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 #include <linux/ratelimit.h>
  37
  38 #include <asm/stacktrace.h>
  39 #include <asm/ptrace.h>
  40 #include <asm/timex.h>
  41 #include <linux/uaccess.h>
  42 #include <asm/pgtable.h>
  43 #include <asm/processor.h>
  44 #include <asm/traps.h>
  45 #include <asm/hw_breakpoint.h>
  46
  47 /*
  48  * Machine specific interrupt handlers
  49  */
  50
  51 extern void kernel_exception(void);
  52 extern void user_exception(void);
  53
  54 extern void fast_syscall_kernel(void);
  55 extern void fast_syscall_user(void);
  56 extern void fast_alloca(void);
  57 extern void fast_unaligned(void);
  58 extern void fast_second_level_miss(void);
  59 extern void fast_store_prohibited(void);
  60 extern void fast_coprocessor(void);
  61
  62 extern void do_illegal_instruction (struct pt_regs*);
  63 extern void do_interrupt (struct pt_regs*);
  64 extern void do_nmi(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 #if XTENSA_FAKE_NMI
 150 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 151 #endif
 152 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 153 { -1, -1, 0 }
 154
 155 };
 156
 157 /* The exception table <exc_table> serves two functions:
 158  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 159  * 2. it is a temporary memory buffer for the exception handlers.
 160  */
 161
 162 DEFINE_PER_CPU(struct exc_table, exc_table);
 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         pr_info_ratelimited("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,
 188                             exccause);
 189         force_sig(SIGILL, current);
 190 }
 191
 192 /*
 193  * Multi-hit exception. This if fatal!
 194  */
 195
 196 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 197 {
 198         die("Caught multihit exception", regs, SIGKILL);
 199 }
 200
 201 /*
 202  * IRQ handler.
 203  */
 204
 205 extern void do_IRQ(int, struct pt_regs *);
 206
 207 #if XTENSA_FAKE_NMI
 208
 209 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
 210
 211 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
 212       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
 213 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
 214 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
 215
 216 static inline void check_valid_nmi(void)
 217 {
 218         unsigned intread = get_sr(interrupt);
 219         unsigned intenable = get_sr(intenable);
 220
 221         BUG_ON(intread & intenable &
 222                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
 223                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
 224                  BIT(XCHAL_PROFILING_INTERRUPT)));
 225 }
 226
 227 #else
 228
 229 static inline void check_valid_nmi(void)
 230 {
 231 }
 232
 233 #endif
 234
 235 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 236
 237 DEFINE_PER_CPU(unsigned long, nmi_count);
 238
 239 void do_nmi(struct pt_regs *regs)
 240 {
 241         struct pt_regs *old_regs;
 242
 243         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
 244                 trace_hardirqs_off();
 245
 246         old_regs = set_irq_regs(regs);
 247         nmi_enter();
 248         ++*this_cpu_ptr(&nmi_count);
 249         check_valid_nmi();
 250         xtensa_pmu_irq_handler(0, NULL);
 251         nmi_exit();
 252         set_irq_regs(old_regs);
 253 }
 254 #endif
 255
 256 void do_interrupt(struct pt_regs *regs)
 257 {
 258         static const unsigned int_level_mask[] = {
 259                 0,
 260                 XCHAL_INTLEVEL1_MASK,
 261                 XCHAL_INTLEVEL2_MASK,
 262                 XCHAL_INTLEVEL3_MASK,
 263                 XCHAL_INTLEVEL4_MASK,
 264                 XCHAL_INTLEVEL5_MASK,
 265                 XCHAL_INTLEVEL6_MASK,
 266                 XCHAL_INTLEVEL7_MASK,
 267         };
 268         struct pt_regs *old_regs;
 269
 270         trace_hardirqs_off();
 271
 272         old_regs = set_irq_regs(regs);
 273         irq_enter();
 274
 275         for (;;) {
 276                 unsigned intread = get_sr(interrupt);
 277                 unsigned intenable = get_sr(intenable);
 278                 unsigned int_at_level = intread & intenable;
 279                 unsigned level;
 280
 281                 for (level = LOCKLEVEL; level > 0; --level) {
 282                         if (int_at_level & int_level_mask[level]) {
 283                                 int_at_level &= int_level_mask[level];
 284                                 break;
 285                         }
 286                 }
 287
 288                 if (level == 0)
 289                         break;
 290
 291                 do_IRQ(__ffs(int_at_level), regs);
 292         }
 293
 294         irq_exit();
 295         set_irq_regs(old_regs);
 296 }
 297
 298 /*
 299  * Illegal instruction. Fatal if in kernel space.
 300  */
 301
 302 void
 303 do_illegal_instruction(struct pt_regs *regs)
 304 {
 305         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 306
 307         /* If in user mode, send SIGILL signal to current process. */
 308
 309         pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 310                             current->comm, task_pid_nr(current), regs->pc);
 311         force_sig(SIGILL, current);
 312 }
 313
 314
 315 /*
 316  * Handle unaligned memory accesses from user space. Kill task.
 317  *
 318  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 319  * accesses causes from user space.
 320  */
 321
 322 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 323 void
 324 do_unaligned_user (struct pt_regs *regs)
 325 {
 326         siginfo_t info;
 327
 328         __die_if_kernel("Unhandled unaligned exception in kernel",
 329                         regs, SIGKILL);
 330
 331         current->thread.bad_vaddr = regs->excvaddr;
 332         current->thread.error_code = -3;
 333         pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
 334                             "(pid = %d, pc = %#010lx)\n",
 335                             regs->excvaddr, current->comm,
 336                             task_pid_nr(current), regs->pc);
 337         info.si_signo = SIGBUS;
 338         info.si_errno = 0;
 339         info.si_code = BUS_ADRALN;
 340         info.si_addr = (void *) regs->excvaddr;
 341         force_sig_info(SIGSEGV, &info, current);
 342
 343 }
 344 #endif
 345
 346 /* Handle debug events.
 347  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 348  * preemption disabled to avoid rescheduling and keep mapping of hardware
 349  * breakpoint structures to debug registers intact, so that
 350  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 351  */
 352 void
 353 do_debug(struct pt_regs *regs)
 354 {
 355 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 356         int ret = check_hw_breakpoint(regs);
 357
 358         preempt_enable();
 359         if (ret == 0)
 360                 return;
 361 #endif
 362         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 363
 364         /* If in user mode, send SIGTRAP signal to current process */
 365
 366         force_sig(SIGTRAP, current);
 367 }
 368
 369
 370 #define set_handler(type, cause, handler)                               \
 371         do {                                                            \
 372                 unsigned int cpu;                                       \
 373                                                                         \
 374                 for_each_possible_cpu(cpu)                              \
 375                         per_cpu(exc_table, cpu).type[cause] = (handler);\
 376         } while (0)
 377
 378 /* Set exception C handler - for temporary use when probing exceptions */
 379
 380 void * __init trap_set_handler(int cause, void *handler)
 381 {
 382         void *previous = per_cpu(exc_table, 0).default_handler[cause];
 383
 384         set_handler(default_handler, cause, handler);
 385         return previous;
 386 }
 387
 388
 389 static void trap_init_excsave(void)
 390 {
 391         unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
 392         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 393 }
 394
 395 static void trap_init_debug(void)
 396 {
 397         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
 398
 399         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
 400         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
 401                              :: "a"(debugsave));
 402 }
 403
 404 /*
 405  * Initialize dispatch tables.
 406  *
 407  * The exception vectors are stored compressed the __init section in the
 408  * dispatch_init_table. This function initializes the following three tables
 409  * from that compressed table:
 410  * - fast user          first dispatch table for user exceptions
 411  * - fast kernel        first dispatch table for kernel exceptions
 412  * - default C-handler  C-handler called by the default fast handler.
 413  *
 414  * See vectors.S for more details.
 415  */
 416
 417 void __init trap_init(void)
 418 {
 419         int i;
 420
 421         /* Setup default vectors. */
 422
 423         for (i = 0; i < EXCCAUSE_N; i++) {
 424                 set_handler(fast_user_handler, i, user_exception);
 425                 set_handler(fast_kernel_handler, i, kernel_exception);
 426                 set_handler(default_handler, i, do_unhandled);
 427         }
 428
 429         /* Setup specific handlers. */
 430
 431         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 432
 433                 int fast = dispatch_init_table[i].fast;
 434                 int cause = dispatch_init_table[i].cause;
 435                 void *handler = dispatch_init_table[i].handler;
 436
 437                 if (fast == 0)
 438                         set_handler(default_handler, cause, handler);
 439                 if (fast && fast & USER)
 440                         set_handler(fast_user_handler, cause, handler);
 441                 if (fast && fast & KRNL)
 442                         set_handler(fast_kernel_handler, cause, handler);
 443         }
 444
 445         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 446         trap_init_excsave();
 447         trap_init_debug();
 448 }
 449
 450 #ifdef CONFIG_SMP
 451 void secondary_trap_init(void)
 452 {
 453         trap_init_excsave();
 454         trap_init_debug();
 455 }
 456 #endif
 457
 458 /*
 459  * This function dumps the current valid window frame and other base registers.
 460  */
 461
 462 void show_regs(struct pt_regs * regs)
 463 {
 464         int i, wmask;
 465
 466         show_regs_print_info(KERN_DEFAULT);
 467
 468         wmask = regs->wmask & ~1;
 469
 470         for (i = 0; i < 16; i++) {
 471                 if ((i % 8) == 0)
 472                         pr_info("a%02d:", i);
 473                 pr_cont(" %08lx", regs->areg[i]);
 474         }
 475         pr_cont("\n");
 476         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 477                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
 478         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 479                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
 480         if (user_mode(regs))
 481                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 482                         regs->windowbase, regs->windowstart, regs->wmask,
 483                         regs->syscall);
 484 }
 485
 486 static int show_trace_cb(struct stackframe *frame, void *data)
 487 {
 488         if (kernel_text_address(frame->pc))
 489                 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc);
 490         return 0;
 491 }
 492
 493 void show_trace(struct task_struct *task, unsigned long *sp)
 494 {
 495         if (!sp)
 496                 sp = stack_pointer(task);
 497
 498         pr_info("Call Trace:\n");
 499         walk_stackframe(sp, show_trace_cb, NULL);
 500 #ifndef CONFIG_KALLSYMS
 501         pr_cont("\n");
 502 #endif
 503 }
 504
 505 static int kstack_depth_to_print = 24;
 506
 507 void show_stack(struct task_struct *task, unsigned long *sp)
 508 {
 509         int i = 0;
 510         unsigned long *stack;
 511
 512         if (!sp)
 513                 sp = stack_pointer(task);
 514         stack = sp;
 515
 516         pr_info("Stack:\n");
 517
 518         for (i = 0; i < kstack_depth_to_print; i++) {
 519                 if (kstack_end(sp))
 520                         break;
 521                 pr_cont(" %08lx", *sp++);
 522                 if (i % 8 == 7)
 523                         pr_cont("\n");
 524         }
 525         show_trace(task, stack);
 526 }
 527
 528 DEFINE_SPINLOCK(die_lock);
 529
 530 void die(const char * str, struct pt_regs * regs, long err)
 531 {
 532         static int die_counter;
 533
 534         console_verbose();
 535         spin_lock_irq(&die_lock);
 536
 537         pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter,
 538                 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "");
 539         show_regs(regs);
 540         if (!user_mode(regs))
 541                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 542
 543         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 544         spin_unlock_irq(&die_lock);
 545
 546         if (in_interrupt())
 547                 panic("Fatal exception in interrupt");
 548
 549         if (panic_on_oops)
 550                 panic("Fatal exception");
 551
 552         do_exit(err);
 553 }