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/openprom.h> 31 #include <asm/oplib.h> 32 #include <asm/asi.h> 33 #include <asm/lsu.h> 34 #include <asm/sections.h> 35 #include <asm/mmu_context.h> 36 #include <asm/setup.h> 37 38 int show_unhandled_signals = 1; 39 40 static void __kprobes unhandled_fault(unsigned long address, 41 struct task_struct *tsk, 42 struct pt_regs *regs) 43 { 44 if ((unsigned long) address < PAGE_SIZE) { 45 printk(KERN_ALERT "Unable to handle kernel NULL " 46 "pointer dereference\n"); 47 } else { 48 printk(KERN_ALERT "Unable to handle kernel paging request " 49 "at virtual address %016lx\n", (unsigned long)address); 50 } 51 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 52 (tsk->mm ? 53 CTX_HWBITS(tsk->mm->context) : 54 CTX_HWBITS(tsk->active_mm->context))); 55 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 56 (tsk->mm ? (unsigned long) tsk->mm->pgd : 57 (unsigned long) tsk->active_mm->pgd)); 58 die_if_kernel("Oops", regs); 59 } 60 61 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 62 { 63 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 64 regs->tpc); 65 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 66 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]); 67 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 68 dump_stack(); 69 unhandled_fault(regs->tpc, current, regs); 70 } 71 72 /* 73 * We now make sure that mmap_lock is held in all paths that call 74 * this. Additionally, to prevent kswapd from ripping ptes from 75 * under us, raise interrupts around the time that we look at the 76 * pte, kswapd will have to wait to get his smp ipi response from 77 * us. vmtruncate likewise. This saves us having to get pte lock. 78 */ 79 static unsigned int get_user_insn(unsigned long tpc) 80 { 81 pgd_t *pgdp = pgd_offset(current->mm, tpc); 82 p4d_t *p4dp; 83 pud_t *pudp; 84 pmd_t *pmdp; 85 pte_t *ptep, pte; 86 unsigned long pa; 87 u32 insn = 0; 88 89 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp))) 90 goto out; 91 p4dp = p4d_offset(pgdp, tpc); 92 if (p4d_none(*p4dp) || unlikely(p4d_bad(*p4dp))) 93 goto out; 94 pudp = pud_offset(p4dp, tpc); 95 if (pud_none(*pudp) || unlikely(pud_bad(*pudp))) 96 goto out; 97 98 /* This disables preemption for us as well. */ 99 local_irq_disable(); 100 101 pmdp = pmd_offset(pudp, tpc); 102 if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp))) 103 goto out_irq_enable; 104 105 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 106 if (is_hugetlb_pmd(*pmdp)) { 107 pa = pmd_pfn(*pmdp) << PAGE_SHIFT; 108 pa += tpc & ~HPAGE_MASK; 109 110 /* Use phys bypass so we don't pollute dtlb/dcache. */ 111 __asm__ __volatile__("lduwa [%1] %2, %0" 112 : "=r" (insn) 113 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 114 } else 115 #endif 116 { 117 ptep = pte_offset_map(pmdp, tpc); 118 pte = *ptep; 119 if (pte_present(pte)) { 120 pa = (pte_pfn(pte) << PAGE_SHIFT); 121 pa += (tpc & ~PAGE_MASK); 122 123 /* Use phys bypass so we don't pollute dtlb/dcache. */ 124 __asm__ __volatile__("lduwa [%1] %2, %0" 125 : "=r" (insn) 126 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 127 } 128 pte_unmap(ptep); 129 } 130 out_irq_enable: 131 local_irq_enable(); 132 out: 133 return insn; 134 } 135 136 static inline void 137 show_signal_msg(struct pt_regs *regs, int sig, int code, 138 unsigned long address, struct task_struct *tsk) 139 { 140 if (!unhandled_signal(tsk, sig)) 141 return; 142 143 if (!printk_ratelimit()) 144 return; 145 146 printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x", 147 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, 148 tsk->comm, task_pid_nr(tsk), address, 149 (void *)regs->tpc, (void *)regs->u_regs[UREG_I7], 150 (void *)regs->u_regs[UREG_FP], code); 151 152 print_vma_addr(KERN_CONT " in ", regs->tpc); 153 154 printk(KERN_CONT "\n"); 155 } 156 157 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 158 unsigned long fault_addr, unsigned int insn, 159 int fault_code) 160 { 161 unsigned long addr; 162 163 if (fault_code & FAULT_CODE_ITLB) { 164 addr = regs->tpc; 165 } else { 166 /* If we were able to probe the faulting instruction, use it 167 * to compute a precise fault address. Otherwise use the fault 168 * time provided address which may only have page granularity. 169 */ 170 if (insn) 171 addr = compute_effective_address(regs, insn, 0); 172 else 173 addr = fault_addr; 174 } 175 176 if (unlikely(show_unhandled_signals)) 177 show_signal_msg(regs, sig, code, addr, current); 178 179 force_sig_fault(sig, code, (void __user *) addr, 0); 180 } 181 182 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 183 { 184 if (!insn) { 185 if (!regs->tpc || (regs->tpc & 0x3)) 186 return 0; 187 if (regs->tstate & TSTATE_PRIV) { 188 insn = *(unsigned int *) regs->tpc; 189 } else { 190 insn = get_user_insn(regs->tpc); 191 } 192 } 193 return insn; 194 } 195 196 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code, 197 int fault_code, unsigned int insn, 198 unsigned long address) 199 { 200 unsigned char asi = ASI_P; 201 202 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 203 goto cannot_handle; 204 205 /* If user insn could be read (thus insn is zero), that 206 * is fine. We will just gun down the process with a signal 207 * in that case. 208 */ 209 210 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 211 (insn & 0xc0800000) == 0xc0800000) { 212 if (insn & 0x2000) 213 asi = (regs->tstate >> 24); 214 else 215 asi = (insn >> 5); 216 if ((asi & 0xf2) == 0x82) { 217 if (insn & 0x1000000) { 218 handle_ldf_stq(insn, regs); 219 } else { 220 /* This was a non-faulting load. Just clear the 221 * destination register(s) and continue with the next 222 * instruction. -jj 223 */ 224 handle_ld_nf(insn, regs); 225 } 226 return; 227 } 228 } 229 230 /* Is this in ex_table? */ 231 if (regs->tstate & TSTATE_PRIV) { 232 const struct exception_table_entry *entry; 233 234 entry = search_exception_tables(regs->tpc); 235 if (entry) { 236 regs->tpc = entry->fixup; 237 regs->tnpc = regs->tpc + 4; 238 return; 239 } 240 } else { 241 /* The si_code was set to make clear whether 242 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 243 */ 244 do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code); 245 return; 246 } 247 248 cannot_handle: 249 unhandled_fault (address, current, regs); 250 } 251 252 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs) 253 { 254 static int times; 255 256 if (times++ < 10) 257 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports " 258 "64-bit TPC [%lx]\n", 259 current->comm, current->pid, 260 regs->tpc); 261 show_regs(regs); 262 } 263 264 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 265 { 266 enum ctx_state prev_state = exception_enter(); 267 struct mm_struct *mm = current->mm; 268 struct vm_area_struct *vma; 269 unsigned int insn = 0; 270 int si_code, fault_code; 271 vm_fault_t fault; 272 unsigned long address, mm_rss; 273 unsigned int flags = FAULT_FLAG_DEFAULT; 274 275 fault_code = get_thread_fault_code(); 276 277 if (kprobe_page_fault(regs, 0)) 278 goto exit_exception; 279 280 si_code = SEGV_MAPERR; 281 address = current_thread_info()->fault_address; 282 283 if ((fault_code & FAULT_CODE_ITLB) && 284 (fault_code & FAULT_CODE_DTLB)) 285 BUG(); 286 287 if (test_thread_flag(TIF_32BIT)) { 288 if (!(regs->tstate & TSTATE_PRIV)) { 289 if (unlikely((regs->tpc >> 32) != 0)) { 290 bogus_32bit_fault_tpc(regs); 291 goto intr_or_no_mm; 292 } 293 } 294 if (unlikely((address >> 32) != 0)) 295 goto intr_or_no_mm; 296 } 297 298 if (regs->tstate & TSTATE_PRIV) { 299 unsigned long tpc = regs->tpc; 300 301 /* Sanity check the PC. */ 302 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) || 303 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 304 /* Valid, no problems... */ 305 } else { 306 bad_kernel_pc(regs, address); 307 goto exit_exception; 308 } 309 } else 310 flags |= FAULT_FLAG_USER; 311 312 /* 313 * If we're in an interrupt or have no user 314 * context, we must not take the fault.. 315 */ 316 if (faulthandler_disabled() || !mm) 317 goto intr_or_no_mm; 318 319 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 320 321 if (!mmap_read_trylock(mm)) { 322 if ((regs->tstate & TSTATE_PRIV) && 323 !search_exception_tables(regs->tpc)) { 324 insn = get_fault_insn(regs, insn); 325 goto handle_kernel_fault; 326 } 327 328 retry: 329 mmap_read_lock(mm); 330 } 331 332 if (fault_code & FAULT_CODE_BAD_RA) 333 goto do_sigbus; 334 335 vma = find_vma(mm, address); 336 if (!vma) 337 goto bad_area; 338 339 /* Pure DTLB misses do not tell us whether the fault causing 340 * load/store/atomic was a write or not, it only says that there 341 * was no match. So in such a case we (carefully) read the 342 * instruction to try and figure this out. It's an optimization 343 * so it's ok if we can't do this. 344 * 345 * Special hack, window spill/fill knows the exact fault type. 346 */ 347 if (((fault_code & 348 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 349 (vma->vm_flags & VM_WRITE) != 0) { 350 insn = get_fault_insn(regs, 0); 351 if (!insn) 352 goto continue_fault; 353 /* All loads, stores and atomics have bits 30 and 31 both set 354 * in the instruction. Bit 21 is set in all stores, but we 355 * have to avoid prefetches which also have bit 21 set. 356 */ 357 if ((insn & 0xc0200000) == 0xc0200000 && 358 (insn & 0x01780000) != 0x01680000) { 359 /* Don't bother updating thread struct value, 360 * because update_mmu_cache only cares which tlb 361 * the access came from. 362 */ 363 fault_code |= FAULT_CODE_WRITE; 364 } 365 } 366 continue_fault: 367 368 if (vma->vm_start <= address) 369 goto good_area; 370 if (!(vma->vm_flags & VM_GROWSDOWN)) 371 goto bad_area; 372 if (!(fault_code & FAULT_CODE_WRITE)) { 373 /* Non-faulting loads shouldn't expand stack. */ 374 insn = get_fault_insn(regs, insn); 375 if ((insn & 0xc0800000) == 0xc0800000) { 376 unsigned char asi; 377 378 if (insn & 0x2000) 379 asi = (regs->tstate >> 24); 380 else 381 asi = (insn >> 5); 382 if ((asi & 0xf2) == 0x82) 383 goto bad_area; 384 } 385 } 386 if (expand_stack(vma, address)) 387 goto bad_area; 388 /* 389 * Ok, we have a good vm_area for this memory access, so 390 * we can handle it.. 391 */ 392 good_area: 393 si_code = SEGV_ACCERR; 394 395 /* If we took a ITLB miss on a non-executable page, catch 396 * that here. 397 */ 398 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 399 WARN(address != regs->tpc, 400 "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc); 401 WARN_ON(regs->tstate & TSTATE_PRIV); 402 goto bad_area; 403 } 404 405 if (fault_code & FAULT_CODE_WRITE) { 406 if (!(vma->vm_flags & VM_WRITE)) 407 goto bad_area; 408 409 /* Spitfire has an icache which does not snoop 410 * processor stores. Later processors do... 411 */ 412 if (tlb_type == spitfire && 413 (vma->vm_flags & VM_EXEC) != 0 && 414 vma->vm_file != NULL) 415 set_thread_fault_code(fault_code | 416 FAULT_CODE_BLKCOMMIT); 417 418 flags |= FAULT_FLAG_WRITE; 419 } else { 420 /* Allow reads even for write-only mappings */ 421 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 422 goto bad_area; 423 } 424 425 fault = handle_mm_fault(vma, address, flags); 426 427 if (fault_signal_pending(fault, regs)) 428 goto exit_exception; 429 430 if (unlikely(fault & VM_FAULT_ERROR)) { 431 if (fault & VM_FAULT_OOM) 432 goto out_of_memory; 433 else if (fault & VM_FAULT_SIGSEGV) 434 goto bad_area; 435 else if (fault & VM_FAULT_SIGBUS) 436 goto do_sigbus; 437 BUG(); 438 } 439 440 if (flags & FAULT_FLAG_ALLOW_RETRY) { 441 if (fault & VM_FAULT_MAJOR) { 442 current->maj_flt++; 443 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 444 1, regs, address); 445 } else { 446 current->min_flt++; 447 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 448 1, regs, address); 449 } 450 if (fault & VM_FAULT_RETRY) { 451 flags |= FAULT_FLAG_TRIED; 452 453 /* No need to mmap_read_unlock(mm) as we would 454 * have already released it in __lock_page_or_retry 455 * in mm/filemap.c. 456 */ 457 458 goto retry; 459 } 460 } 461 mmap_read_unlock(mm); 462 463 mm_rss = get_mm_rss(mm); 464 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) 465 mm_rss -= (mm->context.thp_pte_count * (HPAGE_SIZE / PAGE_SIZE)); 466 #endif 467 if (unlikely(mm_rss > 468 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit)) 469 tsb_grow(mm, MM_TSB_BASE, mm_rss); 470 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) 471 mm_rss = mm->context.hugetlb_pte_count + mm->context.thp_pte_count; 472 mm_rss *= REAL_HPAGE_PER_HPAGE; 473 if (unlikely(mm_rss > 474 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) { 475 if (mm->context.tsb_block[MM_TSB_HUGE].tsb) 476 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 477 else 478 hugetlb_setup(regs); 479 480 } 481 #endif 482 exit_exception: 483 exception_exit(prev_state); 484 return; 485 486 /* 487 * Something tried to access memory that isn't in our memory map.. 488 * Fix it, but check if it's kernel or user first.. 489 */ 490 bad_area: 491 insn = get_fault_insn(regs, insn); 492 mmap_read_unlock(mm); 493 494 handle_kernel_fault: 495 do_kernel_fault(regs, si_code, fault_code, insn, address); 496 goto exit_exception; 497 498 /* 499 * We ran out of memory, or some other thing happened to us that made 500 * us unable to handle the page fault gracefully. 501 */ 502 out_of_memory: 503 insn = get_fault_insn(regs, insn); 504 mmap_read_unlock(mm); 505 if (!(regs->tstate & TSTATE_PRIV)) { 506 pagefault_out_of_memory(); 507 goto exit_exception; 508 } 509 goto handle_kernel_fault; 510 511 intr_or_no_mm: 512 insn = get_fault_insn(regs, 0); 513 goto handle_kernel_fault; 514 515 do_sigbus: 516 insn = get_fault_insn(regs, insn); 517 mmap_read_unlock(mm); 518 519 /* 520 * Send a sigbus, regardless of whether we were in kernel 521 * or user mode. 522 */ 523 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code); 524 525 /* Kernel mode? Handle exceptions or die */ 526 if (regs->tstate & TSTATE_PRIV) 527 goto handle_kernel_fault; 528 } 529