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.h> 28 #include <linux/init.h> 29 #include <linux/module.h> 30 #include <linux/stringify.h> 31 #include <linux/kallsyms.h> 32 #include <linux/delay.h> 33 #include <linux/hardirq.h> 34 35 #include <asm/stacktrace.h> 36 #include <asm/ptrace.h> 37 #include <asm/timex.h> 38 #include <asm/uaccess.h> 39 #include <asm/pgtable.h> 40 #include <asm/processor.h> 41 #include <asm/traps.h> 42 43 #ifdef CONFIG_KGDB 44 extern int gdb_enter; 45 extern int return_from_debug_flag; 46 #endif 47 48 /* 49 * Machine specific interrupt handlers 50 */ 51 52 extern void kernel_exception(void); 53 extern void user_exception(void); 54 55 extern void fast_syscall_kernel(void); 56 extern void fast_syscall_user(void); 57 extern void fast_alloca(void); 58 extern void fast_unaligned(void); 59 extern void fast_second_level_miss(void); 60 extern void fast_store_prohibited(void); 61 extern void fast_coprocessor(void); 62 63 extern void do_illegal_instruction (struct pt_regs*); 64 extern void do_interrupt (struct pt_regs*); 65 extern void do_nmi(struct pt_regs *); 66 extern void do_unaligned_user (struct pt_regs*); 67 extern void do_multihit (struct pt_regs*, unsigned long); 68 extern void do_page_fault (struct pt_regs*, unsigned long); 69 extern void do_debug (struct pt_regs*); 70 extern void system_call (struct pt_regs*); 71 72 /* 73 * The vector table must be preceded by a save area (which 74 * implies it must be in RAM, unless one places RAM immediately 75 * before a ROM and puts the vector at the start of the ROM (!)) 76 */ 77 78 #define KRNL 0x01 79 #define USER 0x02 80 81 #define COPROCESSOR(x) \ 82 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 83 84 typedef struct { 85 int cause; 86 int fast; 87 void* handler; 88 } dispatch_init_table_t; 89 90 static dispatch_init_table_t __initdata dispatch_init_table[] = { 91 92 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 93 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 94 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 95 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 96 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 97 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 98 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 99 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 100 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 101 /* EXCCAUSE_PRIVILEGED unhandled */ 102 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 103 #ifdef CONFIG_XTENSA_UNALIGNED_USER 104 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 105 #endif 106 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 107 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 108 #endif 109 #ifdef CONFIG_MMU 110 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 111 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 112 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 113 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 114 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 115 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 116 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 117 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 118 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 119 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 120 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 123 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 124 #endif /* CONFIG_MMU */ 125 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 126 #if XTENSA_HAVE_COPROCESSOR(0) 127 COPROCESSOR(0), 128 #endif 129 #if XTENSA_HAVE_COPROCESSOR(1) 130 COPROCESSOR(1), 131 #endif 132 #if XTENSA_HAVE_COPROCESSOR(2) 133 COPROCESSOR(2), 134 #endif 135 #if XTENSA_HAVE_COPROCESSOR(3) 136 COPROCESSOR(3), 137 #endif 138 #if XTENSA_HAVE_COPROCESSOR(4) 139 COPROCESSOR(4), 140 #endif 141 #if XTENSA_HAVE_COPROCESSOR(5) 142 COPROCESSOR(5), 143 #endif 144 #if XTENSA_HAVE_COPROCESSOR(6) 145 COPROCESSOR(6), 146 #endif 147 #if XTENSA_HAVE_COPROCESSOR(7) 148 COPROCESSOR(7), 149 #endif 150 #if XTENSA_FAKE_NMI 151 { EXCCAUSE_MAPPED_NMI, 0, do_nmi }, 152 #endif 153 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 154 { -1, -1, 0 } 155 156 }; 157 158 /* The exception table <exc_table> serves two functions: 159 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 160 * 2. it is a temporary memory buffer for the exception handlers. 161 */ 162 163 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]); 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 irqreturn_t xtensa_pmu_irq_handler(int irq, void *dev_id); 209 210 DEFINE_PER_CPU(unsigned long, nmi_count); 211 212 void do_nmi(struct pt_regs *regs) 213 { 214 struct pt_regs *old_regs; 215 216 if ((regs->ps & PS_INTLEVEL_MASK) < LOCKLEVEL) 217 trace_hardirqs_off(); 218 219 old_regs = set_irq_regs(regs); 220 nmi_enter(); 221 ++*this_cpu_ptr(&nmi_count); 222 xtensa_pmu_irq_handler(0, NULL); 223 nmi_exit(); 224 set_irq_regs(old_regs); 225 } 226 #endif 227 228 void do_interrupt(struct pt_regs *regs) 229 { 230 static const unsigned int_level_mask[] = { 231 0, 232 XCHAL_INTLEVEL1_MASK, 233 XCHAL_INTLEVEL2_MASK, 234 XCHAL_INTLEVEL3_MASK, 235 XCHAL_INTLEVEL4_MASK, 236 XCHAL_INTLEVEL5_MASK, 237 XCHAL_INTLEVEL6_MASK, 238 XCHAL_INTLEVEL7_MASK, 239 }; 240 struct pt_regs *old_regs; 241 242 trace_hardirqs_off(); 243 244 old_regs = set_irq_regs(regs); 245 irq_enter(); 246 247 for (;;) { 248 unsigned intread = get_sr(interrupt); 249 unsigned intenable = get_sr(intenable); 250 unsigned int_at_level = intread & intenable; 251 unsigned level; 252 253 for (level = LOCKLEVEL; level > 0; --level) { 254 if (int_at_level & int_level_mask[level]) { 255 int_at_level &= int_level_mask[level]; 256 break; 257 } 258 } 259 260 if (level == 0) 261 break; 262 263 do_IRQ(__ffs(int_at_level), regs); 264 } 265 266 irq_exit(); 267 set_irq_regs(old_regs); 268 } 269 270 /* 271 * Illegal instruction. Fatal if in kernel space. 272 */ 273 274 void 275 do_illegal_instruction(struct pt_regs *regs) 276 { 277 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 278 279 /* If in user mode, send SIGILL signal to current process. */ 280 281 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 282 current->comm, task_pid_nr(current), regs->pc); 283 force_sig(SIGILL, current); 284 } 285 286 287 /* 288 * Handle unaligned memory accesses from user space. Kill task. 289 * 290 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 291 * accesses causes from user space. 292 */ 293 294 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 295 void 296 do_unaligned_user (struct pt_regs *regs) 297 { 298 siginfo_t info; 299 300 __die_if_kernel("Unhandled unaligned exception in kernel", 301 regs, SIGKILL); 302 303 current->thread.bad_vaddr = regs->excvaddr; 304 current->thread.error_code = -3; 305 printk("Unaligned memory access to %08lx in '%s' " 306 "(pid = %d, pc = %#010lx)\n", 307 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 308 info.si_signo = SIGBUS; 309 info.si_errno = 0; 310 info.si_code = BUS_ADRALN; 311 info.si_addr = (void *) regs->excvaddr; 312 force_sig_info(SIGSEGV, &info, current); 313 314 } 315 #endif 316 317 void 318 do_debug(struct pt_regs *regs) 319 { 320 #ifdef CONFIG_KGDB 321 /* If remote debugging is configured AND enabled, we give control to 322 * kgdb. Otherwise, we fall through, perhaps giving control to the 323 * native debugger. 324 */ 325 326 if (gdb_enter) { 327 extern void gdb_handle_exception(struct pt_regs *); 328 gdb_handle_exception(regs); 329 return_from_debug_flag = 1; 330 return; 331 } 332 #endif 333 334 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 335 336 /* If in user mode, send SIGTRAP signal to current process */ 337 338 force_sig(SIGTRAP, current); 339 } 340 341 342 static void set_handler(int idx, void *handler) 343 { 344 unsigned int cpu; 345 346 for_each_possible_cpu(cpu) 347 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler; 348 } 349 350 /* Set exception C handler - for temporary use when probing exceptions */ 351 352 void * __init trap_set_handler(int cause, void *handler) 353 { 354 void *previous = (void *)per_cpu(exc_table, 0)[ 355 EXC_TABLE_DEFAULT / 4 + cause]; 356 set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler); 357 return previous; 358 } 359 360 361 static void trap_init_excsave(void) 362 { 363 unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table); 364 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 365 } 366 367 /* 368 * Initialize dispatch tables. 369 * 370 * The exception vectors are stored compressed the __init section in the 371 * dispatch_init_table. This function initializes the following three tables 372 * from that compressed table: 373 * - fast user first dispatch table for user exceptions 374 * - fast kernel first dispatch table for kernel exceptions 375 * - default C-handler C-handler called by the default fast handler. 376 * 377 * See vectors.S for more details. 378 */ 379 380 void __init trap_init(void) 381 { 382 int i; 383 384 /* Setup default vectors. */ 385 386 for(i = 0; i < 64; i++) { 387 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 388 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 389 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 390 } 391 392 /* Setup specific handlers. */ 393 394 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 395 396 int fast = dispatch_init_table[i].fast; 397 int cause = dispatch_init_table[i].cause; 398 void *handler = dispatch_init_table[i].handler; 399 400 if (fast == 0) 401 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 402 if (fast && fast & USER) 403 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 404 if (fast && fast & KRNL) 405 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 406 } 407 408 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 409 trap_init_excsave(); 410 } 411 412 #ifdef CONFIG_SMP 413 void secondary_trap_init(void) 414 { 415 trap_init_excsave(); 416 } 417 #endif 418 419 /* 420 * This function dumps the current valid window frame and other base registers. 421 */ 422 423 void show_regs(struct pt_regs * regs) 424 { 425 int i, wmask; 426 427 show_regs_print_info(KERN_DEFAULT); 428 429 wmask = regs->wmask & ~1; 430 431 for (i = 0; i < 16; i++) { 432 if ((i % 8) == 0) 433 printk(KERN_INFO "a%02d:", i); 434 printk(KERN_CONT " %08lx", regs->areg[i]); 435 } 436 printk(KERN_CONT "\n"); 437 438 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 439 regs->pc, regs->ps, regs->depc, regs->excvaddr); 440 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 441 regs->lbeg, regs->lend, regs->lcount, regs->sar); 442 if (user_mode(regs)) 443 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 444 regs->windowbase, regs->windowstart, regs->wmask, 445 regs->syscall); 446 } 447 448 static int show_trace_cb(struct stackframe *frame, void *data) 449 { 450 if (kernel_text_address(frame->pc)) { 451 printk(" [<%08lx>] ", frame->pc); 452 print_symbol("%s\n", frame->pc); 453 } 454 return 0; 455 } 456 457 void show_trace(struct task_struct *task, unsigned long *sp) 458 { 459 if (!sp) 460 sp = stack_pointer(task); 461 462 printk("Call Trace:"); 463 #ifdef CONFIG_KALLSYMS 464 printk("\n"); 465 #endif 466 walk_stackframe(sp, show_trace_cb, NULL); 467 printk("\n"); 468 } 469 470 /* 471 * This routine abuses get_user()/put_user() to reference pointers 472 * with at least a bit of error checking ... 473 */ 474 475 static int kstack_depth_to_print = 24; 476 477 void show_stack(struct task_struct *task, unsigned long *sp) 478 { 479 int i = 0; 480 unsigned long *stack; 481 482 if (!sp) 483 sp = stack_pointer(task); 484 stack = sp; 485 486 printk("\nStack: "); 487 488 for (i = 0; i < kstack_depth_to_print; i++) { 489 if (kstack_end(sp)) 490 break; 491 if (i && ((i % 8) == 0)) 492 printk("\n "); 493 printk("%08lx ", *sp++); 494 } 495 printk("\n"); 496 show_trace(task, stack); 497 } 498 499 void show_code(unsigned int *pc) 500 { 501 long i; 502 503 printk("\nCode:"); 504 505 for(i = -3 ; i < 6 ; i++) { 506 unsigned long insn; 507 if (__get_user(insn, pc + i)) { 508 printk(" (Bad address in pc)\n"); 509 break; 510 } 511 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 512 } 513 } 514 515 DEFINE_SPINLOCK(die_lock); 516 517 void die(const char * str, struct pt_regs * regs, long err) 518 { 519 static int die_counter; 520 int nl = 0; 521 522 console_verbose(); 523 spin_lock_irq(&die_lock); 524 525 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 526 #ifdef CONFIG_PREEMPT 527 printk("PREEMPT "); 528 nl = 1; 529 #endif 530 if (nl) 531 printk("\n"); 532 show_regs(regs); 533 if (!user_mode(regs)) 534 show_stack(NULL, (unsigned long*)regs->areg[1]); 535 536 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 537 spin_unlock_irq(&die_lock); 538 539 if (in_interrupt()) 540 panic("Fatal exception in interrupt"); 541 542 if (panic_on_oops) 543 panic("Fatal exception"); 544 545 do_exit(err); 546 } 547