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/signal.h>
  28 #include <linux/sched/debug.h>
  29 #include <linux/sched/task_stack.h>
  30 #include <linux/init.h>
  31 #include <linux/module.h>
  32 #include <linux/stringify.h>
  33 #include <linux/kallsyms.h>
  34 #include <linux/delay.h>
  35 #include <linux/hardirq.h>
  36
  37 #include <asm/stacktrace.h>
  38 #include <asm/ptrace.h>
  39 #include <asm/timex.h>
  40 #include <linux/uaccess.h>
  41 #include <asm/pgtable.h>
  42 #include <asm/processor.h>
  43 #include <asm/traps.h>
  44 #include <asm/hw_breakpoint.h>
  45
  46 /*
  47  * Machine specific interrupt handlers
  48  */
  49
  50 extern void kernel_exception(void);
  51 extern void user_exception(void);
  52
  53 extern void fast_syscall_kernel(void);
  54 extern void fast_syscall_user(void);
  55 extern void fast_alloca(void);
  56 extern void fast_unaligned(void);
  57 extern void fast_second_level_miss(void);
  58 extern void fast_store_prohibited(void);
  59 extern void fast_coprocessor(void);
  60
  61 extern void do_illegal_instruction (struct pt_regs*);
  62 extern void do_interrupt (struct pt_regs*);
  63 extern void do_nmi(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 #endif
 104 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 105 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 106 #endif
 107 #ifdef CONFIG_MMU
 108 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 109 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 110 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 111 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 112 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 113 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 114 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 115 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 116 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 117 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 118 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 121 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 122 #endif /* CONFIG_MMU */
 123 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 124 #if XTENSA_HAVE_COPROCESSOR(0)
 125 COPROCESSOR(0),
 126 #endif
 127 #if XTENSA_HAVE_COPROCESSOR(1)
 128 COPROCESSOR(1),
 129 #endif
 130 #if XTENSA_HAVE_COPROCESSOR(2)
 131 COPROCESSOR(2),
 132 #endif
 133 #if XTENSA_HAVE_COPROCESSOR(3)
 134 COPROCESSOR(3),
 135 #endif
 136 #if XTENSA_HAVE_COPROCESSOR(4)
 137 COPROCESSOR(4),
 138 #endif
 139 #if XTENSA_HAVE_COPROCESSOR(5)
 140 COPROCESSOR(5),
 141 #endif
 142 #if XTENSA_HAVE_COPROCESSOR(6)
 143 COPROCESSOR(6),
 144 #endif
 145 #if XTENSA_HAVE_COPROCESSOR(7)
 146 COPROCESSOR(7),
 147 #endif
 148 #if XTENSA_FAKE_NMI
 149 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 150 #endif
 151 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 152 { -1, -1, 0 }
 153
 154 };
 155
 156 /* The exception table <exc_table> serves two functions:
 157  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 158  * 2. it is a temporary memory buffer for the exception handlers.
 159  */
 160
 161 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
 162
 163 DEFINE_PER_CPU(struct debug_table, debug_table);
 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 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
 209
 210 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
 211       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
 212 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
 213 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
 214
 215 static inline void check_valid_nmi(void)
 216 {
 217         unsigned intread = get_sr(interrupt);
 218         unsigned intenable = get_sr(intenable);
 219
 220         BUG_ON(intread & intenable &
 221                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
 222                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
 223                  BIT(XCHAL_PROFILING_INTERRUPT)));
 224 }
 225
 226 #else
 227
 228 static inline void check_valid_nmi(void)
 229 {
 230 }
 231
 232 #endif
 233
 234 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 235
 236 DEFINE_PER_CPU(unsigned long, nmi_count);
 237
 238 void do_nmi(struct pt_regs *regs)
 239 {
 240         struct pt_regs *old_regs;
 241
 242         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
 243                 trace_hardirqs_off();
 244
 245         old_regs = set_irq_regs(regs);
 246         nmi_enter();
 247         ++*this_cpu_ptr(&nmi_count);
 248         check_valid_nmi();
 249         xtensa_pmu_irq_handler(0, NULL);
 250         nmi_exit();
 251         set_irq_regs(old_regs);
 252 }
 253 #endif
 254
 255 void do_interrupt(struct pt_regs *regs)
 256 {
 257         static const unsigned int_level_mask[] = {
 258                 0,
 259                 XCHAL_INTLEVEL1_MASK,
 260                 XCHAL_INTLEVEL2_MASK,
 261                 XCHAL_INTLEVEL3_MASK,
 262                 XCHAL_INTLEVEL4_MASK,
 263                 XCHAL_INTLEVEL5_MASK,
 264                 XCHAL_INTLEVEL6_MASK,
 265                 XCHAL_INTLEVEL7_MASK,
 266         };
 267         struct pt_regs *old_regs;
 268
 269         trace_hardirqs_off();
 270
 271         old_regs = set_irq_regs(regs);
 272         irq_enter();
 273
 274         for (;;) {
 275                 unsigned intread = get_sr(interrupt);
 276                 unsigned intenable = get_sr(intenable);
 277                 unsigned int_at_level = intread & intenable;
 278                 unsigned level;
 279
 280                 for (level = LOCKLEVEL; level > 0; --level) {
 281                         if (int_at_level & int_level_mask[level]) {
 282                                 int_at_level &= int_level_mask[level];
 283                                 break;
 284                         }
 285                 }
 286
 287                 if (level == 0)
 288                         break;
 289
 290                 do_IRQ(__ffs(int_at_level), regs);
 291         }
 292
 293         irq_exit();
 294         set_irq_regs(old_regs);
 295 }
 296
 297 /*
 298  * Illegal instruction. Fatal if in kernel space.
 299  */
 300
 301 void
 302 do_illegal_instruction(struct pt_regs *regs)
 303 {
 304         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 305
 306         /* If in user mode, send SIGILL signal to current process. */
 307
 308         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 309             current->comm, task_pid_nr(current), regs->pc);
 310         force_sig(SIGILL, current);
 311 }
 312
 313
 314 /*
 315  * Handle unaligned memory accesses from user space. Kill task.
 316  *
 317  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 318  * accesses causes from user space.
 319  */
 320
 321 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 322 void
 323 do_unaligned_user (struct pt_regs *regs)
 324 {
 325         siginfo_t info;
 326
 327         __die_if_kernel("Unhandled unaligned exception in kernel",
 328                         regs, SIGKILL);
 329
 330         current->thread.bad_vaddr = regs->excvaddr;
 331         current->thread.error_code = -3;
 332         printk("Unaligned memory access to %08lx in '%s' "
 333                "(pid = %d, pc = %#010lx)\n",
 334                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 335         info.si_signo = SIGBUS;
 336         info.si_errno = 0;
 337         info.si_code = BUS_ADRALN;
 338         info.si_addr = (void *) regs->excvaddr;
 339         force_sig_info(SIGBUS, &info, current);
 340
 341 }
 342 #endif
 343
 344 /* Handle debug events.
 345  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 346  * preemption disabled to avoid rescheduling and keep mapping of hardware
 347  * breakpoint structures to debug registers intact, so that
 348  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 349  */
 350 void
 351 do_debug(struct pt_regs *regs)
 352 {
 353 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 354         int ret = check_hw_breakpoint(regs);
 355
 356         preempt_enable();
 357         if (ret == 0)
 358                 return;
 359 #endif
 360         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 361
 362         /* If in user mode, send SIGTRAP signal to current process */
 363
 364         force_sig(SIGTRAP, current);
 365 }
 366
 367
 368 static void set_handler(int idx, void *handler)
 369 {
 370         unsigned int cpu;
 371
 372         for_each_possible_cpu(cpu)
 373                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
 374 }
 375
 376 /* Set exception C handler - for temporary use when probing exceptions */
 377
 378 void * __init trap_set_handler(int cause, void *handler)
 379 {
 380         void *previous = (void *)per_cpu(exc_table, 0)[
 381                 EXC_TABLE_DEFAULT / 4 + cause];
 382         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
 383         return previous;
 384 }
 385
 386
 387 static void trap_init_excsave(void)
 388 {
 389         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
 390         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 391 }
 392
 393 static void trap_init_debug(void)
 394 {
 395         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
 396
 397         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
 398         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
 399                              :: "a"(debugsave));
 400 }
 401
 402 /*
 403  * Initialize dispatch tables.
 404  *
 405  * The exception vectors are stored compressed the __init section in the
 406  * dispatch_init_table. This function initializes the following three tables
 407  * from that compressed table:
 408  * - fast user          first dispatch table for user exceptions
 409  * - fast kernel        first dispatch table for kernel exceptions
 410  * - default C-handler  C-handler called by the default fast handler.
 411  *
 412  * See vectors.S for more details.
 413  */
 414
 415 void __init trap_init(void)
 416 {
 417         int i;
 418
 419         /* Setup default vectors. */
 420
 421         for(i = 0; i < 64; i++) {
 422                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 423                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 424                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 425         }
 426
 427         /* Setup specific handlers. */
 428
 429         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 430
 431                 int fast = dispatch_init_table[i].fast;
 432                 int cause = dispatch_init_table[i].cause;
 433                 void *handler = dispatch_init_table[i].handler;
 434
 435                 if (fast == 0)
 436                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 437                 if (fast && fast & USER)
 438                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 439                 if (fast && fast & KRNL)
 440                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 441         }
 442
 443         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 444         trap_init_excsave();
 445         trap_init_debug();
 446 }
 447
 448 #ifdef CONFIG_SMP
 449 void secondary_trap_init(void)
 450 {
 451         trap_init_excsave();
 452         trap_init_debug();
 453 }
 454 #endif
 455
 456 /*
 457  * This function dumps the current valid window frame and other base registers.
 458  */
 459
 460 void show_regs(struct pt_regs * regs)
 461 {
 462         int i, wmask;
 463
 464         show_regs_print_info(KERN_DEFAULT);
 465
 466         wmask = regs->wmask & ~1;
 467
 468         for (i = 0; i < 16; i++) {
 469                 if ((i % 8) == 0)
 470                         pr_info("a%02d:", i);
 471                 pr_cont(" %08lx", regs->areg[i]);
 472         }
 473         pr_cont("\n");
 474         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 475                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
 476         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 477                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
 478         if (user_mode(regs))
 479                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 480                         regs->windowbase, regs->windowstart, regs->wmask,
 481                         regs->syscall);
 482 }
 483
 484 static int show_trace_cb(struct stackframe *frame, void *data)
 485 {
 486         if (kernel_text_address(frame->pc))
 487                 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc);
 488         return 0;
 489 }
 490
 491 void show_trace(struct task_struct *task, unsigned long *sp)
 492 {
 493         if (!sp)
 494                 sp = stack_pointer(task);
 495
 496         pr_info("Call Trace:\n");
 497         walk_stackframe(sp, show_trace_cb, NULL);
 498 #ifndef CONFIG_KALLSYMS
 499         pr_cont("\n");
 500 #endif
 501 }
 502
 503 static int kstack_depth_to_print = 24;
 504
 505 void show_stack(struct task_struct *task, unsigned long *sp)
 506 {
 507         int i = 0;
 508         unsigned long *stack;
 509
 510         if (!sp)
 511                 sp = stack_pointer(task);
 512         stack = sp;
 513
 514         pr_info("Stack:\n");
 515
 516         for (i = 0; i < kstack_depth_to_print; i++) {
 517                 if (kstack_end(sp))
 518                         break;
 519                 pr_cont(" %08lx", *sp++);
 520                 if (i % 8 == 7)
 521                         pr_cont("\n");
 522         }
 523         show_trace(task, stack);
 524 }
 525
 526 DEFINE_SPINLOCK(die_lock);
 527
 528 void die(const char * str, struct pt_regs * regs, long err)
 529 {
 530         static int die_counter;
 531
 532         console_verbose();
 533         spin_lock_irq(&die_lock);
 534
 535         pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter,
 536                 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "");
 537         show_regs(regs);
 538         if (!user_mode(regs))
 539                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 540
 541         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 542         spin_unlock_irq(&die_lock);
 543
 544         if (in_interrupt())
 545                 panic("Fatal exception in interrupt");
 546
 547         if (panic_on_oops)
 548                 panic("Fatal exception");
 549
 550         do_exit(err);
 551 }