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 - 2013 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/stacktrace.h> 36 #include <asm/ptrace.h> 37 #include <asm/timex.h> 38 #include <asm/uaccess.h> 39 #include <asm/pgtable.h> 40 #include <asm/processor.h> 41 #include <asm/traps.h> 42 43 #ifdef CONFIG_KGDB 44 extern int gdb_enter; 45 extern int return_from_debug_flag; 46 #endif 47 48 /* 49 * Machine specific interrupt handlers 50 */ 51 52 extern void kernel_exception(void); 53 extern void user_exception(void); 54 55 extern void fast_syscall_kernel(void); 56 extern void fast_syscall_user(void); 57 extern void fast_alloca(void); 58 extern void fast_unaligned(void); 59 extern void fast_second_level_miss(void); 60 extern void fast_store_prohibited(void); 61 extern void fast_coprocessor(void); 62 63 extern void do_illegal_instruction (struct pt_regs*); 64 extern void do_interrupt (struct pt_regs*); 65 extern void do_unaligned_user (struct pt_regs*); 66 extern void do_multihit (struct pt_regs*, unsigned long); 67 extern void do_page_fault (struct pt_regs*, unsigned long); 68 extern void do_debug (struct pt_regs*); 69 extern void system_call (struct pt_regs*); 70 71 /* 72 * The vector table must be preceded by a save area (which 73 * implies it must be in RAM, unless one places RAM immediately 74 * before a ROM and puts the vector at the start of the ROM (!)) 75 */ 76 77 #define KRNL 0x01 78 #define USER 0x02 79 80 #define COPROCESSOR(x) \ 81 { EXCCAUSE_COPROCESSOR ## x ## _DISABLED, USER, fast_coprocessor } 82 83 typedef struct { 84 int cause; 85 int fast; 86 void* handler; 87 } dispatch_init_table_t; 88 89 static dispatch_init_table_t __initdata dispatch_init_table[] = { 90 91 { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, 92 { EXCCAUSE_SYSTEM_CALL, KRNL, fast_syscall_kernel }, 93 { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, 94 { EXCCAUSE_SYSTEM_CALL, 0, system_call }, 95 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */ 96 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/ 97 { EXCCAUSE_LEVEL1_INTERRUPT, 0, do_interrupt }, 98 { EXCCAUSE_ALLOCA, USER|KRNL, fast_alloca }, 99 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */ 100 /* EXCCAUSE_PRIVILEGED unhandled */ 101 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 102 #ifdef CONFIG_XTENSA_UNALIGNED_USER 103 { EXCCAUSE_UNALIGNED, USER, fast_unaligned }, 104 #else 105 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 106 #endif 107 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 108 #endif 109 #ifdef CONFIG_MMU 110 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 111 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 112 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 113 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 114 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 115 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 116 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 117 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 118 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 119 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 120 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 122 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 123 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 124 #endif /* CONFIG_MMU */ 125 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 126 #if XTENSA_HAVE_COPROCESSOR(0) 127 COPROCESSOR(0), 128 #endif 129 #if XTENSA_HAVE_COPROCESSOR(1) 130 COPROCESSOR(1), 131 #endif 132 #if XTENSA_HAVE_COPROCESSOR(2) 133 COPROCESSOR(2), 134 #endif 135 #if XTENSA_HAVE_COPROCESSOR(3) 136 COPROCESSOR(3), 137 #endif 138 #if XTENSA_HAVE_COPROCESSOR(4) 139 COPROCESSOR(4), 140 #endif 141 #if XTENSA_HAVE_COPROCESSOR(5) 142 COPROCESSOR(5), 143 #endif 144 #if XTENSA_HAVE_COPROCESSOR(6) 145 COPROCESSOR(6), 146 #endif 147 #if XTENSA_HAVE_COPROCESSOR(7) 148 COPROCESSOR(7), 149 #endif 150 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 151 { -1, -1, 0 } 152 153 }; 154 155 /* The exception table <exc_table> serves two functions: 156 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 157 * 2. it is a temporary memory buffer for the exception handlers. 158 */ 159 160 unsigned long exc_table[EXC_TABLE_SIZE/4]; 161 162 void die(const char*, struct pt_regs*, long); 163 164 static inline void 165 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 166 { 167 if (!user_mode(regs)) 168 die(str, regs, err); 169 } 170 171 /* 172 * Unhandled Exceptions. Kill user task or panic if in kernel space. 173 */ 174 175 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 176 { 177 __die_if_kernel("Caught unhandled exception - should not happen", 178 regs, SIGKILL); 179 180 /* If in user mode, send SIGILL signal to current process */ 181 printk("Caught unhandled exception in '%s' " 182 "(pid = %d, pc = %#010lx) - should not happen\n" 183 "\tEXCCAUSE is %ld\n", 184 current->comm, task_pid_nr(current), regs->pc, exccause); 185 force_sig(SIGILL, current); 186 } 187 188 /* 189 * Multi-hit exception. This if fatal! 190 */ 191 192 void do_multihit(struct pt_regs *regs, unsigned long exccause) 193 { 194 die("Caught multihit exception", regs, SIGKILL); 195 } 196 197 /* 198 * IRQ handler. 199 */ 200 201 extern void do_IRQ(int, struct pt_regs *); 202 203 void do_interrupt(struct pt_regs *regs) 204 { 205 static const unsigned int_level_mask[] = { 206 0, 207 XCHAL_INTLEVEL1_MASK, 208 XCHAL_INTLEVEL2_MASK, 209 XCHAL_INTLEVEL3_MASK, 210 XCHAL_INTLEVEL4_MASK, 211 XCHAL_INTLEVEL5_MASK, 212 XCHAL_INTLEVEL6_MASK, 213 XCHAL_INTLEVEL7_MASK, 214 }; 215 struct pt_regs *old_regs = set_irq_regs(regs); 216 217 irq_enter(); 218 219 for (;;) { 220 unsigned intread = get_sr(interrupt); 221 unsigned intenable = get_sr(intenable); 222 unsigned int_at_level = intread & intenable; 223 unsigned level; 224 225 for (level = LOCKLEVEL; level > 0; --level) { 226 if (int_at_level & int_level_mask[level]) { 227 int_at_level &= int_level_mask[level]; 228 break; 229 } 230 } 231 232 if (level == 0) 233 break; 234 235 do_IRQ(__ffs(int_at_level), regs); 236 } 237 238 irq_exit(); 239 set_irq_regs(old_regs); 240 } 241 242 /* 243 * Illegal instruction. Fatal if in kernel space. 244 */ 245 246 void 247 do_illegal_instruction(struct pt_regs *regs) 248 { 249 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 250 251 /* If in user mode, send SIGILL signal to current process. */ 252 253 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 254 current->comm, task_pid_nr(current), regs->pc); 255 force_sig(SIGILL, current); 256 } 257 258 259 /* 260 * Handle unaligned memory accesses from user space. Kill task. 261 * 262 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 263 * accesses causes from user space. 264 */ 265 266 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 267 #ifndef CONFIG_XTENSA_UNALIGNED_USER 268 void 269 do_unaligned_user (struct pt_regs *regs) 270 { 271 siginfo_t info; 272 273 __die_if_kernel("Unhandled unaligned exception in kernel", 274 regs, SIGKILL); 275 276 current->thread.bad_vaddr = regs->excvaddr; 277 current->thread.error_code = -3; 278 printk("Unaligned memory access to %08lx in '%s' " 279 "(pid = %d, pc = %#010lx)\n", 280 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 281 info.si_signo = SIGBUS; 282 info.si_errno = 0; 283 info.si_code = BUS_ADRALN; 284 info.si_addr = (void *) regs->excvaddr; 285 force_sig_info(SIGSEGV, &info, current); 286 287 } 288 #endif 289 #endif 290 291 void 292 do_debug(struct pt_regs *regs) 293 { 294 #ifdef CONFIG_KGDB 295 /* If remote debugging is configured AND enabled, we give control to 296 * kgdb. Otherwise, we fall through, perhaps giving control to the 297 * native debugger. 298 */ 299 300 if (gdb_enter) { 301 extern void gdb_handle_exception(struct pt_regs *); 302 gdb_handle_exception(regs); 303 return_from_debug_flag = 1; 304 return; 305 } 306 #endif 307 308 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 309 310 /* If in user mode, send SIGTRAP signal to current process */ 311 312 force_sig(SIGTRAP, current); 313 } 314 315 316 /* Set exception C handler - for temporary use when probing exceptions */ 317 318 void * __init trap_set_handler(int cause, void *handler) 319 { 320 unsigned long *entry = &exc_table[EXC_TABLE_DEFAULT / 4 + cause]; 321 void *previous = (void *)*entry; 322 *entry = (unsigned long)handler; 323 return previous; 324 } 325 326 327 /* 328 * Initialize dispatch tables. 329 * 330 * The exception vectors are stored compressed the __init section in the 331 * dispatch_init_table. This function initializes the following three tables 332 * from that compressed table: 333 * - fast user first dispatch table for user exceptions 334 * - fast kernel first dispatch table for kernel exceptions 335 * - default C-handler C-handler called by the default fast handler. 336 * 337 * See vectors.S for more details. 338 */ 339 340 #define set_handler(idx,handler) (exc_table[idx] = (unsigned long) (handler)) 341 342 void __init trap_init(void) 343 { 344 int i; 345 346 /* Setup default vectors. */ 347 348 for(i = 0; i < 64; i++) { 349 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 350 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 351 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 352 } 353 354 /* Setup specific handlers. */ 355 356 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 357 358 int fast = dispatch_init_table[i].fast; 359 int cause = dispatch_init_table[i].cause; 360 void *handler = dispatch_init_table[i].handler; 361 362 if (fast == 0) 363 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 364 if (fast && fast & USER) 365 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 366 if (fast && fast & KRNL) 367 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 368 } 369 370 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 371 372 i = (unsigned long)exc_table; 373 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (i)); 374 } 375 376 /* 377 * This function dumps the current valid window frame and other base registers. 378 */ 379 380 void show_regs(struct pt_regs * regs) 381 { 382 int i, wmask; 383 384 show_regs_print_info(KERN_DEFAULT); 385 386 wmask = regs->wmask & ~1; 387 388 for (i = 0; i < 16; i++) { 389 if ((i % 8) == 0) 390 printk(KERN_INFO "a%02d:", i); 391 printk(KERN_CONT " %08lx", regs->areg[i]); 392 } 393 printk(KERN_CONT "\n"); 394 395 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 396 regs->pc, regs->ps, regs->depc, regs->excvaddr); 397 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 398 regs->lbeg, regs->lend, regs->lcount, regs->sar); 399 if (user_mode(regs)) 400 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 401 regs->windowbase, regs->windowstart, regs->wmask, 402 regs->syscall); 403 } 404 405 static int show_trace_cb(struct stackframe *frame, void *data) 406 { 407 if (kernel_text_address(frame->pc)) { 408 printk(" [<%08lx>] ", frame->pc); 409 print_symbol("%s\n", frame->pc); 410 } 411 return 0; 412 } 413 414 void show_trace(struct task_struct *task, unsigned long *sp) 415 { 416 if (!sp) 417 sp = stack_pointer(task); 418 419 printk("Call Trace:"); 420 #ifdef CONFIG_KALLSYMS 421 printk("\n"); 422 #endif 423 walk_stackframe(sp, show_trace_cb, NULL); 424 printk("\n"); 425 } 426 427 /* 428 * This routine abuses get_user()/put_user() to reference pointers 429 * with at least a bit of error checking ... 430 */ 431 432 static int kstack_depth_to_print = 24; 433 434 void show_stack(struct task_struct *task, unsigned long *sp) 435 { 436 int i = 0; 437 unsigned long *stack; 438 439 if (!sp) 440 sp = stack_pointer(task); 441 stack = sp; 442 443 printk("\nStack: "); 444 445 for (i = 0; i < kstack_depth_to_print; i++) { 446 if (kstack_end(sp)) 447 break; 448 if (i && ((i % 8) == 0)) 449 printk("\n "); 450 printk("%08lx ", *sp++); 451 } 452 printk("\n"); 453 show_trace(task, stack); 454 } 455 456 void show_code(unsigned int *pc) 457 { 458 long i; 459 460 printk("\nCode:"); 461 462 for(i = -3 ; i < 6 ; i++) { 463 unsigned long insn; 464 if (__get_user(insn, pc + i)) { 465 printk(" (Bad address in pc)\n"); 466 break; 467 } 468 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 469 } 470 } 471 472 DEFINE_SPINLOCK(die_lock); 473 474 void die(const char * str, struct pt_regs * regs, long err) 475 { 476 static int die_counter; 477 int nl = 0; 478 479 console_verbose(); 480 spin_lock_irq(&die_lock); 481 482 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 483 #ifdef CONFIG_PREEMPT 484 printk("PREEMPT "); 485 nl = 1; 486 #endif 487 if (nl) 488 printk("\n"); 489 show_regs(regs); 490 if (!user_mode(regs)) 491 show_stack(NULL, (unsigned long*)regs->areg[1]); 492 493 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 494 spin_unlock_irq(&die_lock); 495 496 if (in_interrupt()) 497 panic("Fatal exception in interrupt"); 498 499 if (panic_on_oops) 500 panic("Fatal exception"); 501 502 do_exit(err); 503 } 504