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 DEFINE_PER_CPU(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         struct pt_regs *old_regs = set_irq_regs(regs);
 216
 217         irq_enter();
 218
 219         for (;;) {
 220                 unsigned intread = get_sr(interrupt);
 221                 unsigned intenable = get_sr(intenable);
 222                 unsigned int_at_level = intread & intenable;
 223                 unsigned level;
 224
 225                 for (level = LOCKLEVEL; level > 0; --level) {
 226                         if (int_at_level & int_level_mask[level]) {
 227                                 int_at_level &= int_level_mask[level];
 228                                 break;
 229                         }
 230                 }
 231
 232                 if (level == 0)
 233                         break;
 234
 235                 do_IRQ(__ffs(int_at_level), regs);
 236         }
 237
 238         irq_exit();
 239         set_irq_regs(old_regs);
 240 }
 241
 242 /*
 243  * Illegal instruction. Fatal if in kernel space.
 244  */
 245
 246 void
 247 do_illegal_instruction(struct pt_regs *regs)
 248 {
 249         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 250
 251         /* If in user mode, send SIGILL signal to current process. */
 252
 253         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 254             current->comm, task_pid_nr(current), regs->pc);
 255         force_sig(SIGILL, current);
 256 }
 257
 258
 259 /*
 260  * Handle unaligned memory accesses from user space. Kill task.
 261  *
 262  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 263  * accesses causes from user space.
 264  */
 265
 266 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 267 #ifndef CONFIG_XTENSA_UNALIGNED_USER
 268 void
 269 do_unaligned_user (struct pt_regs *regs)
 270 {
 271         siginfo_t info;
 272
 273         __die_if_kernel("Unhandled unaligned exception in kernel",
 274                         regs, SIGKILL);
 275
 276         current->thread.bad_vaddr = regs->excvaddr;
 277         current->thread.error_code = -3;
 278         printk("Unaligned memory access to %08lx in '%s' "
 279                "(pid = %d, pc = %#010lx)\n",
 280                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 281         info.si_signo = SIGBUS;
 282         info.si_errno = 0;
 283         info.si_code = BUS_ADRALN;
 284         info.si_addr = (void *) regs->excvaddr;
 285         force_sig_info(SIGSEGV, &info, current);
 286
 287 }
 288 #endif
 289 #endif
 290
 291 void
 292 do_debug(struct pt_regs *regs)
 293 {
 294 #ifdef CONFIG_KGDB
 295         /* If remote debugging is configured AND enabled, we give control to
 296          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 297          * native debugger.
 298          */
 299
 300         if (gdb_enter) {
 301                 extern void gdb_handle_exception(struct pt_regs *);
 302                 gdb_handle_exception(regs);
 303                 return_from_debug_flag = 1;
 304                 return;
 305         }
 306 #endif
 307
 308         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 309
 310         /* If in user mode, send SIGTRAP signal to current process */
 311
 312         force_sig(SIGTRAP, current);
 313 }
 314
 315
 316 static void set_handler(int idx, void *handler)
 317 {
 318         unsigned int cpu;
 319
 320         for_each_possible_cpu(cpu)
 321                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
 322 }
 323
 324 /* Set exception C handler - for temporary use when probing exceptions */
 325
 326 void * __init trap_set_handler(int cause, void *handler)
 327 {
 328         void *previous = (void *)per_cpu(exc_table, 0)[
 329                 EXC_TABLE_DEFAULT / 4 + cause];
 330         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
 331         return previous;
 332 }
 333
 334
 335 static void trap_init_excsave(void)
 336 {
 337         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
 338         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 339 }
 340
 341 /*
 342  * Initialize dispatch tables.
 343  *
 344  * The exception vectors are stored compressed the __init section in the
 345  * dispatch_init_table. This function initializes the following three tables
 346  * from that compressed table:
 347  * - fast user          first dispatch table for user exceptions
 348  * - fast kernel        first dispatch table for kernel exceptions
 349  * - default C-handler  C-handler called by the default fast handler.
 350  *
 351  * See vectors.S for more details.
 352  */
 353
 354 void __init trap_init(void)
 355 {
 356         int i;
 357
 358         /* Setup default vectors. */
 359
 360         for(i = 0; i < 64; i++) {
 361                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 362                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 363                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 364         }
 365
 366         /* Setup specific handlers. */
 367
 368         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 369
 370                 int fast = dispatch_init_table[i].fast;
 371                 int cause = dispatch_init_table[i].cause;
 372                 void *handler = dispatch_init_table[i].handler;
 373
 374                 if (fast == 0)
 375                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 376                 if (fast && fast & USER)
 377                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 378                 if (fast && fast & KRNL)
 379                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 380         }
 381
 382         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 383         trap_init_excsave();
 384 }
 385
 386 #ifdef CONFIG_SMP
 387 void secondary_trap_init(void)
 388 {
 389         trap_init_excsave();
 390 }
 391 #endif
 392
 393 /*
 394  * This function dumps the current valid window frame and other base registers.
 395  */
 396
 397 void show_regs(struct pt_regs * regs)
 398 {
 399         int i, wmask;
 400
 401         show_regs_print_info(KERN_DEFAULT);
 402
 403         wmask = regs->wmask & ~1;
 404
 405         for (i = 0; i < 16; i++) {
 406                 if ((i % 8) == 0)
 407                         printk(KERN_INFO "a%02d:", i);
 408                 printk(KERN_CONT " %08lx", regs->areg[i]);
 409         }
 410         printk(KERN_CONT "\n");
 411
 412         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 413                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 414         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 415                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 416         if (user_mode(regs))
 417                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 418                        regs->windowbase, regs->windowstart, regs->wmask,
 419                        regs->syscall);
 420 }
 421
 422 static int show_trace_cb(struct stackframe *frame, void *data)
 423 {
 424         if (kernel_text_address(frame->pc)) {
 425                 printk(" [<%08lx>] ", frame->pc);
 426                 print_symbol("%s\n", frame->pc);
 427         }
 428         return 0;
 429 }
 430
 431 void show_trace(struct task_struct *task, unsigned long *sp)
 432 {
 433         if (!sp)
 434                 sp = stack_pointer(task);
 435
 436         printk("Call Trace:");
 437 #ifdef CONFIG_KALLSYMS
 438         printk("\n");
 439 #endif
 440         walk_stackframe(sp, show_trace_cb, NULL);
 441         printk("\n");
 442 }
 443
 444 /*
 445  * This routine abuses get_user()/put_user() to reference pointers
 446  * with at least a bit of error checking ...
 447  */
 448
 449 static int kstack_depth_to_print = 24;
 450
 451 void show_stack(struct task_struct *task, unsigned long *sp)
 452 {
 453         int i = 0;
 454         unsigned long *stack;
 455
 456         if (!sp)
 457                 sp = stack_pointer(task);
 458         stack = sp;
 459
 460         printk("\nStack: ");
 461
 462         for (i = 0; i < kstack_depth_to_print; i++) {
 463                 if (kstack_end(sp))
 464                         break;
 465                 if (i && ((i % 8) == 0))
 466                         printk("\n       ");
 467                 printk("%08lx ", *sp++);
 468         }
 469         printk("\n");
 470         show_trace(task, stack);
 471 }
 472
 473 void show_code(unsigned int *pc)
 474 {
 475         long i;
 476
 477         printk("\nCode:");
 478
 479         for(i = -3 ; i < 6 ; i++) {
 480                 unsigned long insn;
 481                 if (__get_user(insn, pc + i)) {
 482                         printk(" (Bad address in pc)\n");
 483                         break;
 484                 }
 485                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 486         }
 487 }
 488
 489 DEFINE_SPINLOCK(die_lock);
 490
 491 void die(const char * str, struct pt_regs * regs, long err)
 492 {
 493         static int die_counter;
 494         int nl = 0;
 495
 496         console_verbose();
 497         spin_lock_irq(&die_lock);
 498
 499         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 500 #ifdef CONFIG_PREEMPT
 501         printk("PREEMPT ");
 502         nl = 1;
 503 #endif
 504         if (nl)
 505                 printk("\n");
 506         show_regs(regs);
 507         if (!user_mode(regs))
 508                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 509
 510         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 511         spin_unlock_irq(&die_lock);
 512
 513         if (in_interrupt())
 514                 panic("Fatal exception in interrupt");
 515
 516         if (panic_on_oops)
 517                 panic("Fatal exception");
 518
 519         do_exit(err);
 520 }