1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc. 4 * 5 * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net) 6 * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz) 7 */ 8 9 #include <asm/head.h> 10 11 #include <linux/string.h> 12 #include <linux/types.h> 13 #include <linux/sched.h> 14 #include <linux/sched/debug.h> 15 #include <linux/ptrace.h> 16 #include <linux/mman.h> 17 #include <linux/signal.h> 18 #include <linux/mm.h> 19 #include <linux/extable.h> 20 #include <linux/init.h> 21 #include <linux/perf_event.h> 22 #include <linux/interrupt.h> 23 #include <linux/kprobes.h> 24 #include <linux/kdebug.h> 25 #include <linux/percpu.h> 26 #include <linux/context_tracking.h> 27 #include <linux/uaccess.h> 28 29 #include <asm/page.h> 30 #include <asm/pgtable.h> 31 #include <asm/openprom.h> 32 #include <asm/oplib.h> 33 #include <asm/asi.h> 34 #include <asm/lsu.h> 35 #include <asm/sections.h> 36 #include <asm/mmu_context.h> 37 #include <asm/setup.h> 38 39 int show_unhandled_signals = 1; 40 41 static void __kprobes unhandled_fault(unsigned long address, 42 struct task_struct *tsk, 43 struct pt_regs *regs) 44 { 45 if ((unsigned long) address < PAGE_SIZE) { 46 printk(KERN_ALERT "Unable to handle kernel NULL " 47 "pointer dereference\n"); 48 } else { 49 printk(KERN_ALERT "Unable to handle kernel paging request " 50 "at virtual address %016lx\n", (unsigned long)address); 51 } 52 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 53 (tsk->mm ? 54 CTX_HWBITS(tsk->mm->context) : 55 CTX_HWBITS(tsk->active_mm->context))); 56 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 57 (tsk->mm ? (unsigned long) tsk->mm->pgd : 58 (unsigned long) tsk->active_mm->pgd)); 59 die_if_kernel("Oops", regs); 60 } 61 62 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 63 { 64 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 65 regs->tpc); 66 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 67 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]); 68 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 69 dump_stack(); 70 unhandled_fault(regs->tpc, current, regs); 71 } 72 73 /* 74 * We now make sure that mmap_sem is held in all paths that call 75 * this. Additionally, to prevent kswapd from ripping ptes from 76 * under us, raise interrupts around the time that we look at the 77 * pte, kswapd will have to wait to get his smp ipi response from 78 * us. vmtruncate likewise. This saves us having to get pte lock. 79 */ 80 static unsigned int get_user_insn(unsigned long tpc) 81 { 82 pgd_t *pgdp = pgd_offset(current->mm, tpc); 83 p4d_t *p4dp; 84 pud_t *pudp; 85 pmd_t *pmdp; 86 pte_t *ptep, pte; 87 unsigned long pa; 88 u32 insn = 0; 89 90 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp))) 91 goto out; 92 p4dp = p4d_offset(pgdp, tpc); 93 if (p4d_none(*p4dp) || unlikely(p4d_bad(*p4dp))) 94 goto out; 95 pudp = pud_offset(p4dp, tpc); 96 if (pud_none(*pudp) || unlikely(pud_bad(*pudp))) 97 goto out; 98 99 /* This disables preemption for us as well. */ 100 local_irq_disable(); 101 102 pmdp = pmd_offset(pudp, tpc); 103 if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp))) 104 goto out_irq_enable; 105 106 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 107 if (is_hugetlb_pmd(*pmdp)) { 108 pa = pmd_pfn(*pmdp) << PAGE_SHIFT; 109 pa += tpc & ~HPAGE_MASK; 110 111 /* Use phys bypass so we don't pollute dtlb/dcache. */ 112 __asm__ __volatile__("lduwa [%1] %2, %0" 113 : "=r" (insn) 114 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 115 } else 116 #endif 117 { 118 ptep = pte_offset_map(pmdp, tpc); 119 pte = *ptep; 120 if (pte_present(pte)) { 121 pa = (pte_pfn(pte) << PAGE_SHIFT); 122 pa += (tpc & ~PAGE_MASK); 123 124 /* Use phys bypass so we don't pollute dtlb/dcache. */ 125 __asm__ __volatile__("lduwa [%1] %2, %0" 126 : "=r" (insn) 127 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 128 } 129 pte_unmap(ptep); 130 } 131 out_irq_enable: 132 local_irq_enable(); 133 out: 134 return insn; 135 } 136 137 static inline void 138 show_signal_msg(struct pt_regs *regs, int sig, int code, 139 unsigned long address, struct task_struct *tsk) 140 { 141 if (!unhandled_signal(tsk, sig)) 142 return; 143 144 if (!printk_ratelimit()) 145 return; 146 147 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x", 148 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 149 tsk->comm, task_pid_nr(tsk), address, 150 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7], 151 (void *)regs->u_regs[UREG_FP], code); 152 153 print_vma_addr(KERN_CONT " in ", regs->tpc); 154 155 printk(KERN_CONT "\n"); 156 } 157 158 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 159 unsigned long fault_addr, unsigned int insn, 160 int fault_code) 161 { 162 unsigned long addr; 163 164 if (fault_code & FAULT_CODE_ITLB) { 165 addr = regs->tpc; 166 } else { 167 /* If we were able to probe the faulting instruction, use it 168 * to compute a precise fault address. Otherwise use the fault 169 * time provided address which may only have page granularity. 170 */ 171 if (insn) 172 addr = compute_effective_address(regs, insn, 0); 173 else 174 addr = fault_addr; 175 } 176 177 if (unlikely(show_unhandled_signals)) 178 show_signal_msg(regs, sig, code, addr, current); 179 180 force_sig_fault(sig, code, (void __user *) addr, 0); 181 } 182 183 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 184 { 185 if (!insn) { 186 if (!regs->tpc || (regs->tpc & 0x3)) 187 return 0; 188 if (regs->tstate & TSTATE_PRIV) { 189 insn = *(unsigned int *) regs->tpc; 190 } else { 191 insn = get_user_insn(regs->tpc); 192 } 193 } 194 return insn; 195 } 196 197 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code, 198 int fault_code, unsigned int insn, 199 unsigned long address) 200 { 201 unsigned char asi = ASI_P; 202 203 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 204 goto cannot_handle; 205 206 /* If user insn could be read (thus insn is zero), that 207 * is fine. We will just gun down the process with a signal 208 * in that case. 209 */ 210 211 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 212 (insn & 0xc0800000) == 0xc0800000) { 213 if (insn & 0x2000) 214 asi = (regs->tstate >> 24); 215 else 216 asi = (insn >> 5); 217 if ((asi & 0xf2) == 0x82) { 218 if (insn & 0x1000000) { 219 handle_ldf_stq(insn, regs); 220 } else { 221 /* This was a non-faulting load. Just clear the 222 * destination register(s) and continue with the next 223 * instruction. -jj 224 */ 225 handle_ld_nf(insn, regs); 226 } 227 return; 228 } 229 } 230 231 /* Is this in ex_table? */ 232 if (regs->tstate & TSTATE_PRIV) { 233 const struct exception_table_entry *entry; 234 235 entry = search_exception_tables(regs->tpc); 236 if (entry) { 237 regs->tpc = entry->fixup; 238 regs->tnpc = regs->tpc + 4; 239 return; 240 } 241 } else { 242 /* The si_code was set to make clear whether 243 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 244 */ 245 do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code); 246 return; 247 } 248 249 cannot_handle: 250 unhandled_fault (address, current, regs); 251 } 252 253 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs) 254 { 255 static int times; 256 257 if (times++ < 10) 258 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports " 259 "64-bit TPC [%lx]\n", 260 current->comm, current->pid, 261 regs->tpc); 262 show_regs(regs); 263 } 264 265 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 266 { 267 enum ctx_state prev_state = exception_enter(); 268 struct mm_struct *mm = current->mm; 269 struct vm_area_struct *vma; 270 unsigned int insn = 0; 271 int si_code, fault_code; 272 vm_fault_t fault; 273 unsigned long address, mm_rss; 274 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 275 276 fault_code = get_thread_fault_code(); 277 278 if (kprobe_page_fault(regs, 0)) 279 goto exit_exception; 280 281 si_code = SEGV_MAPERR; 282 address = current_thread_info()->fault_address; 283 284 if ((fault_code & FAULT_CODE_ITLB) && 285 (fault_code & FAULT_CODE_DTLB)) 286 BUG(); 287 288 if (test_thread_flag(TIF_32BIT)) { 289 if (!(regs->tstate & TSTATE_PRIV)) { 290 if (unlikely((regs->tpc >> 32) != 0)) { 291 bogus_32bit_fault_tpc(regs); 292 goto intr_or_no_mm; 293 } 294 } 295 if (unlikely((address >> 32) != 0)) 296 goto intr_or_no_mm; 297 } 298 299 if (regs->tstate & TSTATE_PRIV) { 300 unsigned long tpc = regs->tpc; 301 302 /* Sanity check the PC. */ 303 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) || 304 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 305 /* Valid, no problems... */ 306 } else { 307 bad_kernel_pc(regs, address); 308 goto exit_exception; 309 } 310 } else 311 flags |= FAULT_FLAG_USER; 312 313 /* 314 * If we're in an interrupt or have no user 315 * context, we must not take the fault.. 316 */ 317 if (faulthandler_disabled() || !mm) 318 goto intr_or_no_mm; 319 320 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 321 322 if (!down_read_trylock(&mm->mmap_sem)) { 323 if ((regs->tstate & TSTATE_PRIV) && 324 !search_exception_tables(regs->tpc)) { 325 insn = get_fault_insn(regs, insn); 326 goto handle_kernel_fault; 327 } 328 329 retry: 330 down_read(&mm->mmap_sem); 331 } 332 333 if (fault_code & FAULT_CODE_BAD_RA) 334 goto do_sigbus; 335 336 vma = find_vma(mm, address); 337 if (!vma) 338 goto bad_area; 339 340 /* Pure DTLB misses do not tell us whether the fault causing 341 * load/store/atomic was a write or not, it only says that there 342 * was no match. So in such a case we (carefully) read the 343 * instruction to try and figure this out. It's an optimization 344 * so it's ok if we can't do this. 345 * 346 * Special hack, window spill/fill knows the exact fault type. 347 */ 348 if (((fault_code & 349 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 350 (vma->vm_flags & VM_WRITE) != 0) { 351 insn = get_fault_insn(regs, 0); 352 if (!insn) 353 goto continue_fault; 354 /* All loads, stores and atomics have bits 30 and 31 both set 355 * in the instruction. Bit 21 is set in all stores, but we 356 * have to avoid prefetches which also have bit 21 set. 357 */ 358 if ((insn & 0xc0200000) == 0xc0200000 && 359 (insn & 0x01780000) != 0x01680000) { 360 /* Don't bother updating thread struct value, 361 * because update_mmu_cache only cares which tlb 362 * the access came from. 363 */ 364 fault_code |= FAULT_CODE_WRITE; 365 } 366 } 367 continue_fault: 368 369 if (vma->vm_start <= address) 370 goto good_area; 371 if (!(vma->vm_flags & VM_GROWSDOWN)) 372 goto bad_area; 373 if (!(fault_code & FAULT_CODE_WRITE)) { 374 /* Non-faulting loads shouldn't expand stack. */ 375 insn = get_fault_insn(regs, insn); 376 if ((insn & 0xc0800000) == 0xc0800000) { 377 unsigned char asi; 378 379 if (insn & 0x2000) 380 asi = (regs->tstate >> 24); 381 else 382 asi = (insn >> 5); 383 if ((asi & 0xf2) == 0x82) 384 goto bad_area; 385 } 386 } 387 if (expand_stack(vma, address)) 388 goto bad_area; 389 /* 390 * Ok, we have a good vm_area for this memory access, so 391 * we can handle it.. 392 */ 393 good_area: 394 si_code = SEGV_ACCERR; 395 396 /* If we took a ITLB miss on a non-executable page, catch 397 * that here. 398 */ 399 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 400 WARN(address != regs->tpc, 401 "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc); 402 WARN_ON(regs->tstate & TSTATE_PRIV); 403 goto bad_area; 404 } 405 406 if (fault_code & FAULT_CODE_WRITE) { 407 if (!(vma->vm_flags & VM_WRITE)) 408 goto bad_area; 409 410 /* Spitfire has an icache which does not snoop 411 * processor stores. Later processors do... 412 */ 413 if (tlb_type == spitfire && 414 (vma->vm_flags & VM_EXEC) != 0 && 415 vma->vm_file != NULL) 416 set_thread_fault_code(fault_code | 417 FAULT_CODE_BLKCOMMIT); 418 419 flags |= FAULT_FLAG_WRITE; 420 } else { 421 /* Allow reads even for write-only mappings */ 422 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 423 goto bad_area; 424 } 425 426 fault = handle_mm_fault(vma, address, flags); 427 428 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 429 goto exit_exception; 430 431 if (unlikely(fault & VM_FAULT_ERROR)) { 432 if (fault & VM_FAULT_OOM) 433 goto out_of_memory; 434 else if (fault & VM_FAULT_SIGSEGV) 435 goto bad_area; 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_TRANSPARENT_HUGEPAGE) 467 mm_rss -= (mm->context.thp_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.hugetlb_pte_count + mm->context.thp_pte_count; 474 mm_rss *= REAL_HPAGE_PER_HPAGE; 475 if (unlikely(mm_rss > 476 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) { 477 if (mm->context.tsb_block[MM_TSB_HUGE].tsb) 478 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 479 else 480 hugetlb_setup(regs); 481 482 } 483 #endif 484 exit_exception: 485 exception_exit(prev_state); 486 return; 487 488 /* 489 * Something tried to access memory that isn't in our memory map.. 490 * Fix it, but check if it's kernel or user first.. 491 */ 492 bad_area: 493 insn = get_fault_insn(regs, insn); 494 up_read(&mm->mmap_sem); 495 496 handle_kernel_fault: 497 do_kernel_fault(regs, si_code, fault_code, insn, address); 498 goto exit_exception; 499 500 /* 501 * We ran out of memory, or some other thing happened to us that made 502 * us unable to handle the page fault gracefully. 503 */ 504 out_of_memory: 505 insn = get_fault_insn(regs, insn); 506 up_read(&mm->mmap_sem); 507 if (!(regs->tstate & TSTATE_PRIV)) { 508 pagefault_out_of_memory(); 509 goto exit_exception; 510 } 511 goto handle_kernel_fault; 512 513 intr_or_no_mm: 514 insn = get_fault_insn(regs, 0); 515 goto handle_kernel_fault; 516 517 do_sigbus: 518 insn = get_fault_insn(regs, insn); 519 up_read(&mm->mmap_sem); 520 521 /* 522 * Send a sigbus, regardless of whether we were in kernel 523 * or user mode. 524 */ 525 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code); 526 527 /* Kernel mode? Handle exceptions or die */ 528 if (regs->tstate & TSTATE_PRIV) 529 goto handle_kernel_fault; 530 } 531