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 #endif
 105 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 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 DEFINE_PER_CPU(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  */
 199
 200 extern void do_IRQ(int, struct pt_regs *);
 201
 202 void do_interrupt(struct pt_regs *regs)
 203 {
 204         static const unsigned int_level_mask[] = {
 205                 0,
 206                 XCHAL_INTLEVEL1_MASK,
 207                 XCHAL_INTLEVEL2_MASK,
 208                 XCHAL_INTLEVEL3_MASK,
 209                 XCHAL_INTLEVEL4_MASK,
 210                 XCHAL_INTLEVEL5_MASK,
 211                 XCHAL_INTLEVEL6_MASK,
 212                 XCHAL_INTLEVEL7_MASK,
 213         };
 214         struct pt_regs *old_regs = set_irq_regs(regs);
 215
 216         irq_enter();
 217
 218         for (;;) {
 219                 unsigned intread = get_sr(interrupt);
 220                 unsigned intenable = get_sr(intenable);
 221                 unsigned int_at_level = intread & intenable;
 222                 unsigned level;
 223
 224                 for (level = LOCKLEVEL; level > 0; --level) {
 225                         if (int_at_level & int_level_mask[level]) {
 226                                 int_at_level &= int_level_mask[level];
 227                                 break;
 228                         }
 229                 }
 230
 231                 if (level == 0)
 232                         break;
 233
 234                 do_IRQ(__ffs(int_at_level), regs);
 235         }
 236
 237         irq_exit();
 238         set_irq_regs(old_regs);
 239 }
 240
 241 /*
 242  * Illegal instruction. Fatal if in kernel space.
 243  */
 244
 245 void
 246 do_illegal_instruction(struct pt_regs *regs)
 247 {
 248         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 249
 250         /* If in user mode, send SIGILL signal to current process. */
 251
 252         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 253             current->comm, task_pid_nr(current), regs->pc);
 254         force_sig(SIGILL, current);
 255 }
 256
 257
 258 /*
 259  * Handle unaligned memory accesses from user space. Kill task.
 260  *
 261  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 262  * accesses causes from user space.
 263  */
 264
 265 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 266 void
 267 do_unaligned_user (struct pt_regs *regs)
 268 {
 269         siginfo_t info;
 270
 271         __die_if_kernel("Unhandled unaligned exception in kernel",
 272                         regs, SIGKILL);
 273
 274         current->thread.bad_vaddr = regs->excvaddr;
 275         current->thread.error_code = -3;
 276         printk("Unaligned memory access to %08lx in '%s' "
 277                "(pid = %d, pc = %#010lx)\n",
 278                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 279         info.si_signo = SIGBUS;
 280         info.si_errno = 0;
 281         info.si_code = BUS_ADRALN;
 282         info.si_addr = (void *) regs->excvaddr;
 283         force_sig_info(SIGSEGV, &info, current);
 284
 285 }
 286 #endif
 287
 288 void
 289 do_debug(struct pt_regs *regs)
 290 {
 291 #ifdef CONFIG_KGDB
 292         /* If remote debugging is configured AND enabled, we give control to
 293          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 294          * native debugger.
 295          */
 296
 297         if (gdb_enter) {
 298                 extern void gdb_handle_exception(struct pt_regs *);
 299                 gdb_handle_exception(regs);
 300                 return_from_debug_flag = 1;
 301                 return;
 302         }
 303 #endif
 304
 305         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 306
 307         /* If in user mode, send SIGTRAP signal to current process */
 308
 309         force_sig(SIGTRAP, current);
 310 }
 311
 312
 313 static void set_handler(int idx, void *handler)
 314 {
 315         unsigned int cpu;
 316
 317         for_each_possible_cpu(cpu)
 318                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
 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         void *previous = (void *)per_cpu(exc_table, 0)[
 326                 EXC_TABLE_DEFAULT / 4 + cause];
 327         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
 328         return previous;
 329 }
 330
 331
 332 static void trap_init_excsave(void)
 333 {
 334         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
 335         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 336 }
 337
 338 /*
 339  * Initialize dispatch tables.
 340  *
 341  * The exception vectors are stored compressed the __init section in the
 342  * dispatch_init_table. This function initializes the following three tables
 343  * from that compressed table:
 344  * - fast user          first dispatch table for user exceptions
 345  * - fast kernel        first dispatch table for kernel exceptions
 346  * - default C-handler  C-handler called by the default fast handler.
 347  *
 348  * See vectors.S for more details.
 349  */
 350
 351 void __init trap_init(void)
 352 {
 353         int i;
 354
 355         /* Setup default vectors. */
 356
 357         for(i = 0; i < 64; i++) {
 358                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 359                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 360                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 361         }
 362
 363         /* Setup specific handlers. */
 364
 365         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 366
 367                 int fast = dispatch_init_table[i].fast;
 368                 int cause = dispatch_init_table[i].cause;
 369                 void *handler = dispatch_init_table[i].handler;
 370
 371                 if (fast == 0)
 372                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 373                 if (fast && fast & USER)
 374                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 375                 if (fast && fast & KRNL)
 376                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 377         }
 378
 379         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 380         trap_init_excsave();
 381 }
 382
 383 #ifdef CONFIG_SMP
 384 void secondary_trap_init(void)
 385 {
 386         trap_init_excsave();
 387 }
 388 #endif
 389
 390 /*
 391  * This function dumps the current valid window frame and other base registers.
 392  */
 393
 394 void show_regs(struct pt_regs * regs)
 395 {
 396         int i, wmask;
 397
 398         show_regs_print_info(KERN_DEFAULT);
 399
 400         wmask = regs->wmask & ~1;
 401
 402         for (i = 0; i < 16; i++) {
 403                 if ((i % 8) == 0)
 404                         printk(KERN_INFO "a%02d:", i);
 405                 printk(KERN_CONT " %08lx", regs->areg[i]);
 406         }
 407         printk(KERN_CONT "\n");
 408
 409         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 410                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 411         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 412                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 413         if (user_mode(regs))
 414                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 415                        regs->windowbase, regs->windowstart, regs->wmask,
 416                        regs->syscall);
 417 }
 418
 419 static int show_trace_cb(struct stackframe *frame, void *data)
 420 {
 421         if (kernel_text_address(frame->pc)) {
 422                 printk(" [<%08lx>] ", frame->pc);
 423                 print_symbol("%s\n", frame->pc);
 424         }
 425         return 0;
 426 }
 427
 428 void show_trace(struct task_struct *task, unsigned long *sp)
 429 {
 430         if (!sp)
 431                 sp = stack_pointer(task);
 432
 433         printk("Call Trace:");
 434 #ifdef CONFIG_KALLSYMS
 435         printk("\n");
 436 #endif
 437         walk_stackframe(sp, show_trace_cb, NULL);
 438         printk("\n");
 439 }
 440
 441 /*
 442  * This routine abuses get_user()/put_user() to reference pointers
 443  * with at least a bit of error checking ...
 444  */
 445
 446 static int kstack_depth_to_print = 24;
 447
 448 void show_stack(struct task_struct *task, unsigned long *sp)
 449 {
 450         int i = 0;
 451         unsigned long *stack;
 452
 453         if (!sp)
 454                 sp = stack_pointer(task);
 455         stack = sp;
 456
 457         printk("\nStack: ");
 458
 459         for (i = 0; i < kstack_depth_to_print; i++) {
 460                 if (kstack_end(sp))
 461                         break;
 462                 if (i && ((i % 8) == 0))
 463                         printk("\n       ");
 464                 printk("%08lx ", *sp++);
 465         }
 466         printk("\n");
 467         show_trace(task, stack);
 468 }
 469
 470 void show_code(unsigned int *pc)
 471 {
 472         long i;
 473
 474         printk("\nCode:");
 475
 476         for(i = -3 ; i < 6 ; i++) {
 477                 unsigned long insn;
 478                 if (__get_user(insn, pc + i)) {
 479                         printk(" (Bad address in pc)\n");
 480                         break;
 481                 }
 482                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 483         }
 484 }
 485
 486 DEFINE_SPINLOCK(die_lock);
 487
 488 void die(const char * str, struct pt_regs * regs, long err)
 489 {
 490         static int die_counter;
 491         int nl = 0;
 492
 493         console_verbose();
 494         spin_lock_irq(&die_lock);
 495
 496         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 497 #ifdef CONFIG_PREEMPT
 498         printk("PREEMPT ");
 499         nl = 1;
 500 #endif
 501         if (nl)
 502                 printk("\n");
 503         show_regs(regs);
 504         if (!user_mode(regs))
 505                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 506
 507         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 508         spin_unlock_irq(&die_lock);
 509
 510         if (in_interrupt())
 511                 panic("Fatal exception in interrupt");
 512
 513         if (panic_on_oops)
 514                 panic("Fatal exception");
 515
 516         do_exit(err);
 517 }