1 /* 2 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc. 3 * 4 * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net) 5 * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz) 6 */ 7 8 #include <asm/head.h> 9 10 #include <linux/string.h> 11 #include <linux/types.h> 12 #include <linux/sched.h> 13 #include <linux/ptrace.h> 14 #include <linux/mman.h> 15 #include <linux/signal.h> 16 #include <linux/mm.h> 17 #include <linux/module.h> 18 #include <linux/init.h> 19 #include <linux/perf_event.h> 20 #include <linux/interrupt.h> 21 #include <linux/kprobes.h> 22 #include <linux/kdebug.h> 23 #include <linux/percpu.h> 24 #include <linux/context_tracking.h> 25 26 #include <asm/page.h> 27 #include <asm/pgtable.h> 28 #include <asm/openprom.h> 29 #include <asm/oplib.h> 30 #include <asm/uaccess.h> 31 #include <asm/asi.h> 32 #include <asm/lsu.h> 33 #include <asm/sections.h> 34 #include <asm/mmu_context.h> 35 #include <asm/setup.h> 36 37 int show_unhandled_signals = 1; 38 39 static inline __kprobes int notify_page_fault(struct pt_regs *regs) 40 { 41 int ret = 0; 42 43 /* kprobe_running() needs smp_processor_id() */ 44 if (kprobes_built_in() && !user_mode(regs)) { 45 preempt_disable(); 46 if (kprobe_running() && kprobe_fault_handler(regs, 0)) 47 ret = 1; 48 preempt_enable(); 49 } 50 return ret; 51 } 52 53 static void __kprobes unhandled_fault(unsigned long address, 54 struct task_struct *tsk, 55 struct pt_regs *regs) 56 { 57 if ((unsigned long) address < PAGE_SIZE) { 58 printk(KERN_ALERT "Unable to handle kernel NULL " 59 "pointer dereference\n"); 60 } else { 61 printk(KERN_ALERT "Unable to handle kernel paging request " 62 "at virtual address %016lx\n", (unsigned long)address); 63 } 64 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 65 (tsk->mm ? 66 CTX_HWBITS(tsk->mm->context) : 67 CTX_HWBITS(tsk->active_mm->context))); 68 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 69 (tsk->mm ? (unsigned long) tsk->mm->pgd : 70 (unsigned long) tsk->active_mm->pgd)); 71 die_if_kernel("Oops", regs); 72 } 73 74 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 75 { 76 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 77 regs->tpc); 78 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 79 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]); 80 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 81 dump_stack(); 82 unhandled_fault(regs->tpc, current, regs); 83 } 84 85 /* 86 * We now make sure that mmap_sem is held in all paths that call 87 * this. Additionally, to prevent kswapd from ripping ptes from 88 * under us, raise interrupts around the time that we look at the 89 * pte, kswapd will have to wait to get his smp ipi response from 90 * us. vmtruncate likewise. This saves us having to get pte lock. 91 */ 92 static unsigned int get_user_insn(unsigned long tpc) 93 { 94 pgd_t *pgdp = pgd_offset(current->mm, tpc); 95 pud_t *pudp; 96 pmd_t *pmdp; 97 pte_t *ptep, pte; 98 unsigned long pa; 99 u32 insn = 0; 100 101 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp))) 102 goto out; 103 pudp = pud_offset(pgdp, tpc); 104 if (pud_none(*pudp) || unlikely(pud_bad(*pudp))) 105 goto out; 106 107 /* This disables preemption for us as well. */ 108 local_irq_disable(); 109 110 pmdp = pmd_offset(pudp, tpc); 111 if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp))) 112 goto out_irq_enable; 113 114 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 115 if (pmd_trans_huge(*pmdp)) { 116 if (pmd_trans_splitting(*pmdp)) 117 goto out_irq_enable; 118 119 pa = pmd_pfn(*pmdp) << PAGE_SHIFT; 120 pa += tpc & ~HPAGE_MASK; 121 122 /* Use phys bypass so we don't pollute dtlb/dcache. */ 123 __asm__ __volatile__("lduwa [%1] %2, %0" 124 : "=r" (insn) 125 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 126 } else 127 #endif 128 { 129 ptep = pte_offset_map(pmdp, tpc); 130 pte = *ptep; 131 if (pte_present(pte)) { 132 pa = (pte_pfn(pte) << PAGE_SHIFT); 133 pa += (tpc & ~PAGE_MASK); 134 135 /* Use phys bypass so we don't pollute dtlb/dcache. */ 136 __asm__ __volatile__("lduwa [%1] %2, %0" 137 : "=r" (insn) 138 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 139 } 140 pte_unmap(ptep); 141 } 142 out_irq_enable: 143 local_irq_enable(); 144 out: 145 return insn; 146 } 147 148 static inline void 149 show_signal_msg(struct pt_regs *regs, int sig, int code, 150 unsigned long address, struct task_struct *tsk) 151 { 152 if (!unhandled_signal(tsk, sig)) 153 return; 154 155 if (!printk_ratelimit()) 156 return; 157 158 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x", 159 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 160 tsk->comm, task_pid_nr(tsk), address, 161 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7], 162 (void *)regs->u_regs[UREG_FP], code); 163 164 print_vma_addr(KERN_CONT " in ", regs->tpc); 165 166 printk(KERN_CONT "\n"); 167 } 168 169 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 170 unsigned long fault_addr, unsigned int insn, 171 int fault_code) 172 { 173 unsigned long addr; 174 siginfo_t info; 175 176 info.si_code = code; 177 info.si_signo = sig; 178 info.si_errno = 0; 179 if (fault_code & FAULT_CODE_ITLB) { 180 addr = regs->tpc; 181 } else { 182 /* If we were able to probe the faulting instruction, use it 183 * to compute a precise fault address. Otherwise use the fault 184 * time provided address which may only have page granularity. 185 */ 186 if (insn) 187 addr = compute_effective_address(regs, insn, 0); 188 else 189 addr = fault_addr; 190 } 191 info.si_addr = (void __user *) addr; 192 info.si_trapno = 0; 193 194 if (unlikely(show_unhandled_signals)) 195 show_signal_msg(regs, sig, code, addr, current); 196 197 force_sig_info(sig, &info, current); 198 } 199 200 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 201 { 202 if (!insn) { 203 if (!regs->tpc || (regs->tpc & 0x3)) 204 return 0; 205 if (regs->tstate & TSTATE_PRIV) { 206 insn = *(unsigned int *) regs->tpc; 207 } else { 208 insn = get_user_insn(regs->tpc); 209 } 210 } 211 return insn; 212 } 213 214 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code, 215 int fault_code, unsigned int insn, 216 unsigned long address) 217 { 218 unsigned char asi = ASI_P; 219 220 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 221 goto cannot_handle; 222 223 /* If user insn could be read (thus insn is zero), that 224 * is fine. We will just gun down the process with a signal 225 * in that case. 226 */ 227 228 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 229 (insn & 0xc0800000) == 0xc0800000) { 230 if (insn & 0x2000) 231 asi = (regs->tstate >> 24); 232 else 233 asi = (insn >> 5); 234 if ((asi & 0xf2) == 0x82) { 235 if (insn & 0x1000000) { 236 handle_ldf_stq(insn, regs); 237 } else { 238 /* This was a non-faulting load. Just clear the 239 * destination register(s) and continue with the next 240 * instruction. -jj 241 */ 242 handle_ld_nf(insn, regs); 243 } 244 return; 245 } 246 } 247 248 /* Is this in ex_table? */ 249 if (regs->tstate & TSTATE_PRIV) { 250 const struct exception_table_entry *entry; 251 252 entry = search_exception_tables(regs->tpc); 253 if (entry) { 254 regs->tpc = entry->fixup; 255 regs->tnpc = regs->tpc + 4; 256 return; 257 } 258 } else { 259 /* The si_code was set to make clear whether 260 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 261 */ 262 do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code); 263 return; 264 } 265 266 cannot_handle: 267 unhandled_fault (address, current, regs); 268 } 269 270 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs) 271 { 272 static int times; 273 274 if (times++ < 10) 275 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports " 276 "64-bit TPC [%lx]\n", 277 current->comm, current->pid, 278 regs->tpc); 279 show_regs(regs); 280 } 281 282 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 283 { 284 enum ctx_state prev_state = exception_enter(); 285 struct mm_struct *mm = current->mm; 286 struct vm_area_struct *vma; 287 unsigned int insn = 0; 288 int si_code, fault_code, fault; 289 unsigned long address, mm_rss; 290 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 291 292 fault_code = get_thread_fault_code(); 293 294 if (notify_page_fault(regs)) 295 goto exit_exception; 296 297 si_code = SEGV_MAPERR; 298 address = current_thread_info()->fault_address; 299 300 if ((fault_code & FAULT_CODE_ITLB) && 301 (fault_code & FAULT_CODE_DTLB)) 302 BUG(); 303 304 if (test_thread_flag(TIF_32BIT)) { 305 if (!(regs->tstate & TSTATE_PRIV)) { 306 if (unlikely((regs->tpc >> 32) != 0)) { 307 bogus_32bit_fault_tpc(regs); 308 goto intr_or_no_mm; 309 } 310 } 311 if (unlikely((address >> 32) != 0)) 312 goto intr_or_no_mm; 313 } 314 315 if (regs->tstate & TSTATE_PRIV) { 316 unsigned long tpc = regs->tpc; 317 318 /* Sanity check the PC. */ 319 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) || 320 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 321 /* Valid, no problems... */ 322 } else { 323 bad_kernel_pc(regs, address); 324 goto exit_exception; 325 } 326 } else 327 flags |= FAULT_FLAG_USER; 328 329 /* 330 * If we're in an interrupt or have no user 331 * context, we must not take the fault.. 332 */ 333 if (in_atomic() || !mm) 334 goto intr_or_no_mm; 335 336 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 337 338 if (!down_read_trylock(&mm->mmap_sem)) { 339 if ((regs->tstate & TSTATE_PRIV) && 340 !search_exception_tables(regs->tpc)) { 341 insn = get_fault_insn(regs, insn); 342 goto handle_kernel_fault; 343 } 344 345 retry: 346 down_read(&mm->mmap_sem); 347 } 348 349 if (fault_code & FAULT_CODE_BAD_RA) 350 goto do_sigbus; 351 352 vma = find_vma(mm, address); 353 if (!vma) 354 goto bad_area; 355 356 /* Pure DTLB misses do not tell us whether the fault causing 357 * load/store/atomic was a write or not, it only says that there 358 * was no match. So in such a case we (carefully) read the 359 * instruction to try and figure this out. It's an optimization 360 * so it's ok if we can't do this. 361 * 362 * Special hack, window spill/fill knows the exact fault type. 363 */ 364 if (((fault_code & 365 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 366 (vma->vm_flags & VM_WRITE) != 0) { 367 insn = get_fault_insn(regs, 0); 368 if (!insn) 369 goto continue_fault; 370 /* All loads, stores and atomics have bits 30 and 31 both set 371 * in the instruction. Bit 21 is set in all stores, but we 372 * have to avoid prefetches which also have bit 21 set. 373 */ 374 if ((insn & 0xc0200000) == 0xc0200000 && 375 (insn & 0x01780000) != 0x01680000) { 376 /* Don't bother updating thread struct value, 377 * because update_mmu_cache only cares which tlb 378 * the access came from. 379 */ 380 fault_code |= FAULT_CODE_WRITE; 381 } 382 } 383 continue_fault: 384 385 if (vma->vm_start <= address) 386 goto good_area; 387 if (!(vma->vm_flags & VM_GROWSDOWN)) 388 goto bad_area; 389 if (!(fault_code & FAULT_CODE_WRITE)) { 390 /* Non-faulting loads shouldn't expand stack. */ 391 insn = get_fault_insn(regs, insn); 392 if ((insn & 0xc0800000) == 0xc0800000) { 393 unsigned char asi; 394 395 if (insn & 0x2000) 396 asi = (regs->tstate >> 24); 397 else 398 asi = (insn >> 5); 399 if ((asi & 0xf2) == 0x82) 400 goto bad_area; 401 } 402 } 403 if (expand_stack(vma, address)) 404 goto bad_area; 405 /* 406 * Ok, we have a good vm_area for this memory access, so 407 * we can handle it.. 408 */ 409 good_area: 410 si_code = SEGV_ACCERR; 411 412 /* If we took a ITLB miss on a non-executable page, catch 413 * that here. 414 */ 415 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 416 BUG_ON(address != regs->tpc); 417 BUG_ON(regs->tstate & TSTATE_PRIV); 418 goto bad_area; 419 } 420 421 if (fault_code & FAULT_CODE_WRITE) { 422 if (!(vma->vm_flags & VM_WRITE)) 423 goto bad_area; 424 425 /* Spitfire has an icache which does not snoop 426 * processor stores. Later processors do... 427 */ 428 if (tlb_type == spitfire && 429 (vma->vm_flags & VM_EXEC) != 0 && 430 vma->vm_file != NULL) 431 set_thread_fault_code(fault_code | 432 FAULT_CODE_BLKCOMMIT); 433 434 flags |= FAULT_FLAG_WRITE; 435 } else { 436 /* Allow reads even for write-only mappings */ 437 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 438 goto bad_area; 439 } 440 441 fault = handle_mm_fault(mm, vma, address, flags); 442 443 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 444 goto exit_exception; 445 446 if (unlikely(fault & VM_FAULT_ERROR)) { 447 if (fault & VM_FAULT_OOM) 448 goto out_of_memory; 449 else if (fault & VM_FAULT_SIGBUS) 450 goto do_sigbus; 451 BUG(); 452 } 453 454 if (flags & FAULT_FLAG_ALLOW_RETRY) { 455 if (fault & VM_FAULT_MAJOR) { 456 current->maj_flt++; 457 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 458 1, regs, address); 459 } else { 460 current->min_flt++; 461 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 462 1, regs, address); 463 } 464 if (fault & VM_FAULT_RETRY) { 465 flags &= ~FAULT_FLAG_ALLOW_RETRY; 466 flags |= FAULT_FLAG_TRIED; 467 468 /* No need to up_read(&mm->mmap_sem) as we would 469 * have already released it in __lock_page_or_retry 470 * in mm/filemap.c. 471 */ 472 473 goto retry; 474 } 475 } 476 up_read(&mm->mmap_sem); 477 478 mm_rss = get_mm_rss(mm); 479 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 480 mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE)); 481 #endif 482 if (unlikely(mm_rss > 483 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit)) 484 tsb_grow(mm, MM_TSB_BASE, mm_rss); 485 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 486 mm_rss = mm->context.huge_pte_count; 487 if (unlikely(mm_rss > 488 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) { 489 if (mm->context.tsb_block[MM_TSB_HUGE].tsb) 490 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 491 else 492 hugetlb_setup(regs); 493 494 } 495 #endif 496 exit_exception: 497 exception_exit(prev_state); 498 return; 499 500 /* 501 * Something tried to access memory that isn't in our memory map.. 502 * Fix it, but check if it's kernel or user first.. 503 */ 504 bad_area: 505 insn = get_fault_insn(regs, insn); 506 up_read(&mm->mmap_sem); 507 508 handle_kernel_fault: 509 do_kernel_fault(regs, si_code, fault_code, insn, address); 510 goto exit_exception; 511 512 /* 513 * We ran out of memory, or some other thing happened to us that made 514 * us unable to handle the page fault gracefully. 515 */ 516 out_of_memory: 517 insn = get_fault_insn(regs, insn); 518 up_read(&mm->mmap_sem); 519 if (!(regs->tstate & TSTATE_PRIV)) { 520 pagefault_out_of_memory(); 521 goto exit_exception; 522 } 523 goto handle_kernel_fault; 524 525 intr_or_no_mm: 526 insn = get_fault_insn(regs, 0); 527 goto handle_kernel_fault; 528 529 do_sigbus: 530 insn = get_fault_insn(regs, insn); 531 up_read(&mm->mmap_sem); 532 533 /* 534 * Send a sigbus, regardless of whether we were in kernel 535 * or user mode. 536 */ 537 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code); 538 539 /* Kernel mode? Handle exceptions or die */ 540 if (regs->tstate & TSTATE_PRIV) 541 goto handle_kernel_fault; 542 } 543