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_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 (INTREAD); 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_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 /* 297 * Initialize dispatch tables. 298 * 299 * The exception vectors are stored compressed the __init section in the 300 * dispatch_init_table. This function initializes the following three tables 301 * from that compressed table: 302 * - fast user first dispatch table for user exceptions 303 * - fast kernel first dispatch table for kernel exceptions 304 * - default C-handler C-handler called by the default fast handler. 305 * 306 * See vectors.S for more details. 307 */ 308 309 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 310 311 void __init trap_init(void) 312 { 313 int i; 314 315 /* Setup default vectors. */ 316 317 for(i = 0; i < 64; i++) { 318 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 319 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 320 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 321 } 322 323 /* Setup specific handlers. */ 324 325 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 326 327 int fast = dispatch_init_table[i].fast; 328 int cause = dispatch_init_table[i].cause; 329 void *handler = dispatch_init_table[i].handler; 330 331 if (fast == 0) 332 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 333 if (fast && fast & USER) 334 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 335 if (fast && fast & KRNL) 336 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 337 } 338 339 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 340 341 i = (unsigned long)exc_table; 342 __asm__ __volatile__("wsr %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i)); 343 } 344 345 /* 346 * This function dumps the current valid window frame and other base registers. 347 */ 348 349 void show_regs(struct pt_regs * regs) 350 { 351 int i, wmask; 352 353 wmask = regs->wmask & ~1; 354 355 for (i = 0; i < 16; i++) { 356 if ((i % 8) == 0) 357 printk(KERN_INFO "a%02d:", i); 358 printk(KERN_CONT " %08lx", regs->areg[i]); 359 } 360 printk(KERN_CONT "\n"); 361 362 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 363 regs->pc, regs->ps, regs->depc, regs->excvaddr); 364 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 365 regs->lbeg, regs->lend, regs->lcount, regs->sar); 366 if (user_mode(regs)) 367 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 368 regs->windowbase, regs->windowstart, regs->wmask, 369 regs->syscall); 370 } 371 372 static __always_inline unsigned long *stack_pointer(struct task_struct *task) 373 { 374 unsigned long *sp; 375 376 if (!task || task == current) 377 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); 378 else 379 sp = (unsigned long *)task->thread.sp; 380 381 return sp; 382 } 383 384 void show_trace(struct task_struct *task, unsigned long *sp) 385 { 386 unsigned long a0, a1, pc; 387 unsigned long sp_start, sp_end; 388 389 if (sp) 390 a1 = (unsigned long)sp; 391 else 392 a1 = (unsigned long)stack_pointer(task); 393 394 sp_start = a1 & ~(THREAD_SIZE-1); 395 sp_end = sp_start + THREAD_SIZE; 396 397 printk("Call Trace:"); 398 #ifdef CONFIG_KALLSYMS 399 printk("\n"); 400 #endif 401 spill_registers(); 402 403 while (a1 > sp_start && a1 < sp_end) { 404 sp = (unsigned long*)a1; 405 406 a0 = *(sp - 4); 407 a1 = *(sp - 3); 408 409 if (a1 <= (unsigned long) sp) 410 break; 411 412 pc = MAKE_PC_FROM_RA(a0, a1); 413 414 if (kernel_text_address(pc)) { 415 printk(" [<%08lx>] ", pc); 416 print_symbol("%s\n", pc); 417 } 418 } 419 printk("\n"); 420 } 421 422 /* 423 * This routine abuses get_user()/put_user() to reference pointers 424 * with at least a bit of error checking ... 425 */ 426 427 static int kstack_depth_to_print = 24; 428 429 void show_stack(struct task_struct *task, unsigned long *sp) 430 { 431 int i = 0; 432 unsigned long *stack; 433 434 if (!sp) 435 sp = stack_pointer(task); 436 stack = sp; 437 438 printk("\nStack: "); 439 440 for (i = 0; i < kstack_depth_to_print; i++) { 441 if (kstack_end(sp)) 442 break; 443 if (i && ((i % 8) == 0)) 444 printk("\n "); 445 printk("%08lx ", *sp++); 446 } 447 printk("\n"); 448 show_trace(task, stack); 449 } 450 451 void dump_stack(void) 452 { 453 show_stack(current, NULL); 454 } 455 456 EXPORT_SYMBOL(dump_stack); 457 458 459 void show_code(unsigned int *pc) 460 { 461 long i; 462 463 printk("\nCode:"); 464 465 for(i = -3 ; i < 6 ; i++) { 466 unsigned long insn; 467 if (__get_user(insn, pc + i)) { 468 printk(" (Bad address in pc)\n"); 469 break; 470 } 471 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 472 } 473 } 474 475 DEFINE_SPINLOCK(die_lock); 476 477 void die(const char * str, struct pt_regs * regs, long err) 478 { 479 static int die_counter; 480 int nl = 0; 481 482 console_verbose(); 483 spin_lock_irq(&die_lock); 484 485 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 486 #ifdef CONFIG_PREEMPT 487 printk("PREEMPT "); 488 nl = 1; 489 #endif 490 if (nl) 491 printk("\n"); 492 show_regs(regs); 493 if (!user_mode(regs)) 494 show_stack(NULL, (unsigned long*)regs->areg[1]); 495 496 add_taint(TAINT_DIE); 497 spin_unlock_irq(&die_lock); 498 499 if (in_interrupt()) 500 panic("Fatal exception in interrupt"); 501 502 if (panic_on_oops) 503 panic("Fatal exception"); 504 505 do_exit(err); 506 } 507 508 509