1 /* 2 * linux/arch/arm/mm/fault.c 3 * 4 * Copyright (C) 1995 Linus Torvalds 5 * Modifications for ARM processor (c) 1995-2004 Russell King 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #include <linux/module.h> 12 #include <linux/signal.h> 13 #include <linux/ptrace.h> 14 #include <linux/mm.h> 15 #include <linux/init.h> 16 17 #include <asm/system.h> 18 #include <asm/pgtable.h> 19 #include <asm/tlbflush.h> 20 #include <asm/uaccess.h> 21 22 #include "fault.h" 23 24 /* 25 * This is useful to dump out the page tables associated with 26 * 'addr' in mm 'mm'. 27 */ 28 void show_pte(struct mm_struct *mm, unsigned long addr) 29 { 30 pgd_t *pgd; 31 32 if (!mm) 33 mm = &init_mm; 34 35 printk(KERN_ALERT "pgd = %p\n", mm->pgd); 36 pgd = pgd_offset(mm, addr); 37 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); 38 39 do { 40 pmd_t *pmd; 41 pte_t *pte; 42 43 if (pgd_none(*pgd)) 44 break; 45 46 if (pgd_bad(*pgd)) { 47 printk("(bad)"); 48 break; 49 } 50 51 pmd = pmd_offset(pgd, addr); 52 #if PTRS_PER_PMD != 1 53 printk(", *pmd=%08lx", pmd_val(*pmd)); 54 #endif 55 56 if (pmd_none(*pmd)) 57 break; 58 59 if (pmd_bad(*pmd)) { 60 printk("(bad)"); 61 break; 62 } 63 64 #ifndef CONFIG_HIGHMEM 65 /* We must not map this if we have highmem enabled */ 66 pte = pte_offset_map(pmd, addr); 67 printk(", *pte=%08lx", pte_val(*pte)); 68 printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE])); 69 pte_unmap(pte); 70 #endif 71 } while(0); 72 73 printk("\n"); 74 } 75 76 /* 77 * Oops. The kernel tried to access some page that wasn't present. 78 */ 79 static void 80 __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 81 struct pt_regs *regs) 82 { 83 /* 84 * Are we prepared to handle this kernel fault? 85 */ 86 if (fixup_exception(regs)) 87 return; 88 89 /* 90 * No handler, we'll have to terminate things with extreme prejudice. 91 */ 92 bust_spinlocks(1); 93 printk(KERN_ALERT 94 "Unable to handle kernel %s at virtual address %08lx\n", 95 (addr < PAGE_SIZE) ? "NULL pointer dereference" : 96 "paging request", addr); 97 98 show_pte(mm, addr); 99 die("Oops", regs, fsr); 100 bust_spinlocks(0); 101 do_exit(SIGKILL); 102 } 103 104 /* 105 * Something tried to access memory that isn't in our memory map.. 106 * User mode accesses just cause a SIGSEGV 107 */ 108 static void 109 __do_user_fault(struct task_struct *tsk, unsigned long addr, 110 unsigned int fsr, unsigned int sig, int code, 111 struct pt_regs *regs) 112 { 113 struct siginfo si; 114 115 #ifdef CONFIG_DEBUG_USER 116 if (user_debug & UDBG_SEGV) { 117 printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n", 118 tsk->comm, sig, addr, fsr); 119 show_pte(tsk->mm, addr); 120 show_regs(regs); 121 } 122 #endif 123 124 tsk->thread.address = addr; 125 tsk->thread.error_code = fsr; 126 tsk->thread.trap_no = 14; 127 si.si_signo = sig; 128 si.si_errno = 0; 129 si.si_code = code; 130 si.si_addr = (void __user *)addr; 131 force_sig_info(sig, &si, tsk); 132 } 133 134 void 135 do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr, 136 unsigned int fsr, struct pt_regs *regs) 137 { 138 /* 139 * If we are in kernel mode at this point, we 140 * have no context to handle this fault with. 141 */ 142 if (user_mode(regs)) 143 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs); 144 else 145 __do_kernel_fault(mm, addr, fsr, regs); 146 } 147 148 #define VM_FAULT_BADMAP (-20) 149 #define VM_FAULT_BADACCESS (-21) 150 151 static int 152 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 153 struct task_struct *tsk) 154 { 155 struct vm_area_struct *vma; 156 int fault, mask; 157 158 vma = find_vma(mm, addr); 159 fault = VM_FAULT_BADMAP; 160 if (!vma) 161 goto out; 162 if (vma->vm_start > addr) 163 goto check_stack; 164 165 /* 166 * Ok, we have a good vm_area for this 167 * memory access, so we can handle it. 168 */ 169 good_area: 170 if (fsr & (1 << 11)) /* write? */ 171 mask = VM_WRITE; 172 else 173 mask = VM_READ|VM_EXEC; 174 175 fault = VM_FAULT_BADACCESS; 176 if (!(vma->vm_flags & mask)) 177 goto out; 178 179 /* 180 * If for any reason at all we couldn't handle 181 * the fault, make sure we exit gracefully rather 182 * than endlessly redo the fault. 183 */ 184 survive: 185 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11)); 186 187 /* 188 * Handle the "normal" cases first - successful and sigbus 189 */ 190 switch (fault) { 191 case VM_FAULT_MAJOR: 192 tsk->maj_flt++; 193 return fault; 194 case VM_FAULT_MINOR: 195 tsk->min_flt++; 196 case VM_FAULT_SIGBUS: 197 return fault; 198 } 199 200 if (tsk->pid != 1) 201 goto out; 202 203 /* 204 * If we are out of memory for pid1, sleep for a while and retry 205 */ 206 up_read(&mm->mmap_sem); 207 yield(); 208 down_read(&mm->mmap_sem); 209 goto survive; 210 211 check_stack: 212 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) 213 goto good_area; 214 out: 215 return fault; 216 } 217 218 static int 219 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 220 { 221 struct task_struct *tsk; 222 struct mm_struct *mm; 223 int fault, sig, code; 224 225 tsk = current; 226 mm = tsk->mm; 227 228 /* 229 * If we're in an interrupt or have no user 230 * context, we must not take the fault.. 231 */ 232 if (in_interrupt() || !mm) 233 goto no_context; 234 235 /* 236 * As per x86, we may deadlock here. However, since the kernel only 237 * validly references user space from well defined areas of the code, 238 * we can bug out early if this is from code which shouldn't. 239 */ 240 if (!down_read_trylock(&mm->mmap_sem)) { 241 if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc)) 242 goto no_context; 243 down_read(&mm->mmap_sem); 244 } 245 246 fault = __do_page_fault(mm, addr, fsr, tsk); 247 up_read(&mm->mmap_sem); 248 249 /* 250 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR 251 */ 252 if (fault >= VM_FAULT_MINOR) 253 return 0; 254 255 /* 256 * If we are in kernel mode at this point, we 257 * have no context to handle this fault with. 258 */ 259 if (!user_mode(regs)) 260 goto no_context; 261 262 switch (fault) { 263 case VM_FAULT_OOM: 264 /* 265 * We ran out of memory, or some other thing 266 * happened to us that made us unable to handle 267 * the page fault gracefully. 268 */ 269 printk("VM: killing process %s\n", tsk->comm); 270 do_exit(SIGKILL); 271 return 0; 272 273 case VM_FAULT_SIGBUS: 274 /* 275 * We had some memory, but were unable to 276 * successfully fix up this page fault. 277 */ 278 sig = SIGBUS; 279 code = BUS_ADRERR; 280 break; 281 282 default: 283 /* 284 * Something tried to access memory that 285 * isn't in our memory map.. 286 */ 287 sig = SIGSEGV; 288 code = fault == VM_FAULT_BADACCESS ? 289 SEGV_ACCERR : SEGV_MAPERR; 290 break; 291 } 292 293 __do_user_fault(tsk, addr, fsr, sig, code, regs); 294 return 0; 295 296 no_context: 297 __do_kernel_fault(mm, addr, fsr, regs); 298 return 0; 299 } 300 301 /* 302 * First Level Translation Fault Handler 303 * 304 * We enter here because the first level page table doesn't contain 305 * a valid entry for the address. 306 * 307 * If the address is in kernel space (>= TASK_SIZE), then we are 308 * probably faulting in the vmalloc() area. 309 * 310 * If the init_task's first level page tables contains the relevant 311 * entry, we copy the it to this task. If not, we send the process 312 * a signal, fixup the exception, or oops the kernel. 313 * 314 * NOTE! We MUST NOT take any locks for this case. We may be in an 315 * interrupt or a critical region, and should only copy the information 316 * from the master page table, nothing more. 317 */ 318 static int 319 do_translation_fault(unsigned long addr, unsigned int fsr, 320 struct pt_regs *regs) 321 { 322 struct task_struct *tsk; 323 unsigned int index; 324 pgd_t *pgd, *pgd_k; 325 pmd_t *pmd, *pmd_k; 326 327 if (addr < TASK_SIZE) 328 return do_page_fault(addr, fsr, regs); 329 330 index = pgd_index(addr); 331 332 /* 333 * FIXME: CP15 C1 is write only on ARMv3 architectures. 334 */ 335 pgd = cpu_get_pgd() + index; 336 pgd_k = init_mm.pgd + index; 337 338 if (pgd_none(*pgd_k)) 339 goto bad_area; 340 341 if (!pgd_present(*pgd)) 342 set_pgd(pgd, *pgd_k); 343 344 pmd_k = pmd_offset(pgd_k, addr); 345 pmd = pmd_offset(pgd, addr); 346 347 if (pmd_none(*pmd_k)) 348 goto bad_area; 349 350 copy_pmd(pmd, pmd_k); 351 return 0; 352 353 bad_area: 354 tsk = current; 355 356 do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); 357 return 0; 358 } 359 360 /* 361 * Some section permission faults need to be handled gracefully. 362 * They can happen due to a __{get,put}_user during an oops. 363 */ 364 static int 365 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 366 { 367 struct task_struct *tsk = current; 368 do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); 369 return 0; 370 } 371 372 /* 373 * This abort handler always returns "fault". 374 */ 375 static int 376 do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 377 { 378 return 1; 379 } 380 381 static struct fsr_info { 382 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); 383 int sig; 384 int code; 385 const char *name; 386 } fsr_info[] = { 387 /* 388 * The following are the standard ARMv3 and ARMv4 aborts. ARMv5 389 * defines these to be "precise" aborts. 390 */ 391 { do_bad, SIGSEGV, 0, "vector exception" }, 392 { do_bad, SIGILL, BUS_ADRALN, "alignment exception" }, 393 { do_bad, SIGKILL, 0, "terminal exception" }, 394 { do_bad, SIGILL, BUS_ADRALN, "alignment exception" }, 395 { do_bad, SIGBUS, 0, "external abort on linefetch" }, 396 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "section translation fault" }, 397 { do_bad, SIGBUS, 0, "external abort on linefetch" }, 398 { do_page_fault, SIGSEGV, SEGV_MAPERR, "page translation fault" }, 399 { do_bad, SIGBUS, 0, "external abort on non-linefetch" }, 400 { do_bad, SIGSEGV, SEGV_ACCERR, "section domain fault" }, 401 { do_bad, SIGBUS, 0, "external abort on non-linefetch" }, 402 { do_bad, SIGSEGV, SEGV_ACCERR, "page domain fault" }, 403 { do_bad, SIGBUS, 0, "external abort on translation" }, 404 { do_sect_fault, SIGSEGV, SEGV_ACCERR, "section permission fault" }, 405 { do_bad, SIGBUS, 0, "external abort on translation" }, 406 { do_page_fault, SIGSEGV, SEGV_ACCERR, "page permission fault" }, 407 /* 408 * The following are "imprecise" aborts, which are signalled by bit 409 * 10 of the FSR, and may not be recoverable. These are only 410 * supported if the CPU abort handler supports bit 10. 411 */ 412 { do_bad, SIGBUS, 0, "unknown 16" }, 413 { do_bad, SIGBUS, 0, "unknown 17" }, 414 { do_bad, SIGBUS, 0, "unknown 18" }, 415 { do_bad, SIGBUS, 0, "unknown 19" }, 416 { do_bad, SIGBUS, 0, "lock abort" }, /* xscale */ 417 { do_bad, SIGBUS, 0, "unknown 21" }, 418 { do_bad, SIGBUS, BUS_OBJERR, "imprecise external abort" }, /* xscale */ 419 { do_bad, SIGBUS, 0, "unknown 23" }, 420 { do_bad, SIGBUS, 0, "dcache parity error" }, /* xscale */ 421 { do_bad, SIGBUS, 0, "unknown 25" }, 422 { do_bad, SIGBUS, 0, "unknown 26" }, 423 { do_bad, SIGBUS, 0, "unknown 27" }, 424 { do_bad, SIGBUS, 0, "unknown 28" }, 425 { do_bad, SIGBUS, 0, "unknown 29" }, 426 { do_bad, SIGBUS, 0, "unknown 30" }, 427 { do_bad, SIGBUS, 0, "unknown 31" } 428 }; 429 430 void __init 431 hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), 432 int sig, const char *name) 433 { 434 if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) { 435 fsr_info[nr].fn = fn; 436 fsr_info[nr].sig = sig; 437 fsr_info[nr].name = name; 438 } 439 } 440 441 /* 442 * Dispatch a data abort to the relevant handler. 443 */ 444 asmlinkage void 445 do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 446 { 447 const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6); 448 struct siginfo info; 449 450 if (!inf->fn(addr, fsr, regs)) 451 return; 452 453 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n", 454 inf->name, fsr, addr); 455 456 info.si_signo = inf->sig; 457 info.si_errno = 0; 458 info.si_code = inf->code; 459 info.si_addr = (void __user *)addr; 460 notify_die("", regs, &info, fsr, 0); 461 } 462 463 asmlinkage void 464 do_PrefetchAbort(unsigned long addr, struct pt_regs *regs) 465 { 466 do_translation_fault(addr, 0, regs); 467 } 468 469