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/config.h> 12 #include <linux/module.h> 13 #include <linux/signal.h> 14 #include <linux/ptrace.h> 15 #include <linux/mm.h> 16 #include <linux/init.h> 17 18 #include <asm/system.h> 19 #include <asm/pgtable.h> 20 #include <asm/tlbflush.h> 21 #include <asm/uaccess.h> 22 23 #include "fault.h" 24 25 /* 26 * This is useful to dump out the page tables associated with 27 * 'addr' in mm 'mm'. 28 */ 29 void show_pte(struct mm_struct *mm, unsigned long addr) 30 { 31 pgd_t *pgd; 32 33 if (!mm) 34 mm = &init_mm; 35 36 printk(KERN_ALERT "pgd = %p\n", mm->pgd); 37 pgd = pgd_offset(mm, addr); 38 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); 39 40 do { 41 pmd_t *pmd; 42 pte_t *pte; 43 44 if (pgd_none(*pgd)) 45 break; 46 47 if (pgd_bad(*pgd)) { 48 printk("(bad)"); 49 break; 50 } 51 52 pmd = pmd_offset(pgd, addr); 53 #if PTRS_PER_PMD != 1 54 printk(", *pmd=%08lx", pmd_val(*pmd)); 55 #endif 56 57 if (pmd_none(*pmd)) 58 break; 59 60 if (pmd_bad(*pmd)) { 61 printk("(bad)"); 62 break; 63 } 64 65 #ifndef CONFIG_HIGHMEM 66 /* We must not map this if we have highmem enabled */ 67 pte = pte_offset_map(pmd, addr); 68 printk(", *pte=%08lx", pte_val(*pte)); 69 printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE])); 70 pte_unmap(pte); 71 #endif 72 } while(0); 73 74 printk("\n"); 75 } 76 77 /* 78 * Oops. The kernel tried to access some page that wasn't present. 79 */ 80 static void 81 __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 82 struct pt_regs *regs) 83 { 84 /* 85 * Are we prepared to handle this kernel fault? 86 */ 87 if (fixup_exception(regs)) 88 return; 89 90 /* 91 * No handler, we'll have to terminate things with extreme prejudice. 92 */ 93 bust_spinlocks(1); 94 printk(KERN_ALERT 95 "Unable to handle kernel %s at virtual address %08lx\n", 96 (addr < PAGE_SIZE) ? "NULL pointer dereference" : 97 "paging request", addr); 98 99 show_pte(mm, addr); 100 die("Oops", regs, fsr); 101 bust_spinlocks(0); 102 do_exit(SIGKILL); 103 } 104 105 /* 106 * Something tried to access memory that isn't in our memory map.. 107 * User mode accesses just cause a SIGSEGV 108 */ 109 static void 110 __do_user_fault(struct task_struct *tsk, unsigned long addr, 111 unsigned int fsr, int code, 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 at 0x%08lx, code 0x%03x\n", 118 tsk->comm, 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 = SIGSEGV; 128 si.si_errno = 0; 129 si.si_code = code; 130 si.si_addr = (void __user *)addr; 131 force_sig_info(SIGSEGV, &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, 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, 205 * sleep for a while and retry 206 */ 207 yield(); 208 goto survive; 209 210 check_stack: 211 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) 212 goto good_area; 213 out: 214 return fault; 215 } 216 217 static int 218 do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 219 { 220 struct task_struct *tsk; 221 struct mm_struct *mm; 222 int fault; 223 224 tsk = current; 225 mm = tsk->mm; 226 227 /* 228 * If we're in an interrupt or have no user 229 * context, we must not take the fault.. 230 */ 231 if (in_interrupt() || !mm) 232 goto no_context; 233 234 down_read(&mm->mmap_sem); 235 fault = __do_page_fault(mm, addr, fsr, tsk); 236 up_read(&mm->mmap_sem); 237 238 /* 239 * Handle the "normal" case first 240 */ 241 if (fault > 0) 242 return 0; 243 244 /* 245 * We had some memory, but were unable to 246 * successfully fix up this page fault. 247 */ 248 if (fault == 0) 249 goto do_sigbus; 250 251 /* 252 * If we are in kernel mode at this point, we 253 * have no context to handle this fault with. 254 */ 255 if (!user_mode(regs)) 256 goto no_context; 257 258 if (fault == VM_FAULT_OOM) { 259 /* 260 * We ran out of memory, or some other thing happened to 261 * us that made us unable to handle the page fault gracefully. 262 */ 263 printk("VM: killing process %s\n", tsk->comm); 264 do_exit(SIGKILL); 265 } else 266 __do_user_fault(tsk, addr, fsr, fault == VM_FAULT_BADACCESS ? 267 SEGV_ACCERR : SEGV_MAPERR, regs); 268 return 0; 269 270 271 /* 272 * We ran out of memory, or some other thing happened to us that made 273 * us unable to handle the page fault gracefully. 274 */ 275 do_sigbus: 276 /* 277 * Send a sigbus, regardless of whether we were in kernel 278 * or user mode. 279 */ 280 tsk->thread.address = addr; 281 tsk->thread.error_code = fsr; 282 tsk->thread.trap_no = 14; 283 force_sig(SIGBUS, tsk); 284 #ifdef CONFIG_DEBUG_USER 285 if (user_debug & UDBG_BUS) { 286 printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n", 287 current->comm, addr, instruction_pointer(regs)); 288 } 289 #endif 290 291 /* Kernel mode? Handle exceptions or die */ 292 if (user_mode(regs)) 293 return 0; 294 295 no_context: 296 __do_kernel_fault(mm, addr, fsr, regs); 297 return 0; 298 } 299 300 /* 301 * First Level Translation Fault Handler 302 * 303 * We enter here because the first level page table doesn't contain 304 * a valid entry for the address. 305 * 306 * If the address is in kernel space (>= TASK_SIZE), then we are 307 * probably faulting in the vmalloc() area. 308 * 309 * If the init_task's first level page tables contains the relevant 310 * entry, we copy the it to this task. If not, we send the process 311 * a signal, fixup the exception, or oops the kernel. 312 * 313 * NOTE! We MUST NOT take any locks for this case. We may be in an 314 * interrupt or a critical region, and should only copy the information 315 * from the master page table, nothing more. 316 */ 317 static int 318 do_translation_fault(unsigned long addr, unsigned int fsr, 319 struct pt_regs *regs) 320 { 321 struct task_struct *tsk; 322 unsigned int index; 323 pgd_t *pgd, *pgd_k; 324 pmd_t *pmd, *pmd_k; 325 326 if (addr < TASK_SIZE) 327 return do_page_fault(addr, fsr, regs); 328 329 index = pgd_index(addr); 330 331 /* 332 * FIXME: CP15 C1 is write only on ARMv3 architectures. 333 */ 334 pgd = cpu_get_pgd() + index; 335 pgd_k = init_mm.pgd + index; 336 337 if (pgd_none(*pgd_k)) 338 goto bad_area; 339 340 if (!pgd_present(*pgd)) 341 set_pgd(pgd, *pgd_k); 342 343 pmd_k = pmd_offset(pgd_k, addr); 344 pmd = pmd_offset(pgd, addr); 345 346 if (pmd_none(*pmd_k)) 347 goto bad_area; 348 349 copy_pmd(pmd, pmd_k); 350 return 0; 351 352 bad_area: 353 tsk = current; 354 355 do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); 356 return 0; 357 } 358 359 /* 360 * Some section permission faults need to be handled gracefully. 361 * They can happen due to a __{get,put}_user during an oops. 362 */ 363 static int 364 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 365 { 366 struct task_struct *tsk = current; 367 do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); 368 return 0; 369 } 370 371 /* 372 * This abort handler always returns "fault". 373 */ 374 static int 375 do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 376 { 377 return 1; 378 } 379 380 static struct fsr_info { 381 int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); 382 int sig; 383 const char *name; 384 } fsr_info[] = { 385 /* 386 * The following are the standard ARMv3 and ARMv4 aborts. ARMv5 387 * defines these to be "precise" aborts. 388 */ 389 { do_bad, SIGSEGV, "vector exception" }, 390 { do_bad, SIGILL, "alignment exception" }, 391 { do_bad, SIGKILL, "terminal exception" }, 392 { do_bad, SIGILL, "alignment exception" }, 393 { do_bad, SIGBUS, "external abort on linefetch" }, 394 { do_translation_fault, SIGSEGV, "section translation fault" }, 395 { do_bad, SIGBUS, "external abort on linefetch" }, 396 { do_page_fault, SIGSEGV, "page translation fault" }, 397 { do_bad, SIGBUS, "external abort on non-linefetch" }, 398 { do_bad, SIGSEGV, "section domain fault" }, 399 { do_bad, SIGBUS, "external abort on non-linefetch" }, 400 { do_bad, SIGSEGV, "page domain fault" }, 401 { do_bad, SIGBUS, "external abort on translation" }, 402 { do_sect_fault, SIGSEGV, "section permission fault" }, 403 { do_bad, SIGBUS, "external abort on translation" }, 404 { do_page_fault, SIGSEGV, "page permission fault" }, 405 /* 406 * The following are "imprecise" aborts, which are signalled by bit 407 * 10 of the FSR, and may not be recoverable. These are only 408 * supported if the CPU abort handler supports bit 10. 409 */ 410 { do_bad, SIGBUS, "unknown 16" }, 411 { do_bad, SIGBUS, "unknown 17" }, 412 { do_bad, SIGBUS, "unknown 18" }, 413 { do_bad, SIGBUS, "unknown 19" }, 414 { do_bad, SIGBUS, "lock abort" }, /* xscale */ 415 { do_bad, SIGBUS, "unknown 21" }, 416 { do_bad, SIGBUS, "imprecise external abort" }, /* xscale */ 417 { do_bad, SIGBUS, "unknown 23" }, 418 { do_bad, SIGBUS, "dcache parity error" }, /* xscale */ 419 { do_bad, SIGBUS, "unknown 25" }, 420 { do_bad, SIGBUS, "unknown 26" }, 421 { do_bad, SIGBUS, "unknown 27" }, 422 { do_bad, SIGBUS, "unknown 28" }, 423 { do_bad, SIGBUS, "unknown 29" }, 424 { do_bad, SIGBUS, "unknown 30" }, 425 { do_bad, SIGBUS, "unknown 31" } 426 }; 427 428 void __init 429 hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), 430 int sig, const char *name) 431 { 432 if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) { 433 fsr_info[nr].fn = fn; 434 fsr_info[nr].sig = sig; 435 fsr_info[nr].name = name; 436 } 437 } 438 439 /* 440 * Dispatch a data abort to the relevant handler. 441 */ 442 asmlinkage void 443 do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 444 { 445 const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6); 446 447 if (!inf->fn(addr, fsr, regs)) 448 return; 449 450 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n", 451 inf->name, fsr, addr); 452 force_sig(inf->sig, current); 453 show_pte(current->mm, addr); 454 die_if_kernel("Oops", regs, 0); 455 } 456 457 asmlinkage void 458 do_PrefetchAbort(unsigned long addr, struct pt_regs *regs) 459 { 460 do_translation_fault(addr, 0, regs); 461 } 462 463