 264  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 265  * accesses causes from user space.
 266  */
 267
 268 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 269 #ifndef CONFIG_XTENSA_UNALIGNED_USER
 270 void
 271 do_unaligned_user (struct pt_regs *regs)
 272 {
 273         siginfo_t info;
 274
 275         __die_if_kernel("Unhandled unaligned exception in kernel",
 276                         regs, SIGKILL);
 277
 278         current->thread.bad_vaddr = regs->excvaddr;
 279         current->thread.error_code = -3;
 280         printk("Unaligned memory access to %08lx in '%s' "
 281                "(pid = %d, pc = %#010lx)\n",
 282                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 283         info.si_signo = SIGBUS;
 284         info.si_errno = 0;
 285         info.si_code = BUS_ADRALN;
 286         info.si_addr = (void *) regs->excvaddr;
 287         force_sig_info(SIGSEGV, &info, current);
 288
 289 }
 290 #endif
 291 #endif
 292
 293 void
 294 do_debug(struct pt_regs *regs)
 295 {
 296 #ifdef CONFIG_KGDB
 297         /* If remote debugging is configured AND enabled, we give control to
 298          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 299          * native debugger.
 300          */
 301
 302         if (gdb_enter) {
 303                 extern void gdb_handle_exception(struct pt_regs *);
 304                 gdb_handle_exception(regs);
 305                 return_from_debug_flag = 1;
 306                 return;
 307         }
 308 #endif
 309
 310         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 311
 312         /* If in user mode, send SIGTRAP signal to current process */
 313
 314         force_sig(SIGTRAP, current);
 315 }
 316
 317
 318 /* Set exception C handler - for temporary use when probing exceptions */
 319
 320 void * __init trap_set_handler(int cause, void *handler)
 321 {
 322         unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause];
 323         void *previous = (void *)*entry;
 324         *entry = (unsigned long)handler;
 325         return previous;
 326 }
 327
 328
 329 /*
 330  * Initialize dispatch tables.
 331  *
 332  * The exception vectors are stored compressed the __init section in the
 333  * dispatch_init_table. This function initializes the following three tables
 334  * from that compressed table:
 335  * - fast user          first dispatch table for user exceptions
 336  * - fast kernel        first dispatch table for kernel exceptions
 337  * - default C-handler  C-handler called by the default fast handler.
 338  *
 339  * See vectors.S for more details.
 340  */
 341
 342 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
 343
 344 void __init trap_init(void)
 345 {
 346         int i;
 347
 348         /* Setup default vectors. */
 349
 350         for(i = 0; i < 64; i++) {
 351                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 352                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 353                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 354         }
 355
 356         /* Setup specific handlers. */
 357
 358         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 359
 360                 int fast = dispatch_init_table[i].fast;
 361                 int cause = dispatch_init_table[i].cause;
 362                 void *handler = dispatch_init_table[i].handler;
 363
 364                 if (fast == 0)
 365                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 366                 if (fast && fast & USER)
 367                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 368                 if (fast && fast & KRNL)
 369                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 370         }
 371
 372         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 373
 374         i = (unsigned long)exc_table;
 375         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (i));
 376 }
 377
 378 /*
 379  * This function dumps the current valid window frame and other base registers.
 380  */
 381
 382 void show_regs(struct pt_regs * regs)
 383 {
 384         int i, wmask;
 385
 386         show_regs_print_info(KERN_DEFAULT);
 387
 388         wmask = regs->wmask & ~1;
 389
 390         for (i = 0; i < 16; i++) {
 391                 if ((i % 8) == 0)
 392                         printk(KERN_INFO "a%02d:", i);
 393                 printk(KERN_CONT " %08lx", regs->areg[i]);
 394         }
 395         printk(KERN_CONT "\n");
 396
 397         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 398                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 399         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 400                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 401         if (user_mode(regs))
 402                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 403                        regs->windowbase, regs->windowstart, regs->wmask,
 404                        regs->syscall);
 405 }
 406
 407 static __always_inline unsigned long *stack_pointer(struct task_struct *task)
 408 {
 409         unsigned long *sp;
 410
 411         if (!task || task == current)
 412                 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp));
 413         else
 414                 sp = (unsigned long *)task->thread.sp;
 415
 416         return sp;
 417 }
 418
 419 void show_trace(struct task_struct *task, unsigned long *sp)
 420 {
 421         unsigned long a0, a1, pc;
 422         unsigned long sp_start, sp_end;
 423
 424         if (sp)
 425                 a1 = (unsigned long)sp;
 426         else
 427                 a1 = (unsigned long)stack_pointer(task);
 428
 429         sp_start = a1 & ~(THREAD_SIZE-1);
 430         sp_end = sp_start + THREAD_SIZE;
 431
 432         printk("Call Trace:");
 433 #ifdef CONFIG_KALLSYMS
 434         printk("\n");
 435 #endif
 436         spill_registers();
 437
 438         while (a1 > sp_start && a1 < sp_end) {
 439                 sp = (unsigned long*)a1;
 440
 441                 a0 = *(sp - 4);
 442                 a1 = *(sp - 3);
 443
 444                 if (a1 <= (unsigned long) sp)
 445                         break;
 446
 447                 pc = MAKE_PC_FROM_RA(a0, a1);
 448
 449                 if (kernel_text_address(pc)) {
 450                         printk(" [<%08lx>] ", pc);
 451                         print_symbol("%s\n", pc);
 452                 }
 453         }
 454         printk("\n");
 455 }
 456
 457 /*
 458  * This routine abuses get_user()/put_user() to reference pointers
 459  * with at least a bit of error checking ...
 460  */
 461
 462 static int kstack_depth_to_print = 24;
 463
 464 void show_stack(struct task_struct *task, unsigned long *sp)
 465 {
 466         int i = 0;
 467         unsigned long *stack;
 468
 469         if (!sp)
 470                 sp = stack_pointer(task);
 471         stack = sp;
 472
 473         printk("\nStack: ");
 474
 475         for (i = 0; i < kstack_depth_to_print; i++) {
 476                 if (kstack_end(sp))
 477                         break;
 478                 if (i && ((i % 8) == 0))
 479                         printk("\n       ");
 480                 printk("%08lx ", *sp++);
 481         }
 482         printk("\n");
 483         show_trace(task, stack);
 484 }
 485
 486 void show_code(unsigned int *pc)
 487 {
 488         long i;
 489
 490         printk("\nCode:");
 491
 492         for(i = -3 ; i < 6 ; i++) {
 493                 unsigned long insn;
 494                 if (__get_user(insn, pc + i)) {
 495                         printk(" (Bad address in pc)\n");
 496                         break;
 497                 }
 498                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 499         }
 500 }
 501
 502 DEFINE_SPINLOCK(die_lock);
 503
 504 void die(const char * str, struct pt_regs * regs, long err)
 505 {
 506         static int die_counter;
 507         int nl = 0;
 508
 509         console_verbose();
 510         spin_lock_irq(&die_lock);
 511
 512         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 513 #ifdef CONFIG_PREEMPT
 514         printk("PREEMPT ");
 515         nl = 1;
 516 #endif
 517         if (nl)
 518                 printk("\n");
 519         show_regs(regs);
 520         if (!user_mode(regs))
 521                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 522
 523         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 524         spin_unlock_irq(&die_lock);
 525
 526         if (in_interrupt())
 527                 panic("Fatal exception in interrupt");
 528
 529         if (panic_on_oops)
 530                 panic("Fatal exception");
 531
 532         do_exit(err);
 533 }