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 37 #include <asm/stacktrace.h> 38 #include <asm/ptrace.h> 39 #include <asm/timex.h> 40 #include <linux/uaccess.h> 41 #include <asm/pgtable.h> 42 #include <asm/processor.h> 43 #include <asm/traps.h> 44 #include <asm/hw_breakpoint.h> 45 46 /* 47 * Machine specific interrupt handlers 48 */ 49 50 extern void kernel_exception(void); 51 extern void user_exception(void); 52 53 extern void fast_syscall_kernel(void); 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, KRNL, fast_syscall_kernel }, 92 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 93 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 94 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 95 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 96 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 97 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 98 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 99 /* EXCCAUSE_PRIVILEGED unhandled */ 100 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 101 #ifdef CONFIG_XTENSA_UNALIGNED_USER 102 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 103 #endif 104 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 105 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 106 #endif 107 #ifdef CONFIG_MMU 108 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 109 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 110 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 111 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 112 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 113 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 114 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 115 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 116 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 117 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 118 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 121 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 122 #endif /* CONFIG_MMU */ 123 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 124 #if XTENSA_HAVE_COPROCESSOR(0) 125 COPROCESSOR(0), 126 #endif 127 #if XTENSA_HAVE_COPROCESSOR(1) 128 COPROCESSOR(1), 129 #endif 130 #if XTENSA_HAVE_COPROCESSOR(2) 131 COPROCESSOR(2), 132 #endif 133 #if XTENSA_HAVE_COPROCESSOR(3) 134 COPROCESSOR(3), 135 #endif 136 #if XTENSA_HAVE_COPROCESSOR(4) 137 COPROCESSOR(4), 138 #endif 139 #if XTENSA_HAVE_COPROCESSOR(5) 140 COPROCESSOR(5), 141 #endif 142 #if XTENSA_HAVE_COPROCESSOR(6) 143 COPROCESSOR(6), 144 #endif 145 #if XTENSA_HAVE_COPROCESSOR(7) 146 COPROCESSOR(7), 147 #endif 148 #if XTENSA_FAKE_NMI 149 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 150 #endif 151 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 152 { -1, -1, 0 } 153 154 }; 155 156 /* The exception table <exc_table> serves two functions: 157 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 158 * 2. it is a temporary memory buffer for the exception handlers. 159 */ 160 161 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]); 162 163 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 printk("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, exccause); 188 force_sig(SIGILL, current); 189 } 190 191 /* 192 * Multi-hit exception. This if fatal! 193 */ 194 195 void do_multihit(struct pt_regs *regs, unsigned long exccause) 196 { 197 die("Caught multihit exception", regs, SIGKILL); 198 } 199 200 /* 201 * IRQ handler. 202 */ 203 204 extern void do_IRQ(int, struct pt_regs *); 205 206 #if XTENSA_FAKE_NMI 207 208 #define IS_POW2(v) (((v) & ((v) - 1)) == 0) 209 210 #if !(PROFILING_INTLEVEL == XCHAL_EXCM_LEVEL && \ 211 IS_POW2(XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL))) 212 #warning "Fake NMI is requested for PMM, but there are other IRQs at or above its level." 213 #warning "Fake NMI will be used, but there will be a bugcheck if one of those IRQs fire." 214 215 static inline void check_valid_nmi(void) 216 { 217 unsigned intread = get_sr(interrupt); 218 unsigned intenable = get_sr(intenable); 219 220 BUG_ON(intread & intenable & 221 ~(XTENSA_INTLEVEL_ANDBELOW_MASK(PROFILING_INTLEVEL) ^ 222 XTENSA_INTLEVEL_MASK(PROFILING_INTLEVEL) ^ 223 BIT(XCHAL_PROFILING_INTERRUPT))); 224 } 225 226 #else 227 228 static inline void check_valid_nmi(void) 229 { 230 } 231 232 #endif 233 234 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id); 235 236 DEFINE_PER_CPU(unsigned long, nmi_count); 237 238 void do_nmi(struct pt_regs *regs) 239 { 240 struct pt_regs *old_regs; 241 242 if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL) 243 trace_hardirqs_off(); 244 245 old_regs = set_irq_regs(regs); 246 nmi_enter(); 247 ++*this_cpu_ptr(&nmi_count); 248 check_valid_nmi(); 249 xtensa_pmu_irq_handler(0, NULL); 250 nmi_exit(); 251 set_irq_regs(old_regs); 252 } 253 #endif 254 255 void do_interrupt(struct pt_regs *regs) 256 { 257 static const unsigned int_level_mask[] = { 258 0, 259 XCHAL_INTLEVEL1_MASK, 260 XCHAL_INTLEVEL2_MASK, 261 XCHAL_INTLEVEL3_MASK, 262 XCHAL_INTLEVEL4_MASK, 263 XCHAL_INTLEVEL5_MASK, 264 XCHAL_INTLEVEL6_MASK, 265 XCHAL_INTLEVEL7_MASK, 266 }; 267 struct pt_regs *old_regs; 268 269 trace_hardirqs_off(); 270 271 old_regs = set_irq_regs(regs); 272 irq_enter(); 273 274 for (;;) { 275 unsigned intread = get_sr(interrupt); 276 unsigned intenable = get_sr(intenable); 277 unsigned int_at_level = intread & intenable; 278 unsigned level; 279 280 for (level = LOCKLEVEL; level > 0; --level) { 281 if (int_at_level & int_level_mask[level]) { 282 int_at_level &= int_level_mask[level]; 283 break; 284 } 285 } 286 287 if (level == 0) 288 break; 289 290 do_IRQ(__ffs(int_at_level), regs); 291 } 292 293 irq_exit(); 294 set_irq_regs(old_regs); 295 } 296 297 /* 298 * Illegal instruction. Fatal if in kernel space. 299 */ 300 301 void 302 do_illegal_instruction(struct pt_regs *regs) 303 { 304 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 305 306 /* If in user mode, send SIGILL signal to current process. */ 307 308 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 309 current->comm, task_pid_nr(current), regs->pc); 310 force_sig(SIGILL, current); 311 } 312 313 314 /* 315 * Handle unaligned memory accesses from user space. Kill task. 316 * 317 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 318 * accesses causes from user space. 319 */ 320 321 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 322 void 323 do_unaligned_user (struct pt_regs *regs) 324 { 325 siginfo_t info; 326 327 __die_if_kernel("Unhandled unaligned exception in kernel", 328 regs, SIGKILL); 329 330 current->thread.bad_vaddr = regs->excvaddr; 331 current->thread.error_code = -3; 332 printk("Unaligned memory access to %08lx in '%s' " 333 "(pid = %d, pc = %#010lx)\n", 334 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 335 info.si_signo = SIGBUS; 336 info.si_errno = 0; 337 info.si_code = BUS_ADRALN; 338 info.si_addr = (void *) regs->excvaddr; 339 force_sig_info(SIGSEGV, &info, current); 340 341 } 342 #endif 343 344 /* Handle debug events. 345 * When CONFIG_HAVE_HW_BREAKPOINT is on this handler is called with 346 * preemption disabled to avoid rescheduling and keep mapping of hardware 347 * breakpoint structures to debug registers intact, so that 348 * DEBUGCAUSE.DBNUM could be used in case of data breakpoint hit. 349 */ 350 void 351 do_debug(struct pt_regs *regs) 352 { 353 #ifdef CONFIG_HAVE_HW_BREAKPOINT 354 int ret = check_hw_breakpoint(regs); 355 356 preempt_enable(); 357 if (ret == 0) 358 return; 359 #endif 360 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 361 362 /* If in user mode, send SIGTRAP signal to current process */ 363 364 force_sig(SIGTRAP, current); 365 } 366 367 368 static void set_handler(int idx, void *handler) 369 { 370 unsigned int cpu; 371 372 for_each_possible_cpu(cpu) 373 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler; 374 } 375 376 /* Set exception C handler - for temporary use when probing exceptions */ 377 378 void * __init trap_set_handler(int cause, void *handler) 379 { 380 void *previous = (void *)per_cpu(exc_table, 0)[ 381 EXC_TABLE_DEFAULT / 4 + cause]; 382 set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler); 383 return previous; 384 } 385 386 387 static void trap_init_excsave(void) 388 { 389 unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table); 390 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 391 } 392 393 static void trap_init_debug(void) 394 { 395 unsigned long debugsave = (unsigned long)this_cpu_ptr(&debug_table); 396 397 this_cpu_ptr(&debug_table)->debug_exception = debug_exception; 398 __asm__ __volatile__("wsr %0, excsave" __stringify(XCHAL_DEBUGLEVEL) 399 :: "a"(debugsave)); 400 } 401 402 /* 403 * Initialize dispatch tables. 404 * 405 * The exception vectors are stored compressed the __init section in the 406 * dispatch_init_table. This function initializes the following three tables 407 * from that compressed table: 408 * - fast user first dispatch table for user exceptions 409 * - fast kernel first dispatch table for kernel exceptions 410 * - default C-handler C-handler called by the default fast handler. 411 * 412 * See vectors.S for more details. 413 */ 414 415 void __init trap_init(void) 416 { 417 int i; 418 419 /* Setup default vectors. */ 420 421 for(i = 0; i < 64; i++) { 422 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 423 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 424 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 425 } 426 427 /* Setup specific handlers. */ 428 429 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 430 431 int fast = dispatch_init_table[i].fast; 432 int cause = dispatch_init_table[i].cause; 433 void *handler = dispatch_init_table[i].handler; 434 435 if (fast == 0) 436 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 437 if (fast && fast & USER) 438 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 439 if (fast && fast & KRNL) 440 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 441 } 442 443 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 444 trap_init_excsave(); 445 trap_init_debug(); 446 } 447 448 #ifdef CONFIG_SMP 449 void secondary_trap_init(void) 450 { 451 trap_init_excsave(); 452 trap_init_debug(); 453 } 454 #endif 455 456 /* 457 * This function dumps the current valid window frame and other base registers. 458 */ 459 460 void show_regs(struct pt_regs * regs) 461 { 462 int i, wmask; 463 464 show_regs_print_info(KERN_DEFAULT); 465 466 wmask = regs->wmask & ~1; 467 468 for (i = 0; i < 16; i++) { 469 if ((i % 8) == 0) 470 pr_info("a%02d:", i); 471 pr_cont(" %08lx", regs->areg[i]); 472 } 473 pr_cont("\n"); 474 pr_info("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 475 regs->pc, regs->ps, regs->depc, regs->excvaddr); 476 pr_info("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 477 regs->lbeg, regs->lend, regs->lcount, regs->sar); 478 if (user_mode(regs)) 479 pr_cont("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 480 regs->windowbase, regs->windowstart, regs->wmask, 481 regs->syscall); 482 } 483 484 static int show_trace_cb(struct stackframe *frame, void *data) 485 { 486 if (kernel_text_address(frame->pc)) 487 pr_cont(" [<%08lx>] %pB\n", frame->pc, (void *)frame->pc); 488 return 0; 489 } 490 491 void show_trace(struct task_struct *task, unsigned long *sp) 492 { 493 if (!sp) 494 sp = stack_pointer(task); 495 496 pr_info("Call Trace:\n"); 497 walk_stackframe(sp, show_trace_cb, NULL); 498 #ifndef CONFIG_KALLSYMS 499 pr_cont("\n"); 500 #endif 501 } 502 503 static int kstack_depth_to_print = 24; 504 505 void show_stack(struct task_struct *task, unsigned long *sp) 506 { 507 int i = 0; 508 unsigned long *stack; 509 510 if (!sp) 511 sp = stack_pointer(task); 512 stack = sp; 513 514 pr_info("Stack:\n"); 515 516 for (i = 0; i < kstack_depth_to_print; i++) { 517 if (kstack_end(sp)) 518 break; 519 pr_cont(" %08lx", *sp++); 520 if (i % 8 == 7) 521 pr_cont("\n"); 522 } 523 show_trace(task, stack); 524 } 525 526 DEFINE_SPINLOCK(die_lock); 527 528 void die(const char * str, struct pt_regs * regs, long err) 529 { 530 static int die_counter; 531 532 console_verbose(); 533 spin_lock_irq(&die_lock); 534 535 pr_info("%s: sig: %ld [#%d]%s\n", str, err, ++die_counter, 536 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : ""); 537 show_regs(regs); 538 if (!user_mode(regs)) 539 show_stack(NULL, (unsigned long*)regs->areg[1]); 540 541 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 542 spin_unlock_irq(&die_lock); 543 544 if (in_interrupt()) 545 panic("Fatal exception in interrupt"); 546 547 if (panic_on_oops) 548 panic("Fatal exception"); 549 550 do_exit(err); 551 } 552