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_nmi(struct pt_regs *);
  66 extern void do_unaligned_user (struct pt_regs*);
  67 extern void do_multihit (struct pt_regs*, unsigned long);
  68 extern void do_page_fault (struct pt_regs*, unsigned long);
  69 extern void do_debug (struct pt_regs*);
  70 extern void system_call (struct pt_regs*);
  71
  72 /*
  73  * The vector table must be preceded by a save area (which
  74  * implies it must be in RAM, unless one places RAM immediately
  75  * before a ROM and puts the vector at the start of the ROM (!))
  76  */
  77
  78 #define KRNL            0x01
  79 #define USER            0x02
  80
  81 #define COPROCESSOR(x)                                                  \
  82 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor }
  83
  84 typedef struct {
  85         int cause;
  86         int fast;
  87         void* handler;
  88 } dispatch_init_table_t;
  89
  90 static dispatch_init_table_t __initdata dispatch_init_table[] = {
  91
  92 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  93 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
  94 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  95 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  96 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  97 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  98 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
  99 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
 100 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
 101 /* EXCCAUSE_PRIVILEGED unhandled */
 102 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 103 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 104 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 105 #endif
 106 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 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 #if XTENSA_FAKE_NMI
 151 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 152 #endif
 153 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 154 { -1, -1, 0 }
 155
 156 };
 157
 158 /* The exception table <exc_table> serves two functions:
 159  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 160  * 2. it is a temporary memory buffer for the exception handlers.
 161  */
 162
 163 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
 164
 165 void die(const char*, struct pt_regs*, long);
 166
 167 static inline void
 168 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 169 {
 170         if (!user_mode(regs))
 171                 die(str, regs, err);
 172 }
 173
 174 /*
 175  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 176  */
 177
 178 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 179 {
 180         __die_if_kernel("Caught unhandled exception - should not happen",
 181                         regs, SIGKILL);
 182
 183         /* If in user mode, send SIGILL signal to current process */
 184         printk("Caught unhandled exception in '%s' "
 185                "(pid = %d, pc = %#010lx) - should not happen\n"
 186                "\tEXCCAUSE is %ld\n",
 187                current->comm, task_pid_nr(current), regs->pc, exccause);
 188         force_sig(SIGILL, current);
 189 }
 190
 191 /*
 192  * Multi-hit exception. This if fatal!
 193  */
 194
 195 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 196 {
 197         die("Caught multihit exception", regs, SIGKILL);
 198 }
 199
 200 /*
 201  * IRQ handler.
 202  */
 203
 204 extern void do_IRQ(int, struct pt_regs *);
 205
 206 #if XTENSA_FAKE_NMI
 207
 208 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 209
 210 DEFINE_PER_CPU(unsigned long, nmi_count);
 211
 212 void do_nmi(struct pt_regs *regs)
 213 {
 214         struct pt_regs *old_regs;
 215
 216         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
 217                 trace_hardirqs_off();
 218
 219         old_regs = set_irq_regs(regs);
 220         nmi_enter();
 221         ++*this_cpu_ptr(&nmi_count);
 222         xtensa_pmu_irq_handler(0, NULL);
 223         nmi_exit();
 224         set_irq_regs(old_regs);
 225 }
 226 #endif
 227
 228 void do_interrupt(struct pt_regs *regs)
 229 {
 230         static const unsigned int_level_mask[] = {
 231                 0,
 232                 XCHAL_INTLEVEL1_MASK,
 233                 XCHAL_INTLEVEL2_MASK,
 234                 XCHAL_INTLEVEL3_MASK,
 235                 XCHAL_INTLEVEL4_MASK,
 236                 XCHAL_INTLEVEL5_MASK,
 237                 XCHAL_INTLEVEL6_MASK,
 238                 XCHAL_INTLEVEL7_MASK,
 239         };
 240         struct pt_regs *old_regs;
 241
 242         trace_hardirqs_off();
 243
 244         old_regs = set_irq_regs(regs);
 245         irq_enter();
 246
 247         for (;;) {
 248                 unsigned intread = get_sr(interrupt);
 249                 unsigned intenable = get_sr(intenable);
 250                 unsigned int_at_level = intread & intenable;
 251                 unsigned level;
 252
 253                 for (level = LOCKLEVEL; level > 0; --level) {
 254                         if (int_at_level & int_level_mask[level]) {
 255                                 int_at_level &= int_level_mask[level];
 256                                 break;
 257                         }
 258                 }
 259
 260                 if (level == 0)
 261                         break;
 262
 263                 do_IRQ(__ffs(int_at_level), regs);
 264         }
 265
 266         irq_exit();
 267         set_irq_regs(old_regs);
 268 }
 269
 270 /*
 271  * Illegal instruction. Fatal if in kernel space.
 272  */
 273
 274 void
 275 do_illegal_instruction(struct pt_regs *regs)
 276 {
 277         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 278
 279         /* If in user mode, send SIGILL signal to current process. */
 280
 281         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 282             current->comm, task_pid_nr(current), regs->pc);
 283         force_sig(SIGILL, current);
 284 }
 285
 286
 287 /*
 288  * Handle unaligned memory accesses from user space. Kill task.
 289  *
 290  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 291  * accesses causes from user space.
 292  */
 293
 294 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 295 void
 296 do_unaligned_user (struct pt_regs *regs)
 297 {
 298         siginfo_t info;
 299
 300         __die_if_kernel("Unhandled unaligned exception in kernel",
 301                         regs, SIGKILL);
 302
 303         current->thread.bad_vaddr = regs->excvaddr;
 304         current->thread.error_code = -3;
 305         printk("Unaligned memory access to %08lx in '%s' "
 306                "(pid = %d, pc = %#010lx)\n",
 307                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 308         info.si_signo = SIGBUS;
 309         info.si_errno = 0;
 310         info.si_code = BUS_ADRALN;
 311         info.si_addr = (void *) regs->excvaddr;
 312         force_sig_info(SIGSEGV, &info, current);
 313
 314 }
 315 #endif
 316
 317 void
 318 do_debug(struct pt_regs *regs)
 319 {
 320 #ifdef CONFIG_KGDB
 321         /* If remote debugging is configured AND enabled, we give control to
 322          * kgdb.  Otherwise, we fall through, perhaps giving control to the
 323          * native debugger.
 324          */
 325
 326         if (gdb_enter) {
 327                 extern void gdb_handle_exception(struct pt_regs *);
 328                 gdb_handle_exception(regs);
 329                 return_from_debug_flag = 1;
 330                 return;
 331         }
 332 #endif
 333
 334         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 335
 336         /* If in user mode, send SIGTRAP signal to current process */
 337
 338         force_sig(SIGTRAP, current);
 339 }
 340
 341
 342 static void set_handler(int idx, void *handler)
 343 {
 344         unsigned int cpu;
 345
 346         for_each_possible_cpu(cpu)
 347                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
 348 }
 349
 350 /* Set exception C handler - for temporary use when probing exceptions */
 351
 352 void * __init trap_set_handler(int cause, void *handler)
 353 {
 354         void *previous = (void *)per_cpu(exc_table, 0)[
 355                 EXC_TABLE_DEFAULT / 4 + cause];
 356         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
 357         return previous;
 358 }
 359
 360
 361 static void trap_init_excsave(void)
 362 {
 363         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
 364         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 365 }
 366
 367 /*
 368  * Initialize dispatch tables.
 369  *
 370  * The exception vectors are stored compressed the __init section in the
 371  * dispatch_init_table. This function initializes the following three tables
 372  * from that compressed table:
 373  * - fast user          first dispatch table for user exceptions
 374  * - fast kernel        first dispatch table for kernel exceptions
 375  * - default C-handler  C-handler called by the default fast handler.
 376  *
 377  * See vectors.S for more details.
 378  */
 379
 380 void __init trap_init(void)
 381 {
 382         int i;
 383
 384         /* Setup default vectors. */
 385
 386         for(i = 0; i < 64; i++) {
 387                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 388                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 389                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 390         }
 391
 392         /* Setup specific handlers. */
 393
 394         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 395
 396                 int fast = dispatch_init_table[i].fast;
 397                 int cause = dispatch_init_table[i].cause;
 398                 void *handler = dispatch_init_table[i].handler;
 399
 400                 if (fast == 0)
 401                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 402                 if (fast && fast & USER)
 403                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 404                 if (fast && fast & KRNL)
 405                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 406         }
 407
 408         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 409         trap_init_excsave();
 410 }
 411
 412 #ifdef CONFIG_SMP
 413 void secondary_trap_init(void)
 414 {
 415         trap_init_excsave();
 416 }
 417 #endif
 418
 419 /*
 420  * This function dumps the current valid window frame and other base registers.
 421  */
 422
 423 void show_regs(struct pt_regs * regs)
 424 {
 425         int i, wmask;
 426
 427         show_regs_print_info(KERN_DEFAULT);
 428
 429         wmask = regs->wmask & ~1;
 430
 431         for (i = 0; i < 16; i++) {
 432                 if ((i % 8) == 0)
 433                         printk(KERN_INFO "a%02d:", i);
 434                 printk(KERN_CONT " %08lx", regs->areg[i]);
 435         }
 436         printk(KERN_CONT "\n");
 437
 438         printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 439                regs->pc, regs->ps, regs->depc, regs->excvaddr);
 440         printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 441                regs->lbeg, regs->lend, regs->lcount, regs->sar);
 442         if (user_mode(regs))
 443                 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 444                        regs->windowbase, regs->windowstart, regs->wmask,
 445                        regs->syscall);
 446 }
 447
 448 static int show_trace_cb(struct stackframe *frame, void *data)
 449 {
 450         if (kernel_text_address(frame->pc)) {
 451                 printk(" [<%08lx>] ", frame->pc);
 452                 print_symbol("%s\n", frame->pc);
 453         }
 454         return 0;
 455 }
 456
 457 void show_trace(struct task_struct *task, unsigned long *sp)
 458 {
 459         if (!sp)
 460                 sp = stack_pointer(task);
 461
 462         printk("Call Trace:");
 463 #ifdef CONFIG_KALLSYMS
 464         printk("\n");
 465 #endif
 466         walk_stackframe(sp, show_trace_cb, NULL);
 467         printk("\n");
 468 }
 469
 470 /*
 471  * This routine abuses get_user()/put_user() to reference pointers
 472  * with at least a bit of error checking ...
 473  */
 474
 475 static int kstack_depth_to_print = 24;
 476
 477 void show_stack(struct task_struct *task, unsigned long *sp)
 478 {
 479         int i = 0;
 480         unsigned long *stack;
 481
 482         if (!sp)
 483                 sp = stack_pointer(task);
 484         stack = sp;
 485
 486         printk("\nStack: ");
 487
 488         for (i = 0; i < kstack_depth_to_print; i++) {
 489                 if (kstack_end(sp))
 490                         break;
 491                 if (i && ((i % 8) == 0))
 492                         printk("\n       ");
 493                 printk("%08lx ", *sp++);
 494         }
 495         printk("\n");
 496         show_trace(task, stack);
 497 }
 498
 499 void show_code(unsigned int *pc)
 500 {
 501         long i;
 502
 503         printk("\nCode:");
 504
 505         for(i = -3 ; i < 6 ; i++) {
 506                 unsigned long insn;
 507                 if (__get_user(insn, pc + i)) {
 508                         printk(" (Bad address in pc)\n");
 509                         break;
 510                 }
 511                 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
 512         }
 513 }
 514
 515 DEFINE_SPINLOCK(die_lock);
 516
 517 void die(const char * str, struct pt_regs * regs, long err)
 518 {
 519         static int die_counter;
 520         int nl = 0;
 521
 522         console_verbose();
 523         spin_lock_irq(&die_lock);
 524
 525         printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter);
 526 #ifdef CONFIG_PREEMPT
 527         printk("PREEMPT ");
 528         nl = 1;
 529 #endif
 530         if (nl)
 531                 printk("\n");
 532         show_regs(regs);
 533         if (!user_mode(regs))
 534                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 535
 536         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 537         spin_unlock_irq(&die_lock);
 538
 539         if (in_interrupt())
 540                 panic("Fatal exception in interrupt");
 541
 542         if (panic_on_oops)
 543                 panic("Fatal exception");
 544
 545         do_exit(err);
 546 }