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 extern void kernel_exception(void); 52 extern void user_exception(void); 53 54 extern void fast_illegal_instruction_user(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 #ifdef CONFIG_USER_ABI_CALL0_PROBE 92 { EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user }, 93 #endif 94 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 95 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 96 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 97 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 98 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 99 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 100 #ifdef SUPPORT_WINDOWED 101 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 102 #endif 103 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 104 /* EXCCAUSE_PRIVILEGED unhandled */ 105 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 106 #ifdef CONFIG_XTENSA_UNALIGNED_USER 107 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 108 #endif 109 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 110 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 111 #endif 112 #ifdef CONFIG_MMU 113 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 114 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 115 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 116 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 117 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 118 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 119 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 120 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 121 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 122 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 123 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 124 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 125 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 126 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 127 #endif /* CONFIG_MMU */ 128 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 129 #if XTENSA_HAVE_COPROCESSOR(0) 130 COPROCESSOR(0), 131 #endif 132 #if XTENSA_HAVE_COPROCESSOR(1) 133 COPROCESSOR(1), 134 #endif 135 #if XTENSA_HAVE_COPROCESSOR(2) 136 COPROCESSOR(2), 137 #endif 138 #if XTENSA_HAVE_COPROCESSOR(3) 139 COPROCESSOR(3), 140 #endif 141 #if XTENSA_HAVE_COPROCESSOR(4) 142 COPROCESSOR(4), 143 #endif 144 #if XTENSA_HAVE_COPROCESSOR(5) 145 COPROCESSOR(5), 146 #endif 147 #if XTENSA_HAVE_COPROCESSOR(6) 148 COPROCESSOR(6), 149 #endif 150 #if XTENSA_HAVE_COPROCESSOR(7) 151 COPROCESSOR(7), 152 #endif 153 #if XTENSA_FAKE_NMI 154 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 155 #endif 156 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 157 { -1, -1, 0 } 158 159 }; 160 161 /* The exception table <exc_table> serves two functions: 162 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 163 * 2. it is a temporary memory buffer for the exception handlers. 164 */ 165 166 DEFINE_PER_CPU(struct exc_table, exc_table); 167 DEFINE_PER_CPU(struct debug_table, debug_table); 168 169 void die(const char*, struct pt_regs*, long); 170 171 static inline void 172 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 173 { 174 if (!user_mode(regs)) 175 die(str, regs, err); 176 } 177 178 /* 179 * Unhandled Exceptions. Kill user task or panic if in kernel space. 180 */ 181 182 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 183 { 184 __die_if_kernel("Caught unhandled exception - should not happen", 185 regs, SIGKILL); 186 187 /* If in user mode, send SIGILL signal to current process */ 188 pr_info_ratelimited("Caught unhandled exception in '%s' " 189 "(pid = %d, pc = %#010lx) - should not happen\n" 190 "\tEXCCAUSE is %ld\n", 191 current->comm, task_pid_nr(current), regs->pc, 192 exccause); 193 force_sig(SIGILL); 194 } 195 196 /* 197 * Multi-hit exception. This if fatal! 198 */ 199 200 void do_multihit(struct pt_regs *regs, unsigned long exccause) 201 { 202 die("Caught multihit exception", regs, SIGKILL); 203 } 204 205 /* 206 * IRQ handler. 207 */ 208 209 extern void do_IRQ(int, struct pt_regs *); 210 211 #if XTENSA_FAKE_NMI 212 213 #define IS_POW2(v) (((v) & ((v) - 1)) == 0) 214 215 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \ 216 IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))) 217 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level." 218 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire." 219 220 static inline void check_valid_nmi(void) 221 { 222 unsigned intread = xtensa_get_sr(interrupt); 223 unsigned intenable = xtensa_get_sr(intenable); 224 225 BUG_ON(intread & intenable & 226 ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^ 227 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^ 228 BIT(XCHAL_PROFILING_INTERRUPT))); 229 } 230 231 #else 232 233 static inline void check_valid_nmi(void) 234 { 235 } 236 237 #endif 238 239 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id); 240 241 DEFINE_PER_CPU(unsigned long, nmi_count); 242 243 void do_nmi(struct pt_regs *regs) 244 { 245 struct pt_regs *old_regs; 246 247 if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL) 248 trace_hardirqs_off(); 249 250 old_regs = set_irq_regs(regs); 251 nmi_enter(); 252 ++*this_cpu_ptr(&nmi_count); 253 check_valid_nmi(); 254 xtensa_pmu_irq_handler(0, NULL); 255 nmi_exit(); 256 set_irq_regs(old_regs); 257 } 258 #endif 259 260 void do_interrupt(struct pt_regs *regs) 261 { 262 static const unsigned int_level_mask[] = { 263 0, 264 XCHAL_INTLEVEL1_MASK, 265 XCHAL_INTLEVEL2_MASK, 266 XCHAL_INTLEVEL3_MASK, 267 XCHAL_INTLEVEL4_MASK, 268 XCHAL_INTLEVEL5_MASK, 269 XCHAL_INTLEVEL6_MASK, 270 XCHAL_INTLEVEL7_MASK, 271 }; 272 struct pt_regs *old_regs; 273 unsigned unhandled = ~0u; 274 275 trace_hardirqs_off(); 276 277 old_regs = set_irq_regs(regs); 278 irq_enter(); 279 280 for (;;) { 281 unsigned intread = xtensa_get_sr(interrupt); 282 unsigned intenable = xtensa_get_sr(intenable); 283 unsigned int_at_level = intread & intenable; 284 unsigned level; 285 286 for (level = LOCKLEVEL; level > 0; --level) { 287 if (int_at_level & int_level_mask[level]) { 288 int_at_level &= int_level_mask[level]; 289 if (int_at_level & unhandled) 290 int_at_level &= unhandled; 291 else 292 unhandled |= int_level_mask[level]; 293 break; 294 } 295 } 296 297 if (level == 0) 298 break; 299 300 /* clear lowest pending irq in the unhandled mask */ 301 unhandled ^= (int_at_level & -int_at_level); 302 do_IRQ(__ffs(int_at_level), regs); 303 } 304 305 irq_exit(); 306 set_irq_regs(old_regs); 307 } 308 309 /* 310 * Illegal instruction. Fatal if in kernel space. 311 */ 312 313 void 314 do_illegal_instruction(struct pt_regs *regs) 315 { 316 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 317 318 /* If in user mode, send SIGILL signal to current process. */ 319 320 pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 321 current->comm, task_pid_nr(current), regs->pc); 322 force_sig(SIGILL); 323 } 324 325 326 /* 327 * Handle unaligned memory accesses from user space. Kill task. 328 * 329 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 330 * accesses causes from user space. 331 */ 332 333 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 334 void 335 do_unaligned_user (struct pt_regs *regs) 336 { 337 __die_if_kernel("Unhandled unaligned exception in kernel", 338 regs, SIGKILL); 339 340 current->thread.bad_vaddr = regs->excvaddr; 341 current->thread.error_code = -3; 342 pr_info_ratelimited("Unaligned memory access to %08lx in '%s' " 343 "(pid = %d, pc = %#010lx)\n", 344 regs->excvaddr, current->comm, 345 task_pid_nr(current), regs->pc); 346 force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr); 347 } 348 #endif 349 350 /* Handle debug events. 351 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with 352 * preemption disabled to avoid rescheduling and keep mapping of hardware 353 * breakpoint structures to debug registers intact, so that 354 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit. 355 */ 356 void 357 do_debug(struct pt_regs *regs) 358 { 359 #ifdef CONFIG_HAVE_HW_BREAKPOINT 360 int ret = check_hw_breakpoint(regs); 361 362 preempt_enable(); 363 if (ret == 0) 364 return; 365 #endif 366 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 367 368 /* If in user mode, send SIGTRAP signal to current process */ 369 370 force_sig(SIGTRAP); 371 } 372 373 374 #define set_handler(type, cause, handler) \ 375 do { \ 376 unsigned int cpu; \ 377 \ 378 for_each_possible_cpu(cpu) \ 379 per_cpu(exc_table, cpu).type[cause] = (handler);\ 380 } while (0) 381 382 /* Set exception C handler - for temporary use when probing exceptions */ 383 384 void * __init trap_set_handler(int cause, void *handler) 385 { 386 void *previous = per_cpu(exc_table, 0).default_handler[cause]; 387 388 set_handler(default_handler, cause, handler); 389 return previous; 390 } 391 392 393 static void trap_init_excsave(void) 394 { 395 unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table); 396 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 397 } 398 399 static void trap_init_debug(void) 400 { 401 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table); 402 403 this_cpu_ptr(&debug_table)->debug_exception = debug_exception; 404 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL) 405 :: "a"(debugsave)); 406 } 407 408 /* 409 * Initialize dispatch tables. 410 * 411 * The exception vectors are stored compressed the __init section in the 412 * dispatch_init_table. This function initializes the following three tables 413 * from that compressed table: 414 * - fast user first dispatch table for user exceptions 415 * - fast kernel first dispatch table for kernel exceptions 416 * - default C-handler C-handler called by the default fast handler. 417 * 418 * See vectors.S for more details. 419 */ 420 421 void __init trap_init(void) 422 { 423 int i; 424 425 /* Setup default vectors. */ 426 427 for (i = 0; i < EXCCAUSE_N; i++) { 428 set_handler(fast_user_handler, i, user_exception); 429 set_handler(fast_kernel_handler, i, kernel_exception); 430 set_handler(default_handler, i, do_unhandled); 431 } 432 433 /* Setup specific handlers. */ 434 435 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 436 int fast = dispatch_init_table[i].fast; 437 int cause = dispatch_init_table[i].cause; 438 void *handler = dispatch_init_table[i].handler; 439 440 if (fast == 0) 441 set_handler(default_handler, cause, handler); 442 if ((fast & USER) != 0) 443 set_handler(fast_user_handler, cause, handler); 444 if ((fast & KRNL) != 0) 445 set_handler(fast_kernel_handler, cause, handler); 446 } 447 448 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 449 trap_init_excsave(); 450 trap_init_debug(); 451 } 452 453 #ifdef CONFIG_SMP 454 void secondary_trap_init(void) 455 { 456 trap_init_excsave(); 457 trap_init_debug(); 458 } 459 #endif 460 461 /* 462 * This function dumps the current valid window frame and other base registers. 463 */ 464 465 void show_regs(struct pt_regs * regs) 466 { 467 int i; 468 469 show_regs_print_info(KERN_DEFAULT); 470 471 for (i = 0; i < 16; i++) { 472 if ((i % 8) == 0) 473 pr_info("a%02d:", i); 474 pr_cont(" %08lx", regs->areg[i]); 475 } 476 pr_cont("\n"); 477 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 478 regs->pc, regs->ps, regs->depc, regs->excvaddr); 479 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 480 regs->lbeg, regs->lend, regs->lcount, regs->sar); 481 if (user_mode(regs)) 482 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 483 regs->windowbase, regs->windowstart, regs->wmask, 484 regs->syscall); 485 } 486 487 static int show_trace_cb(struct stackframe *frame, void *data) 488 { 489 const char *loglvl = data; 490 491 if (kernel_text_address(frame->pc)) 492 printk("%s [<%08lx>] %pB\n", 493 loglvl, frame->pc, (void *)frame->pc); 494 return 0; 495 } 496 497 static void show_trace(struct task_struct *task, unsigned long *sp, 498 const char *loglvl) 499 { 500 if (!sp) 501 sp = stack_pointer(task); 502 503 printk("%sCall Trace:\n", loglvl); 504 walk_stackframe(sp, show_trace_cb, (void *)loglvl); 505 } 506 507 #define STACK_DUMP_ENTRY_SIZE 4 508 #define STACK_DUMP_LINE_SIZE 32 509 static size_t kstack_depth_to_print = CONFIG_PRINT_STACK_DEPTH; 510 511 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl) 512 { 513 size_t len; 514 515 if (!sp) 516 sp = stack_pointer(task); 517 518 len = min((-(size_t)sp) & (THREAD_SIZE - STACK_DUMP_ENTRY_SIZE), 519 kstack_depth_to_print * STACK_DUMP_ENTRY_SIZE); 520 521 printk("%sStack:\n", loglvl); 522 print_hex_dump(loglvl, " ", DUMP_PREFIX_NONE, 523 STACK_DUMP_LINE_SIZE, STACK_DUMP_ENTRY_SIZE, 524 sp, len, false); 525 show_trace(task, sp, loglvl); 526 } 527 528 DEFINE_SPINLOCK(die_lock); 529 530 void __noreturn die(const char * str, struct pt_regs * regs, long err) 531 { 532 static int die_counter; 533 const char *pr = ""; 534 535 if (IS_ENABLED(CONFIG_PREEMPTION)) 536 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT"; 537 538 console_verbose(); 539 spin_lock_irq(&die_lock); 540 541 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, pr); 542 show_regs(regs); 543 if (!user_mode(regs)) 544 show_stack(NULL, (unsigned long *)regs->areg[1], KERN_INFO); 545 546 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 547 spin_unlock_irq(&die_lock); 548 549 if (in_interrupt()) 550 panic("Fatal exception in interrupt"); 551 552 if (panic_on_oops) 553 panic("Fatal exception"); 554 555 make_task_dead(err); 556 } 557