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 #endif 105 { EXCCAUSE_UNALIGNED, 0, do_unaligned_user }, 106 { EXCCAUSE_UNALIGNED, KRNL, fast_unaligned }, 107 #endif 108 #ifdef CONFIG_MMU 109 { EXCCAUSE_ITLB_MISS, 0, do_page_fault }, 110 { EXCCAUSE_ITLB_MISS, USER|KRNL, fast_second_level_miss}, 111 { EXCCAUSE_ITLB_MULTIHIT, 0, do_multihit }, 112 { EXCCAUSE_ITLB_PRIVILEGE, 0, do_page_fault }, 113 /* EXCCAUSE_SIZE_RESTRICTION unhandled */ 114 { EXCCAUSE_FETCH_CACHE_ATTRIBUTE, 0, do_page_fault }, 115 { EXCCAUSE_DTLB_MISS, USER|KRNL, fast_second_level_miss}, 116 { EXCCAUSE_DTLB_MISS, 0, do_page_fault }, 117 { EXCCAUSE_DTLB_MULTIHIT, 0, do_multihit }, 118 { EXCCAUSE_DTLB_PRIVILEGE, 0, do_page_fault }, 119 /* EXCCAUSE_DTLB_SIZE_RESTRICTION unhandled */ 120 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, USER|KRNL, fast_store_prohibited }, 121 { EXCCAUSE_STORE_CACHE_ATTRIBUTE, 0, do_page_fault }, 122 { EXCCAUSE_LOAD_CACHE_ATTRIBUTE, 0, do_page_fault }, 123 #endif /* CONFIG_MMU */ 124 /* XCCHAL_EXCCAUSE_FLOATING_POINT unhandled */ 125 #if XTENSA_HAVE_COPROCESSOR(0) 126 COPROCESSOR(0), 127 #endif 128 #if XTENSA_HAVE_COPROCESSOR(1) 129 COPROCESSOR(1), 130 #endif 131 #if XTENSA_HAVE_COPROCESSOR(2) 132 COPROCESSOR(2), 133 #endif 134 #if XTENSA_HAVE_COPROCESSOR(3) 135 COPROCESSOR(3), 136 #endif 137 #if XTENSA_HAVE_COPROCESSOR(4) 138 COPROCESSOR(4), 139 #endif 140 #if XTENSA_HAVE_COPROCESSOR(5) 141 COPROCESSOR(5), 142 #endif 143 #if XTENSA_HAVE_COPROCESSOR(6) 144 COPROCESSOR(6), 145 #endif 146 #if XTENSA_HAVE_COPROCESSOR(7) 147 COPROCESSOR(7), 148 #endif 149 { EXCCAUSE_MAPPED_DEBUG, 0, do_debug }, 150 { -1, -1, 0 } 151 152 }; 153 154 /* The exception table <exc_table> serves two functions: 155 * 1. it contains three dispatch tables (fast_user, fast_kernel, default-c) 156 * 2. it is a temporary memory buffer for the exception handlers. 157 */ 158 159 DEFINE_PER_CPU(unsigned long, exc_table[EXC_TABLE_SIZE/4]); 160 161 void die(const char*, struct pt_regs*, long); 162 163 static inline void 164 __die_if_kernel(const char *str, struct pt_regs *regs, long err) 165 { 166 if (!user_mode(regs)) 167 die(str, regs, err); 168 } 169 170 /* 171 * Unhandled Exceptions. Kill user task or panic if in kernel space. 172 */ 173 174 void do_unhandled(struct pt_regs *regs, unsigned long exccause) 175 { 176 __die_if_kernel("Caught unhandled exception - should not happen", 177 regs, SIGKILL); 178 179 /* If in user mode, send SIGILL signal to current process */ 180 printk("Caught unhandled exception in '%s' " 181 "(pid = %d, pc = %#010lx) - should not happen\n" 182 "\tEXCCAUSE is %ld\n", 183 current->comm, task_pid_nr(current), regs->pc, exccause); 184 force_sig(SIGILL, current); 185 } 186 187 /* 188 * Multi-hit exception. This if fatal! 189 */ 190 191 void do_multihit(struct pt_regs *regs, unsigned long exccause) 192 { 193 die("Caught multihit exception", regs, SIGKILL); 194 } 195 196 /* 197 * IRQ handler. 198 */ 199 200 extern void do_IRQ(int, struct pt_regs *); 201 202 void do_interrupt(struct pt_regs *regs) 203 { 204 static const unsigned int_level_mask[] = { 205 0, 206 XCHAL_INTLEVEL1_MASK, 207 XCHAL_INTLEVEL2_MASK, 208 XCHAL_INTLEVEL3_MASK, 209 XCHAL_INTLEVEL4_MASK, 210 XCHAL_INTLEVEL5_MASK, 211 XCHAL_INTLEVEL6_MASK, 212 XCHAL_INTLEVEL7_MASK, 213 }; 214 struct pt_regs *old_regs = set_irq_regs(regs); 215 216 irq_enter(); 217 218 for (;;) { 219 unsigned intread = get_sr(interrupt); 220 unsigned intenable = get_sr(intenable); 221 unsigned int_at_level = intread & intenable; 222 unsigned level; 223 224 for (level = LOCKLEVEL; level > 0; --level) { 225 if (int_at_level & int_level_mask[level]) { 226 int_at_level &= int_level_mask[level]; 227 break; 228 } 229 } 230 231 if (level == 0) 232 break; 233 234 do_IRQ(__ffs(int_at_level), regs); 235 } 236 237 irq_exit(); 238 set_irq_regs(old_regs); 239 } 240 241 /* 242 * Illegal instruction. Fatal if in kernel space. 243 */ 244 245 void 246 do_illegal_instruction(struct pt_regs *regs) 247 { 248 __die_if_kernel("Illegal instruction in kernel", regs, SIGKILL); 249 250 /* If in user mode, send SIGILL signal to current process. */ 251 252 printk("Illegal Instruction in '%s' (pid = %d, pc = %#010lx)\n", 253 current->comm, task_pid_nr(current), regs->pc); 254 force_sig(SIGILL, current); 255 } 256 257 258 /* 259 * Handle unaligned memory accesses from user space. Kill task. 260 * 261 * If CONFIG_UNALIGNED_USER is not set, we don't allow unaligned memory 262 * accesses causes from user space. 263 */ 264 265 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION 266 void 267 do_unaligned_user (struct pt_regs *regs) 268 { 269 siginfo_t info; 270 271 __die_if_kernel("Unhandled unaligned exception in kernel", 272 regs, SIGKILL); 273 274 current->thread.bad_vaddr = regs->excvaddr; 275 current->thread.error_code = -3; 276 printk("Unaligned memory access to %08lx in '%s' " 277 "(pid = %d, pc = %#010lx)\n", 278 regs->excvaddr, current->comm, task_pid_nr(current), regs->pc); 279 info.si_signo = SIGBUS; 280 info.si_errno = 0; 281 info.si_code = BUS_ADRALN; 282 info.si_addr = (void *) regs->excvaddr; 283 force_sig_info(SIGSEGV, &info, current); 284 285 } 286 #endif 287 288 void 289 do_debug(struct pt_regs *regs) 290 { 291 #ifdef CONFIG_KGDB 292 /* If remote debugging is configured AND enabled, we give control to 293 * kgdb. Otherwise, we fall through, perhaps giving control to the 294 * native debugger. 295 */ 296 297 if (gdb_enter) { 298 extern void gdb_handle_exception(struct pt_regs *); 299 gdb_handle_exception(regs); 300 return_from_debug_flag = 1; 301 return; 302 } 303 #endif 304 305 __die_if_kernel("Breakpoint in kernel", regs, SIGKILL); 306 307 /* If in user mode, send SIGTRAP signal to current process */ 308 309 force_sig(SIGTRAP, current); 310 } 311 312 313 static void set_handler(int idx, void *handler) 314 { 315 unsigned int cpu; 316 317 for_each_possible_cpu(cpu) 318 per_cpu(exc_table, cpu)[idx] = (unsigned long)handler; 319 } 320 321 /* Set exception C handler - for temporary use when probing exceptions */ 322 323 void * __init trap_set_handler(int cause, void *handler) 324 { 325 void *previous = (void *)per_cpu(exc_table, 0)[ 326 EXC_TABLE_DEFAULT / 4 + cause]; 327 set_handler(EXC_TABLE_DEFAULT / 4 + cause, handler); 328 return previous; 329 } 330 331 332 static void trap_init_excsave(void) 333 { 334 unsigned long excsave1 = (unsigned long)this_cpu_ptr(exc_table); 335 __asm__ __volatile__("wsr %0, excsave1\n" : : "a" (excsave1)); 336 } 337 338 /* 339 * Initialize dispatch tables. 340 * 341 * The exception vectors are stored compressed the __init section in the 342 * dispatch_init_table. This function initializes the following three tables 343 * from that compressed table: 344 * - fast user first dispatch table for user exceptions 345 * - fast kernel first dispatch table for kernel exceptions 346 * - default C-handler C-handler called by the default fast handler. 347 * 348 * See vectors.S for more details. 349 */ 350 351 void __init trap_init(void) 352 { 353 int i; 354 355 /* Setup default vectors. */ 356 357 for(i = 0; i < 64; i++) { 358 set_handler(EXC_TABLE_FAST_USER/4 + i, user_exception); 359 set_handler(EXC_TABLE_FAST_KERNEL/4 + i, kernel_exception); 360 set_handler(EXC_TABLE_DEFAULT/4 + i, do_unhandled); 361 } 362 363 /* Setup specific handlers. */ 364 365 for(i = 0; dispatch_init_table[i].cause >= 0; i++) { 366 367 int fast = dispatch_init_table[i].fast; 368 int cause = dispatch_init_table[i].cause; 369 void *handler = dispatch_init_table[i].handler; 370 371 if (fast == 0) 372 set_handler (EXC_TABLE_DEFAULT/4 + cause, handler); 373 if (fast && fast & USER) 374 set_handler (EXC_TABLE_FAST_USER/4 + cause, handler); 375 if (fast && fast & KRNL) 376 set_handler (EXC_TABLE_FAST_KERNEL/4 + cause, handler); 377 } 378 379 /* Initialize EXCSAVE_1 to hold the address of the exception table. */ 380 trap_init_excsave(); 381 } 382 383 #ifdef CONFIG_SMP 384 void secondary_trap_init(void) 385 { 386 trap_init_excsave(); 387 } 388 #endif 389 390 /* 391 * This function dumps the current valid window frame and other base registers. 392 */ 393 394 void show_regs(struct pt_regs * regs) 395 { 396 int i, wmask; 397 398 show_regs_print_info(KERN_DEFAULT); 399 400 wmask = regs->wmask & ~1; 401 402 for (i = 0; i < 16; i++) { 403 if ((i % 8) == 0) 404 printk(KERN_INFO "a%02d:", i); 405 printk(KERN_CONT " %08lx", regs->areg[i]); 406 } 407 printk(KERN_CONT "\n"); 408 409 printk("pc: %08lx, ps: %08lx, depc: %08lx, excvaddr: %08lx\n", 410 regs->pc, regs->ps, regs->depc, regs->excvaddr); 411 printk("lbeg: %08lx, lend: %08lx lcount: %08lx, sar: %08lx\n", 412 regs->lbeg, regs->lend, regs->lcount, regs->sar); 413 if (user_mode(regs)) 414 printk("wb: %08lx, ws: %08lx, wmask: %08lx, syscall: %ld\n", 415 regs->windowbase, regs->windowstart, regs->wmask, 416 regs->syscall); 417 } 418 419 static int show_trace_cb(struct stackframe *frame, void *data) 420 { 421 if (kernel_text_address(frame->pc)) { 422 printk(" [<%08lx>] ", frame->pc); 423 print_symbol("%s\n", frame->pc); 424 } 425 return 0; 426 } 427 428 void show_trace(struct task_struct *task, unsigned long *sp) 429 { 430 if (!sp) 431 sp = stack_pointer(task); 432 433 printk("Call Trace:"); 434 #ifdef CONFIG_KALLSYMS 435 printk("\n"); 436 #endif 437 walk_stackframe(sp, show_trace_cb, NULL); 438 printk("\n"); 439 } 440 441 /* 442 * This routine abuses get_user()/put_user() to reference pointers 443 * with at least a bit of error checking ... 444 */ 445 446 static int kstack_depth_to_print = 24; 447 448 void show_stack(struct task_struct *task, unsigned long *sp) 449 { 450 int i = 0; 451 unsigned long *stack; 452 453 if (!sp) 454 sp = stack_pointer(task); 455 stack = sp; 456 457 printk("\nStack: "); 458 459 for (i = 0; i < kstack_depth_to_print; i++) { 460 if (kstack_end(sp)) 461 break; 462 if (i && ((i % 8) == 0)) 463 printk("\n "); 464 printk("%08lx ", *sp++); 465 } 466 printk("\n"); 467 show_trace(task, stack); 468 } 469 470 void show_code(unsigned int *pc) 471 { 472 long i; 473 474 printk("\nCode:"); 475 476 for(i = -3 ; i < 6 ; i++) { 477 unsigned long insn; 478 if (__get_user(insn, pc + i)) { 479 printk(" (Bad address in pc)\n"); 480 break; 481 } 482 printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>')); 483 } 484 } 485 486 DEFINE_SPINLOCK(die_lock); 487 488 void die(const char * str, struct pt_regs * regs, long err) 489 { 490 static int die_counter; 491 int nl = 0; 492 493 console_verbose(); 494 spin_lock_irq(&die_lock); 495 496 printk("%s: sig: %ld [#%d]\n", str, err, ++die_counter); 497 #ifdef CONFIG_PREEMPT 498 printk("PREEMPT "); 499 nl = 1; 500 #endif 501 if (nl) 502 printk("\n"); 503 show_regs(regs); 504 if (!user_mode(regs)) 505 show_stack(NULL, (unsigned long*)regs->areg[1]); 506 507 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 508 spin_unlock_irq(&die_lock); 509 510 if (in_interrupt()) 511 panic("Fatal exception in interrupt"); 512 513 if (panic_on_oops) 514 panic("Fatal exception"); 515 516 do_exit(err); 517 } 518