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 } 554