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 - 2013 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/stacktrace.h>
  36 #include <asm/ptrace.h>
  37 #include <asm/timex.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/processor.h>
  41 #include <asm/traps.h>
  42
  43 #ifdef CONFIG_KGDB
  44 extern int gdb_enter;
  45 extern int return_from_debug_flag;
  46 #endif
  47
  48 /*
  49  * Machine specific interrupt handlers
  50  */
  51
  52 extern void kernel_exception(void);
  53 extern void user_exception(void);
  54
  55 extern void fast_syscall_kernel(void);
  56 extern void fast_syscall_user(void);
  57 extern void fast_alloca(void);
  58 extern void fast_unaligned(void);
  59 extern void fast_second_level_miss(void);
  60 extern void fast_store_prohibited(void);
  61 extern void fast_coprocessor(void);
  62
  63 extern void do_illegal_instruction (struct pt_regs*);
  64 extern void do_interrupt (struct pt_regs*);
  65 extern void do_unaligned_user (struct pt_regs*);
  66 extern void do_multihit (struct pt_regs*, unsigned long);
  67 extern void do_page_fault (struct pt_regs*, unsigned long);
  68 extern void do_debug (struct pt_regs*);
  69 extern void system_call (struct pt_regs*);
  70
  71 /*
  72  * The vector table must be preceded by a save area (which
  73  * implies it must be in RAM, unless one places RAM immediately
  74  * before a ROM and puts the vector at the start of the ROM (!))
  75  */
  76
  77 #define KRNL            0x01
  78 #define USER            0x02
  79
  80 #define COPROCESSOR(x)                                                  \
  81 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
  82
  83 typedef struct {
  84         int cause;
  85         int fast;
  86         void* handler;
  87 } dispatch_init_table_t;
  88
  89 static dispatch_init_table_t __initdata dispatch_init_table[] = {
  90
  91 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  92 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
  93 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  94 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  96 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  97 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
  98 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
  99 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
 100 /* EXCCAUSE_PRIVILEGED unhandled */
 101 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 102 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 103 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 104 #else
 105 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 106 #endif
 107 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 108 #endif
 109 #ifdef CONFIG_MMU
 110 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 111 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 112 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 113 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 114 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 115 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 116 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 117 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 118 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 119 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 120 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 123 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 124 #endif /* CONFIG_MMU */
 125 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 126 #if XTENSA_HAVE_COPROCESSOR(0)
 127 COPROCESSOR(0),
 128 #endif
 129 #if XTENSA_HAVE_COPROCESSOR(1)
 130 COPROCESSOR(1),
 131 #endif
 132 #if XTENSA_HAVE_COPROCESSOR(2)
 133 COPROCESSOR(2),
 134 #endif
 135 #if XTENSA_HAVE_COPROCESSOR(3)
 136 COPROCESSOR(3),
 137 #endif
 138 #if XTENSA_HAVE_COPROCESSOR(4)
 139 COPROCESSOR(4),
 140 #endif
 141 #if XTENSA_HAVE_COPROCESSOR(5)
 142 COPROCESSOR(5),
 143 #endif
 144 #if XTENSA_HAVE_COPROCESSOR(6)
 145 COPROCESSOR(6),
 146 #endif
 147 #if XTENSA_HAVE_COPROCESSOR(7)
 148 COPROCESSOR(7),
 149 #endif
 150 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 151 { -1, -1, 0 }
 152
 153 };
 154
 155 /* The exception table <exc_table> serves two functions:
 156  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 157  * 2. it is a temporary memory buffer for the exception handlers.
 158  */
 159
 160 unsigned long exc_table[EXC_TABLE_SIZE/4];
 161
 162 void die(const char*, struct pt_regs*, long);
 163
 164 static inline void
 165 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 166 {
 167         if (!user_mode(regs))
 168                 die(str, regs, err);
 169 }
 170
 171 /*
 172  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 173  */
 174
 175 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 176 {
 177         __die_if_kernel("Caught unhandled exception - should not happen",
 178                         regs, SIGKILL);
 179
 180         /* If in user mode, send SIGILL signal to current process */
 181         printk("Caught unhandled exception in '%s' "
 182                "(pid = %d, pc = %#010lx) - should not happen\n"
 183                "\tEXCCAUSE is %ld\n",
 184                current->comm, task_pid_nr(current), regs->pc, exccause);
 185         force_sig(SIGILL, current);
 186 }
 187
 188 /*
 189  * Multi-hit exception. This if fatal!
 190  */
 191
 192 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 193 {
 194         die("Caught multihit exception", regs, SIGKILL);
 195 }
 196
 197 /*
 198  * IRQ handler.
 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
 216         for (;;) {
 217                 unsigned intread = get_sr(interrupt);
 218                 unsigned intenable = get_sr(intenable);
 219                 unsigned int_at_level = intread & intenable;
 220                 unsigned level;
 221
 222                 for (level = LOCKLEVEL; level > 0; --level) {
 223                         if (int_at_level & int_level_mask[level]) {
 224                                 int_at_level &= int_level_mask[level];
 225                                 break;
 226                         }
 227                 }
 228
 229                 if (level == 0)
 230                         return;
 231
 232                 /*
 233                  * Clear the interrupt before processing, in case it's
 234                  *  edge-triggered or software-generated
 235                  */
 236                 while (int_at_level) {
 237                         unsigned i = __ffs(int_at_level);
 238                         unsigned mask = 1 << i;
 239
 240                         int_at_level ^= mask;
 241                         set_sr(mask, intclear);
 242                         do_IRQ(i, regs);
 243                 }
 244         }
 245 }
 246
 247 /*
 248  * Illegal instruction. Fatal if in kernel space.
 249  */
 250
 251 void
 252 do_illegal_instruction(struct pt_regs *regs)
 253 {
 254         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 255
 256         /* If in user mode, send SIGILL signal to current process. */
 257
 258         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 259             current->comm, task_pid_nr(current), regs->pc);
 260         force_sig(SIGILL, current);
 261 }
 262
 263
 264 /*
 265  * Handle unaligned memory accesses from user space. Kill task.
 266  *
 267  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 268  * accesses causes from user space.
 269  */
 270
 271 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 272 #ifndef CONFIG_XTENSA_UNALIGNED_USER
 273 void
 274 do_unaligned_user (struct pt_regs *regs)
 275 {
 276         siginfo_t info;
 277
 278         __die_if_kernel("Unhandled unaligned exception in kernel",
 279                         regs, SIGKILL);
 280
 281         current->thread.bad_vaddr = regs->excvaddr;
 282         current->thread.error_code = -3;
 283         printk("Unaligned memory access to %08lx in '%s' "
 284                "(pid = %d, pc = %#010lx)\n",
 285                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 286         info.si_signo = SIGBUS;
 287         info.si_errno = 0;
 288         info.si_code = BUS_ADRALN;
 289         info.si_addr = (void *) regs->excvaddr;
 290         force_sig_info(SIGSEGV, &info, current);
 291
 292 }
 293 #endif
 294 #endif
 295
 296 void
 297 do_debug(struct pt_regs *regs)
 298 {
 299 #ifdef CONFIG_KGDB
 300         /* If remote debugging is configured AND enabled, we give control to
 301          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 302          * native debugger.
 303          */
 304
 305         if (gdb_enter) {
 306                 extern void gdb_handle_exception(struct pt_regs *);
 307                 gdb_handle_exception(regs);
 308                 return_from_debug_flag = 1;
 309                 return;
 310         }
 311 #endif
 312
 313         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 314
 315         /* If in user mode, send SIGTRAP signal to current process */
 316
 317         force_sig(SIGTRAP, current);
 318 }
 319
 320
 321 /* Set exception C handler - for temporary use when probing exceptions */
 322
 323 void * __init trap_set_handler(int cause, void *handler)
 324 {
 325         unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause];
 326         void *previous = (void *)*entry;
 327         *entry = (unsigned long)handler;
 328         return previous;
 329 }
 330
 331
 332 /*
 333  * Initialize dispatch tables.
 334  *
 335  * The exception vectors are stored compressed the __init section in the
 336  * dispatch_init_table. This function initializes the following three tables
 337  * from that compressed table:
 338  * - fast user          first dispatch table for user exceptions
 339  * - fast kernel        first dispatch table for kernel exceptions
 340  * - default C-handler  C-handler called by the default fast handler.
 341  *
 342  * See vectors.S for more details.
 343  */
 344
 345 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler))
 346
 347 void __init trap_init(void)
 348 {
 349         int i;
 350
 351         /* Setup default vectors. */
 352
 353         for(i = 0; i < 64; i++) {
 354                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 355                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 356                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 357         }
 358
 359         /* Setup specific handlers. */
 360
 361         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 362
 363                 int fast = dispatch_init_table[i].fast;
 364                 int cause = dispatch_init_table[i].cause;
 365                 void *handler = dispatch_init_table[i].handler;
 366
 367                 if (fast == 0)
 368                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 369                 if (fast && fast & USER)
 370                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 371                 if (fast && fast & KRNL)
 372                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 373         }
 374
 375         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 376
 377         i = (unsigned long)exc_table;
 378         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (i));
 379 }
 380
 381 /*
 382  * This function dumps the current valid window frame and other base registers.
 383  */
 384
 385 void show_regs(struct pt_regs * regs)
 386 {
 387         int i, wmask;
 388
 389         show_regs_print_info(KERN_DEFAULT);
 390
 391         wmask = regs->wmask & ~1;
 392
 393         for (i = 0; i < 16; i++) {
 394                 if ((i % 8) == 0)
 395                         printk(KERN_INFO "a%02d:", i);
 396                 printk(KERN_CONT " %08lx", regs->areg[i]);
 397         }
 398         printk(KERN_CONT "\n");
 399
 400         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 401                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 402         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 403                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 404         if (user_mode(regs))
 405                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 406                        regs->windowbase, regs->windowstart, regs->wmask,
 407                        regs->syscall);
 408 }
 409
 410 static int show_trace_cb(struct stackframe *frame, void *data)
 411 {
 412         if (kernel_text_address(frame->pc)) {
 413                 printk(" [<%08lx>] ", frame->pc);
 414                 print_symbol("%s\n", frame->pc);
 415         }
 416         return 0;
 417 }
 418
 419 void show_trace(struct task_struct *task, unsigned long *sp)
 420 {
 421         if (!sp)
 422                 sp = stack_pointer(task);
 423
 424         printk("Call Trace:");
 425 #ifdef CONFIG_KALLSYMS
 426         printk("\n");
 427 #endif
 428         walk_stackframe(sp, show_trace_cb, NULL);
 429         printk("\n");
 430 }
 431
 432 /*
 433  * This routine abuses get_user()/put_user() to reference pointers
 434  * with at least a bit of error checking ...
 435  */
 436
 437 static int kstack_depth_to_print = 24;
 438
 439 void show_stack(struct task_struct *task, unsigned long *sp)
 440 {
 441         int i = 0;
 442         unsigned long *stack;
 443
 444         if (!sp)
 445                 sp = stack_pointer(task);
 446         stack = sp;
 447
 448         printk("\nStack: ");
 449
 450         for (i = 0; i < kstack_depth_to_print; i++) {
 451                 if (kstack_end(sp))
 452                         break;
 453                 if (i && ((i % 8) == 0))
 454                         printk("\n       ");
 455                 printk("%08lx ", *sp++);
 456         }
 457         printk("\n");
 458         show_trace(task, stack);
 459 }
 460
 461 void show_code(unsigned int *pc)
 462 {
 463         long i;
 464
 465         printk("\nCode:");
 466
 467         for(i = -3 ; i < 6 ; i++) {
 468                 unsigned long insn;
 469                 if (__get_user(insn, pc + i)) {
 470                         printk(" (Bad address in pc)\n");
 471                         break;
 472                 }
 473                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 474         }
 475 }
 476
 477 DEFINE_SPINLOCK(die_lock);
 478
 479 void die(const char * str, struct pt_regs * regs, long err)
 480 {
 481         static int die_counter;
 482         int nl = 0;
 483
 484         console_verbose();
 485         spin_lock_irq(&die_lock);
 486
 487         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 488 #ifdef CONFIG_PREEMPT
 489         printk("PREEMPT ");
 490         nl = 1;
 491 #endif
 492         if (nl)
 493                 printk("\n");
 494         show_regs(regs);
 495         if (!user_mode(regs))
 496                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 497
 498         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 499         spin_unlock_irq(&die_lock);
 500
 501         if (in_interrupt())
 502                 panic("Fatal exception in interrupt");
 503
 504         if (panic_on_oops)
 505                 panic("Fatal exception");
 506
 507         do_exit(err);
 508 }