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_user(void); 55 extern void fast_alloca(void); 56 extern void fast_unaligned(void); 57 extern void fast_second_level_miss(void); 58 extern void fast_store_prohibited(void); 59 extern void fast_coprocessor(void); 60 61 extern void do_illegal_instruction (struct pt_regs*); 62 extern void do_interrupt (struct pt_regs*); 63 extern void do_nmi(struct pt_regs *); 64 extern void do_unaligned_user (struct pt_regs*); 65 extern void do_multihit (struct pt_regs*, unsigned long); 66 extern void do_page_fault (struct pt_regs*, unsigned long); 67 extern void do_debug (struct pt_regs*); 68 extern void system_call (struct pt_regs*); 69 70 /* 71 * The vector table must be preceded by a save area (which 72 * implies it must be in RAM, unless one places RAM immediately 73 * before a ROM and puts the vector at the start of the ROM (!)) 74 */ 75 76 #define KRNL 0x01 77 #define USER 0x02 78 79 #define COPROCESSOR(x) \ 80 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 81 82 typedef struct { 83 int cause; 84 int fast; 85 void* handler; 86 } dispatch_init_table_t; 87 88 static dispatch_init_table_t __initdata dispatch_init_table[] = { 89 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 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 97 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 98 /* EXCCAUSE_PRIVILEGED unhandled */ 99 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 100 #ifdef CONFIG_XTENSA_UNALIGNED_USER 101 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 102 #endif 103 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 104 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 105 #endif 106 #ifdef CONFIG_MMU 107 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 108 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 109 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 110 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 111 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 112 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 113 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 114 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 115 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 116 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 117 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 120 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 121 #endif /* CONFIG_MMU */ 122 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 123 #if XTENSA_HAVE_COPROCESSOR(0) 124 COPROCESSOR(0), 125 #endif 126 #if XTENSA_HAVE_COPROCESSOR(1) 127 COPROCESSOR(1), 128 #endif 129 #if XTENSA_HAVE_COPROCESSOR(2) 130 COPROCESSOR(2), 131 #endif 132 #if XTENSA_HAVE_COPROCESSOR(3) 133 COPROCESSOR(3), 134 #endif 135 #if XTENSA_HAVE_COPROCESSOR(4) 136 COPROCESSOR(4), 137 #endif 138 #if XTENSA_HAVE_COPROCESSOR(5) 139 COPROCESSOR(5), 140 #endif 141 #if XTENSA_HAVE_COPROCESSOR(6) 142 COPROCESSOR(6), 143 #endif 144 #if XTENSA_HAVE_COPROCESSOR(7) 145 COPROCESSOR(7), 146 #endif 147 #if XTENSA_FAKE_NMI 148 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 149 #endif 150 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 151 { -1, -1, 0 } 152 153 }; 154 155 /* The exception table <exc_table> serves two functions: 156 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 157 * 2. it is a temporary memory buffer for the exception handlers. 158 */ 159 160 DEFINE_PER_CPU(struct exc_table, exc_table); 161 DEFINE_PER_CPU(struct debug_table, debug_table); 162 163 void die(const char*, struct pt_regs*, long); 164 165 static inline void 166 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 167 { 168 if (!user_mode(regs)) 169 die(str, regs, err); 170 } 171 172 /* 173 * Unhandled Exceptions. Kill user task or panic if in kernel space. 174 */ 175 176 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 177 { 178 __die_if_kernel("Caught unhandled exception - should not happen", 179 regs, SIGKILL); 180 181 /* If in user mode, send SIGILL signal to current process */ 182 pr_info_ratelimited("Caught unhandled exception in '%s' " 183 "(pid = %d, pc = %#010lx) - should not happen\n" 184 "\tEXCCAUSE is %ld\n", 185 current->comm, task_pid_nr(current), regs->pc, 186 exccause); 187 force_sig(SIGILL, current); 188 } 189 190 /* 191 * Multi-hit exception. This if fatal! 192 */ 193 194 void do_multihit(struct pt_regs *regs, unsigned long exccause) 195 { 196 die("Caught multihit exception", regs, SIGKILL); 197 } 198 199 /* 200 * IRQ handler. 201 */ 202 203 extern void do_IRQ(int, struct pt_regs *); 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 void do_nmi(struct pt_regs *regs) 238 { 239 struct pt_regs *old_regs; 240 241 if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL) 242 trace_hardirqs_off(); 243 244 old_regs = set_irq_regs(regs); 245 nmi_enter(); 246 ++*this_cpu_ptr(&nmi_count); 247 check_valid_nmi(); 248 xtensa_pmu_irq_handler(0, NULL); 249 nmi_exit(); 250 set_irq_regs(old_regs); 251 } 252 #endif 253 254 void do_interrupt(struct pt_regs *regs) 255 { 256 static const unsigned int_level_mask[] = { 257 0, 258 XCHAL_INTLEVEL1_MASK, 259 XCHAL_INTLEVEL2_MASK, 260 XCHAL_INTLEVEL3_MASK, 261 XCHAL_INTLEVEL4_MASK, 262 XCHAL_INTLEVEL5_MASK, 263 XCHAL_INTLEVEL6_MASK, 264 XCHAL_INTLEVEL7_MASK, 265 }; 266 struct pt_regs *old_regs; 267 268 trace_hardirqs_off(); 269 270 old_regs = set_irq_regs(regs); 271 irq_enter(); 272 273 for (;;) { 274 unsigned intread = xtensa_get_sr(interrupt); 275 unsigned intenable = xtensa_get_sr(intenable); 276 unsigned int_at_level = intread & intenable; 277 unsigned level; 278 279 for (level = LOCKLEVEL; level > 0; --level) { 280 if (int_at_level & int_level_mask[level]) { 281 int_at_level &= int_level_mask[level]; 282 break; 283 } 284 } 285 286 if (level == 0) 287 break; 288 289 do_IRQ(__ffs(int_at_level), regs); 290 } 291 292 irq_exit(); 293 set_irq_regs(old_regs); 294 } 295 296 /* 297 * Illegal instruction. Fatal if in kernel space. 298 */ 299 300 void 301 do_illegal_instruction(struct pt_regs *regs) 302 { 303 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 304 305 /* If in user mode, send SIGILL signal to current process. */ 306 307 pr_info_ratelimited("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 308 current->comm, task_pid_nr(current), regs->pc); 309 force_sig(SIGILL, current); 310 } 311 312 313 /* 314 * Handle unaligned memory accesses from user space. Kill task. 315 * 316 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 317 * accesses causes from user space. 318 */ 319 320 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 321 void 322 do_unaligned_user (struct pt_regs *regs) 323 { 324 __die_if_kernel("Unhandled unaligned exception in kernel", 325 regs, SIGKILL); 326 327 current->thread.bad_vaddr = regs->excvaddr; 328 current->thread.error_code = -3; 329 pr_info_ratelimited("Unaligned memory access to %08lx in '%s' " 330 "(pid = %d, pc = %#010lx)\n", 331 regs->excvaddr, current->comm, 332 task_pid_nr(current), regs->pc); 333 force_sig_fault(SIGBUS, BUS_ADRALN, (void *) regs->excvaddr, current); 334 } 335 #endif 336 337 /* Handle debug events. 338 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with 339 * preemption disabled to avoid rescheduling and keep mapping of hardware 340 * breakpoint structures to debug registers intact, so that 341 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit. 342 */ 343 void 344 do_debug(struct pt_regs *regs) 345 { 346 #ifdef CONFIG_HAVE_HW_BREAKPOINT 347 int ret = check_hw_breakpoint(regs); 348 349 preempt_enable(); 350 if (ret == 0) 351 return; 352 #endif 353 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 354 355 /* If in user mode, send SIGTRAP signal to current process */ 356 357 force_sig(SIGTRAP, current); 358 } 359 360 361 #define set_handler(type, cause, handler) \ 362 do { \ 363 unsigned int cpu; \ 364 \ 365 for_each_possible_cpu(cpu) \ 366 per_cpu(exc_table, cpu).type[cause] = (handler);\ 367 } while (0) 368 369 /* Set exception C handler - for temporary use when probing exceptions */ 370 371 void * __init trap_set_handler(int cause, void *handler) 372 { 373 void *previous = per_cpu(exc_table, 0).default_handler[cause]; 374 375 set_handler(default_handler, cause, handler); 376 return previous; 377 } 378 379 380 static void trap_init_excsave(void) 381 { 382 unsigned long excsave1 = (unsigned long)this_cpu_ptr(&exc_table); 383 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 384 } 385 386 static void trap_init_debug(void) 387 { 388 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table); 389 390 this_cpu_ptr(&debug_table)->debug_exception = debug_exception; 391 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL) 392 :: "a"(debugsave)); 393 } 394 395 /* 396 * Initialize dispatch tables. 397 * 398 * The exception vectors are stored compressed the __init section in the 399 * dispatch_init_table. This function initializes the following three tables 400 * from that compressed table: 401 * - fast user first dispatch table for user exceptions 402 * - fast kernel first dispatch table for kernel exceptions 403 * - default C-handler C-handler called by the default fast handler. 404 * 405 * See vectors.S for more details. 406 */ 407 408 void __init trap_init(void) 409 { 410 int i; 411 412 /* Setup default vectors. */ 413 414 for (i = 0; i < EXCCAUSE_N; i++) { 415 set_handler(fast_user_handler, i, user_exception); 416 set_handler(fast_kernel_handler, i, kernel_exception); 417 set_handler(default_handler, i, do_unhandled); 418 } 419 420 /* Setup specific handlers. */ 421 422 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 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(default_handler, cause, handler); 429 if ((fast & USER) != 0) 430 set_handler(fast_user_handler, cause, handler); 431 if ((fast & KRNL) != 0) 432 set_handler(fast_kernel_handler, cause, handler); 433 } 434 435 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 436 trap_init_excsave(); 437 trap_init_debug(); 438 } 439 440 #ifdef CONFIG_SMP 441 void secondary_trap_init(void) 442 { 443 trap_init_excsave(); 444 trap_init_debug(); 445 } 446 #endif 447 448 /* 449 * This function dumps the current valid window frame and other base registers. 450 */ 451 452 void show_regs(struct pt_regs * regs) 453 { 454 int i, wmask; 455 456 show_regs_print_info(KERN_DEFAULT); 457 458 wmask = regs->wmask & ~1; 459 460 for (i = 0; i < 16; i++) { 461 if ((i % 8) == 0) 462 pr_info("a%02d:", i); 463 pr_cont(" %08lx", regs->areg[i]); 464 } 465 pr_cont("\n"); 466 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 467 regs->pc, regs->ps, regs->depc, regs->excvaddr); 468 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 469 regs->lbeg, regs->lend, regs->lcount, regs->sar); 470 if (user_mode(regs)) 471 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 472 regs->windowbase, regs->windowstart, regs->wmask, 473 regs->syscall); 474 } 475 476 static int show_trace_cb(struct stackframe *frame, void *data) 477 { 478 if (kernel_text_address(frame->pc)) 479 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc); 480 return 0; 481 } 482 483 void show_trace(struct task_struct *task, unsigned long *sp) 484 { 485 if (!sp) 486 sp = stack_pointer(task); 487 488 pr_info("Call Trace:\n"); 489 walk_stackframe(sp, show_trace_cb, NULL); 490 #ifndef CONFIG_KALLSYMS 491 pr_cont("\n"); 492 #endif 493 } 494 495 static int kstack_depth_to_print = 24; 496 497 void show_stack(struct task_struct *task, unsigned long *sp) 498 { 499 int i = 0; 500 unsigned long *stack; 501 502 if (!sp) 503 sp = stack_pointer(task); 504 stack = sp; 505 506 pr_info("Stack:\n"); 507 508 for (i = 0; i < kstack_depth_to_print; i++) { 509 if (kstack_end(sp)) 510 break; 511 pr_cont(" %08lx", *sp++); 512 if (i % 8 == 7) 513 pr_cont("\n"); 514 } 515 show_trace(task, stack); 516 } 517 518 DEFINE_SPINLOCK(die_lock); 519 520 void die(const char * str, struct pt_regs * regs, long err) 521 { 522 static int die_counter; 523 524 console_verbose(); 525 spin_lock_irq(&die_lock); 526 527 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, 528 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : ""); 529 show_regs(regs); 530 if (!user_mode(regs)) 531 show_stack(NULL, (unsigned long*)regs->areg[1]); 532 533 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 534 spin_unlock_irq(&die_lock); 535 536 if (in_interrupt()) 537 panic("Fatal exception in interrupt"); 538 539 if (panic_on_oops) 540 panic("Fatal exception"); 541 542 do_exit(err); 543 } 544