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 41 #ifdef CONFIG_KGDB 42 extern int gdb_enter; 43 extern int return_from_debug_flag; 44 #endif 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_unaligned_user (struct pt_regs*); 64 extern void do_multihit (struct pt_regs*, unsigned long); 65 extern void do_page_fault (struct pt_regs*, unsigned long); 66 extern void do_debug (struct pt_regs*); 67 extern void system_call (struct pt_regs*); 68 69 /* 70 * The vector table must be preceded by a save area (which 71 * implies it must be in RAM, unless one places RAM immediately 72 * before a ROM and puts the vector at the start of the ROM (!)) 73 */ 74 75 #define KRNL 0x01 76 #define USER 0x02 77 78 #define COPROCESSOR(x) \ 79 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 80 81 typedef struct { 82 int cause; 83 int fast; 84 void* handler; 85 } dispatch_init_table_t; 86 87 static dispatch_init_table_t __initdata dispatch_init_table[] = { 88 89 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 90 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 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 #else 103 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 104 #endif 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 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 149 { -1, -1, 0 } 150 151 }; 152 153 /* The exception table <exc_table> serves two functions: 154 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 155 * 2. it is a temporary memory buffer for the exception handlers. 156 */ 157 158 unsigned long exc_table[EXC_TABLE_SIZE/4]; 159 160 void die(const char*, struct pt_regs*, long); 161 162 static inline void 163 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 164 { 165 if (!user_mode(regs)) 166 die(str, regs, err); 167 } 168 169 /* 170 * Unhandled Exceptions. Kill user task or panic if in kernel space. 171 */ 172 173 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 174 { 175 __die_if_kernel("Caught unhandled exception - should not happen", 176 regs, SIGKILL); 177 178 /* If in user mode, send SIGILL signal to current process */ 179 printk("Caught unhandled exception in '%s' " 180 "(pid = %d, pc = %#010lx) - should not happen\n" 181 "\tEXCCAUSE is %ld\n", 182 current->comm, task_pid_nr(current), regs->pc, exccause); 183 force_sig(SIGILL, current); 184 } 185 186 /* 187 * Multi-hit exception. This if fatal! 188 */ 189 190 void do_multihit(struct pt_regs *regs, unsigned long exccause) 191 { 192 die("Caught multihit exception", regs, SIGKILL); 193 } 194 195 /* 196 * Level-1 interrupt. 197 * We currently have no priority encoding. 198 */ 199 200 unsigned long ignored_level1_interrupts; 201 extern void do_IRQ(int, struct pt_regs *); 202 203 void do_interrupt (struct pt_regs *regs) 204 { 205 unsigned long intread = get_sr (interrupt); 206 unsigned long intenable = get_sr (intenable); 207 int i, mask; 208 209 /* Handle all interrupts (no priorities). 210 * (Clear the interrupt before processing, in case it's 211 * edge-triggered or software-generated) 212 */ 213 214 for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) { 215 if (mask & (intread & intenable)) { 216 set_sr (mask, intclear); 217 do_IRQ (i,regs); 218 } 219 } 220 } 221 222 /* 223 * Illegal instruction. Fatal if in kernel space. 224 */ 225 226 void 227 do_illegal_instruction(struct pt_regs *regs) 228 { 229 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 230 231 /* If in user mode, send SIGILL signal to current process. */ 232 233 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 234 current->comm, task_pid_nr(current), regs->pc); 235 force_sig(SIGILL, current); 236 } 237 238 239 /* 240 * Handle unaligned memory accesses from user space. Kill task. 241 * 242 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 243 * accesses causes from user space. 244 */ 245 246 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 247 #ifndef CONFIG_XTENSA_UNALIGNED_USER 248 void 249 do_unaligned_user (struct pt_regs *regs) 250 { 251 siginfo_t info; 252 253 __die_if_kernel("Unhandled unaligned exception in kernel", 254 regs, SIGKILL); 255 256 current->thread.bad_vaddr = regs->excvaddr; 257 current->thread.error_code = -3; 258 printk("Unaligned memory access to %08lx in '%s' " 259 "(pid = %d, pc = %#010lx)\n", 260 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 261 info.si_signo = SIGBUS; 262 info.si_errno = 0; 263 info.si_code = BUS_ADRALN; 264 info.si_addr = (void *) regs->excvaddr; 265 force_sig_info(SIGSEGV, &info, current); 266 267 } 268 #endif 269 #endif 270 271 void 272 do_debug(struct pt_regs *regs) 273 { 274 #ifdef CONFIG_KGDB 275 /* If remote debugging is configured AND enabled, we give control to 276 * kgdb. Otherwise, we fall through, perhaps giving control to the 277 * native debugger. 278 */ 279 280 if (gdb_enter) { 281 extern void gdb_handle_exception(struct pt_regs *); 282 gdb_handle_exception(regs); 283 return_from_debug_flag = 1; 284 return; 285 } 286 #endif 287 288 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 289 290 /* If in user mode, send SIGTRAP signal to current process */ 291 292 force_sig(SIGTRAP, current); 293 } 294 295 296 /* Set exception C handler - for temporary use when probing exceptions */ 297 298 void * __init trap_set_handler(int cause, void *handler) 299 { 300 unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause]; 301 void *previous = (void *)*entry; 302 *entry = (unsigned long)handler; 303 return previous; 304 } 305 306 307 /* 308 * Initialize dispatch tables. 309 * 310 * The exception vectors are stored compressed the __init section in the 311 * dispatch_init_table. This function initializes the following three tables 312 * from that compressed table: 313 * - fast user first dispatch table for user exceptions 314 * - fast kernel first dispatch table for kernel exceptions 315 * - default C-handler C-handler called by the default fast handler. 316 * 317 * See vectors.S for more details. 318 */ 319 320 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 321 322 void __init trap_init(void) 323 { 324 int i; 325 326 /* Setup default vectors. */ 327 328 for(i = 0; i < 64; i++) { 329 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 330 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 331 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 332 } 333 334 /* Setup specific handlers. */ 335 336 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 337 338 int fast = dispatch_init_table[i].fast; 339 int cause = dispatch_init_table[i].cause; 340 void *handler = dispatch_init_table[i].handler; 341 342 if (fast == 0) 343 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 344 if (fast && fast & USER) 345 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 346 if (fast && fast & KRNL) 347 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 348 } 349 350 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 351 352 i = (unsigned long)exc_table; 353 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (i)); 354 } 355 356 /* 357 * This function dumps the current valid window frame and other base registers. 358 */ 359 360 void show_regs(struct pt_regs * regs) 361 { 362 int i, wmask; 363 364 wmask = regs->wmask & ~1; 365 366 for (i = 0; i < 16; i++) { 367 if ((i % 8) == 0) 368 printk(KERN_INFO "a%02d:", i); 369 printk(KERN_CONT " %08lx", regs->areg[i]); 370 } 371 printk(KERN_CONT "\n"); 372 373 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 374 regs->pc, regs->ps, regs->depc, regs->excvaddr); 375 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 376 regs->lbeg, regs->lend, regs->lcount, regs->sar); 377 if (user_mode(regs)) 378 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 379 regs->windowbase, regs->windowstart, regs->wmask, 380 regs->syscall); 381 } 382 383 static __always_inline unsigned long *stack_pointer(struct task_struct *task) 384 { 385 unsigned long *sp; 386 387 if (!task || task == current) 388 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); 389 else 390 sp = (unsigned long *)task->thread.sp; 391 392 return sp; 393 } 394 395 static inline void spill_registers(void) 396 { 397 unsigned int a0, ps; 398 399 __asm__ __volatile__ ( 400 "movi a14, " __stringify(PS_EXCM_BIT | 1) "\n\t" 401 "mov a12, a0\n\t" 402 "rsr a13, sar\n\t" 403 "xsr a14, ps\n\t" 404 "movi a0, _spill_registers\n\t" 405 "rsync\n\t" 406 "callx0 a0\n\t" 407 "mov a0, a12\n\t" 408 "wsr a13, sar\n\t" 409 "wsr a14, ps\n\t" 410 :: "a" (&a0), "a" (&ps) 411 : "a2", "a3", "a4", "a7", "a11", "a12", "a13", "a14", "a15", "memory"); 412 } 413 414 void show_trace(struct task_struct *task, unsigned long *sp) 415 { 416 unsigned long a0, a1, pc; 417 unsigned long sp_start, sp_end; 418 419 if (sp) 420 a1 = (unsigned long)sp; 421 else 422 a1 = (unsigned long)stack_pointer(task); 423 424 sp_start = a1 & ~(THREAD_SIZE-1); 425 sp_end = sp_start + THREAD_SIZE; 426 427 printk("Call Trace:"); 428 #ifdef CONFIG_KALLSYMS 429 printk("\n"); 430 #endif 431 spill_registers(); 432 433 while (a1 > sp_start && a1 < sp_end) { 434 sp = (unsigned long*)a1; 435 436 a0 = *(sp - 4); 437 a1 = *(sp - 3); 438 439 if (a1 <= (unsigned long) sp) 440 break; 441 442 pc = MAKE_PC_FROM_RA(a0, a1); 443 444 if (kernel_text_address(pc)) { 445 printk(" [<%08lx>] ", pc); 446 print_symbol("%s\n", pc); 447 } 448 } 449 printk("\n"); 450 } 451 452 /* 453 * This routine abuses get_user()/put_user() to reference pointers 454 * with at least a bit of error checking ... 455 */ 456 457 static int kstack_depth_to_print = 24; 458 459 void show_stack(struct task_struct *task, unsigned long *sp) 460 { 461 int i = 0; 462 unsigned long *stack; 463 464 if (!sp) 465 sp = stack_pointer(task); 466 stack = sp; 467 468 printk("\nStack: "); 469 470 for (i = 0; i < kstack_depth_to_print; i++) { 471 if (kstack_end(sp)) 472 break; 473 if (i && ((i % 8) == 0)) 474 printk("\n "); 475 printk("%08lx ", *sp++); 476 } 477 printk("\n"); 478 show_trace(task, stack); 479 } 480 481 void dump_stack(void) 482 { 483 show_stack(current, NULL); 484 } 485 486 EXPORT_SYMBOL(dump_stack); 487 488 489 void show_code(unsigned int *pc) 490 { 491 long i; 492 493 printk("\nCode:"); 494 495 for(i = -3 ; i < 6 ; i++) { 496 unsigned long insn; 497 if (__get_user(insn, pc + i)) { 498 printk(" (Bad address in pc)\n"); 499 break; 500 } 501 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 502 } 503 } 504 505 DEFINE_SPINLOCK(die_lock); 506 507 void die(const char * str, struct pt_regs * regs, long err) 508 { 509 static int die_counter; 510 int nl = 0; 511 512 console_verbose(); 513 spin_lock_irq(&die_lock); 514 515 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 516 #ifdef CONFIG_PREEMPT 517 printk("PREEMPT "); 518 nl = 1; 519 #endif 520 if (nl) 521 printk("\n"); 522 show_regs(regs); 523 if (!user_mode(regs)) 524 show_stack(NULL, (unsigned long*)regs->areg[1]); 525 526 add_taint(TAINT_DIE); 527 spin_unlock_irq(&die_lock); 528 529 if (in_interrupt()) 530 panic("Fatal exception in interrupt"); 531 532 if (panic_on_oops) 533 panic("Fatal exception"); 534 535 do_exit(err); 536 } 537 538 539