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_illegal_instruction_user(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 #ifdef CONFIG_USER_ABI_CALL0_PROBE
  92 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER,      fast_illegal_instruction_user },
  93 #endif
  94 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  95 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  96 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  97 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  98 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  99 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
 100 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
 101 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
 102 /* EXCCAUSE_PRIVILEGED unhandled */
 103 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 104 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 105 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 106 #endif
 107 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 108 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 109 #endif
 110 #ifdef CONFIG_MMU
 111 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 112 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 113 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 114 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 115 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 116 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 117 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 118 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 119 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 120 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 121 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 123 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 124 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 125 #endif /* CONFIG_MMU */
 126 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 127 #if XTENSA_HAVE_COPROCESSOR(0)
 128 COPROCESSOR(0),
 129 #endif
 130 #if XTENSA_HAVE_COPROCESSOR(1)
 131 COPROCESSOR(1),
 132 #endif
 133 #if XTENSA_HAVE_COPROCESSOR(2)
 134 COPROCESSOR(2),
 135 #endif
 136 #if XTENSA_HAVE_COPROCESSOR(3)
 137 COPROCESSOR(3),
 138 #endif
 139 #if XTENSA_HAVE_COPROCESSOR(4)
 140 COPROCESSOR(4),
 141 #endif
 142 #if XTENSA_HAVE_COPROCESSOR(5)
 143 COPROCESSOR(5),
 144 #endif
 145 #if XTENSA_HAVE_COPROCESSOR(6)
 146 COPROCESSOR(6),
 147 #endif
 148 #if XTENSA_HAVE_COPROCESSOR(7)
 149 COPROCESSOR(7),
 150 #endif
 151 #if XTENSA_FAKE_NMI
 152 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 153 #endif
 154 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 155 { -1, -1, 0 }
 156
 157 };
 158
 159 /* The exception table <exc_table> serves two functions:
 160  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 161  * 2. it is a temporary memory buffer for the exception handlers.
 162  */
 163
 164 DEFINE_PER_CPU(struct exc_table, exc_table);
 165 DEFINE_PER_CPU(struct debug_table, debug_table);
 166
 167 void die(const char*, struct pt_regs*, long);
 168
 169 static inline void
 170 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 171 {
 172         if (!user_mode(regs))
 173                 die(str, regs, err);
 174 }
 175
 176 /*
 177  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 178  */
 179
 180 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 181 {
 182         __die_if_kernel("Caught unhandled exception - should not happen",
 183                         regs, SIGKILL);
 184
 185         /* If in user mode, send SIGILL signal to current process */
 186         pr_info_ratelimited("Caught unhandled exception in '%s' "
 187                             "(pid = %d, pc = %#010lx) - should not happen\n"
 188                             "\tEXCCAUSE is %ld\n",
 189                             current->comm, task_pid_nr(current), regs->pc,
 190                             exccause);
 191         force_sig(SIGILL);
 192 }
 193
 194 /*
 195  * Multi-hit exception. This if fatal!
 196  */
 197
 198 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 199 {
 200         die("Caught multihit exception", regs, SIGKILL);
 201 }
 202
 203 /*
 204  * IRQ handler.
 205  */
 206
 207 extern void do_IRQ(int, struct pt_regs *);
 208
 209 #if XTENSA_FAKE_NMI
 210
 211 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
 212
 213 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
 214       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
 215 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
 216 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
 217
 218 static inline void check_valid_nmi(void)
 219 {
 220         unsigned intread = xtensa_get_sr(interrupt);
 221         unsigned intenable = xtensa_get_sr(intenable);
 222
 223         BUG_ON(intread & intenable &
 224                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
 225                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
 226                  BIT(XCHAL_PROFILING_INTERRUPT)));
 227 }
 228
 229 #else
 230
 231 static inline void check_valid_nmi(void)
 232 {
 233 }
 234
 235 #endif
 236
 237 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 238
 239 DEFINE_PER_CPU(unsigned long, nmi_count);
 240
 241 void do_nmi(struct pt_regs *regs)
 242 {
 243         struct pt_regs *old_regs;
 244
 245         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
 246                 trace_hardirqs_off();
 247
 248         old_regs = set_irq_regs(regs);
 249         nmi_enter();
 250         ++*this_cpu_ptr(&nmi_count);
 251         check_valid_nmi();
 252         xtensa_pmu_irq_handler(0, NULL);
 253         nmi_exit();
 254         set_irq_regs(old_regs);
 255 }
 256 #endif
 257
 258 void do_interrupt(struct pt_regs *regs)
 259 {
 260         static const unsigned int_level_mask[] = {
 261                 0,
 262                 XCHAL_INTLEVEL1_MASK,
 263                 XCHAL_INTLEVEL2_MASK,
 264                 XCHAL_INTLEVEL3_MASK,
 265                 XCHAL_INTLEVEL4_MASK,
 266                 XCHAL_INTLEVEL5_MASK,
 267                 XCHAL_INTLEVEL6_MASK,
 268                 XCHAL_INTLEVEL7_MASK,
 269         };
 270         struct pt_regs *old_regs;
 271
 272         trace_hardirqs_off();
 273
 274         old_regs = set_irq_regs(regs);
 275         irq_enter();
 276
 277         for (;;) {
 278                 unsigned intread = xtensa_get_sr(interrupt);
 279                 unsigned intenable = xtensa_get_sr(intenable);
 280                 unsigned int_at_level = intread & intenable;
 281                 unsigned level;
 282
 283                 for (level = LOCKLEVEL; level > 0; --level) {
 284                         if (int_at_level & int_level_mask[level]) {
 285                                 int_at_level &= int_level_mask[level];
 286                                 break;
 287                         }
 288                 }
 289
 290                 if (level == 0)
 291                         break;
 292
 293                 do_IRQ(__ffs(int_at_level), regs);
 294         }
 295
 296         irq_exit();
 297         set_irq_regs(old_regs);
 298 }
 299
 300 /*
 301  * Illegal instruction. Fatal if in kernel space.
 302  */
 303
 304 void
 305 do_illegal_instruction(struct pt_regs *regs)
 306 {
 307         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 308
 309         /* If in user mode, send SIGILL signal to current process. */
 310
 311         pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 312                             current->comm, task_pid_nr(current), regs->pc);
 313         force_sig(SIGILL);
 314 }
 315
 316
 317 /*
 318  * Handle unaligned memory accesses from user space. Kill task.
 319  *
 320  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 321  * accesses causes from user space.
 322  */
 323
 324 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 325 void
 326 do_unaligned_user (struct pt_regs *regs)
 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         force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
 338 }
 339 #endif
 340
 341 /* Handle debug events.
 342  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 343  * preemption disabled to avoid rescheduling and keep mapping of hardware
 344  * breakpoint structures to debug registers intact, so that
 345  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 346  */
 347 void
 348 do_debug(struct pt_regs *regs)
 349 {
 350 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 351         int ret = check_hw_breakpoint(regs);
 352
 353         preempt_enable();
 354         if (ret == 0)
 355                 return;
 356 #endif
 357         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 358
 359         /* If in user mode, send SIGTRAP signal to current process */
 360
 361         force_sig(SIGTRAP);
 362 }
 363
 364
 365 #define set_handler(type, cause, handler)                               \
 366         do {                                                            \
 367                 unsigned int cpu;                                       \
 368                                                                         \
 369                 for_each_possible_cpu(cpu)                              \
 370                         per_cpu(exc_table, cpu).type[cause] = (handler);\
 371         } while (0)
 372
 373 /* Set exception C handler - for temporary use when probing exceptions */
 374
 375 void * __init trap_set_handler(int cause, void *handler)
 376 {
 377         void *previous = per_cpu(exc_table, 0).default_handler[cause];
 378
 379         set_handler(default_handler, cause, handler);
 380         return previous;
 381 }
 382
 383
 384 static void trap_init_excsave(void)
 385 {
 386         unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table);
 387         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 388 }
 389
 390 static void trap_init_debug(void)
 391 {
 392         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
 393
 394         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
 395         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
 396                              :: "a"(debugsave));
 397 }
 398
 399 /*
 400  * Initialize dispatch tables.
 401  *
 402  * The exception vectors are stored compressed the __init section in the
 403  * dispatch_init_table. This function initializes the following three tables
 404  * from that compressed table:
 405  * - fast user          first dispatch table for user exceptions
 406  * - fast kernel        first dispatch table for kernel exceptions
 407  * - default C-handler  C-handler called by the default fast handler.
 408  *
 409  * See vectors.S for more details.
 410  */
 411
 412 void __init trap_init(void)
 413 {
 414         int i;
 415
 416         /* Setup default vectors. */
 417
 418         for (i = 0; i < EXCCAUSE_N; i++) {
 419                 set_handler(fast_user_handler, i, user_exception);
 420                 set_handler(fast_kernel_handler, i, kernel_exception);
 421                 set_handler(default_handler, i, do_unhandled);
 422         }
 423
 424         /* Setup specific handlers. */
 425
 426         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 427                 int fast = dispatch_init_table[i].fast;
 428                 int cause = dispatch_init_table[i].cause;
 429                 void *handler = dispatch_init_table[i].handler;
 430
 431                 if (fast == 0)
 432                         set_handler(default_handler, cause, handler);
 433                 if ((fast & USER) != 0)
 434                         set_handler(fast_user_handler, cause, handler);
 435                 if ((fast & KRNL) != 0)
 436                         set_handler(fast_kernel_handler, cause, handler);
 437         }
 438
 439         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 440         trap_init_excsave();
 441         trap_init_debug();
 442 }
 443
 444 #ifdef CONFIG_SMP
 445 void secondary_trap_init(void)
 446 {
 447         trap_init_excsave();
 448         trap_init_debug();
 449 }
 450 #endif
 451
 452 /*
 453  * This function dumps the current valid window frame and other base registers.
 454  */
 455
 456 void show_regs(struct pt_regs * regs)
 457 {
 458         int i, wmask;
 459
 460         show_regs_print_info(KERN_DEFAULT);
 461
 462         wmask = regs->wmask & ~1;
 463
 464         for (i = 0; i < 16; i++) {
 465                 if ((i % 8) == 0)
 466                         pr_info("a%02d:", i);
 467                 pr_cont(" %08lx", regs->areg[i]);
 468         }
 469         pr_cont("\n");
 470         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 471                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
 472         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 473                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
 474         if (user_mode(regs))
 475                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 476                         regs->windowbase, regs->windowstart, regs->wmask,
 477                         regs->syscall);
 478 }
 479
 480 static int show_trace_cb(struct stackframe *frame, void *data)
 481 {
 482         if (kernel_text_address(frame->pc))
 483                 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc);
 484         return 0;
 485 }
 486
 487 void show_trace(struct task_struct *task, unsigned long *sp)
 488 {
 489         if (!sp)
 490                 sp = stack_pointer(task);
 491
 492         pr_info("Call Trace:\n");
 493         walk_stackframe(sp, show_trace_cb, NULL);
 494 }
 495
 496 #define STACK_DUMP_ENTRY_SIZE 4
 497 #define STACK_DUMP_LINE_SIZE 32
 498 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
 499
 500 void show_stack(struct task_struct *task, unsigned long *sp)
 501 {
 502         size_t len;
 503
 504         if (!sp)
 505                 sp = stack_pointer(task);
 506
 507         len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
 508                   kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
 509
 510         pr_info("Stack:\n");
 511         print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
 512                        STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
 513                        sp, len, false);
 514         show_trace(task, sp);
 515 }
 516
 517 DEFINE_SPINLOCK(die_lock);
 518
 519 void die(const char * str, struct pt_regs * regs, long err)
 520 {
 521         static int die_counter;
 522         const char *pr = "";
 523
 524         if (IS_ENABLED(CONFIG_PREEMPTION))
 525                 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
 526
 527         console_verbose();
 528         spin_lock_irq(&die_lock);
 529
 530         pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
 531         show_regs(regs);
 532         if (!user_mode(regs))
 533                 show_stack(NULL, (unsigned long*)regs->areg[1]);
 534
 535         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 536         spin_unlock_irq(&die_lock);
 537
 538         if (in_interrupt())
 539                 panic("Fatal exception in interrupt");
 540
 541         if (panic_on_oops)
 542                 panic("Fatal exception");
 543
 544         do_exit(err);
 545 }