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 - 2005 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/ptrace.h> 36 #include <asm/timex.h> 37 #include <asm/uaccess.h> 38 #include <asm/pgtable.h> 39 #include <asm/processor.h> 40 #include <asm/traps.h> 41 42 #ifdef CONFIG_KGDB 43 extern int gdb_enter; 44 extern int return_from_debug_flag; 45 #endif 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_kernel(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_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 #else 104 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 105 #endif 106 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 107 #endif 108 #ifdef CONFIG_MMU 109 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 110 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 111 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 112 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 113 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 114 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 115 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 116 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 117 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 118 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 119 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 122 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 123 #endif /* CONFIG_MMU */ 124 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 125 #if XTENSA_HAVE_COPROCESSOR(0) 126 COPROCESSOR(0), 127 #endif 128 #if XTENSA_HAVE_COPROCESSOR(1) 129 COPROCESSOR(1), 130 #endif 131 #if XTENSA_HAVE_COPROCESSOR(2) 132 COPROCESSOR(2), 133 #endif 134 #if XTENSA_HAVE_COPROCESSOR(3) 135 COPROCESSOR(3), 136 #endif 137 #if XTENSA_HAVE_COPROCESSOR(4) 138 COPROCESSOR(4), 139 #endif 140 #if XTENSA_HAVE_COPROCESSOR(5) 141 COPROCESSOR(5), 142 #endif 143 #if XTENSA_HAVE_COPROCESSOR(6) 144 COPROCESSOR(6), 145 #endif 146 #if XTENSA_HAVE_COPROCESSOR(7) 147 COPROCESSOR(7), 148 #endif 149 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 150 { -1, -1, 0 } 151 152 }; 153 154 /* The exception table <exc_table> serves two functions: 155 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 156 * 2. it is a temporary memory buffer for the exception handlers. 157 */ 158 159 unsigned long exc_table[EXC_TABLE_SIZE/4]; 160 161 void die(const char*, struct pt_regs*, long); 162 163 static inline void 164 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 165 { 166 if (!user_mode(regs)) 167 die(str, regs, err); 168 } 169 170 /* 171 * Unhandled Exceptions. Kill user task or panic if in kernel space. 172 */ 173 174 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 175 { 176 __die_if_kernel("Caught unhandled exception - should not happen", 177 regs, SIGKILL); 178 179 /* If in user mode, send SIGILL signal to current process */ 180 printk("Caught unhandled exception in '%s' " 181 "(pid = %d, pc = %#010lx) - should not happen\n" 182 "\tEXCCAUSE is %ld\n", 183 current->comm, task_pid_nr(current), regs->pc, exccause); 184 force_sig(SIGILL, current); 185 } 186 187 /* 188 * Multi-hit exception. This if fatal! 189 */ 190 191 void do_multihit(struct pt_regs *regs, unsigned long exccause) 192 { 193 die("Caught multihit exception", regs, SIGKILL); 194 } 195 196 /* 197 * IRQ handler. 198 * PS.INTLEVEL is the current IRQ priority level. 199 */ 200 201 extern void do_IRQ(int, struct pt_regs *); 202 203 void do_interrupt(struct pt_regs *regs) 204 { 205 static const unsigned int_level_mask[] = { 206 0, 207 XCHAL_INTLEVEL1_MASK, 208 XCHAL_INTLEVEL2_MASK, 209 XCHAL_INTLEVEL3_MASK, 210 XCHAL_INTLEVEL4_MASK, 211 XCHAL_INTLEVEL5_MASK, 212 XCHAL_INTLEVEL6_MASK, 213 XCHAL_INTLEVEL7_MASK, 214 }; 215 unsigned level = get_sr(ps) & PS_INTLEVEL_MASK; 216 217 if (WARN_ON_ONCE(level >= ARRAY_SIZE(int_level_mask))) 218 return; 219 220 for (;;) { 221 unsigned intread = get_sr(interrupt); 222 unsigned intenable = get_sr(intenable); 223 unsigned int_at_level = intread & intenable & 224 int_level_mask[level]; 225 226 if (!int_at_level) 227 return; 228 229 /* 230 * Clear the interrupt before processing, in case it's 231 * edge-triggered or software-generated 232 */ 233 while (int_at_level) { 234 unsigned i = __ffs(int_at_level); 235 unsigned mask = 1 << i; 236 237 int_at_level ^= mask; 238 set_sr(mask, intclear); 239 do_IRQ(i, regs); 240 } 241 } 242 } 243 244 /* 245 * Illegal instruction. Fatal if in kernel space. 246 */ 247 248 void 249 do_illegal_instruction(struct pt_regs *regs) 250 { 251 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 252 253 /* If in user mode, send SIGILL signal to current process. */ 254 255 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 256 current->comm, task_pid_nr(current), regs->pc); 257 force_sig(SIGILL, current); 258 } 259 260 261 /* 262 * Handle unaligned memory accesses from user space. Kill task. 263 * 264 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 265 * accesses causes from user space. 266 */ 267 268 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 269 #ifndef CONFIG_XTENSA_UNALIGNED_USER 270 void 271 do_unaligned_user (struct pt_regs *regs) 272 { 273 siginfo_t info; 274 275 __die_if_kernel("Unhandled unaligned exception in kernel", 276 regs, SIGKILL); 277 278 current->thread.bad_vaddr = regs->excvaddr; 279 current->thread.error_code = -3; 280 printk("Unaligned memory access to %08lx in '%s' " 281 "(pid = %d, pc = %#010lx)\n", 282 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 283 info.si_signo = SIGBUS; 284 info.si_errno = 0; 285 info.si_code = BUS_ADRALN; 286 info.si_addr = (void *) regs->excvaddr; 287 force_sig_info(SIGSEGV, &info, current); 288 289 } 290 #endif 291 #endif 292 293 void 294 do_debug(struct pt_regs *regs) 295 { 296 #ifdef CONFIG_KGDB 297 /* If remote debugging is configured AND enabled, we give control to 298 * kgdb. Otherwise, we fall through, perhaps giving control to the 299 * native debugger. 300 */ 301 302 if (gdb_enter) { 303 extern void gdb_handle_exception(struct pt_regs *); 304 gdb_handle_exception(regs); 305 return_from_debug_flag = 1; 306 return; 307 } 308 #endif 309 310 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 311 312 /* If in user mode, send SIGTRAP signal to current process */ 313 314 force_sig(SIGTRAP, current); 315 } 316 317 318 /* Set exception C handler - for temporary use when probing exceptions */ 319 320 void * __init trap_set_handler(int cause, void *handler) 321 { 322 unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause]; 323 void *previous = (void *)*entry; 324 *entry = (unsigned long)handler; 325 return previous; 326 } 327 328 329 /* 330 * Initialize dispatch tables. 331 * 332 * The exception vectors are stored compressed the __init section in the 333 * dispatch_init_table. This function initializes the following three tables 334 * from that compressed table: 335 * - fast user first dispatch table for user exceptions 336 * - fast kernel first dispatch table for kernel exceptions 337 * - default C-handler C-handler called by the default fast handler. 338 * 339 * See vectors.S for more details. 340 */ 341 342 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 343 344 void __init trap_init(void) 345 { 346 int i; 347 348 /* Setup default vectors. */ 349 350 for(i = 0; i < 64; i++) { 351 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 352 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 353 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 354 } 355 356 /* Setup specific handlers. */ 357 358 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 359 360 int fast = dispatch_init_table[i].fast; 361 int cause = dispatch_init_table[i].cause; 362 void *handler = dispatch_init_table[i].handler; 363 364 if (fast == 0) 365 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 366 if (fast && fast & USER) 367 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 368 if (fast && fast & KRNL) 369 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 370 } 371 372 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 373 374 i = (unsigned long)exc_table; 375 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (i)); 376 } 377 378 /* 379 * This function dumps the current valid window frame and other base registers. 380 */ 381 382 void show_regs(struct pt_regs * regs) 383 { 384 int i, wmask; 385 386 wmask = regs->wmask & ~1; 387 388 for (i = 0; i < 16; i++) { 389 if ((i % 8) == 0) 390 printk(KERN_INFO "a%02d:", i); 391 printk(KERN_CONT " %08lx", regs->areg[i]); 392 } 393 printk(KERN_CONT "\n"); 394 395 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 396 regs->pc, regs->ps, regs->depc, regs->excvaddr); 397 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 398 regs->lbeg, regs->lend, regs->lcount, regs->sar); 399 if (user_mode(regs)) 400 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 401 regs->windowbase, regs->windowstart, regs->wmask, 402 regs->syscall); 403 } 404 405 static __always_inline unsigned long *stack_pointer(struct task_struct *task) 406 { 407 unsigned long *sp; 408 409 if (!task || task == current) 410 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); 411 else 412 sp = (unsigned long *)task->thread.sp; 413 414 return sp; 415 } 416 417 void show_trace(struct task_struct *task, unsigned long *sp) 418 { 419 unsigned long a0, a1, pc; 420 unsigned long sp_start, sp_end; 421 422 if (sp) 423 a1 = (unsigned long)sp; 424 else 425 a1 = (unsigned long)stack_pointer(task); 426 427 sp_start = a1 & ~(THREAD_SIZE-1); 428 sp_end = sp_start + THREAD_SIZE; 429 430 printk("Call Trace:"); 431 #ifdef CONFIG_KALLSYMS 432 printk("\n"); 433 #endif 434 spill_registers(); 435 436 while (a1 > sp_start && a1 < sp_end) { 437 sp = (unsigned long*)a1; 438 439 a0 = *(sp - 4); 440 a1 = *(sp - 3); 441 442 if (a1 <= (unsigned long) sp) 443 break; 444 445 pc = MAKE_PC_FROM_RA(a0, a1); 446 447 if (kernel_text_address(pc)) { 448 printk(" [<%08lx>] ", pc); 449 print_symbol("%s\n", pc); 450 } 451 } 452 printk("\n"); 453 } 454 455 /* 456 * This routine abuses get_user()/put_user() to reference pointers 457 * with at least a bit of error checking ... 458 */ 459 460 static int kstack_depth_to_print = 24; 461 462 void show_stack(struct task_struct *task, unsigned long *sp) 463 { 464 int i = 0; 465 unsigned long *stack; 466 467 if (!sp) 468 sp = stack_pointer(task); 469 stack = sp; 470 471 printk("\nStack: "); 472 473 for (i = 0; i < kstack_depth_to_print; i++) { 474 if (kstack_end(sp)) 475 break; 476 if (i && ((i % 8) == 0)) 477 printk("\n "); 478 printk("%08lx ", *sp++); 479 } 480 printk("\n"); 481 show_trace(task, stack); 482 } 483 484 void dump_stack(void) 485 { 486 show_stack(current, NULL); 487 } 488 489 EXPORT_SYMBOL(dump_stack); 490 491 492 void show_code(unsigned int *pc) 493 { 494 long i; 495 496 printk("\nCode:"); 497 498 for(i = -3 ; i < 6 ; i++) { 499 unsigned long insn; 500 if (__get_user(insn, pc + i)) { 501 printk(" (Bad address in pc)\n"); 502 break; 503 } 504 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 505 } 506 } 507 508 DEFINE_SPINLOCK(die_lock); 509 510 void die(const char * str, struct pt_regs * regs, long err) 511 { 512 static int die_counter; 513 int nl = 0; 514 515 console_verbose(); 516 spin_lock_irq(&die_lock); 517 518 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 519 #ifdef CONFIG_PREEMPT 520 printk("PREEMPT "); 521 nl = 1; 522 #endif 523 if (nl) 524 printk("\n"); 525 show_regs(regs); 526 if (!user_mode(regs)) 527 show_stack(NULL, (unsigned long*)regs->areg[1]); 528 529 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 530 spin_unlock_irq(&die_lock); 531 532 if (in_interrupt()) 533 panic("Fatal exception in interrupt"); 534 535 if (panic_on_oops) 536 panic("Fatal exception"); 537 538 do_exit(err); 539 } 540