1/* 2 * linux/arch/unicore32/mm/fault.c 3 * 4 * Code specific to PKUnity SoC and UniCore ISA 5 * 6 * Copyright (C) 2001-2010 GUAN Xue-tao 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12#include <linux/module.h> 13#include <linux/signal.h> 14#include <linux/mm.h> 15#include <linux/hardirq.h> 16#include <linux/init.h> 17#include <linux/kprobes.h> 18#include <linux/uaccess.h> 19#include <linux/page-flags.h> 20#include <linux/sched.h> 21#include <linux/io.h> 22 23#include <asm/pgtable.h> 24#include <asm/tlbflush.h> 25 26/* 27 * Fault status register encodings. We steal bit 31 for our own purposes. 28 */ 29#define FSR_LNX_PF (1 << 31) 30 31static inline int fsr_fs(unsigned int fsr) 32{ 33 /* xyabcde will be abcde+xy */ 34 return (fsr & 31) + ((fsr & (3 << 5)) >> 5); 35} 36 37/* 38 * This is useful to dump out the page tables associated with 39 * 'addr' in mm 'mm'. 40 */ 41void show_pte(struct mm_struct *mm, unsigned long addr) 42{ 43 pgd_t *pgd; 44 45 if (!mm) 46 mm = &init_mm; 47 48 printk(KERN_ALERT "pgd = %p\n", mm->pgd); 49 pgd = pgd_offset(mm, addr); 50 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); 51 52 do { 53 pmd_t *pmd; 54 pte_t *pte; 55 56 if (pgd_none(*pgd)) 57 break; 58 59 if (pgd_bad(*pgd)) { 60 printk("(bad)"); 61 break; 62 } 63 64 pmd = pmd_offset((pud_t *) pgd, addr); 65 if (PTRS_PER_PMD != 1) 66 printk(", *pmd=%08lx", pmd_val(*pmd)); 67 68 if (pmd_none(*pmd)) 69 break; 70 71 if (pmd_bad(*pmd)) { 72 printk("(bad)"); 73 break; 74 } 75 76 /* We must not map this if we have highmem enabled */ 77 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT))) 78 break; 79 80 pte = pte_offset_map(pmd, addr); 81 printk(", *pte=%08lx", pte_val(*pte)); 82 pte_unmap(pte); 83 } while (0); 84 85 printk("\n"); 86} 87 88/* 89 * Oops. The kernel tried to access some page that wasn't present. 90 */ 91static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, 92 unsigned int fsr, struct pt_regs *regs) 93{ 94 /* 95 * Are we prepared to handle this kernel fault? 96 */ 97 if (fixup_exception(regs)) 98 return; 99 100 /* 101 * No handler, we'll have to terminate things with extreme prejudice. 102 */ 103 bust_spinlocks(1); 104 printk(KERN_ALERT 105 "Unable to handle kernel %s at virtual address %08lx\n", 106 (addr < PAGE_SIZE) ? "NULL pointer dereference" : 107 "paging request", addr); 108 109 show_pte(mm, addr); 110 die("Oops", regs, fsr); 111 bust_spinlocks(0); 112 do_exit(SIGKILL); 113} 114 115/* 116 * Something tried to access memory that isn't in our memory map.. 117 * User mode accesses just cause a SIGSEGV 118 */ 119static void __do_user_fault(struct task_struct *tsk, unsigned long addr, 120 unsigned int fsr, unsigned int sig, int code, 121 struct pt_regs *regs) 122{ 123 struct siginfo si; 124 125 tsk->thread.address = addr; 126 tsk->thread.error_code = fsr; 127 tsk->thread.trap_no = 14; 128 si.si_signo = sig; 129 si.si_errno = 0; 130 si.si_code = code; 131 si.si_addr = (void __user *)addr; 132 force_sig_info(sig, &si, tsk); 133} 134 135void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 136{ 137 struct task_struct *tsk = current; 138 struct mm_struct *mm = tsk->active_mm; 139 140 /* 141 * If we are in kernel mode at this point, we 142 * have no context to handle this fault with. 143 */ 144 if (user_mode(regs)) 145 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs); 146 else 147 __do_kernel_fault(mm, addr, fsr, regs); 148} 149 150#define VM_FAULT_BADMAP 0x010000 151#define VM_FAULT_BADACCESS 0x020000 152 153/* 154 * Check that the permissions on the VMA allow for the fault which occurred. 155 * If we encountered a write fault, we must have write permission, otherwise 156 * we allow any permission. 157 */ 158static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma) 159{ 160 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC; 161 162 if (!(fsr ^ 0x12)) /* write? */ 163 mask = VM_WRITE; 164 if (fsr & FSR_LNX_PF) 165 mask = VM_EXEC; 166 167 return vma->vm_flags & mask ? false : true; 168} 169 170static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr, 171 unsigned int flags, struct task_struct *tsk) 172{ 173 struct vm_area_struct *vma; 174 int fault; 175 176 vma = find_vma(mm, addr); 177 fault = VM_FAULT_BADMAP; 178 if (unlikely(!vma)) 179 goto out; 180 if (unlikely(vma->vm_start > addr)) 181 goto check_stack; 182 183 /* 184 * Ok, we have a good vm_area for this 185 * memory access, so we can handle it. 186 */ 187good_area: 188 if (access_error(fsr, vma)) { 189 fault = VM_FAULT_BADACCESS; 190 goto out; 191 } 192 193 /* 194 * If for any reason at all we couldn't handle the fault, make 195 * sure we exit gracefully rather than endlessly redo the fault. 196 */ 197 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags); 198 return fault; 199 200check_stack: 201 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) 202 goto good_area; 203out: 204 return fault; 205} 206 207static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 208{ 209 struct task_struct *tsk; 210 struct mm_struct *mm; 211 int fault, sig, code; 212 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 213 214 tsk = current; 215 mm = tsk->mm; 216 217 /* 218 * If we're in an interrupt or have no user 219 * context, we must not take the fault.. 220 */ 221 if (in_atomic() || !mm) 222 goto no_context; 223 224 if (user_mode(regs)) 225 flags |= FAULT_FLAG_USER; 226 if (!(fsr ^ 0x12)) 227 flags |= FAULT_FLAG_WRITE; 228 229 /* 230 * As per x86, we may deadlock here. However, since the kernel only 231 * validly references user space from well defined areas of the code, 232 * we can bug out early if this is from code which shouldn't. 233 */ 234 if (!down_read_trylock(&mm->mmap_sem)) { 235 if (!user_mode(regs) 236 && !search_exception_tables(regs->UCreg_pc)) 237 goto no_context; 238retry: 239 down_read(&mm->mmap_sem); 240 } else { 241 /* 242 * The above down_read_trylock() might have succeeded in 243 * which case, we'll have missed the might_sleep() from 244 * down_read() 245 */ 246 might_sleep(); 247#ifdef CONFIG_DEBUG_VM 248 if (!user_mode(regs) && 249 !search_exception_tables(regs->UCreg_pc)) 250 goto no_context; 251#endif 252 } 253 254 fault = __do_pf(mm, addr, fsr, flags, tsk); 255 256 /* If we need to retry but a fatal signal is pending, handle the 257 * signal first. We do not need to release the mmap_sem because 258 * it would already be released in __lock_page_or_retry in 259 * mm/filemap.c. */ 260 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 261 return 0; 262 263 if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) { 264 if (fault & VM_FAULT_MAJOR) 265 tsk->maj_flt++; 266 else 267 tsk->min_flt++; 268 if (fault & VM_FAULT_RETRY) { 269 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk 270 * of starvation. */ 271 flags &= ~FAULT_FLAG_ALLOW_RETRY; 272 goto retry; 273 } 274 } 275 276 up_read(&mm->mmap_sem); 277 278 /* 279 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR 280 */ 281 if (likely(!(fault & 282 (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS)))) 283 return 0; 284 285 /* 286 * If we are in kernel mode at this point, we 287 * have no context to handle this fault with. 288 */ 289 if (!user_mode(regs)) 290 goto no_context; 291 292 if (fault & VM_FAULT_OOM) { 293 /* 294 * We ran out of memory, call the OOM killer, and return to 295 * userspace (which will retry the fault, or kill us if we 296 * got oom-killed) 297 */ 298 pagefault_out_of_memory(); 299 return 0; 300 } 301 302 if (fault & VM_FAULT_SIGBUS) { 303 /* 304 * We had some memory, but were unable to 305 * successfully fix up this page fault. 306 */ 307 sig = SIGBUS; 308 code = BUS_ADRERR; 309 } else { 310 /* 311 * Something tried to access memory that 312 * isn't in our memory map.. 313 */ 314 sig = SIGSEGV; 315 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR; 316 } 317 318 __do_user_fault(tsk, addr, fsr, sig, code, regs); 319 return 0; 320 321no_context: 322 __do_kernel_fault(mm, addr, fsr, regs); 323 return 0; 324} 325 326/* 327 * First Level Translation Fault Handler 328 * 329 * We enter here because the first level page table doesn't contain 330 * a valid entry for the address. 331 * 332 * If the address is in kernel space (>= TASK_SIZE), then we are 333 * probably faulting in the vmalloc() area. 334 * 335 * If the init_task's first level page tables contains the relevant 336 * entry, we copy the it to this task. If not, we send the process 337 * a signal, fixup the exception, or oops the kernel. 338 * 339 * NOTE! We MUST NOT take any locks for this case. We may be in an 340 * interrupt or a critical region, and should only copy the information 341 * from the master page table, nothing more. 342 */ 343static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 344{ 345 unsigned int index; 346 pgd_t *pgd, *pgd_k; 347 pmd_t *pmd, *pmd_k; 348 349 if (addr < TASK_SIZE) 350 return do_pf(addr, fsr, regs); 351 352 if (user_mode(regs)) 353 goto bad_area; 354 355 index = pgd_index(addr); 356 357 pgd = cpu_get_pgd() + index; 358 pgd_k = init_mm.pgd + index; 359 360 if (pgd_none(*pgd_k)) 361 goto bad_area; 362 363 pmd_k = pmd_offset((pud_t *) pgd_k, addr); 364 pmd = pmd_offset((pud_t *) pgd, addr); 365 366 if (pmd_none(*pmd_k)) 367 goto bad_area; 368 369 set_pmd(pmd, *pmd_k); 370 flush_pmd_entry(pmd); 371 return 0; 372 373bad_area: 374 do_bad_area(addr, fsr, regs); 375 return 0; 376} 377 378/* 379 * This abort handler always returns "fault". 380 */ 381static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 382{ 383 return 1; 384} 385 386static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 387{ 388 unsigned int res1, res2; 389 390 printk("dabt exception but no error!\n"); 391 392 __asm__ __volatile__( 393 "mff %0,f0\n" 394 "mff %1,f1\n" 395 : "=r"(res1), "=r"(res2) 396 : 397 : "memory"); 398 399 printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2); 400 panic("shut up\n"); 401 return 0; 402} 403 404static struct fsr_info { 405 int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs); 406 int sig; 407 int code; 408 const char *name; 409} fsr_info[] = { 410 /* 411 * The following are the standard Unicore-I and UniCore-II aborts. 412 */ 413 { do_good, SIGBUS, 0, "no error" }, 414 { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" }, 415 { do_bad, SIGBUS, BUS_OBJERR, "external exception" }, 416 { do_bad, SIGBUS, 0, "burst operation" }, 417 { do_bad, SIGBUS, 0, "unknown 00100" }, 418 { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"}, 419 { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" }, 420 { do_bad, SIGBUS, 0, "invalid pte" }, 421 { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" }, 422 { do_bad, SIGBUS, 0, "middle page miss" }, 423 { do_bad, SIGBUS, 0, "large page miss" }, 424 { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" }, 425 { do_bad, SIGBUS, 0, "unknown 01100" }, 426 { do_bad, SIGBUS, 0, "unknown 01101" }, 427 { do_bad, SIGBUS, 0, "unknown 01110" }, 428 { do_bad, SIGBUS, 0, "unknown 01111" }, 429 { do_bad, SIGBUS, 0, "addr: up 3G or IO" }, 430 { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" }, 431 { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"}, 432 { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"}, 433 { do_bad, SIGBUS, 0, "unknown 10100" }, 434 { do_bad, SIGBUS, 0, "unknown 10101" }, 435 { do_bad, SIGBUS, 0, "unknown 10110" }, 436 { do_bad, SIGBUS, 0, "unknown 10111" }, 437 { do_bad, SIGBUS, 0, "unknown 11000" }, 438 { do_bad, SIGBUS, 0, "unknown 11001" }, 439 { do_bad, SIGBUS, 0, "unknown 11010" }, 440 { do_bad, SIGBUS, 0, "unknown 11011" }, 441 { do_bad, SIGBUS, 0, "unknown 11100" }, 442 { do_bad, SIGBUS, 0, "unknown 11101" }, 443 { do_bad, SIGBUS, 0, "unknown 11110" }, 444 { do_bad, SIGBUS, 0, "unknown 11111" } 445}; 446 447void __init hook_fault_code(int nr, 448 int (*fn) (unsigned long, unsigned int, struct pt_regs *), 449 int sig, int code, const char *name) 450{ 451 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info)) 452 BUG(); 453 454 fsr_info[nr].fn = fn; 455 fsr_info[nr].sig = sig; 456 fsr_info[nr].code = code; 457 fsr_info[nr].name = name; 458} 459 460/* 461 * Dispatch a data abort to the relevant handler. 462 */ 463asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr, 464 struct pt_regs *regs) 465{ 466 const struct fsr_info *inf = fsr_info + fsr_fs(fsr); 467 struct siginfo info; 468 469 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs)) 470 return; 471 472 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n", 473 inf->name, fsr, addr); 474 475 info.si_signo = inf->sig; 476 info.si_errno = 0; 477 info.si_code = inf->code; 478 info.si_addr = (void __user *)addr; 479 uc32_notify_die("", regs, &info, fsr, 0); 480} 481 482asmlinkage void do_PrefetchAbort(unsigned long addr, 483 unsigned int ifsr, struct pt_regs *regs) 484{ 485 const struct fsr_info *inf = fsr_info + fsr_fs(ifsr); 486 struct siginfo info; 487 488 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs)) 489 return; 490 491 printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n", 492 inf->name, ifsr, addr); 493 494 info.si_signo = inf->sig; 495 info.si_errno = 0; 496 info.si_code = inf->code; 497 info.si_addr = (void __user *)addr; 498 uc32_notify_die("", regs, &info, ifsr, 0); 499} 500