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 33 #include <asm/ptrace.h> 34 #include <asm/timex.h> 35 #include <asm/uaccess.h> 36 #include <asm/pgtable.h> 37 #include <asm/processor.h> 38 39 #ifdef CONFIG_KGDB 40 extern int gdb_enter; 41 extern int return_from_debug_flag; 42 #endif 43 44 /* 45 * Machine specific interrupt handlers 46 */ 47 48 extern void kernel_exception(void); 49 extern void user_exception(void); 50 51 extern void fast_syscall_kernel(void); 52 extern void fast_syscall_user(void); 53 extern void fast_alloca(void); 54 extern void fast_unaligned(void); 55 extern void fast_second_level_miss(void); 56 extern void fast_store_prohibited(void); 57 extern void fast_coprocessor(void); 58 59 extern void do_illegal_instruction (struct pt_regs*); 60 extern void do_interrupt (struct pt_regs*); 61 extern void do_unaligned_user (struct pt_regs*); 62 extern void do_multihit (struct pt_regs*, unsigned long); 63 extern void do_page_fault (struct pt_regs*, unsigned long); 64 extern void do_debug (struct pt_regs*); 65 extern void system_call (struct pt_regs*); 66 67 /* 68 * The vector table must be preceded by a save area (which 69 * implies it must be in RAM, unless one places RAM immediately 70 * before a ROM and puts the vector at the start of the ROM (!)) 71 */ 72 73 #define KRNL 0x01 74 #define USER 0x02 75 76 #define COPROCESSOR(x) \ 77 { XCHAL_EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 78 79 typedef struct { 80 int cause; 81 int fast; 82 void* handler; 83 } dispatch_init_table_t; 84 85 dispatch_init_table_t __init dispatch_init_table[] = { 86 87 { XCHAL_EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 88 { XCHAL_EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 89 { XCHAL_EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 90 { XCHAL_EXCCAUSE_SYSTEM_CALL, 0, system_call }, 91 /* XCHAL_EXCCAUSE_INSTRUCTION_FETCH unhandled */ 92 /* XCHAL_EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 93 { XCHAL_EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 94 { XCHAL_EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 95 /* XCHAL_EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 96 /* XCHAL_EXCCAUSE_PRIVILEGED unhandled */ 97 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 98 #ifdef CONFIG_UNALIGNED_USER 99 { XCHAL_EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 100 #else 101 { XCHAL_EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 102 #endif 103 { XCHAL_EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 104 #endif 105 { XCHAL_EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 106 { XCHAL_EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 107 { XCHAL_EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 108 { XCHAL_EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 109 /* XCHAL_EXCCAUSE_SIZE_RESTRICTION unhandled */ 110 { XCHAL_EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 111 { XCHAL_EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 112 { XCHAL_EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 113 { XCHAL_EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 114 { XCHAL_EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 115 /* XCHAL_EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 116 { XCHAL_EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 117 { XCHAL_EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 118 { XCHAL_EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 119 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 120 #if (XCHAL_CP_MASK & 1) 121 COPROCESSOR(0), 122 #endif 123 #if (XCHAL_CP_MASK & 2) 124 COPROCESSOR(1), 125 #endif 126 #if (XCHAL_CP_MASK & 4) 127 COPROCESSOR(2), 128 #endif 129 #if (XCHAL_CP_MASK & 8) 130 COPROCESSOR(3), 131 #endif 132 #if (XCHAL_CP_MASK & 16) 133 COPROCESSOR(4), 134 #endif 135 #if (XCHAL_CP_MASK & 32) 136 COPROCESSOR(5), 137 #endif 138 #if (XCHAL_CP_MASK & 64) 139 COPROCESSOR(6), 140 #endif 141 #if (XCHAL_CP_MASK & 128) 142 COPROCESSOR(7), 143 #endif 144 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 145 { -1, -1, 0 } 146 147 }; 148 149 /* The exception table <exc_table> serves two functions: 150 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 151 * 2. it is a temporary memory buffer for the exception handlers. 152 */ 153 154 unsigned long exc_table[EXC_TABLE_SIZE/4]; 155 156 void die(const char*, struct pt_regs*, long); 157 158 static inline void 159 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 160 { 161 if (!user_mode(regs)) 162 die(str, regs, err); 163 } 164 165 /* 166 * Unhandled Exceptions. Kill user task or panic if in kernel space. 167 */ 168 169 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 170 { 171 __die_if_kernel("Caught unhandled exception - should not happen", 172 regs, SIGKILL); 173 174 /* If in user mode, send SIGILL signal to current process */ 175 printk("Caught unhandled exception in '%s' " 176 "(pid = %d, pc = %#010lx) - should not happen\n" 177 "\tEXCCAUSE is %ld\n", 178 current->comm, current->pid, regs->pc, exccause); 179 force_sig(SIGILL, current); 180 } 181 182 /* 183 * Multi-hit exception. This if fatal! 184 */ 185 186 void do_multihit(struct pt_regs *regs, unsigned long exccause) 187 { 188 die("Caught multihit exception", regs, SIGKILL); 189 } 190 191 /* 192 * Level-1 interrupt. 193 * We currently have no priority encoding. 194 */ 195 196 unsigned long ignored_level1_interrupts; 197 extern void do_IRQ(int, struct pt_regs *); 198 199 void do_interrupt (struct pt_regs *regs) 200 { 201 unsigned long intread = get_sr (INTREAD); 202 unsigned long intenable = get_sr (INTENABLE); 203 int i, mask; 204 205 /* Handle all interrupts (no priorities). 206 * (Clear the interrupt before processing, in case it's 207 * edge-triggered or software-generated) 208 */ 209 210 for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) { 211 if (mask & (intread & intenable)) { 212 set_sr (mask, INTCLEAR); 213 do_IRQ (i,regs); 214 } 215 } 216 } 217 218 /* 219 * Illegal instruction. Fatal if in kernel space. 220 */ 221 222 void 223 do_illegal_instruction(struct pt_regs *regs) 224 { 225 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 226 227 /* If in user mode, send SIGILL signal to current process. */ 228 229 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 230 current->comm, current->pid, regs->pc); 231 force_sig(SIGILL, current); 232 } 233 234 235 /* 236 * Handle unaligned memory accesses from user space. Kill task. 237 * 238 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 239 * accesses causes from user space. 240 */ 241 242 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 243 #ifndef CONFIG_UNALIGNED_USER 244 void 245 do_unaligned_user (struct pt_regs *regs) 246 { 247 siginfo_t info; 248 249 __die_if_kernel("Unhandled unaligned exception in kernel", 250 regs, SIGKILL); 251 252 current->thread.bad_vaddr = regs->excvaddr; 253 current->thread.error_code = -3; 254 printk("Unaligned memory access to %08lx in '%s' " 255 "(pid = %d, pc = %#010lx)\n", 256 regs->excvaddr, current->comm, current->pid, regs->pc); 257 info.si_signo = SIGBUS; 258 info.si_errno = 0; 259 info.si_code = BUS_ADRALN; 260 info.si_addr = (void *) regs->excvaddr; 261 force_sig_info(SIGSEGV, &info, current); 262 263 } 264 #endif 265 #endif 266 267 void 268 do_debug(struct pt_regs *regs) 269 { 270 #ifdef CONFIG_KGDB 271 /* If remote debugging is configured AND enabled, we give control to 272 * kgdb. Otherwise, we fall through, perhaps giving control to the 273 * native debugger. 274 */ 275 276 if (gdb_enter) { 277 extern void gdb_handle_exception(struct pt_regs *); 278 gdb_handle_exception(regs); 279 return_from_debug_flag = 1; 280 return; 281 } 282 #endif 283 284 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 285 286 /* If in user mode, send SIGTRAP signal to current process */ 287 288 force_sig(SIGTRAP, current); 289 } 290 291 292 /* 293 * Initialize dispatch tables. 294 * 295 * The exception vectors are stored compressed the __init section in the 296 * dispatch_init_table. This function initializes the following three tables 297 * from that compressed table: 298 * - fast user first dispatch table for user exceptions 299 * - fast kernel first dispatch table for kernel exceptions 300 * - default C-handler C-handler called by the default fast handler. 301 * 302 * See vectors.S for more details. 303 */ 304 305 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 306 307 void trap_init(void) 308 { 309 int i; 310 311 /* Setup default vectors. */ 312 313 for(i = 0; i < 64; i++) { 314 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 315 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 316 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 317 } 318 319 /* Setup specific handlers. */ 320 321 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 322 323 int fast = dispatch_init_table[i].fast; 324 int cause = dispatch_init_table[i].cause; 325 void *handler = dispatch_init_table[i].handler; 326 327 if (fast == 0) 328 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 329 if (fast && fast & USER) 330 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 331 if (fast && fast & KRNL) 332 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 333 } 334 335 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 336 337 i = (unsigned long)exc_table; 338 __asm__ __volatile__("wsr %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i)); 339 } 340 341 /* 342 * This function dumps the current valid window frame and other base registers. 343 */ 344 345 void show_regs(struct pt_regs * regs) 346 { 347 int i, wmask; 348 349 wmask = regs->wmask & ~1; 350 351 for (i = 0; i < 32; i++) { 352 if (wmask & (1 << (i / 4))) 353 break; 354 if ((i % 8) == 0) 355 printk ("\n" KERN_INFO "a%02d: ", i); 356 printk("%08lx ", regs->areg[i]); 357 } 358 printk("\n"); 359 360 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 361 regs->pc, regs->ps, regs->depc, regs->excvaddr); 362 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 363 regs->lbeg, regs->lend, regs->lcount, regs->sar); 364 if (user_mode(regs)) 365 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 366 regs->windowbase, regs->windowstart, regs->wmask, 367 regs->syscall); 368 } 369 370 void show_trace(struct task_struct *task, unsigned long *sp) 371 { 372 unsigned long a0, a1, pc; 373 unsigned long sp_start, sp_end; 374 375 a1 = (unsigned long)sp; 376 377 if (a1 == 0) 378 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(a1)); 379 380 381 sp_start = a1 & ~(THREAD_SIZE-1); 382 sp_end = sp_start + THREAD_SIZE; 383 384 printk("Call Trace:"); 385 #ifdef CONFIG_KALLSYMS 386 printk("\n"); 387 #endif 388 spill_registers(); 389 390 while (a1 > sp_start && a1 < sp_end) { 391 sp = (unsigned long*)a1; 392 393 a0 = *(sp - 4); 394 a1 = *(sp - 3); 395 396 if (a1 <= (unsigned long) sp) 397 break; 398 399 pc = MAKE_PC_FROM_RA(a0, a1); 400 401 if (kernel_text_address(pc)) { 402 printk(" [<%08lx>] ", pc); 403 print_symbol("%s\n", pc); 404 } 405 } 406 printk("\n"); 407 } 408 409 /* 410 * This routine abuses get_user()/put_user() to reference pointers 411 * with at least a bit of error checking ... 412 */ 413 414 static int kstack_depth_to_print = 24; 415 416 void show_stack(struct task_struct *task, unsigned long *sp) 417 { 418 int i = 0; 419 unsigned long *stack; 420 421 if (sp == 0) 422 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); 423 424 stack = sp; 425 426 printk("\nStack: "); 427 428 for (i = 0; i < kstack_depth_to_print; i++) { 429 if (kstack_end(sp)) 430 break; 431 if (i && ((i % 8) == 0)) 432 printk("\n "); 433 printk("%08lx ", *sp++); 434 } 435 printk("\n"); 436 show_trace(task, stack); 437 } 438 439 void dump_stack(void) 440 { 441 show_stack(current, NULL); 442 } 443 444 EXPORT_SYMBOL(dump_stack); 445 446 447 void show_code(unsigned int *pc) 448 { 449 long i; 450 451 printk("\nCode:"); 452 453 for(i = -3 ; i < 6 ; i++) { 454 unsigned long insn; 455 if (__get_user(insn, pc + i)) { 456 printk(" (Bad address in pc)\n"); 457 break; 458 } 459 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 460 } 461 } 462 463 spinlock_t die_lock = SPIN_LOCK_UNLOCKED; 464 465 void die(const char * str, struct pt_regs * regs, long err) 466 { 467 static int die_counter; 468 int nl = 0; 469 470 console_verbose(); 471 spin_lock_irq(&die_lock); 472 473 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 474 #ifdef CONFIG_PREEMPT 475 printk("PREEMPT "); 476 nl = 1; 477 #endif 478 if (nl) 479 printk("\n"); 480 show_regs(regs); 481 if (!user_mode(regs)) 482 show_stack(NULL, (unsigned long*)regs->areg[1]); 483 484 spin_unlock_irq(&die_lock); 485 486 if (in_interrupt()) 487 panic("Fatal exception in interrupt"); 488 489 if (panic_on_oops) { 490 printk(KERN_EMERG "Fatal exception: panic in 5 seconds\n"); 491 set_current_state(TASK_UNINTERRUPTIBLE); 492 schedule_timeout(5 * HZ); 493 panic("Fatal exception"); 494 } 495 do_exit(err); 496 } 497 498 499