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 25 #include <asm/page.h> 26 #include <asm/pgtable.h> 27 #include <asm/openprom.h> 28 #include <asm/oplib.h> 29 #include <asm/uaccess.h> 30 #include <asm/asi.h> 31 #include <asm/lsu.h> 32 #include <asm/sections.h> 33 #include <asm/mmu_context.h> 34 35 int show_unhandled_signals = 1; 36 37 static inline __kprobes int notify_page_fault(struct pt_regs *regs) 38 { 39 int ret = 0; 40 41 /* kprobe_running() needs smp_processor_id() */ 42 if (kprobes_built_in() && !user_mode(regs)) { 43 preempt_disable(); 44 if (kprobe_running() && kprobe_fault_handler(regs, 0)) 45 ret = 1; 46 preempt_enable(); 47 } 48 return ret; 49 } 50 51 static void __kprobes unhandled_fault(unsigned long address, 52 struct task_struct *tsk, 53 struct pt_regs *regs) 54 { 55 if ((unsigned long) address < PAGE_SIZE) { 56 printk(KERN_ALERT "Unable to handle kernel NULL " 57 "pointer dereference\n"); 58 } else { 59 printk(KERN_ALERT "Unable to handle kernel paging request " 60 "at virtual address %016lx\n", (unsigned long)address); 61 } 62 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 63 (tsk->mm ? 64 CTX_HWBITS(tsk->mm->context) : 65 CTX_HWBITS(tsk->active_mm->context))); 66 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 67 (tsk->mm ? (unsigned long) tsk->mm->pgd : 68 (unsigned long) tsk->active_mm->pgd)); 69 die_if_kernel("Oops", regs); 70 } 71 72 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 73 { 74 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 75 regs->tpc); 76 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 77 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]); 78 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 79 dump_stack(); 80 unhandled_fault(regs->tpc, current, regs); 81 } 82 83 /* 84 * We now make sure that mmap_sem is held in all paths that call 85 * this. Additionally, to prevent kswapd from ripping ptes from 86 * under us, raise interrupts around the time that we look at the 87 * pte, kswapd will have to wait to get his smp ipi response from 88 * us. vmtruncate likewise. This saves us having to get pte lock. 89 */ 90 static unsigned int get_user_insn(unsigned long tpc) 91 { 92 pgd_t *pgdp = pgd_offset(current->mm, tpc); 93 pud_t *pudp; 94 pmd_t *pmdp; 95 pte_t *ptep, pte; 96 unsigned long pa; 97 u32 insn = 0; 98 unsigned long pstate; 99 100 if (pgd_none(*pgdp)) 101 goto outret; 102 pudp = pud_offset(pgdp, tpc); 103 if (pud_none(*pudp)) 104 goto outret; 105 pmdp = pmd_offset(pudp, tpc); 106 if (pmd_none(*pmdp)) 107 goto outret; 108 109 /* This disables preemption for us as well. */ 110 __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate)); 111 __asm__ __volatile__("wrpr %0, %1, %%pstate" 112 : : "r" (pstate), "i" (PSTATE_IE)); 113 ptep = pte_offset_map(pmdp, tpc); 114 pte = *ptep; 115 if (!pte_present(pte)) 116 goto out; 117 118 pa = (pte_pfn(pte) << PAGE_SHIFT); 119 pa += (tpc & ~PAGE_MASK); 120 121 /* Use phys bypass so we don't pollute dtlb/dcache. */ 122 __asm__ __volatile__("lduwa [%1] %2, %0" 123 : "=r" (insn) 124 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 125 126 out: 127 pte_unmap(ptep); 128 __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate)); 129 outret: 130 return insn; 131 } 132 133 static inline void 134 show_signal_msg(struct pt_regs *regs, int sig, int code, 135 unsigned long address, struct task_struct *tsk) 136 { 137 if (!unhandled_signal(tsk, sig)) 138 return; 139 140 if (!printk_ratelimit()) 141 return; 142 143 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x", 144 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 145 tsk->comm, task_pid_nr(tsk), address, 146 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7], 147 (void *)regs->u_regs[UREG_FP], code); 148 149 print_vma_addr(KERN_CONT " in ", regs->tpc); 150 151 printk(KERN_CONT "\n"); 152 } 153 154 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 155 unsigned int insn, int fault_code) 156 { 157 unsigned long addr; 158 siginfo_t info; 159 160 info.si_code = code; 161 info.si_signo = sig; 162 info.si_errno = 0; 163 if (fault_code & FAULT_CODE_ITLB) 164 addr = regs->tpc; 165 else 166 addr = compute_effective_address(regs, insn, 0); 167 info.si_addr = (void __user *) addr; 168 info.si_trapno = 0; 169 170 if (unlikely(show_unhandled_signals)) 171 show_signal_msg(regs, sig, code, addr, current); 172 173 force_sig_info(sig, &info, current); 174 } 175 176 extern int handle_ldf_stq(u32, struct pt_regs *); 177 extern int handle_ld_nf(u32, struct pt_regs *); 178 179 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 180 { 181 if (!insn) { 182 if (!regs->tpc || (regs->tpc & 0x3)) 183 return 0; 184 if (regs->tstate & TSTATE_PRIV) { 185 insn = *(unsigned int *) regs->tpc; 186 } else { 187 insn = get_user_insn(regs->tpc); 188 } 189 } 190 return insn; 191 } 192 193 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code, 194 int fault_code, unsigned int insn, 195 unsigned long address) 196 { 197 unsigned char asi = ASI_P; 198 199 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 200 goto cannot_handle; 201 202 /* If user insn could be read (thus insn is zero), that 203 * is fine. We will just gun down the process with a signal 204 * in that case. 205 */ 206 207 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 208 (insn & 0xc0800000) == 0xc0800000) { 209 if (insn & 0x2000) 210 asi = (regs->tstate >> 24); 211 else 212 asi = (insn >> 5); 213 if ((asi & 0xf2) == 0x82) { 214 if (insn & 0x1000000) { 215 handle_ldf_stq(insn, regs); 216 } else { 217 /* This was a non-faulting load. Just clear the 218 * destination register(s) and continue with the next 219 * instruction. -jj 220 */ 221 handle_ld_nf(insn, regs); 222 } 223 return; 224 } 225 } 226 227 /* Is this in ex_table? */ 228 if (regs->tstate & TSTATE_PRIV) { 229 const struct exception_table_entry *entry; 230 231 entry = search_exception_tables(regs->tpc); 232 if (entry) { 233 regs->tpc = entry->fixup; 234 regs->tnpc = regs->tpc + 4; 235 return; 236 } 237 } else { 238 /* The si_code was set to make clear whether 239 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 240 */ 241 do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code); 242 return; 243 } 244 245 cannot_handle: 246 unhandled_fault (address, current, regs); 247 } 248 249 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs) 250 { 251 static int times; 252 253 if (times++ < 10) 254 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports " 255 "64-bit TPC [%lx]\n", 256 current->comm, current->pid, 257 regs->tpc); 258 show_regs(regs); 259 } 260 261 static void noinline __kprobes bogus_32bit_fault_address(struct pt_regs *regs, 262 unsigned long addr) 263 { 264 static int times; 265 266 if (times++ < 10) 267 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process " 268 "reports 64-bit fault address [%lx]\n", 269 current->comm, current->pid, addr); 270 show_regs(regs); 271 } 272 273 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 274 { 275 struct mm_struct *mm = current->mm; 276 struct vm_area_struct *vma; 277 unsigned int insn = 0; 278 int si_code, fault_code, fault; 279 unsigned long address, mm_rss; 280 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 281 282 fault_code = get_thread_fault_code(); 283 284 if (notify_page_fault(regs)) 285 return; 286 287 si_code = SEGV_MAPERR; 288 address = current_thread_info()->fault_address; 289 290 if ((fault_code & FAULT_CODE_ITLB) && 291 (fault_code & FAULT_CODE_DTLB)) 292 BUG(); 293 294 if (test_thread_flag(TIF_32BIT)) { 295 if (!(regs->tstate & TSTATE_PRIV)) { 296 if (unlikely((regs->tpc >> 32) != 0)) { 297 bogus_32bit_fault_tpc(regs); 298 goto intr_or_no_mm; 299 } 300 } 301 if (unlikely((address >> 32) != 0)) { 302 bogus_32bit_fault_address(regs, address); 303 goto intr_or_no_mm; 304 } 305 } 306 307 if (regs->tstate & TSTATE_PRIV) { 308 unsigned long tpc = regs->tpc; 309 310 /* Sanity check the PC. */ 311 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) || 312 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 313 /* Valid, no problems... */ 314 } else { 315 bad_kernel_pc(regs, address); 316 return; 317 } 318 } 319 320 /* 321 * If we're in an interrupt or have no user 322 * context, we must not take the fault.. 323 */ 324 if (in_atomic() || !mm) 325 goto intr_or_no_mm; 326 327 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 328 329 if (!down_read_trylock(&mm->mmap_sem)) { 330 if ((regs->tstate & TSTATE_PRIV) && 331 !search_exception_tables(regs->tpc)) { 332 insn = get_fault_insn(regs, insn); 333 goto handle_kernel_fault; 334 } 335 336 retry: 337 down_read(&mm->mmap_sem); 338 } 339 340 vma = find_vma(mm, address); 341 if (!vma) 342 goto bad_area; 343 344 /* Pure DTLB misses do not tell us whether the fault causing 345 * load/store/atomic was a write or not, it only says that there 346 * was no match. So in such a case we (carefully) read the 347 * instruction to try and figure this out. It's an optimization 348 * so it's ok if we can't do this. 349 * 350 * Special hack, window spill/fill knows the exact fault type. 351 */ 352 if (((fault_code & 353 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 354 (vma->vm_flags & VM_WRITE) != 0) { 355 insn = get_fault_insn(regs, 0); 356 if (!insn) 357 goto continue_fault; 358 /* All loads, stores and atomics have bits 30 and 31 both set 359 * in the instruction. Bit 21 is set in all stores, but we 360 * have to avoid prefetches which also have bit 21 set. 361 */ 362 if ((insn & 0xc0200000) == 0xc0200000 && 363 (insn & 0x01780000) != 0x01680000) { 364 /* Don't bother updating thread struct value, 365 * because update_mmu_cache only cares which tlb 366 * the access came from. 367 */ 368 fault_code |= FAULT_CODE_WRITE; 369 } 370 } 371 continue_fault: 372 373 if (vma->vm_start <= address) 374 goto good_area; 375 if (!(vma->vm_flags & VM_GROWSDOWN)) 376 goto bad_area; 377 if (!(fault_code & FAULT_CODE_WRITE)) { 378 /* Non-faulting loads shouldn't expand stack. */ 379 insn = get_fault_insn(regs, insn); 380 if ((insn & 0xc0800000) == 0xc0800000) { 381 unsigned char asi; 382 383 if (insn & 0x2000) 384 asi = (regs->tstate >> 24); 385 else 386 asi = (insn >> 5); 387 if ((asi & 0xf2) == 0x82) 388 goto bad_area; 389 } 390 } 391 if (expand_stack(vma, address)) 392 goto bad_area; 393 /* 394 * Ok, we have a good vm_area for this memory access, so 395 * we can handle it.. 396 */ 397 good_area: 398 si_code = SEGV_ACCERR; 399 400 /* If we took a ITLB miss on a non-executable page, catch 401 * that here. 402 */ 403 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 404 BUG_ON(address != regs->tpc); 405 BUG_ON(regs->tstate & TSTATE_PRIV); 406 goto bad_area; 407 } 408 409 if (fault_code & FAULT_CODE_WRITE) { 410 if (!(vma->vm_flags & VM_WRITE)) 411 goto bad_area; 412 413 /* Spitfire has an icache which does not snoop 414 * processor stores. Later processors do... 415 */ 416 if (tlb_type == spitfire && 417 (vma->vm_flags & VM_EXEC) != 0 && 418 vma->vm_file != NULL) 419 set_thread_fault_code(fault_code | 420 FAULT_CODE_BLKCOMMIT); 421 } else { 422 /* Allow reads even for write-only mappings */ 423 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 424 goto bad_area; 425 } 426 427 flags |= ((fault_code & FAULT_CODE_WRITE) ? FAULT_FLAG_WRITE : 0); 428 fault = handle_mm_fault(mm, vma, address, flags); 429 430 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 431 return; 432 433 if (unlikely(fault & VM_FAULT_ERROR)) { 434 if (fault & VM_FAULT_OOM) 435 goto out_of_memory; 436 else if (fault & VM_FAULT_SIGBUS) 437 goto do_sigbus; 438 BUG(); 439 } 440 441 if (flags & FAULT_FLAG_ALLOW_RETRY) { 442 if (fault & VM_FAULT_MAJOR) { 443 current->maj_flt++; 444 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 445 1, regs, address); 446 } else { 447 current->min_flt++; 448 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 449 1, regs, address); 450 } 451 if (fault & VM_FAULT_RETRY) { 452 flags &= ~FAULT_FLAG_ALLOW_RETRY; 453 flags |= FAULT_FLAG_TRIED; 454 455 /* No need to up_read(&mm->mmap_sem) as we would 456 * have already released it in __lock_page_or_retry 457 * in mm/filemap.c. 458 */ 459 460 goto retry; 461 } 462 } 463 up_read(&mm->mmap_sem); 464 465 mm_rss = get_mm_rss(mm); 466 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 467 mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE)); 468 #endif 469 if (unlikely(mm_rss > 470 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit)) 471 tsb_grow(mm, MM_TSB_BASE, mm_rss); 472 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 473 mm_rss = mm->context.huge_pte_count; 474 if (unlikely(mm_rss > 475 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) 476 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 477 #endif 478 return; 479 480 /* 481 * Something tried to access memory that isn't in our memory map.. 482 * Fix it, but check if it's kernel or user first.. 483 */ 484 bad_area: 485 insn = get_fault_insn(regs, insn); 486 up_read(&mm->mmap_sem); 487 488 handle_kernel_fault: 489 do_kernel_fault(regs, si_code, fault_code, insn, address); 490 return; 491 492 /* 493 * We ran out of memory, or some other thing happened to us that made 494 * us unable to handle the page fault gracefully. 495 */ 496 out_of_memory: 497 insn = get_fault_insn(regs, insn); 498 up_read(&mm->mmap_sem); 499 if (!(regs->tstate & TSTATE_PRIV)) { 500 pagefault_out_of_memory(); 501 return; 502 } 503 goto handle_kernel_fault; 504 505 intr_or_no_mm: 506 insn = get_fault_insn(regs, 0); 507 goto handle_kernel_fault; 508 509 do_sigbus: 510 insn = get_fault_insn(regs, insn); 511 up_read(&mm->mmap_sem); 512 513 /* 514 * Send a sigbus, regardless of whether we were in kernel 515 * or user mode. 516 */ 517 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code); 518 519 /* Kernel mode? Handle exceptions or die */ 520 if (regs->tstate & TSTATE_PRIV) 521 goto handle_kernel_fault; 522 } 523