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