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 34 #include <asm/ptrace.h> 35 #include <asm/timex.h> 36 #include <asm/uaccess.h> 37 #include <asm/pgtable.h> 38 #include <asm/processor.h> 39 40 #ifdef CONFIG_KGDB 41 extern int gdb_enter; 42 extern int return_from_debug_flag; 43 #endif 44 45 /* 46 * Machine specific interrupt handlers 47 */ 48 49 extern void kernel_exception(void); 50 extern void user_exception(void); 51 52 extern void fast_syscall_kernel(void); 53 extern void fast_syscall_user(void); 54 extern void fast_alloca(void); 55 extern void fast_unaligned(void); 56 extern void fast_second_level_miss(void); 57 extern void fast_store_prohibited(void); 58 extern void fast_coprocessor(void); 59 60 extern void do_illegal_instruction (struct pt_regs*); 61 extern void do_interrupt (struct pt_regs*); 62 extern void do_unaligned_user (struct pt_regs*); 63 extern void do_multihit (struct pt_regs*, unsigned long); 64 extern void do_page_fault (struct pt_regs*, unsigned long); 65 extern void do_debug (struct pt_regs*); 66 extern void system_call (struct pt_regs*); 67 68 /* 69 * The vector table must be preceded by a save area (which 70 * implies it must be in RAM, unless one places RAM immediately 71 * before a ROM and puts the vector at the start of the ROM (!)) 72 */ 73 74 #define KRNL 0x01 75 #define USER 0x02 76 77 #define COPROCESSOR(x) \ 78 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 79 80 typedef struct { 81 int cause; 82 int fast; 83 void* handler; 84 } dispatch_init_table_t; 85 86 static dispatch_init_table_t __initdata dispatch_init_table[] = { 87 88 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 89 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 90 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 91 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 92 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 93 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 94 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 95 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 96 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 97 /* EXCCAUSE_PRIVILEGED unhandled */ 98 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 99 #ifdef CONFIG_UNALIGNED_USER 100 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 101 #else 102 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 103 #endif 104 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 105 #endif 106 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 107 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 108 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 109 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 110 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 111 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 112 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 113 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 114 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 115 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 116 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 117 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 119 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 120 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 121 #if (XCHAL_CP_MASK & 1) 122 COPROCESSOR(0), 123 #endif 124 #if (XCHAL_CP_MASK & 2) 125 COPROCESSOR(1), 126 #endif 127 #if (XCHAL_CP_MASK & 4) 128 COPROCESSOR(2), 129 #endif 130 #if (XCHAL_CP_MASK & 8) 131 COPROCESSOR(3), 132 #endif 133 #if (XCHAL_CP_MASK & 16) 134 COPROCESSOR(4), 135 #endif 136 #if (XCHAL_CP_MASK & 32) 137 COPROCESSOR(5), 138 #endif 139 #if (XCHAL_CP_MASK & 64) 140 COPROCESSOR(6), 141 #endif 142 #if (XCHAL_CP_MASK & 128) 143 COPROCESSOR(7), 144 #endif 145 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 146 { -1, -1, 0 } 147 148 }; 149 150 /* The exception table <exc_table> serves two functions: 151 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 152 * 2. it is a temporary memory buffer for the exception handlers. 153 */ 154 155 unsigned long exc_table[EXC_TABLE_SIZE/4]; 156 157 void die(const char*, struct pt_regs*, long); 158 159 static inline void 160 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 161 { 162 if (!user_mode(regs)) 163 die(str, regs, err); 164 } 165 166 /* 167 * Unhandled Exceptions. Kill user task or panic if in kernel space. 168 */ 169 170 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 171 { 172 __die_if_kernel("Caught unhandled exception - should not happen", 173 regs, SIGKILL); 174 175 /* If in user mode, send SIGILL signal to current process */ 176 printk("Caught unhandled exception in '%s' " 177 "(pid = %d, pc = %#010lx) - should not happen\n" 178 "\tEXCCAUSE is %ld\n", 179 current->comm, task_pid_nr(current), regs->pc, exccause); 180 force_sig(SIGILL, current); 181 } 182 183 /* 184 * Multi-hit exception. This if fatal! 185 */ 186 187 void do_multihit(struct pt_regs *regs, unsigned long exccause) 188 { 189 die("Caught multihit exception", regs, SIGKILL); 190 } 191 192 /* 193 * Level-1 interrupt. 194 * We currently have no priority encoding. 195 */ 196 197 unsigned long ignored_level1_interrupts; 198 extern void do_IRQ(int, struct pt_regs *); 199 200 void do_interrupt (struct pt_regs *regs) 201 { 202 unsigned long intread = get_sr (INTREAD); 203 unsigned long intenable = get_sr (INTENABLE); 204 int i, mask; 205 206 /* Handle all interrupts (no priorities). 207 * (Clear the interrupt before processing, in case it's 208 * edge-triggered or software-generated) 209 */ 210 211 for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) { 212 if (mask & (intread & intenable)) { 213 set_sr (mask, INTCLEAR); 214 do_IRQ (i,regs); 215 } 216 } 217 } 218 219 /* 220 * Illegal instruction. Fatal if in kernel space. 221 */ 222 223 void 224 do_illegal_instruction(struct pt_regs *regs) 225 { 226 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 227 228 /* If in user mode, send SIGILL signal to current process. */ 229 230 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 231 current->comm, task_pid_nr(current), regs->pc); 232 force_sig(SIGILL, current); 233 } 234 235 236 /* 237 * Handle unaligned memory accesses from user space. Kill task. 238 * 239 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 240 * accesses causes from user space. 241 */ 242 243 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 244 #ifndef CONFIG_UNALIGNED_USER 245 void 246 do_unaligned_user (struct pt_regs *regs) 247 { 248 siginfo_t info; 249 250 __die_if_kernel("Unhandled unaligned exception in kernel", 251 regs, SIGKILL); 252 253 current->thread.bad_vaddr = regs->excvaddr; 254 current->thread.error_code = -3; 255 printk("Unaligned memory access to %08lx in '%s' " 256 "(pid = %d, pc = %#010lx)\n", 257 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 258 info.si_signo = SIGBUS; 259 info.si_errno = 0; 260 info.si_code = BUS_ADRALN; 261 info.si_addr = (void *) regs->excvaddr; 262 force_sig_info(SIGSEGV, &info, current); 263 264 } 265 #endif 266 #endif 267 268 void 269 do_debug(struct pt_regs *regs) 270 { 271 #ifdef CONFIG_KGDB 272 /* If remote debugging is configured AND enabled, we give control to 273 * kgdb. Otherwise, we fall through, perhaps giving control to the 274 * native debugger. 275 */ 276 277 if (gdb_enter) { 278 extern void gdb_handle_exception(struct pt_regs *); 279 gdb_handle_exception(regs); 280 return_from_debug_flag = 1; 281 return; 282 } 283 #endif 284 285 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 286 287 /* If in user mode, send SIGTRAP signal to current process */ 288 289 force_sig(SIGTRAP, current); 290 } 291 292 293 /* 294 * Initialize dispatch tables. 295 * 296 * The exception vectors are stored compressed the __init section in the 297 * dispatch_init_table. This function initializes the following three tables 298 * from that compressed table: 299 * - fast user first dispatch table for user exceptions 300 * - fast kernel first dispatch table for kernel exceptions 301 * - default C-handler C-handler called by the default fast handler. 302 * 303 * See vectors.S for more details. 304 */ 305 306 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 307 308 void __init trap_init(void) 309 { 310 int i; 311 312 /* Setup default vectors. */ 313 314 for(i = 0; i < 64; i++) { 315 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 316 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 317 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 318 } 319 320 /* Setup specific handlers. */ 321 322 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 323 324 int fast = dispatch_init_table[i].fast; 325 int cause = dispatch_init_table[i].cause; 326 void *handler = dispatch_init_table[i].handler; 327 328 if (fast == 0) 329 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 330 if (fast && fast & USER) 331 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 332 if (fast && fast & KRNL) 333 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 334 } 335 336 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 337 338 i = (unsigned long)exc_table; 339 __asm__ __volatile__("wsr %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i)); 340 } 341 342 /* 343 * This function dumps the current valid window frame and other base registers. 344 */ 345 346 void show_regs(struct pt_regs * regs) 347 { 348 int i, wmask; 349 350 wmask = regs->wmask & ~1; 351 352 for (i = 0; i < 16; i++) { 353 if ((i % 8) == 0) 354 printk ("\n" KERN_INFO "a%02d: ", i); 355 printk("%08lx ", regs->areg[i]); 356 } 357 printk("\n"); 358 359 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 360 regs->pc, regs->ps, regs->depc, regs->excvaddr); 361 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 362 regs->lbeg, regs->lend, regs->lcount, regs->sar); 363 if (user_mode(regs)) 364 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 365 regs->windowbase, regs->windowstart, regs->wmask, 366 regs->syscall); 367 } 368 369 void show_trace(struct task_struct *task, unsigned long *sp) 370 { 371 unsigned long a0, a1, pc; 372 unsigned long sp_start, sp_end; 373 374 a1 = (unsigned long)sp; 375 376 if (a1 == 0) 377 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(a1)); 378 379 380 sp_start = a1 & ~(THREAD_SIZE-1); 381 sp_end = sp_start + THREAD_SIZE; 382 383 printk("Call Trace:"); 384 #ifdef CONFIG_KALLSYMS 385 printk("\n"); 386 #endif 387 spill_registers(); 388 389 while (a1 > sp_start && a1 < sp_end) { 390 sp = (unsigned long*)a1; 391 392 a0 = *(sp - 4); 393 a1 = *(sp - 3); 394 395 if (a1 <= (unsigned long) sp) 396 break; 397 398 pc = MAKE_PC_FROM_RA(a0, a1); 399 400 if (kernel_text_address(pc)) { 401 printk(" [<%08lx>] ", pc); 402 print_symbol("%s\n", pc); 403 } 404 } 405 printk("\n"); 406 } 407 408 /* 409 * This routine abuses get_user()/put_user() to reference pointers 410 * with at least a bit of error checking ... 411 */ 412 413 static int kstack_depth_to_print = 24; 414 415 void show_stack(struct task_struct *task, unsigned long *sp) 416 { 417 int i = 0; 418 unsigned long *stack; 419 420 if (sp == 0) 421 __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); 422 423 stack = sp; 424 425 printk("\nStack: "); 426 427 for (i = 0; i < kstack_depth_to_print; i++) { 428 if (kstack_end(sp)) 429 break; 430 if (i && ((i % 8) == 0)) 431 printk("\n "); 432 printk("%08lx ", *sp++); 433 } 434 printk("\n"); 435 show_trace(task, stack); 436 } 437 438 void dump_stack(void) 439 { 440 show_stack(current, NULL); 441 } 442 443 EXPORT_SYMBOL(dump_stack); 444 445 446 void show_code(unsigned int *pc) 447 { 448 long i; 449 450 printk("\nCode:"); 451 452 for(i = -3 ; i < 6 ; i++) { 453 unsigned long insn; 454 if (__get_user(insn, pc + i)) { 455 printk(" (Bad address in pc)\n"); 456 break; 457 } 458 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 459 } 460 } 461 462 DEFINE_SPINLOCK(die_lock); 463 464 void die(const char * str, struct pt_regs * regs, long err) 465 { 466 static int die_counter; 467 int nl = 0; 468 469 console_verbose(); 470 spin_lock_irq(&die_lock); 471 472 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 473 #ifdef CONFIG_PREEMPT 474 printk("PREEMPT "); 475 nl = 1; 476 #endif 477 if (nl) 478 printk("\n"); 479 show_regs(regs); 480 if (!user_mode(regs)) 481 show_stack(NULL, (unsigned long*)regs->areg[1]); 482 483 add_taint(TAINT_DIE); 484 spin_unlock_irq(&die_lock); 485 486 if (in_interrupt()) 487 panic("Fatal exception in interrupt"); 488 489 if (panic_on_oops) 490 panic("Fatal exception"); 491 492 do_exit(err); 493 } 494 495 496