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/cpu.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched/signal.h>
  29 #include <linux/sched/debug.h>
  30 #include <linux/sched/task_stack.h>
  31 #include <linux/init.h>
  32 #include <linux/module.h>
  33 #include <linux/stringify.h>
  34 #include <linux/kallsyms.h>
  35 #include <linux/delay.h>
  36 #include <linux/hardirq.h>
  37 #include <linux/ratelimit.h>
  38 #include <linux/pgtable.h>
  39
  40 #include <asm/stacktrace.h>
  41 #include <asm/ptrace.h>
  42 #include <asm/timex.h>
  43 #include <linux/uaccess.h>
  44 #include <asm/processor.h>
  45 #include <asm/traps.h>
  46 #include <asm/hw_breakpoint.h>
  47
  48 /*
  49  * Machine specific interrupt handlers
  50  */
  51
  52 static void do_illegal_instruction(struct pt_regs *regs);
  53 static void do_div0(struct pt_regs *regs);
  54 static void do_interrupt(struct pt_regs *regs);
  55 #if XTENSA_FAKE_NMI
  56 static void do_nmi(struct pt_regs *regs);
  57 #endif
  58 #ifdef CONFIG_XTENSA_LOAD_STORE
  59 static void do_load_store(struct pt_regs *regs);
  60 #endif
  61 static void do_unaligned_user(struct pt_regs *regs);
  62 static void do_multihit(struct pt_regs *regs);
  63 #if XTENSA_HAVE_COPROCESSORS
  64 static void do_coprocessor(struct pt_regs *regs);
  65 #endif
  66 static void do_debug(struct pt_regs *regs);
  67
  68 /*
  69  * The vector table must be preceded by a save area (which
  70  * implies it must be in RAM, unless one places RAM immediately
  71  * before a ROM and puts the vector at the start of the ROM (!))
  72  */
  73
  74 #define KRNL            0x01
  75 #define USER            0x02
  76
  77 #define COPROCESSOR(x)                                                  \
  78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER|KRNL, fast_coprocessor },\
  79 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, 0, do_coprocessor }
  80
  81 typedef struct {
  82         int cause;
  83         int fast;
  84         void* handler;
  85 } dispatch_init_table_t;
  86
  87 static dispatch_init_table_t __initdata dispatch_init_table[] = {
  88
  89 #ifdef CONFIG_USER_ABI_CALL0_PROBE
  90 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER,      fast_illegal_instruction_user },
  91 #endif
  92 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  93 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  94 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  96 #ifdef CONFIG_XTENSA_LOAD_STORE
  97 { EXCCAUSE_LOAD_STORE_ERROR,    USER|KRNL, fast_load_store },
  98 { EXCCAUSE_LOAD_STORE_ERROR,    0,         do_load_store },
  99 #endif
 100 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
 101 #ifdef SUPPORT_WINDOWED
 102 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
 103 #endif
 104 { EXCCAUSE_INTEGER_DIVIDE_BY_ZERO, 0,      do_div0 },
 105 /* EXCCAUSE_PRIVILEGED unhandled */
 106 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION || \
 107                 IS_ENABLED(CONFIG_XTENSA_LOAD_STORE)
 108 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 109 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 110 #endif
 111 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 112 #endif
 113 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 114 #ifdef CONFIG_MMU
 115 { EXCCAUSE_ITLB_MISS,                   0,         do_page_fault },
 116 { EXCCAUSE_ITLB_MISS,                   USER|KRNL, fast_second_level_miss},
 117 { EXCCAUSE_DTLB_MISS,                   USER|KRNL, fast_second_level_miss},
 118 { EXCCAUSE_DTLB_MISS,                   0,         do_page_fault },
 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 120 #endif /* CONFIG_MMU */
 121 #ifdef CONFIG_PFAULT
 122 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 123 { EXCCAUSE_ITLB_PRIVILEGE,              0,         do_page_fault },
 124 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 125 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 126 { EXCCAUSE_DTLB_PRIVILEGE,              0,         do_page_fault },
 127 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 128 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 129 #endif
 130 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 131 #if XTENSA_HAVE_COPROCESSOR(0)
 132 COPROCESSOR(0),
 133 #endif
 134 #if XTENSA_HAVE_COPROCESSOR(1)
 135 COPROCESSOR(1),
 136 #endif
 137 #if XTENSA_HAVE_COPROCESSOR(2)
 138 COPROCESSOR(2),
 139 #endif
 140 #if XTENSA_HAVE_COPROCESSOR(3)
 141 COPROCESSOR(3),
 142 #endif
 143 #if XTENSA_HAVE_COPROCESSOR(4)
 144 COPROCESSOR(4),
 145 #endif
 146 #if XTENSA_HAVE_COPROCESSOR(5)
 147 COPROCESSOR(5),
 148 #endif
 149 #if XTENSA_HAVE_COPROCESSOR(6)
 150 COPROCESSOR(6),
 151 #endif
 152 #if XTENSA_HAVE_COPROCESSOR(7)
 153 COPROCESSOR(7),
 154 #endif
 155 #if XTENSA_FAKE_NMI
 156 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 157 #endif
 158 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 159 { -1, -1, 0 }
 160
 161 };
 162
 163 /* The exception table <exc_table> serves two functions:
 164  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 165  * 2. it is a temporary memory buffer for the exception handlers.
 166  */
 167
 168 DEFINE_PER_CPU(struct exc_table, exc_table);
 169 DEFINE_PER_CPU(struct debug_table, debug_table);
 170
 171 void die(const char*, struct pt_regs*, long);
 172
 173 static inline void
 174 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 175 {
 176         if (!user_mode(regs))
 177                 die(str, regs, err);
 178 }
 179
 180 #ifdef CONFIG_PRINT_USER_CODE_ON_UNHANDLED_EXCEPTION
 181 static inline void dump_user_code(struct pt_regs *regs)
 182 {
 183         char buf[32];
 184
 185         if (copy_from_user(buf, (void __user *)(regs->pc & -16), sizeof(buf)) == 0) {
 186                 print_hex_dump(KERN_INFO, " ", DUMP_PREFIX_NONE,
 187                                32, 1, buf, sizeof(buf), false);
 188
 189         }
 190 }
 191 #else
 192 static inline void dump_user_code(struct pt_regs *regs)
 193 {
 194 }
 195 #endif
 196
 197 /*
 198  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 199  */
 200
 201 void do_unhandled(struct pt_regs *regs)
 202 {
 203         __die_if_kernel("Caught unhandled exception - should not happen",
 204                         regs, SIGKILL);
 205
 206         /* If in user mode, send SIGILL signal to current process */
 207         pr_info_ratelimited("Caught unhandled exception in '%s' "
 208                             "(pid = %d, pc = %#010lx) - should not happen\n"
 209                             "\tEXCCAUSE is %ld\n",
 210                             current->comm, task_pid_nr(current), regs->pc,
 211                             regs->exccause);
 212         dump_user_code(regs);
 213         force_sig(SIGILL);
 214 }
 215
 216 /*
 217  * Multi-hit exception. This if fatal!
 218  */
 219
 220 static void do_multihit(struct pt_regs *regs)
 221 {
 222         die("Caught multihit exception", regs, SIGKILL);
 223 }
 224
 225 /*
 226  * IRQ handler.
 227  */
 228
 229 #if XTENSA_FAKE_NMI
 230
 231 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
 232
 233 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
 234       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
 235 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
 236 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
 237
 238 static inline void check_valid_nmi(void)
 239 {
 240         unsigned intread = xtensa_get_sr(interrupt);
 241         unsigned intenable = xtensa_get_sr(intenable);
 242
 243         BUG_ON(intread & intenable &
 244                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
 245                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
 246                  BIT(XCHAL_PROFILING_INTERRUPT)));
 247 }
 248
 249 #else
 250
 251 static inline void check_valid_nmi(void)
 252 {
 253 }
 254
 255 #endif
 256
 257 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 258
 259 DEFINE_PER_CPU(unsigned long, nmi_count);
 260
 261 static void do_nmi(struct pt_regs *regs)
 262 {
 263         struct pt_regs *old_regs = set_irq_regs(regs);
 264
 265         nmi_enter();
 266         ++*this_cpu_ptr(&nmi_count);
 267         check_valid_nmi();
 268         xtensa_pmu_irq_handler(0, NULL);
 269         nmi_exit();
 270         set_irq_regs(old_regs);
 271 }
 272 #endif
 273
 274 static void do_interrupt(struct pt_regs *regs)
 275 {
 276         static const unsigned int_level_mask[] = {
 277                 0,
 278                 XCHAL_INTLEVEL1_MASK,
 279                 XCHAL_INTLEVEL2_MASK,
 280                 XCHAL_INTLEVEL3_MASK,
 281                 XCHAL_INTLEVEL4_MASK,
 282                 XCHAL_INTLEVEL5_MASK,
 283                 XCHAL_INTLEVEL6_MASK,
 284                 XCHAL_INTLEVEL7_MASK,
 285         };
 286         struct pt_regs *old_regs = set_irq_regs(regs);
 287         unsigned unhandled = ~0u;
 288
 289         irq_enter();
 290
 291         for (;;) {
 292                 unsigned intread = xtensa_get_sr(interrupt);
 293                 unsigned intenable = xtensa_get_sr(intenable);
 294                 unsigned int_at_level = intread & intenable;
 295                 unsigned level;
 296
 297                 for (level = LOCKLEVEL; level > 0; --level) {
 298                         if (int_at_level & int_level_mask[level]) {
 299                                 int_at_level &= int_level_mask[level];
 300                                 if (int_at_level & unhandled)
 301                                         int_at_level &= unhandled;
 302                                 else
 303                                         unhandled |= int_level_mask[level];
 304                                 break;
 305                         }
 306                 }
 307
 308                 if (level == 0)
 309                         break;
 310
 311                 /* clear lowest pending irq in the unhandled mask */
 312                 unhandled ^= (int_at_level & -int_at_level);
 313                 do_IRQ(__ffs(int_at_level), regs);
 314         }
 315
 316         irq_exit();
 317         set_irq_regs(old_regs);
 318 }
 319
 320 static bool check_div0(struct pt_regs *regs)
 321 {
 322         static const u8 pattern[] = {'D', 'I', 'V', '0'};
 323         const u8 *p;
 324         u8 buf[5];
 325
 326         if (user_mode(regs)) {
 327                 if (copy_from_user(buf, (void __user *)regs->pc + 2, 5))
 328                         return false;
 329                 p = buf;
 330         } else {
 331                 p = (const u8 *)regs->pc + 2;
 332         }
 333
 334         return memcmp(p, pattern, sizeof(pattern)) == 0 ||
 335                 memcmp(p + 1, pattern, sizeof(pattern)) == 0;
 336 }
 337
 338 /*
 339  * Illegal instruction. Fatal if in kernel space.
 340  */
 341
 342 static void do_illegal_instruction(struct pt_regs *regs)
 343 {
 344 #ifdef CONFIG_USER_ABI_CALL0_PROBE
 345         /*
 346          * When call0 application encounters an illegal instruction fast
 347          * exception handler will attempt to set PS.WOE and retry failing
 348          * instruction.
 349          * If we get here we know that that instruction is also illegal
 350          * with PS.WOE set, so it's not related to the windowed option
 351          * hence PS.WOE may be cleared.
 352          */
 353         if (regs->pc == current_thread_info()->ps_woe_fix_addr)
 354                 regs->ps &= ~PS_WOE_MASK;
 355 #endif
 356         if (check_div0(regs)) {
 357                 do_div0(regs);
 358                 return;
 359         }
 360
 361         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 362
 363         /* If in user mode, send SIGILL signal to current process. */
 364
 365         pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 366                             current->comm, task_pid_nr(current), regs->pc);
 367         force_sig(SIGILL);
 368 }
 369
 370 static void do_div0(struct pt_regs *regs)
 371 {
 372         __die_if_kernel("Unhandled division by 0 in kernel", regs, SIGKILL);
 373         force_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)regs->pc);
 374 }
 375
 376 #ifdef CONFIG_XTENSA_LOAD_STORE
 377 static void do_load_store(struct pt_regs *regs)
 378 {
 379         __die_if_kernel("Unhandled load/store exception in kernel",
 380                         regs, SIGKILL);
 381
 382         pr_info_ratelimited("Load/store error to %08lx in '%s' (pid = %d, pc = %#010lx)\n",
 383                             regs->excvaddr, current->comm,
 384                             task_pid_nr(current), regs->pc);
 385         force_sig_fault(SIGBUS, BUS_ADRERR, (void *)regs->excvaddr);
 386 }
 387 #endif
 388
 389 /*
 390  * Handle unaligned memory accesses from user space. Kill task.
 391  *
 392  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 393  * accesses causes from user space.
 394  */
 395
 396 static void do_unaligned_user(struct pt_regs *regs)
 397 {
 398         __die_if_kernel("Unhandled unaligned exception in kernel",
 399                         regs, SIGKILL);
 400
 401         pr_info_ratelimited("Unaligned memory access to %08lx in '%s' "
 402                             "(pid = %d, pc = %#010lx)\n",
 403                             regs->excvaddr, current->comm,
 404                             task_pid_nr(current), regs->pc);
 405         force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr);
 406 }
 407
 408 #if XTENSA_HAVE_COPROCESSORS
 409 static void do_coprocessor(struct pt_regs *regs)
 410 {
 411         coprocessor_flush_release_all(current_thread_info());
 412 }
 413 #endif
 414
 415 /* Handle debug events.
 416  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 417  * preemption disabled to avoid rescheduling and keep mapping of hardware
 418  * breakpoint structures to debug registers intact, so that
 419  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 420  */
 421 static void do_debug(struct pt_regs *regs)
 422 {
 423 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 424         int ret = check_hw_breakpoint(regs);
 425
 426         preempt_enable();
 427         if (ret == 0)
 428                 return;
 429 #endif
 430         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 431
 432         /* If in user mode, send SIGTRAP signal to current process */
 433
 434         force_sig(SIGTRAP);
 435 }
 436
 437
 438 #define set_handler(type, cause, handler)                               \
 439         do {                                                            \
 440                 unsigned int cpu;                                       \
 441                                                                         \
 442                 for_each_possible_cpu(cpu)                              \
 443                         per_cpu(exc_table, cpu).type[cause] = (handler);\
 444         } while (0)
 445
 446 /* Set exception C handler - for temporary use when probing exceptions */
 447
 448 xtensa_exception_handler *
 449 __init trap_set_handler(int cause, xtensa_exception_handler *handler)
 450 {
 451         void *previous = per_cpu(exc_table, 0).default_handler[cause];
 452
 453         set_handler(default_handler, cause, handler);
 454         return previous;
 455 }
 456
 457
 458 static void trap_init_excsave(void)
 459 {
 460         xtensa_set_sr(this_cpu_ptr(&exc_table), excsave1);
 461 }
 462
 463 static void trap_init_debug(void)
 464 {
 465         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
 466
 467         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
 468         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
 469                              :: "a"(debugsave));
 470 }
 471
 472 /*
 473  * Initialize dispatch tables.
 474  *
 475  * The exception vectors are stored compressed the __init section in the
 476  * dispatch_init_table. This function initializes the following three tables
 477  * from that compressed table:
 478  * - fast user          first dispatch table for user exceptions
 479  * - fast kernel        first dispatch table for kernel exceptions
 480  * - default C-handler  C-handler called by the default fast handler.
 481  *
 482  * See vectors.S for more details.
 483  */
 484
 485 void __init trap_init(void)
 486 {
 487         int i;
 488
 489         /* Setup default vectors. */
 490
 491         for (i = 0; i < EXCCAUSE_N; i++) {
 492                 set_handler(fast_user_handler, i, user_exception);
 493                 set_handler(fast_kernel_handler, i, kernel_exception);
 494                 set_handler(default_handler, i, do_unhandled);
 495         }
 496
 497         /* Setup specific handlers. */
 498
 499         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 500                 int fast = dispatch_init_table[i].fast;
 501                 int cause = dispatch_init_table[i].cause;
 502                 void *handler = dispatch_init_table[i].handler;
 503
 504                 if (fast == 0)
 505                         set_handler(default_handler, cause, handler);
 506                 if ((fast & USER) != 0)
 507                         set_handler(fast_user_handler, cause, handler);
 508                 if ((fast & KRNL) != 0)
 509                         set_handler(fast_kernel_handler, cause, handler);
 510         }
 511
 512         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 513         trap_init_excsave();
 514         trap_init_debug();
 515 }
 516
 517 #ifdef CONFIG_SMP
 518 void secondary_trap_init(void)
 519 {
 520         trap_init_excsave();
 521         trap_init_debug();
 522 }
 523 #endif
 524
 525 /*
 526  * This function dumps the current valid window frame and other base registers.
 527  */
 528
 529 void show_regs(struct pt_regs * regs)
 530 {
 531         int i;
 532
 533         show_regs_print_info(KERN_DEFAULT);
 534
 535         for (i = 0; i < 16; i++) {
 536                 if ((i % 8) == 0)
 537                         pr_info("a%02d:", i);
 538                 pr_cont(" %08lx", regs->areg[i]);
 539         }
 540         pr_cont("\n");
 541         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 542                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
 543         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 544                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
 545         if (user_mode(regs))
 546                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 547                         regs->windowbase, regs->windowstart, regs->wmask,
 548                         regs->syscall);
 549 }
 550
 551 static int show_trace_cb(struct stackframe *frame, void *data)
 552 {
 553         const char *loglvl = data;
 554
 555         if (kernel_text_address(frame->pc))
 556                 printk("%s [<%08lx>] %pB\n",
 557                         loglvl, frame->pc, (void *)frame->pc);
 558         return 0;
 559 }
 560
 561 static void show_trace(struct task_struct *task, unsigned long *sp,
 562                        const char *loglvl)
 563 {
 564         if (!sp)
 565                 sp = stack_pointer(task);
 566
 567         printk("%sCall Trace:\n", loglvl);
 568         walk_stackframe(sp, show_trace_cb, (void *)loglvl);
 569 }
 570
 571 #define STACK_DUMP_ENTRY_SIZE 4
 572 #define STACK_DUMP_LINE_SIZE 16
 573 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH;
 574
 575 struct stack_fragment
 576 {
 577         size_t len;
 578         size_t off;
 579         u8 *sp;
 580         const char *loglvl;
 581 };
 582
 583 static int show_stack_fragment_cb(struct stackframe *frame, void *data)
 584 {
 585         struct stack_fragment *sf = data;
 586
 587         while (sf->off < sf->len) {
 588                 u8 line[STACK_DUMP_LINE_SIZE];
 589                 size_t line_len = sf->len - sf->off > STACK_DUMP_LINE_SIZE ?
 590                         STACK_DUMP_LINE_SIZE : sf->len - sf->off;
 591                 bool arrow = sf->off == 0;
 592
 593                 if (frame && frame->sp == (unsigned long)(sf->sp + sf->off))
 594                         arrow = true;
 595
 596                 __memcpy(line, sf->sp + sf->off, line_len);
 597                 print_hex_dump(sf->loglvl, arrow ? "> " : "  ", DUMP_PREFIX_NONE,
 598                                STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE,
 599                                line, line_len, false);
 600                 sf->off += STACK_DUMP_LINE_SIZE;
 601                 if (arrow)
 602                         return 0;
 603         }
 604         return 1;
 605 }
 606
 607 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 608 {
 609         struct stack_fragment sf;
 610
 611         if (!sp)
 612                 sp = stack_pointer(task);
 613
 614         sf.len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE),
 615                      kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE);
 616         sf.off = 0;
 617         sf.sp = (u8 *)sp;
 618         sf.loglvl = loglvl;
 619
 620         printk("%sStack:\n", loglvl);
 621         walk_stackframe(sp, show_stack_fragment_cb, &sf);
 622         while (sf.off < sf.len)
 623                 show_stack_fragment_cb(NULL, &sf);
 624         show_trace(task, sp, loglvl);
 625 }
 626
 627 DEFINE_SPINLOCK(die_lock);
 628
 629 void __noreturn die(const char * str, struct pt_regs * regs, long err)
 630 {
 631         static int die_counter;
 632         const char *pr = "";
 633
 634         if (IS_ENABLED(CONFIG_PREEMPTION))
 635                 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
 636
 637         console_verbose();
 638         spin_lock_irq(&die_lock);
 639
 640         pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr);
 641         show_regs(regs);
 642         if (!user_mode(regs))
 643                 show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO);
 644
 645         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 646         spin_unlock_irq(&die_lock);
 647
 648         if (in_interrupt())
 649                 panic("Fatal exception in interrupt");
 650
 651         if (panic_on_oops)
 652                 panic("Fatal exception");
 653
 654         make_task_dead(err);
 655 }