1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * PowerPC version 4 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 5 * 6 * Derived from "arch/i386/mm/fault.c" 7 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 8 * 9 * Modified by Cort Dougan and Paul Mackerras. 10 * 11 * Modified for PPC64 by Dave Engebretsen (engebret@ibm.com) 12 */ 13 14 #include <linux/signal.h> 15 #include <linux/sched.h> 16 #include <linux/sched/task_stack.h> 17 #include <linux/kernel.h> 18 #include <linux/errno.h> 19 #include <linux/string.h> 20 #include <linux/types.h> 21 #include <linux/pagemap.h> 22 #include <linux/ptrace.h> 23 #include <linux/mman.h> 24 #include <linux/mm.h> 25 #include <linux/interrupt.h> 26 #include <linux/highmem.h> 27 #include <linux/extable.h> 28 #include <linux/kprobes.h> 29 #include <linux/kdebug.h> 30 #include <linux/perf_event.h> 31 #include <linux/ratelimit.h> 32 #include <linux/context_tracking.h> 33 #include <linux/hugetlb.h> 34 #include <linux/uaccess.h> 35 #include <linux/kfence.h> 36 #include <linux/pkeys.h> 37 38 #include <asm/firmware.h> 39 #include <asm/interrupt.h> 40 #include <asm/page.h> 41 #include <asm/mmu.h> 42 #include <asm/mmu_context.h> 43 #include <asm/siginfo.h> 44 #include <asm/debug.h> 45 #include <asm/kup.h> 46 #include <asm/inst.h> 47 48 49 /* 50 * do_page_fault error handling helpers 51 */ 52 53 static int 54 __bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code) 55 { 56 /* 57 * If we are in kernel mode, bail out with a SEGV, this will 58 * be caught by the assembly which will restore the non-volatile 59 * registers before calling bad_page_fault() 60 */ 61 if (!user_mode(regs)) 62 return SIGSEGV; 63 64 _exception(SIGSEGV, regs, si_code, address); 65 66 return 0; 67 } 68 69 static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address) 70 { 71 return __bad_area_nosemaphore(regs, address, SEGV_MAPERR); 72 } 73 74 static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code, 75 struct mm_struct *mm, struct vm_area_struct *vma) 76 { 77 78 /* 79 * Something tried to access memory that isn't in our memory map.. 80 * Fix it, but check if it's kernel or user first.. 81 */ 82 if (mm) 83 mmap_read_unlock(mm); 84 else 85 vma_end_read(vma); 86 87 return __bad_area_nosemaphore(regs, address, si_code); 88 } 89 90 static noinline int bad_access_pkey(struct pt_regs *regs, unsigned long address, 91 struct mm_struct *mm, 92 struct vm_area_struct *vma) 93 { 94 int pkey; 95 96 /* 97 * We don't try to fetch the pkey from page table because reading 98 * page table without locking doesn't guarantee stable pte value. 99 * Hence the pkey value that we return to userspace can be different 100 * from the pkey that actually caused access error. 101 * 102 * It does *not* guarantee that the VMA we find here 103 * was the one that we faulted on. 104 * 105 * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4); 106 * 2. T1 : set AMR to deny access to pkey=4, touches, page 107 * 3. T1 : faults... 108 * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5); 109 * 5. T1 : enters fault handler, takes mmap_lock, etc... 110 * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really 111 * faulted on a pte with its pkey=4. 112 */ 113 pkey = vma_pkey(vma); 114 115 if (mm) 116 mmap_read_unlock(mm); 117 else 118 vma_end_read(vma); 119 120 /* 121 * If we are in kernel mode, bail out with a SEGV, this will 122 * be caught by the assembly which will restore the non-volatile 123 * registers before calling bad_page_fault() 124 */ 125 if (!user_mode(regs)) 126 return SIGSEGV; 127 128 _exception_pkey(regs, address, pkey); 129 130 return 0; 131 } 132 133 static noinline int bad_access(struct pt_regs *regs, unsigned long address, 134 struct mm_struct *mm, struct vm_area_struct *vma) 135 { 136 return __bad_area(regs, address, SEGV_ACCERR, mm, vma); 137 } 138 139 static int do_sigbus(struct pt_regs *regs, unsigned long address, 140 vm_fault_t fault) 141 { 142 if (!user_mode(regs)) 143 return SIGBUS; 144 145 current->thread.trap_nr = BUS_ADRERR; 146 #ifdef CONFIG_MEMORY_FAILURE 147 if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) { 148 unsigned int lsb = 0; /* shutup gcc */ 149 150 pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n", 151 current->comm, current->pid, address); 152 153 if (fault & VM_FAULT_HWPOISON_LARGE) 154 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); 155 if (fault & VM_FAULT_HWPOISON) 156 lsb = PAGE_SHIFT; 157 158 force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb); 159 return 0; 160 } 161 162 #endif 163 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address); 164 return 0; 165 } 166 167 static int mm_fault_error(struct pt_regs *regs, unsigned long addr, 168 vm_fault_t fault) 169 { 170 /* 171 * Kernel page fault interrupted by SIGKILL. We have no reason to 172 * continue processing. 173 */ 174 if (fatal_signal_pending(current) && !user_mode(regs)) 175 return SIGKILL; 176 177 /* Out of memory */ 178 if (fault & VM_FAULT_OOM) { 179 /* 180 * We ran out of memory, or some other thing happened to us that 181 * made us unable to handle the page fault gracefully. 182 */ 183 if (!user_mode(regs)) 184 return SIGSEGV; 185 pagefault_out_of_memory(); 186 } else { 187 if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| 188 VM_FAULT_HWPOISON_LARGE)) 189 return do_sigbus(regs, addr, fault); 190 else if (fault & VM_FAULT_SIGSEGV) 191 return bad_area_nosemaphore(regs, addr); 192 else 193 BUG(); 194 } 195 return 0; 196 } 197 198 /* Is this a bad kernel fault ? */ 199 static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, 200 unsigned long address, bool is_write) 201 { 202 int is_exec = TRAP(regs) == INTERRUPT_INST_STORAGE; 203 204 if (is_exec) { 205 pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n", 206 address >= TASK_SIZE ? "exec-protected" : "user", 207 address, 208 from_kuid(&init_user_ns, current_uid())); 209 210 // Kernel exec fault is always bad 211 return true; 212 } 213 214 // Kernel fault on kernel address is bad 215 if (address >= TASK_SIZE) 216 return true; 217 218 // Read/write fault blocked by KUAP is bad, it can never succeed. 219 if (bad_kuap_fault(regs, address, is_write)) { 220 pr_crit_ratelimited("Kernel attempted to %s user page (%lx) - exploit attempt? (uid: %d)\n", 221 is_write ? "write" : "read", address, 222 from_kuid(&init_user_ns, current_uid())); 223 224 // Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad 225 if (!search_exception_tables(regs->nip)) 226 return true; 227 228 // Read/write fault in a valid region (the exception table search passed 229 // above), but blocked by KUAP is bad, it can never succeed. 230 return WARN(true, "Bug: %s fault blocked by KUAP!", is_write ? "Write" : "Read"); 231 } 232 233 // What's left? Kernel fault on user and allowed by KUAP in the faulting context. 234 return false; 235 } 236 237 static bool access_pkey_error(bool is_write, bool is_exec, bool is_pkey, 238 struct vm_area_struct *vma) 239 { 240 /* 241 * Make sure to check the VMA so that we do not perform 242 * faults just to hit a pkey fault as soon as we fill in a 243 * page. Only called for current mm, hence foreign == 0 244 */ 245 if (!arch_vma_access_permitted(vma, is_write, is_exec, 0)) 246 return true; 247 248 return false; 249 } 250 251 static bool access_error(bool is_write, bool is_exec, struct vm_area_struct *vma) 252 { 253 /* 254 * Allow execution from readable areas if the MMU does not 255 * provide separate controls over reading and executing. 256 * 257 * Note: That code used to not be enabled for 4xx/BookE. 258 * It is now as I/D cache coherency for these is done at 259 * set_pte_at() time and I see no reason why the test 260 * below wouldn't be valid on those processors. This -may- 261 * break programs compiled with a really old ABI though. 262 */ 263 if (is_exec) { 264 return !(vma->vm_flags & VM_EXEC) && 265 (cpu_has_feature(CPU_FTR_NOEXECUTE) || 266 !(vma->vm_flags & (VM_READ | VM_WRITE))); 267 } 268 269 if (is_write) { 270 if (unlikely(!(vma->vm_flags & VM_WRITE))) 271 return true; 272 return false; 273 } 274 275 /* 276 * VM_READ, VM_WRITE and VM_EXEC may imply read permissions, as 277 * defined in protection_map[]. In that case Read faults can only be 278 * caused by a PROT_NONE mapping. However a non exec access on a 279 * VM_EXEC only mapping is invalid anyway, so report it as such. 280 */ 281 if (unlikely(!vma_is_accessible(vma))) 282 return true; 283 284 if ((vma->vm_flags & VM_ACCESS_FLAGS) == VM_EXEC) 285 return true; 286 287 /* 288 * We should ideally do the vma pkey access check here. But in the 289 * fault path, handle_mm_fault() also does the same check. To avoid 290 * these multiple checks, we skip it here and handle access error due 291 * to pkeys later. 292 */ 293 return false; 294 } 295 296 #ifdef CONFIG_PPC_SMLPAR 297 static inline void cmo_account_page_fault(void) 298 { 299 if (firmware_has_feature(FW_FEATURE_CMO)) { 300 u32 page_ins; 301 302 preempt_disable(); 303 page_ins = be32_to_cpu(get_lppaca()->page_ins); 304 page_ins += 1 << PAGE_FACTOR; 305 get_lppaca()->page_ins = cpu_to_be32(page_ins); 306 preempt_enable(); 307 } 308 } 309 #else 310 static inline void cmo_account_page_fault(void) { } 311 #endif /* CONFIG_PPC_SMLPAR */ 312 313 static void sanity_check_fault(bool is_write, bool is_user, 314 unsigned long error_code, unsigned long address) 315 { 316 /* 317 * Userspace trying to access kernel address, we get PROTFAULT for that. 318 */ 319 if (is_user && address >= TASK_SIZE) { 320 if ((long)address == -1) 321 return; 322 323 pr_crit_ratelimited("%s[%d]: User access of kernel address (%lx) - exploit attempt? (uid: %d)\n", 324 current->comm, current->pid, address, 325 from_kuid(&init_user_ns, current_uid())); 326 return; 327 } 328 329 if (!IS_ENABLED(CONFIG_PPC_BOOK3S)) 330 return; 331 332 /* 333 * For hash translation mode, we should never get a 334 * PROTFAULT. Any update to pte to reduce access will result in us 335 * removing the hash page table entry, thus resulting in a DSISR_NOHPTE 336 * fault instead of DSISR_PROTFAULT. 337 * 338 * A pte update to relax the access will not result in a hash page table 339 * entry invalidate and hence can result in DSISR_PROTFAULT. 340 * ptep_set_access_flags() doesn't do a hpte flush. This is why we have 341 * the special !is_write in the below conditional. 342 * 343 * For platforms that doesn't supports coherent icache and do support 344 * per page noexec bit, we do setup things such that we do the 345 * sync between D/I cache via fault. But that is handled via low level 346 * hash fault code (hash_page_do_lazy_icache()) and we should not reach 347 * here in such case. 348 * 349 * For wrong access that can result in PROTFAULT, the above vma->vm_flags 350 * check should handle those and hence we should fall to the bad_area 351 * handling correctly. 352 * 353 * For embedded with per page exec support that doesn't support coherent 354 * icache we do get PROTFAULT and we handle that D/I cache sync in 355 * set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON 356 * is conditional for server MMU. 357 * 358 * For radix, we can get prot fault for autonuma case, because radix 359 * page table will have them marked noaccess for user. 360 */ 361 if (radix_enabled() || is_write) 362 return; 363 364 WARN_ON_ONCE(error_code & DSISR_PROTFAULT); 365 } 366 367 /* 368 * Define the correct "is_write" bit in error_code based 369 * on the processor family 370 */ 371 #ifdef CONFIG_BOOKE 372 #define page_fault_is_write(__err) ((__err) & ESR_DST) 373 #else 374 #define page_fault_is_write(__err) ((__err) & DSISR_ISSTORE) 375 #endif 376 377 #ifdef CONFIG_BOOKE 378 #define page_fault_is_bad(__err) (0) 379 #elif defined(CONFIG_PPC_8xx) 380 #define page_fault_is_bad(__err) ((__err) & DSISR_NOEXEC_OR_G) 381 #elif defined(CONFIG_PPC64) 382 static int page_fault_is_bad(unsigned long err) 383 { 384 unsigned long flag = DSISR_BAD_FAULT_64S; 385 386 /* 387 * PAPR+ v2.11 § 14.15.3.4.1 (unreleased) 388 * If byte 0, bit 3 of pi-attribute-specifier-type in 389 * ibm,pi-features property is defined, ignore the DSI error 390 * which is caused by the paste instruction on the 391 * suspended NX window. 392 */ 393 if (mmu_has_feature(MMU_FTR_NX_DSI)) 394 flag &= ~DSISR_BAD_COPYPASTE; 395 396 return err & flag; 397 } 398 #else 399 #define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_32S) 400 #endif 401 402 /* 403 * For 600- and 800-family processors, the error_code parameter is DSISR 404 * for a data fault, SRR1 for an instruction fault. 405 * For 400-family processors the error_code parameter is ESR for a data fault, 406 * 0 for an instruction fault. 407 * For 64-bit processors, the error_code parameter is DSISR for a data access 408 * fault, SRR1 & 0x08000000 for an instruction access fault. 409 * 410 * The return value is 0 if the fault was handled, or the signal 411 * number if this is a kernel fault that can't be handled here. 412 */ 413 static int ___do_page_fault(struct pt_regs *regs, unsigned long address, 414 unsigned long error_code) 415 { 416 struct vm_area_struct * vma; 417 struct mm_struct *mm = current->mm; 418 unsigned int flags = FAULT_FLAG_DEFAULT; 419 int is_exec = TRAP(regs) == INTERRUPT_INST_STORAGE; 420 int is_user = user_mode(regs); 421 int is_write = page_fault_is_write(error_code); 422 vm_fault_t fault, major = 0; 423 bool kprobe_fault = kprobe_page_fault(regs, 11); 424 425 if (unlikely(debugger_fault_handler(regs) || kprobe_fault)) 426 return 0; 427 428 if (unlikely(page_fault_is_bad(error_code))) { 429 if (is_user) { 430 _exception(SIGBUS, regs, BUS_OBJERR, address); 431 return 0; 432 } 433 return SIGBUS; 434 } 435 436 /* Additional sanity check(s) */ 437 sanity_check_fault(is_write, is_user, error_code, address); 438 439 /* 440 * The kernel should never take an execute fault nor should it 441 * take a page fault to a kernel address or a page fault to a user 442 * address outside of dedicated places. 443 * 444 * Rather than kfence directly reporting false negatives, search whether 445 * the NIP belongs to the fixup table for cases where fault could come 446 * from functions like copy_from_kernel_nofault(). 447 */ 448 if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write))) { 449 if (is_kfence_address((void *)address) && 450 !search_exception_tables(instruction_pointer(regs)) && 451 kfence_handle_page_fault(address, is_write, regs)) 452 return 0; 453 454 return SIGSEGV; 455 } 456 457 /* 458 * If we're in an interrupt, have no user context or are running 459 * in a region with pagefaults disabled then we must not take the fault 460 */ 461 if (unlikely(faulthandler_disabled() || !mm)) { 462 if (is_user) 463 printk_ratelimited(KERN_ERR "Page fault in user mode" 464 " with faulthandler_disabled()=%d" 465 " mm=%p\n", 466 faulthandler_disabled(), mm); 467 return bad_area_nosemaphore(regs, address); 468 } 469 470 interrupt_cond_local_irq_enable(regs); 471 472 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); 473 474 /* 475 * We want to do this outside mmap_lock, because reading code around nip 476 * can result in fault, which will cause a deadlock when called with 477 * mmap_lock held 478 */ 479 if (is_user) 480 flags |= FAULT_FLAG_USER; 481 if (is_write) 482 flags |= FAULT_FLAG_WRITE; 483 if (is_exec) 484 flags |= FAULT_FLAG_INSTRUCTION; 485 486 if (!(flags & FAULT_FLAG_USER)) 487 goto lock_mmap; 488 489 vma = lock_vma_under_rcu(mm, address); 490 if (!vma) 491 goto lock_mmap; 492 493 if (unlikely(access_pkey_error(is_write, is_exec, 494 (error_code & DSISR_KEYFAULT), vma))) { 495 count_vm_vma_lock_event(VMA_LOCK_SUCCESS); 496 return bad_access_pkey(regs, address, NULL, vma); 497 } 498 499 if (unlikely(access_error(is_write, is_exec, vma))) { 500 count_vm_vma_lock_event(VMA_LOCK_SUCCESS); 501 return bad_access(regs, address, NULL, vma); 502 } 503 504 fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); 505 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) 506 vma_end_read(vma); 507 508 if (!(fault & VM_FAULT_RETRY)) { 509 count_vm_vma_lock_event(VMA_LOCK_SUCCESS); 510 goto done; 511 } 512 count_vm_vma_lock_event(VMA_LOCK_RETRY); 513 if (fault & VM_FAULT_MAJOR) 514 flags |= FAULT_FLAG_TRIED; 515 516 if (fault_signal_pending(fault, regs)) 517 return user_mode(regs) ? 0 : SIGBUS; 518 519 lock_mmap: 520 521 /* When running in the kernel we expect faults to occur only to 522 * addresses in user space. All other faults represent errors in the 523 * kernel and should generate an OOPS. Unfortunately, in the case of an 524 * erroneous fault occurring in a code path which already holds mmap_lock 525 * we will deadlock attempting to validate the fault against the 526 * address space. Luckily the kernel only validly references user 527 * space from well defined areas of code, which are listed in the 528 * exceptions table. lock_mm_and_find_vma() handles that logic. 529 */ 530 retry: 531 vma = lock_mm_and_find_vma(mm, address, regs); 532 if (unlikely(!vma)) 533 return bad_area_nosemaphore(regs, address); 534 535 if (unlikely(access_pkey_error(is_write, is_exec, 536 (error_code & DSISR_KEYFAULT), vma))) 537 return bad_access_pkey(regs, address, mm, vma); 538 539 if (unlikely(access_error(is_write, is_exec, vma))) 540 return bad_access(regs, address, mm, vma); 541 542 /* 543 * If for any reason at all we couldn't handle the fault, 544 * make sure we exit gracefully rather than endlessly redo 545 * the fault. 546 */ 547 fault = handle_mm_fault(vma, address, flags, regs); 548 549 major |= fault & VM_FAULT_MAJOR; 550 551 if (fault_signal_pending(fault, regs)) 552 return user_mode(regs) ? 0 : SIGBUS; 553 554 /* The fault is fully completed (including releasing mmap lock) */ 555 if (fault & VM_FAULT_COMPLETED) 556 goto out; 557 558 /* 559 * Handle the retry right now, the mmap_lock has been released in that 560 * case. 561 */ 562 if (unlikely(fault & VM_FAULT_RETRY)) { 563 flags |= FAULT_FLAG_TRIED; 564 goto retry; 565 } 566 567 mmap_read_unlock(current->mm); 568 569 done: 570 if (unlikely(fault & VM_FAULT_ERROR)) 571 return mm_fault_error(regs, address, fault); 572 573 out: 574 /* 575 * Major/minor page fault accounting. 576 */ 577 if (major) 578 cmo_account_page_fault(); 579 580 return 0; 581 } 582 NOKPROBE_SYMBOL(___do_page_fault); 583 584 static __always_inline void __do_page_fault(struct pt_regs *regs) 585 { 586 long err; 587 588 err = ___do_page_fault(regs, regs->dar, regs->dsisr); 589 if (unlikely(err)) 590 bad_page_fault(regs, err); 591 } 592 593 DEFINE_INTERRUPT_HANDLER(do_page_fault) 594 { 595 __do_page_fault(regs); 596 } 597 598 #ifdef CONFIG_PPC_BOOK3S_64 599 /* Same as do_page_fault but interrupt entry has already run in do_hash_fault */ 600 void hash__do_page_fault(struct pt_regs *regs) 601 { 602 __do_page_fault(regs); 603 } 604 NOKPROBE_SYMBOL(hash__do_page_fault); 605 #endif 606 607 /* 608 * bad_page_fault is called when we have a bad access from the kernel. 609 * It is called from the DSI and ISI handlers in head.S and from some 610 * of the procedures in traps.c. 611 */ 612 static void __bad_page_fault(struct pt_regs *regs, int sig) 613 { 614 int is_write = page_fault_is_write(regs->dsisr); 615 const char *msg; 616 617 /* kernel has accessed a bad area */ 618 619 if (regs->dar < PAGE_SIZE) 620 msg = "Kernel NULL pointer dereference"; 621 else 622 msg = "Unable to handle kernel data access"; 623 624 switch (TRAP(regs)) { 625 case INTERRUPT_DATA_STORAGE: 626 case INTERRUPT_H_DATA_STORAGE: 627 pr_alert("BUG: %s on %s at 0x%08lx\n", msg, 628 is_write ? "write" : "read", regs->dar); 629 break; 630 case INTERRUPT_DATA_SEGMENT: 631 pr_alert("BUG: %s at 0x%08lx\n", msg, regs->dar); 632 break; 633 case INTERRUPT_INST_STORAGE: 634 case INTERRUPT_INST_SEGMENT: 635 pr_alert("BUG: Unable to handle kernel instruction fetch%s", 636 regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n"); 637 break; 638 case INTERRUPT_ALIGNMENT: 639 pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n", 640 regs->dar); 641 break; 642 default: 643 pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n", 644 regs->dar); 645 break; 646 } 647 printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n", 648 regs->nip); 649 650 if (task_stack_end_corrupted(current)) 651 printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); 652 653 die("Kernel access of bad area", regs, sig); 654 } 655 656 void bad_page_fault(struct pt_regs *regs, int sig) 657 { 658 const struct exception_table_entry *entry; 659 660 /* Are we prepared to handle this fault? */ 661 entry = search_exception_tables(instruction_pointer(regs)); 662 if (entry) 663 instruction_pointer_set(regs, extable_fixup(entry)); 664 else 665 __bad_page_fault(regs, sig); 666 } 667 668 #ifdef CONFIG_PPC_BOOK3S_64 669 DEFINE_INTERRUPT_HANDLER(do_bad_page_fault_segv) 670 { 671 bad_page_fault(regs, SIGSEGV); 672 } 673 674 /* 675 * In radix, segment interrupts indicate the EA is not addressable by the 676 * page table geometry, so they are always sent here. 677 * 678 * In hash, this is called if do_slb_fault returns error. Typically it is 679 * because the EA was outside the region allowed by software. 680 */ 681 DEFINE_INTERRUPT_HANDLER(do_bad_segment_interrupt) 682 { 683 int err = regs->result; 684 685 if (err == -EFAULT) { 686 if (user_mode(regs)) 687 _exception(SIGSEGV, regs, SEGV_BNDERR, regs->dar); 688 else 689 bad_page_fault(regs, SIGSEGV); 690 } else if (err == -EINVAL) { 691 unrecoverable_exception(regs); 692 } else { 693 BUG(); 694 } 695 } 696 #endif 697