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.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 <asm/uaccess.h> 39 #include <asm/pgtable.h> 40 #include <asm/processor.h> 41 #include <asm/traps.h> 42 43 #ifdef CONFIG_KGDB 44 extern int gdb_enter; 45 extern int return_from_debug_flag; 46 #endif 47 48 /* 49 * Machine specific interrupt handlers 50 */ 51 52 extern void kernel_exception(void); 53 extern void user_exception(void); 54 55 extern void fast_syscall_kernel(void); 56 extern void fast_syscall_user(void); 57 extern void fast_alloca(void); 58 extern void fast_unaligned(void); 59 extern void fast_second_level_miss(void); 60 extern void fast_store_prohibited(void); 61 extern void fast_coprocessor(void); 62 63 extern void do_illegal_instruction (struct pt_regs*); 64 extern void do_interrupt (struct pt_regs*); 65 extern void do_nmi(struct pt_regs *); 66 extern void do_unaligned_user (struct pt_regs*); 67 extern void do_multihit (struct pt_regs*, unsigned long); 68 extern void do_page_fault (struct pt_regs*, unsigned long); 69 extern void do_debug (struct pt_regs*); 70 extern void system_call (struct pt_regs*); 71 72 /* 73 * The vector table must be preceded by a save area (which 74 * implies it must be in RAM, unless one places RAM immediately 75 * before a ROM and puts the vector at the start of the ROM (!)) 76 */ 77 78 #define KRNL 0x01 79 #define USER 0x02 80 81 #define COPROCESSOR(x) \ 82 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 83 84 typedef struct { 85 int cause; 86 int fast; 87 void* handler; 88 } dispatch_init_table_t; 89 90 static dispatch_init_table_t __initdata dispatch_init_table[] = { 91 92 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 93 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 94 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 95 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 96 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 97 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 98 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 99 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 100 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 101 /* EXCCAUSE_PRIVILEGED unhandled */ 102 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 103 #ifdef CONFIG_XTENSA_UNALIGNED_USER 104 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 105 #endif 106 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 107 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 108 #endif 109 #ifdef CONFIG_MMU 110 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 111 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 112 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 113 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 114 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 115 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 116 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 117 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 118 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 119 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 120 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 123 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 124 #endif /* CONFIG_MMU */ 125 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 126 #if XTENSA_HAVE_COPROCESSOR(0) 127 COPROCESSOR(0), 128 #endif 129 #if XTENSA_HAVE_COPROCESSOR(1) 130 COPROCESSOR(1), 131 #endif 132 #if XTENSA_HAVE_COPROCESSOR(2) 133 COPROCESSOR(2), 134 #endif 135 #if XTENSA_HAVE_COPROCESSOR(3) 136 COPROCESSOR(3), 137 #endif 138 #if XTENSA_HAVE_COPROCESSOR(4) 139 COPROCESSOR(4), 140 #endif 141 #if XTENSA_HAVE_COPROCESSOR(5) 142 COPROCESSOR(5), 143 #endif 144 #if XTENSA_HAVE_COPROCESSOR(6) 145 COPROCESSOR(6), 146 #endif 147 #if XTENSA_HAVE_COPROCESSOR(7) 148 COPROCESSOR(7), 149 #endif 150 #if XTENSA_FAKE_NMI 151 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 152 #endif 153 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 154 { -1, -1, 0 } 155 156 }; 157 158 /* The exception table <exc_table> serves two functions: 159 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 160 * 2. it is a temporary memory buffer for the exception handlers. 161 */ 162 163 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]); 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(SIGSEGV, &info, current); 340 341 } 342 #endif 343 344 void 345 do_debug(struct pt_regs *regs) 346 { 347 #ifdef CONFIG_KGDB 348 /* If remote debugging is configured AND enabled, we give control to 349 * kgdb. Otherwise, we fall through, perhaps giving control to the 350 * native debugger. 351 */ 352 353 if (gdb_enter) { 354 extern void gdb_handle_exception(struct pt_regs *); 355 gdb_handle_exception(regs); 356 return_from_debug_flag = 1; 357 return; 358 } 359 #endif 360 361 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 362 363 /* If in user mode, send SIGTRAP signal to current process */ 364 365 force_sig(SIGTRAP, current); 366 } 367 368 369 static void set_handler(int idx, void *handler) 370 { 371 unsigned int cpu; 372 373 for_each_possible_cpu(cpu) 374 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler; 375 } 376 377 /* Set exception C handler - for temporary use when probing exceptions */ 378 379 void * __init trap_set_handler(int cause, void *handler) 380 { 381 void *previous = (void *)per_cpu(exc_table, 0)[ 382 EXC_TABLE_DEFAULT / 4 + cause]; 383 set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler); 384 return previous; 385 } 386 387 388 static void trap_init_excsave(void) 389 { 390 unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table); 391 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 392 } 393 394 /* 395 * Initialize dispatch tables. 396 * 397 * The exception vectors are stored compressed the __init section in the 398 * dispatch_init_table. This function initializes the following three tables 399 * from that compressed table: 400 * - fast user first dispatch table for user exceptions 401 * - fast kernel first dispatch table for kernel exceptions 402 * - default C-handler C-handler called by the default fast handler. 403 * 404 * See vectors.S for more details. 405 */ 406 407 void __init trap_init(void) 408 { 409 int i; 410 411 /* Setup default vectors. */ 412 413 for(i = 0; i < 64; i++) { 414 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 415 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 416 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 417 } 418 419 /* Setup specific handlers. */ 420 421 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 422 423 int fast = dispatch_init_table[i].fast; 424 int cause = dispatch_init_table[i].cause; 425 void *handler = dispatch_init_table[i].handler; 426 427 if (fast == 0) 428 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 429 if (fast && fast & USER) 430 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 431 if (fast && fast & KRNL) 432 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 433 } 434 435 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 436 trap_init_excsave(); 437 } 438 439 #ifdef CONFIG_SMP 440 void secondary_trap_init(void) 441 { 442 trap_init_excsave(); 443 } 444 #endif 445 446 /* 447 * This function dumps the current valid window frame and other base registers. 448 */ 449 450 void show_regs(struct pt_regs * regs) 451 { 452 int i, wmask; 453 454 show_regs_print_info(KERN_DEFAULT); 455 456 wmask = regs->wmask & ~1; 457 458 for (i = 0; i < 16; i++) { 459 if ((i % 8) == 0) 460 printk(KERN_INFO "a%02d:", i); 461 printk(KERN_CONT " %08lx", regs->areg[i]); 462 } 463 printk(KERN_CONT "\n"); 464 465 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 466 regs->pc, regs->ps, regs->depc, regs->excvaddr); 467 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 468 regs->lbeg, regs->lend, regs->lcount, regs->sar); 469 if (user_mode(regs)) 470 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 471 regs->windowbase, regs->windowstart, regs->wmask, 472 regs->syscall); 473 } 474 475 static int show_trace_cb(struct stackframe *frame, void *data) 476 { 477 if (kernel_text_address(frame->pc)) { 478 printk(" [<%08lx>] ", frame->pc); 479 print_symbol("%s\n", frame->pc); 480 } 481 return 0; 482 } 483 484 void show_trace(struct task_struct *task, unsigned long *sp) 485 { 486 if (!sp) 487 sp = stack_pointer(task); 488 489 printk("Call Trace:"); 490 #ifdef CONFIG_KALLSYMS 491 printk("\n"); 492 #endif 493 walk_stackframe(sp, show_trace_cb, NULL); 494 printk("\n"); 495 } 496 497 /* 498 * This routine abuses get_user()/put_user() to reference pointers 499 * with at least a bit of error checking ... 500 */ 501 502 static int kstack_depth_to_print = 24; 503 504 void show_stack(struct task_struct *task, unsigned long *sp) 505 { 506 int i = 0; 507 unsigned long *stack; 508 509 if (!sp) 510 sp = stack_pointer(task); 511 stack = sp; 512 513 printk("\nStack: "); 514 515 for (i = 0; i < kstack_depth_to_print; i++) { 516 if (kstack_end(sp)) 517 break; 518 if (i && ((i % 8) == 0)) 519 printk("\n "); 520 printk("%08lx ", *sp++); 521 } 522 printk("\n"); 523 show_trace(task, stack); 524 } 525 526 void show_code(unsigned int *pc) 527 { 528 long i; 529 530 printk("\nCode:"); 531 532 for(i = -3 ; i < 6 ; i++) { 533 unsigned long insn; 534 if (__get_user(insn, pc + i)) { 535 printk(" (Bad address in pc)\n"); 536 break; 537 } 538 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 539 } 540 } 541 542 DEFINE_SPINLOCK(die_lock); 543 544 void die(const char * str, struct pt_regs * regs, long err) 545 { 546 static int die_counter; 547 int nl = 0; 548 549 console_verbose(); 550 spin_lock_irq(&die_lock); 551 552 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 553 #ifdef CONFIG_PREEMPT 554 printk("PREEMPT "); 555 nl = 1; 556 #endif 557 if (nl) 558 printk("\n"); 559 show_regs(regs); 560 if (!user_mode(regs)) 561 show_stack(NULL, (unsigned long*)regs->areg[1]); 562 563 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 564 spin_unlock_irq(&die_lock); 565 566 if (in_interrupt()) 567 panic("Fatal exception in interrupt"); 568 569 if (panic_on_oops) 570 panic("Fatal exception"); 571 572 do_exit(err); 573 } 574