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