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/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 <linux/uaccess.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/processor.h>
  41 #include <asm/traps.h>
  42 #include <asm/hw_breakpoint.h>
  43
  44 /*
  45  * Machine specific interrupt handlers
  46  */
  47
  48 extern void kernel_exception(void);
  49 extern void user_exception(void);
  50
  51 extern void fast_syscall_kernel(void);
  52 extern void fast_syscall_user(void);
  53 extern void fast_alloca(void);
  54 extern void fast_unaligned(void);
  55 extern void fast_second_level_miss(void);
  56 extern void fast_store_prohibited(void);
  57 extern void fast_coprocessor(void);
  58
  59 extern void do_illegal_instruction (struct pt_regs*);
  60 extern void do_interrupt (struct pt_regs*);
  61 extern void do_nmi(struct pt_regs *);
  62 extern void do_unaligned_user (struct pt_regs*);
  63 extern void do_multihit (struct pt_regs*, unsigned long);
  64 extern void do_page_fault (struct pt_regs*, unsigned long);
  65 extern void do_debug (struct pt_regs*);
  66 extern void system_call (struct pt_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, fast_coprocessor }
  79
  80 typedef struct {
  81         int cause;
  82         int fast;
  83         void* handler;
  84 } dispatch_init_table_t;
  85
  86 static dispatch_init_table_t __initdata dispatch_init_table[] = {
  87
  88 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0,         do_illegal_instruction},
  89 { EXCCAUSE_SYSTEM_CALL,         KRNL,      fast_syscall_kernel },
  90 { EXCCAUSE_SYSTEM_CALL,         USER,      fast_syscall_user },
  91 { EXCCAUSE_SYSTEM_CALL,         0,         system_call },
  92 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
  93 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
  94 { EXCCAUSE_LEVEL1_INTERRUPT,    0,         do_interrupt },
  95 { EXCCAUSE_ALLOCA,              USER|KRNL, fast_alloca },
  96 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
  97 /* EXCCAUSE_PRIVILEGED unhandled */
  98 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
  99 #ifdef CONFIG_XTENSA_UNALIGNED_USER
 100 { EXCCAUSE_UNALIGNED,           USER,      fast_unaligned },
 101 #endif
 102 { EXCCAUSE_UNALIGNED,           0,         do_unaligned_user },
 103 { EXCCAUSE_UNALIGNED,           KRNL,      fast_unaligned },
 104 #endif
 105 #ifdef CONFIG_MMU
 106 { EXCCAUSE_ITLB_MISS,           0,         do_page_fault },
 107 { EXCCAUSE_ITLB_MISS,           USER|KRNL, fast_second_level_miss},
 108 { EXCCAUSE_ITLB_MULTIHIT,               0,         do_multihit },
 109 { EXCCAUSE_ITLB_PRIVILEGE,      0,         do_page_fault },
 110 /* EXCCAUSE_SIZE_RESTRICTION unhandled */
 111 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE,       0,         do_page_fault },
 112 { EXCCAUSE_DTLB_MISS,           USER|KRNL, fast_second_level_miss},
 113 { EXCCAUSE_DTLB_MISS,           0,         do_page_fault },
 114 { EXCCAUSE_DTLB_MULTIHIT,               0,         do_multihit },
 115 { EXCCAUSE_DTLB_PRIVILEGE,      0,         do_page_fault },
 116 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */
 117 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       USER|KRNL, fast_store_prohibited },
 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE,       0,         do_page_fault },
 119 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE,        0,         do_page_fault },
 120 #endif /* CONFIG_MMU */
 121 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */
 122 #if XTENSA_HAVE_COPROCESSOR(0)
 123 COPROCESSOR(0),
 124 #endif
 125 #if XTENSA_HAVE_COPROCESSOR(1)
 126 COPROCESSOR(1),
 127 #endif
 128 #if XTENSA_HAVE_COPROCESSOR(2)
 129 COPROCESSOR(2),
 130 #endif
 131 #if XTENSA_HAVE_COPROCESSOR(3)
 132 COPROCESSOR(3),
 133 #endif
 134 #if XTENSA_HAVE_COPROCESSOR(4)
 135 COPROCESSOR(4),
 136 #endif
 137 #if XTENSA_HAVE_COPROCESSOR(5)
 138 COPROCESSOR(5),
 139 #endif
 140 #if XTENSA_HAVE_COPROCESSOR(6)
 141 COPROCESSOR(6),
 142 #endif
 143 #if XTENSA_HAVE_COPROCESSOR(7)
 144 COPROCESSOR(7),
 145 #endif
 146 #if XTENSA_FAKE_NMI
 147 { EXCCAUSE_MAPPED_NMI,                  0,              do_nmi },
 148 #endif
 149 { EXCCAUSE_MAPPED_DEBUG,                0,              do_debug },
 150 { -1, -1, 0 }
 151
 152 };
 153
 154 /* The exception table <exc_table> serves two functions:
 155  * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c)
 156  * 2. it is a temporary memory buffer for the exception handlers.
 157  */
 158
 159 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]);
 160
 161 DEFINE_PER_CPU(struct debug_table, debug_table);
 162
 163 void die(const char*, struct pt_regs*, long);
 164
 165 static inline void
 166 __die_if_kernel(const char *str, struct pt_regs *regs, long err)
 167 {
 168         if (!user_mode(regs))
 169                 die(str, regs, err);
 170 }
 171
 172 /*
 173  * Unhandled Exceptions. Kill user task or panic if in kernel space.
 174  */
 175
 176 void do_unhandled(struct pt_regs *regs, unsigned long exccause)
 177 {
 178         __die_if_kernel("Caught unhandled exception - should not happen",
 179                         regs, SIGKILL);
 180
 181         /* If in user mode, send SIGILL signal to current process */
 182         printk("Caught unhandled exception in '%s' "
 183                "(pid = %d, pc = %#010lx) - should not happen\n"
 184                "\tEXCCAUSE is %ld\n",
 185                current->comm, task_pid_nr(current), regs->pc, exccause);
 186         force_sig(SIGILL, current);
 187 }
 188
 189 /*
 190  * Multi-hit exception. This if fatal!
 191  */
 192
 193 void do_multihit(struct pt_regs *regs, unsigned long exccause)
 194 {
 195         die("Caught multihit exception", regs, SIGKILL);
 196 }
 197
 198 /*
 199  * IRQ handler.
 200  */
 201
 202 extern void do_IRQ(int, struct pt_regs *);
 203
 204 #if XTENSA_FAKE_NMI
 205
 206 #define IS_POW2(v) (((v) & ((v) - 1)) == 0)
 207
 208 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \
 209       IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL)))
 210 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level."
 211 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire."
 212
 213 static inline void check_valid_nmi(void)
 214 {
 215         unsigned intread = get_sr(interrupt);
 216         unsigned intenable = get_sr(intenable);
 217
 218         BUG_ON(intread & intenable &
 219                ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^
 220                  XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^
 221                  BIT(XCHAL_PROFILING_INTERRUPT)));
 222 }
 223
 224 #else
 225
 226 static inline void check_valid_nmi(void)
 227 {
 228 }
 229
 230 #endif
 231
 232 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id);
 233
 234 DEFINE_PER_CPU(unsigned long, nmi_count);
 235
 236 void do_nmi(struct pt_regs *regs)
 237 {
 238         struct pt_regs *old_regs;
 239
 240         if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL)
 241                 trace_hardirqs_off();
 242
 243         old_regs = set_irq_regs(regs);
 244         nmi_enter();
 245         ++*this_cpu_ptr(&nmi_count);
 246         check_valid_nmi();
 247         xtensa_pmu_irq_handler(0, NULL);
 248         nmi_exit();
 249         set_irq_regs(old_regs);
 250 }
 251 #endif
 252
 253 void do_interrupt(struct pt_regs *regs)
 254 {
 255         static const unsigned int_level_mask[] = {
 256                 0,
 257                 XCHAL_INTLEVEL1_MASK,
 258                 XCHAL_INTLEVEL2_MASK,
 259                 XCHAL_INTLEVEL3_MASK,
 260                 XCHAL_INTLEVEL4_MASK,
 261                 XCHAL_INTLEVEL5_MASK,
 262                 XCHAL_INTLEVEL6_MASK,
 263                 XCHAL_INTLEVEL7_MASK,
 264         };
 265         struct pt_regs *old_regs;
 266
 267         trace_hardirqs_off();
 268
 269         old_regs = set_irq_regs(regs);
 270         irq_enter();
 271
 272         for (;;) {
 273                 unsigned intread = get_sr(interrupt);
 274                 unsigned intenable = get_sr(intenable);
 275                 unsigned int_at_level = intread & intenable;
 276                 unsigned level;
 277
 278                 for (level = LOCKLEVEL; level > 0; --level) {
 279                         if (int_at_level & int_level_mask[level]) {
 280                                 int_at_level &= int_level_mask[level];
 281                                 break;
 282                         }
 283                 }
 284
 285                 if (level == 0)
 286                         break;
 287
 288                 do_IRQ(__ffs(int_at_level), regs);
 289         }
 290
 291         irq_exit();
 292         set_irq_regs(old_regs);
 293 }
 294
 295 /*
 296  * Illegal instruction. Fatal if in kernel space.
 297  */
 298
 299 void
 300 do_illegal_instruction(struct pt_regs *regs)
 301 {
 302         __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL);
 303
 304         /* If in user mode, send SIGILL signal to current process. */
 305
 306         printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n",
 307             current->comm, task_pid_nr(current), regs->pc);
 308         force_sig(SIGILL, current);
 309 }
 310
 311
 312 /*
 313  * Handle unaligned memory accesses from user space. Kill task.
 314  *
 315  * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory
 316  * accesses causes from user space.
 317  */
 318
 319 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
 320 void
 321 do_unaligned_user (struct pt_regs *regs)
 322 {
 323         siginfo_t info;
 324
 325         __die_if_kernel("Unhandled unaligned exception in kernel",
 326                         regs, SIGKILL);
 327
 328         current->thread.bad_vaddr = regs->excvaddr;
 329         current->thread.error_code = -3;
 330         printk("Unaligned memory access to %08lx in '%s' "
 331                "(pid = %d, pc = %#010lx)\n",
 332                regs->excvaddr, current->comm, task_pid_nr(current), regs->pc);
 333         info.si_signo = SIGBUS;
 334         info.si_errno = 0;
 335         info.si_code = BUS_ADRALN;
 336         info.si_addr = (void *) regs->excvaddr;
 337         force_sig_info(SIGSEGV, &info, current);
 338
 339 }
 340 #endif
 341
 342 /* Handle debug events.
 343  * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with
 344  * preemption disabled to avoid rescheduling and keep mapping of hardware
 345  * breakpoint structures to debug registers intact, so that
 346  * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit.
 347  */
 348 void
 349 do_debug(struct pt_regs *regs)
 350 {
 351 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 352         int ret = check_hw_breakpoint(regs);
 353
 354         preempt_enable();
 355         if (ret == 0)
 356                 return;
 357 #endif
 358         __die_if_kernel("Breakpoint in kernel", regs, SIGKILL);
 359
 360         /* If in user mode, send SIGTRAP signal to current process */
 361
 362         force_sig(SIGTRAP, current);
 363 }
 364
 365
 366 static void set_handler(int idx, void *handler)
 367 {
 368         unsigned int cpu;
 369
 370         for_each_possible_cpu(cpu)
 371                 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler;
 372 }
 373
 374 /* Set exception C handler - for temporary use when probing exceptions */
 375
 376 void * __init trap_set_handler(int cause, void *handler)
 377 {
 378         void *previous = (void *)per_cpu(exc_table, 0)[
 379                 EXC_TABLE_DEFAULT / 4 + cause];
 380         set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler);
 381         return previous;
 382 }
 383
 384
 385 static void trap_init_excsave(void)
 386 {
 387         unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table);
 388         __asm__ __volatile__("wsr  %0, excsave1\n" : : "a" (excsave1));
 389 }
 390
 391 static void trap_init_debug(void)
 392 {
 393         unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table);
 394
 395         this_cpu_ptr(&debug_table)->debug_exception = debug_exception;
 396         __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL)
 397                              :: "a"(debugsave));
 398 }
 399
 400 /*
 401  * Initialize dispatch tables.
 402  *
 403  * The exception vectors are stored compressed the __init section in the
 404  * dispatch_init_table. This function initializes the following three tables
 405  * from that compressed table:
 406  * - fast user          first dispatch table for user exceptions
 407  * - fast kernel        first dispatch table for kernel exceptions
 408  * - default C-handler  C-handler called by the default fast handler.
 409  *
 410  * See vectors.S for more details.
 411  */
 412
 413 void __init trap_init(void)
 414 {
 415         int i;
 416
 417         /* Setup default vectors. */
 418
 419         for(i = 0; i < 64; i++) {
 420                 set_handler(EXC_TABLE_FAST_USER/4   + i, user_exception);
 421                 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception);
 422                 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled);
 423         }
 424
 425         /* Setup specific handlers. */
 426
 427         for(i = 0; dispatch_init_table[i].cause >= 0; i++) {
 428
 429                 int fast = dispatch_init_table[i].fast;
 430                 int cause = dispatch_init_table[i].cause;
 431                 void *handler = dispatch_init_table[i].handler;
 432
 433                 if (fast == 0)
 434                         set_handler (EXC_TABLE_DEFAULT/4 + cause, handler);
 435                 if (fast && fast & USER)
 436                         set_handler (EXC_TABLE_FAST_USER/4 + cause, handler);
 437                 if (fast && fast & KRNL)
 438                         set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler);
 439         }
 440
 441         /* Initialize EXCSAVE_1 to hold the address of the exception table. */
 442         trap_init_excsave();
 443         trap_init_debug();
 444 }
 445
 446 #ifdef CONFIG_SMP
 447 void secondary_trap_init(void)
 448 {
 449         trap_init_excsave();
 450         trap_init_debug();
 451 }
 452 #endif
 453
 454 /*
 455  * This function dumps the current valid window frame and other base registers.
 456  */
 457
 458 void show_regs(struct pt_regs * regs)
 459 {
 460         int i, wmask;
 461
 462         show_regs_print_info(KERN_DEFAULT);
 463
 464         wmask = regs->wmask & ~1;
 465
 466         for (i = 0; i < 16; i++) {
 467                 if ((i % 8) == 0)
 468                         pr_info("a%02d:", i);
 469                 pr_cont(" %08lx", regs->areg[i]);
 470         }
 471         pr_cont("\n");
 472         pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n",
 473                 regs->pc, regs->ps, regs->depc, regs->excvaddr);
 474         pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n",
 475                 regs->lbeg, regs->lend, regs->lcount, regs->sar);
 476         if (user_mode(regs))
 477                 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n",
 478                         regs->windowbase, regs->windowstart, regs->wmask,
 479                         regs->syscall);
 480 }
 481
 482 static int show_trace_cb(struct stackframe *frame, void *data)
 483 {
 484         if (kernel_text_address(frame->pc)) {
 485                 pr_cont(" [<%08lx>]", frame->pc);
 486                 print_symbol(" %s\n", frame->pc);
 487         }
 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 }