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 36 int show_unhandled_signals = 1; 37 38 static inline __kprobes int notify_page_fault(struct pt_regs *regs) 39 { 40 int ret = 0; 41 42 /* kprobe_running() needs smp_processor_id() */ 43 if (kprobes_built_in() && !user_mode(regs)) { 44 preempt_disable(); 45 if (kprobe_running() && kprobe_fault_handler(regs, 0)) 46 ret = 1; 47 preempt_enable(); 48 } 49 return ret; 50 } 51 52 static void __kprobes unhandled_fault(unsigned long address, 53 struct task_struct *tsk, 54 struct pt_regs *regs) 55 { 56 if ((unsigned long) address < PAGE_SIZE) { 57 printk(KERN_ALERT "Unable to handle kernel NULL " 58 "pointer dereference\n"); 59 } else { 60 printk(KERN_ALERT "Unable to handle kernel paging request " 61 "at virtual address %016lx\n", (unsigned long)address); 62 } 63 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 64 (tsk->mm ? 65 CTX_HWBITS(tsk->mm->context) : 66 CTX_HWBITS(tsk->active_mm->context))); 67 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 68 (tsk->mm ? (unsigned long) tsk->mm->pgd : 69 (unsigned long) tsk->active_mm->pgd)); 70 die_if_kernel("Oops", regs); 71 } 72 73 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 74 { 75 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 76 regs->tpc); 77 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 78 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]); 79 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 80 dump_stack(); 81 unhandled_fault(regs->tpc, current, regs); 82 } 83 84 /* 85 * We now make sure that mmap_sem is held in all paths that call 86 * this. Additionally, to prevent kswapd from ripping ptes from 87 * under us, raise interrupts around the time that we look at the 88 * pte, kswapd will have to wait to get his smp ipi response from 89 * us. vmtruncate likewise. This saves us having to get pte lock. 90 */ 91 static unsigned int get_user_insn(unsigned long tpc) 92 { 93 pgd_t *pgdp = pgd_offset(current->mm, tpc); 94 pud_t *pudp; 95 pmd_t *pmdp; 96 pte_t *ptep, pte; 97 unsigned long pa; 98 u32 insn = 0; 99 unsigned long pstate; 100 101 if (pgd_none(*pgdp)) 102 goto outret; 103 pudp = pud_offset(pgdp, tpc); 104 if (pud_none(*pudp)) 105 goto outret; 106 pmdp = pmd_offset(pudp, tpc); 107 if (pmd_none(*pmdp)) 108 goto outret; 109 110 /* This disables preemption for us as well. */ 111 __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate)); 112 __asm__ __volatile__("wrpr %0, %1, %%pstate" 113 : : "r" (pstate), "i" (PSTATE_IE)); 114 ptep = pte_offset_map(pmdp, tpc); 115 pte = *ptep; 116 if (!pte_present(pte)) 117 goto out; 118 119 pa = (pte_pfn(pte) << PAGE_SHIFT); 120 pa += (tpc & ~PAGE_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)); 126 127 out: 128 pte_unmap(ptep); 129 __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate)); 130 outret: 131 return insn; 132 } 133 134 static inline void 135 show_signal_msg(struct pt_regs *regs, int sig, int code, 136 unsigned long address, struct task_struct *tsk) 137 { 138 if (!unhandled_signal(tsk, sig)) 139 return; 140 141 if (!printk_ratelimit()) 142 return; 143 144 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x", 145 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 146 tsk->comm, task_pid_nr(tsk), address, 147 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7], 148 (void *)regs->u_regs[UREG_FP], code); 149 150 print_vma_addr(KERN_CONT " in ", regs->tpc); 151 152 printk(KERN_CONT "\n"); 153 } 154 155 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 156 unsigned int insn, int fault_code) 157 { 158 unsigned long addr; 159 siginfo_t info; 160 161 info.si_code = code; 162 info.si_signo = sig; 163 info.si_errno = 0; 164 if (fault_code & FAULT_CODE_ITLB) 165 addr = regs->tpc; 166 else 167 addr = compute_effective_address(regs, insn, 0); 168 info.si_addr = (void __user *) addr; 169 info.si_trapno = 0; 170 171 if (unlikely(show_unhandled_signals)) 172 show_signal_msg(regs, sig, code, addr, current); 173 174 force_sig_info(sig, &info, current); 175 } 176 177 extern int handle_ldf_stq(u32, struct pt_regs *); 178 extern int handle_ld_nf(u32, struct pt_regs *); 179 180 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 181 { 182 if (!insn) { 183 if (!regs->tpc || (regs->tpc & 0x3)) 184 return 0; 185 if (regs->tstate & TSTATE_PRIV) { 186 insn = *(unsigned int *) regs->tpc; 187 } else { 188 insn = get_user_insn(regs->tpc); 189 } 190 } 191 return insn; 192 } 193 194 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code, 195 int fault_code, unsigned int insn, 196 unsigned long address) 197 { 198 unsigned char asi = ASI_P; 199 200 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 201 goto cannot_handle; 202 203 /* If user insn could be read (thus insn is zero), that 204 * is fine. We will just gun down the process with a signal 205 * in that case. 206 */ 207 208 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 209 (insn & 0xc0800000) == 0xc0800000) { 210 if (insn & 0x2000) 211 asi = (regs->tstate >> 24); 212 else 213 asi = (insn >> 5); 214 if ((asi & 0xf2) == 0x82) { 215 if (insn & 0x1000000) { 216 handle_ldf_stq(insn, regs); 217 } else { 218 /* This was a non-faulting load. Just clear the 219 * destination register(s) and continue with the next 220 * instruction. -jj 221 */ 222 handle_ld_nf(insn, regs); 223 } 224 return; 225 } 226 } 227 228 /* Is this in ex_table? */ 229 if (regs->tstate & TSTATE_PRIV) { 230 const struct exception_table_entry *entry; 231 232 entry = search_exception_tables(regs->tpc); 233 if (entry) { 234 regs->tpc = entry->fixup; 235 regs->tnpc = regs->tpc + 4; 236 return; 237 } 238 } else { 239 /* The si_code was set to make clear whether 240 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 241 */ 242 do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code); 243 return; 244 } 245 246 cannot_handle: 247 unhandled_fault (address, current, regs); 248 } 249 250 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs) 251 { 252 static int times; 253 254 if (times++ < 10) 255 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports " 256 "64-bit TPC [%lx]\n", 257 current->comm, current->pid, 258 regs->tpc); 259 show_regs(regs); 260 } 261 262 static void noinline __kprobes bogus_32bit_fault_address(struct pt_regs *regs, 263 unsigned long addr) 264 { 265 static int times; 266 267 if (times++ < 10) 268 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process " 269 "reports 64-bit fault address [%lx]\n", 270 current->comm, current->pid, addr); 271 show_regs(regs); 272 } 273 274 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 275 { 276 enum ctx_state prev_state = exception_enter(); 277 struct mm_struct *mm = current->mm; 278 struct vm_area_struct *vma; 279 unsigned int insn = 0; 280 int si_code, fault_code, fault; 281 unsigned long address, mm_rss; 282 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 283 284 fault_code = get_thread_fault_code(); 285 286 if (notify_page_fault(regs)) 287 goto exit_exception; 288 289 si_code = SEGV_MAPERR; 290 address = current_thread_info()->fault_address; 291 292 if ((fault_code & FAULT_CODE_ITLB) && 293 (fault_code & FAULT_CODE_DTLB)) 294 BUG(); 295 296 if (test_thread_flag(TIF_32BIT)) { 297 if (!(regs->tstate & TSTATE_PRIV)) { 298 if (unlikely((regs->tpc >> 32) != 0)) { 299 bogus_32bit_fault_tpc(regs); 300 goto intr_or_no_mm; 301 } 302 } 303 if (unlikely((address >> 32) != 0)) { 304 bogus_32bit_fault_address(regs, address); 305 goto intr_or_no_mm; 306 } 307 } 308 309 if (regs->tstate & TSTATE_PRIV) { 310 unsigned long tpc = regs->tpc; 311 312 /* Sanity check the PC. */ 313 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) || 314 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 315 /* Valid, no problems... */ 316 } else { 317 bad_kernel_pc(regs, address); 318 goto exit_exception; 319 } 320 } else 321 flags |= FAULT_FLAG_USER; 322 323 /* 324 * If we're in an interrupt or have no user 325 * context, we must not take the fault.. 326 */ 327 if (in_atomic() || !mm) 328 goto intr_or_no_mm; 329 330 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 331 332 if (!down_read_trylock(&mm->mmap_sem)) { 333 if ((regs->tstate & TSTATE_PRIV) && 334 !search_exception_tables(regs->tpc)) { 335 insn = get_fault_insn(regs, insn); 336 goto handle_kernel_fault; 337 } 338 339 retry: 340 down_read(&mm->mmap_sem); 341 } 342 343 vma = find_vma(mm, address); 344 if (!vma) 345 goto bad_area; 346 347 /* Pure DTLB misses do not tell us whether the fault causing 348 * load/store/atomic was a write or not, it only says that there 349 * was no match. So in such a case we (carefully) read the 350 * instruction to try and figure this out. It's an optimization 351 * so it's ok if we can't do this. 352 * 353 * Special hack, window spill/fill knows the exact fault type. 354 */ 355 if (((fault_code & 356 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 357 (vma->vm_flags & VM_WRITE) != 0) { 358 insn = get_fault_insn(regs, 0); 359 if (!insn) 360 goto continue_fault; 361 /* All loads, stores and atomics have bits 30 and 31 both set 362 * in the instruction. Bit 21 is set in all stores, but we 363 * have to avoid prefetches which also have bit 21 set. 364 */ 365 if ((insn & 0xc0200000) == 0xc0200000 && 366 (insn & 0x01780000) != 0x01680000) { 367 /* Don't bother updating thread struct value, 368 * because update_mmu_cache only cares which tlb 369 * the access came from. 370 */ 371 fault_code |= FAULT_CODE_WRITE; 372 } 373 } 374 continue_fault: 375 376 if (vma->vm_start <= address) 377 goto good_area; 378 if (!(vma->vm_flags & VM_GROWSDOWN)) 379 goto bad_area; 380 if (!(fault_code & FAULT_CODE_WRITE)) { 381 /* Non-faulting loads shouldn't expand stack. */ 382 insn = get_fault_insn(regs, insn); 383 if ((insn & 0xc0800000) == 0xc0800000) { 384 unsigned char asi; 385 386 if (insn & 0x2000) 387 asi = (regs->tstate >> 24); 388 else 389 asi = (insn >> 5); 390 if ((asi & 0xf2) == 0x82) 391 goto bad_area; 392 } 393 } 394 if (expand_stack(vma, address)) 395 goto bad_area; 396 /* 397 * Ok, we have a good vm_area for this memory access, so 398 * we can handle it.. 399 */ 400 good_area: 401 si_code = SEGV_ACCERR; 402 403 /* If we took a ITLB miss on a non-executable page, catch 404 * that here. 405 */ 406 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 407 BUG_ON(address != regs->tpc); 408 BUG_ON(regs->tstate & TSTATE_PRIV); 409 goto bad_area; 410 } 411 412 if (fault_code & FAULT_CODE_WRITE) { 413 if (!(vma->vm_flags & VM_WRITE)) 414 goto bad_area; 415 416 /* Spitfire has an icache which does not snoop 417 * processor stores. Later processors do... 418 */ 419 if (tlb_type == spitfire && 420 (vma->vm_flags & VM_EXEC) != 0 && 421 vma->vm_file != NULL) 422 set_thread_fault_code(fault_code | 423 FAULT_CODE_BLKCOMMIT); 424 425 flags |= FAULT_FLAG_WRITE; 426 } else { 427 /* Allow reads even for write-only mappings */ 428 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 429 goto bad_area; 430 } 431 432 fault = handle_mm_fault(mm, vma, address, flags); 433 434 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 435 goto exit_exception; 436 437 if (unlikely(fault & VM_FAULT_ERROR)) { 438 if (fault & VM_FAULT_OOM) 439 goto out_of_memory; 440 else if (fault & VM_FAULT_SIGBUS) 441 goto do_sigbus; 442 BUG(); 443 } 444 445 if (flags & FAULT_FLAG_ALLOW_RETRY) { 446 if (fault & VM_FAULT_MAJOR) { 447 current->maj_flt++; 448 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 449 1, regs, address); 450 } else { 451 current->min_flt++; 452 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 453 1, regs, address); 454 } 455 if (fault & VM_FAULT_RETRY) { 456 flags &= ~FAULT_FLAG_ALLOW_RETRY; 457 flags |= FAULT_FLAG_TRIED; 458 459 /* No need to up_read(&mm->mmap_sem) as we would 460 * have already released it in __lock_page_or_retry 461 * in mm/filemap.c. 462 */ 463 464 goto retry; 465 } 466 } 467 up_read(&mm->mmap_sem); 468 469 mm_rss = get_mm_rss(mm); 470 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 471 mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE)); 472 #endif 473 if (unlikely(mm_rss > 474 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit)) 475 tsb_grow(mm, MM_TSB_BASE, mm_rss); 476 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 477 mm_rss = mm->context.huge_pte_count; 478 if (unlikely(mm_rss > 479 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) { 480 if (mm->context.tsb_block[MM_TSB_HUGE].tsb) 481 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 482 else 483 hugetlb_setup(regs); 484 485 } 486 #endif 487 exit_exception: 488 exception_exit(prev_state); 489 return; 490 491 /* 492 * Something tried to access memory that isn't in our memory map.. 493 * Fix it, but check if it's kernel or user first.. 494 */ 495 bad_area: 496 insn = get_fault_insn(regs, insn); 497 up_read(&mm->mmap_sem); 498 499 handle_kernel_fault: 500 do_kernel_fault(regs, si_code, fault_code, insn, address); 501 goto exit_exception; 502 503 /* 504 * We ran out of memory, or some other thing happened to us that made 505 * us unable to handle the page fault gracefully. 506 */ 507 out_of_memory: 508 insn = get_fault_insn(regs, insn); 509 up_read(&mm->mmap_sem); 510 if (!(regs->tstate & TSTATE_PRIV)) { 511 pagefault_out_of_memory(); 512 goto exit_exception; 513 } 514 goto handle_kernel_fault; 515 516 intr_or_no_mm: 517 insn = get_fault_insn(regs, 0); 518 goto handle_kernel_fault; 519 520 do_sigbus: 521 insn = get_fault_insn(regs, insn); 522 up_read(&mm->mmap_sem); 523 524 /* 525 * Send a sigbus, regardless of whether we were in kernel 526 * or user mode. 527 */ 528 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code); 529 530 /* Kernel mode? Handle exceptions or die */ 531 if (regs->tstate & TSTATE_PRIV) 532 goto handle_kernel_fault; 533 } 534