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 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 108 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 109 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 110 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 111 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 112 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 113 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 114 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 115 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 116 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 117 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 118 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 119 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 120 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 121 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 122 #if XTENSA_HAVE_COPROCESSOR(0) 123 COPROCESSOR(0), 124 #endif 125 #if XTENSA_HAVE_COPROCESSOR(1) 126 COPROCESSOR(1), 127 #endif 128 #if XTENSA_HAVE_COPROCESSOR(2) 129 COPROCESSOR(2), 130 #endif 131 #if XTENSA_HAVE_COPROCESSOR(3) 132 COPROCESSOR(3), 133 #endif 134 #if XTENSA_HAVE_COPROCESSOR(4) 135 COPROCESSOR(4), 136 #endif 137 #if XTENSA_HAVE_COPROCESSOR(5) 138 COPROCESSOR(5), 139 #endif 140 #if XTENSA_HAVE_COPROCESSOR(6) 141 COPROCESSOR(6), 142 #endif 143 #if XTENSA_HAVE_COPROCESSOR(7) 144 COPROCESSOR(7), 145 #endif 146 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 147 { -1, -1, 0 } 148 149 }; 150 151 /* The exception table <exc_table> serves two functions: 152 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 153 * 2. it is a temporary memory buffer for the exception handlers. 154 */ 155 156 unsigned long exc_table[EXC_TABLE_SIZE/4]; 157 158 void die(const char*, struct pt_regs*, long); 159 160 static inline void 161 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 162 { 163 if (!user_mode(regs)) 164 die(str, regs, err); 165 } 166 167 /* 168 * Unhandled Exceptions. Kill user task or panic if in kernel space. 169 */ 170 171 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 172 { 173 __die_if_kernel("Caught unhandled exception - should not happen", 174 regs, SIGKILL); 175 176 /* If in user mode, send SIGILL signal to current process */ 177 printk("Caught unhandled exception in '%s' " 178 "(pid = %d, pc = %#010lx) - should not happen\n" 179 "\tEXCCAUSE is %ld\n", 180 current->comm, task_pid_nr(current), regs->pc, exccause); 181 force_sig(SIGILL, current); 182 } 183 184 /* 185 * Multi-hit exception. This if fatal! 186 */ 187 188 void do_multihit(struct pt_regs *regs, unsigned long exccause) 189 { 190 die("Caught multihit exception", regs, SIGKILL); 191 } 192 193 /* 194 * Level-1 interrupt. 195 * We currently have no priority encoding. 196 */ 197 198 unsigned long ignored_level1_interrupts; 199 extern void do_IRQ(int, struct pt_regs *); 200 201 void do_interrupt (struct pt_regs *regs) 202 { 203 unsigned long intread = get_sr (INTREAD); 204 unsigned long intenable = get_sr (INTENABLE); 205 int i, mask; 206 207 /* Handle all interrupts (no priorities). 208 * (Clear the interrupt before processing, in case it's 209 * edge-triggered or software-generated) 210 */ 211 212 for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) { 213 if (mask & (intread & intenable)) { 214 set_sr (mask, INTCLEAR); 215 do_IRQ (i,regs); 216 } 217 } 218 } 219 220 /* 221 * Illegal instruction. Fatal if in kernel space. 222 */ 223 224 void 225 do_illegal_instruction(struct pt_regs *regs) 226 { 227 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 228 229 /* If in user mode, send SIGILL signal to current process. */ 230 231 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 232 current->comm, task_pid_nr(current), regs->pc); 233 force_sig(SIGILL, current); 234 } 235 236 237 /* 238 * Handle unaligned memory accesses from user space. Kill task. 239 * 240 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 241 * accesses causes from user space. 242 */ 243 244 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 245 #ifndef CONFIG_UNALIGNED_USER 246 void 247 do_unaligned_user (struct pt_regs *regs) 248 { 249 siginfo_t info; 250 251 __die_if_kernel("Unhandled unaligned exception in kernel", 252 regs, SIGKILL); 253 254 current->thread.bad_vaddr = regs->excvaddr; 255 current->thread.error_code = -3; 256 printk("Unaligned memory access to %08lx in '%s' " 257 "(pid = %d, pc = %#010lx)\n", 258 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 259 info.si_signo = SIGBUS; 260 info.si_errno = 0; 261 info.si_code = BUS_ADRALN; 262 info.si_addr = (void *) regs->excvaddr; 263 force_sig_info(SIGSEGV, &info, current); 264 265 } 266 #endif 267 #endif 268 269 void 270 do_debug(struct pt_regs *regs) 271 { 272 #ifdef CONFIG_KGDB 273 /* If remote debugging is configured AND enabled, we give control to 274 * kgdb. Otherwise, we fall through, perhaps giving control to the 275 * native debugger. 276 */ 277 278 if (gdb_enter) { 279 extern void gdb_handle_exception(struct pt_regs *); 280 gdb_handle_exception(regs); 281 return_from_debug_flag = 1; 282 return; 283 } 284 #endif 285 286 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 287 288 /* If in user mode, send SIGTRAP signal to current process */ 289 290 force_sig(SIGTRAP, current); 291 } 292 293 294 /* 295 * Initialize dispatch tables. 296 * 297 * The exception vectors are stored compressed the __init section in the 298 * dispatch_init_table. This function initializes the following three tables 299 * from that compressed table: 300 * - fast user first dispatch table for user exceptions 301 * - fast kernel first dispatch table for kernel exceptions 302 * - default C-handler C-handler called by the default fast handler. 303 * 304 * See vectors.S for more details. 305 */ 306 307 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 308 309 void __init trap_init(void) 310 { 311 int i; 312 313 /* Setup default vectors. */ 314 315 for(i = 0; i < 64; i++) { 316 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 317 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 318 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 319 } 320 321 /* Setup specific handlers. */ 322 323 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 324 325 int fast = dispatch_init_table[i].fast; 326 int cause = dispatch_init_table[i].cause; 327 void *handler = dispatch_init_table[i].handler; 328 329 if (fast == 0) 330 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 331 if (fast && fast & USER) 332 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 333 if (fast && fast & KRNL) 334 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 335 } 336 337 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 338 339 i = (unsigned long)exc_table; 340 __asm__ __volatile__("wsr %0, "__stringify(EXCSAVE_1)"\n" : : "a" (i)); 341 } 342 343 /* 344 * This function dumps the current valid window frame and other base registers. 345 */ 346 347 void show_regs(struct pt_regs * regs) 348 { 349 int i, wmask; 350 351 wmask = regs->wmask & ~1; 352 353 for (i = 0; i < 16; i++) { 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 DEFINE_SPINLOCK(die_lock); 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 add_taint(TAINT_DIE); 485 spin_unlock_irq(&die_lock); 486 487 if (in_interrupt()) 488 panic("Fatal exception in interrupt"); 489 490 if (panic_on_oops) 491 panic("Fatal exception"); 492 493 do_exit(err); 494 } 495 496 497