x86/xen: resume timer irqs early
[linux/fpc-iii.git] / arch / s390 / mm / fault.c
blobfc6679210d83249e9b34c2f44070ab1021852e91
1 /*
2 * S390 version
3 * Copyright IBM Corp. 1999
4 * Author(s): Hartmut Penner (hp@de.ibm.com)
5 * Ulrich Weigand (uweigand@de.ibm.com)
7 * Derived from "arch/i386/mm/fault.c"
8 * Copyright (C) 1995 Linus Torvalds
9 */
11 #include <linux/kernel_stat.h>
12 #include <linux/perf_event.h>
13 #include <linux/signal.h>
14 #include <linux/sched.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/string.h>
18 #include <linux/types.h>
19 #include <linux/ptrace.h>
20 #include <linux/mman.h>
21 #include <linux/mm.h>
22 #include <linux/compat.h>
23 #include <linux/smp.h>
24 #include <linux/kdebug.h>
25 #include <linux/init.h>
26 #include <linux/console.h>
27 #include <linux/module.h>
28 #include <linux/hardirq.h>
29 #include <linux/kprobes.h>
30 #include <linux/uaccess.h>
31 #include <linux/hugetlb.h>
32 #include <asm/asm-offsets.h>
33 #include <asm/pgtable.h>
34 #include <asm/irq.h>
35 #include <asm/mmu_context.h>
36 #include <asm/facility.h>
37 #include "../kernel/entry.h"
39 #ifndef CONFIG_64BIT
40 #define __FAIL_ADDR_MASK 0x7ffff000
41 #define __SUBCODE_MASK 0x0200
42 #define __PF_RES_FIELD 0ULL
43 #else /* CONFIG_64BIT */
44 #define __FAIL_ADDR_MASK -4096L
45 #define __SUBCODE_MASK 0x0600
46 #define __PF_RES_FIELD 0x8000000000000000ULL
47 #endif /* CONFIG_64BIT */
49 #define VM_FAULT_BADCONTEXT 0x010000
50 #define VM_FAULT_BADMAP 0x020000
51 #define VM_FAULT_BADACCESS 0x040000
52 #define VM_FAULT_SIGNAL 0x080000
54 static unsigned long store_indication __read_mostly;
56 #ifdef CONFIG_64BIT
57 static int __init fault_init(void)
59 if (test_facility(75))
60 store_indication = 0xc00;
61 return 0;
63 early_initcall(fault_init);
64 #endif
66 static inline int notify_page_fault(struct pt_regs *regs)
68 int ret = 0;
70 /* kprobe_running() needs smp_processor_id() */
71 if (kprobes_built_in() && !user_mode(regs)) {
72 preempt_disable();
73 if (kprobe_running() && kprobe_fault_handler(regs, 14))
74 ret = 1;
75 preempt_enable();
77 return ret;
82 * Unlock any spinlocks which will prevent us from getting the
83 * message out.
85 void bust_spinlocks(int yes)
87 if (yes) {
88 oops_in_progress = 1;
89 } else {
90 int loglevel_save = console_loglevel;
91 console_unblank();
92 oops_in_progress = 0;
94 * OK, the message is on the console. Now we call printk()
95 * without oops_in_progress set so that printk will give klogd
96 * a poke. Hold onto your hats...
98 console_loglevel = 15;
99 printk(" ");
100 console_loglevel = loglevel_save;
105 * Returns the address space associated with the fault.
106 * Returns 0 for kernel space and 1 for user space.
108 static inline int user_space_fault(unsigned long trans_exc_code)
111 * The lowest two bits of the translation exception
112 * identification indicate which paging table was used.
114 trans_exc_code &= 3;
115 if (trans_exc_code == 2)
116 /* Access via secondary space, set_fs setting decides */
117 return current->thread.mm_segment.ar4;
118 if (s390_user_mode == HOME_SPACE_MODE)
119 /* User space if the access has been done via home space. */
120 return trans_exc_code == 3;
122 * If the user space is not the home space the kernel runs in home
123 * space. Access via secondary space has already been covered,
124 * access via primary space or access register is from user space
125 * and access via home space is from the kernel.
127 return trans_exc_code != 3;
130 static inline void report_user_fault(struct pt_regs *regs, long signr)
132 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
133 return;
134 if (!unhandled_signal(current, signr))
135 return;
136 if (!printk_ratelimit())
137 return;
138 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
139 regs->int_code);
140 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
141 printk(KERN_CONT "\n");
142 printk(KERN_ALERT "failing address: %lX\n",
143 regs->int_parm_long & __FAIL_ADDR_MASK);
144 show_regs(regs);
148 * Send SIGSEGV to task. This is an external routine
149 * to keep the stack usage of do_page_fault small.
151 static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
153 struct siginfo si;
155 report_user_fault(regs, SIGSEGV);
156 si.si_signo = SIGSEGV;
157 si.si_code = si_code;
158 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
159 force_sig_info(SIGSEGV, &si, current);
162 static noinline void do_no_context(struct pt_regs *regs)
164 const struct exception_table_entry *fixup;
165 unsigned long address;
167 /* Are we prepared to handle this kernel fault? */
168 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
169 if (fixup) {
170 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
171 return;
175 * Oops. The kernel tried to access some bad page. We'll have to
176 * terminate things with extreme prejudice.
178 address = regs->int_parm_long & __FAIL_ADDR_MASK;
179 if (!user_space_fault(regs->int_parm_long))
180 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
181 " at virtual kernel address %p\n", (void *)address);
182 else
183 printk(KERN_ALERT "Unable to handle kernel paging request"
184 " at virtual user address %p\n", (void *)address);
186 die(regs, "Oops");
187 do_exit(SIGKILL);
190 static noinline void do_low_address(struct pt_regs *regs)
192 /* Low-address protection hit in kernel mode means
193 NULL pointer write access in kernel mode. */
194 if (regs->psw.mask & PSW_MASK_PSTATE) {
195 /* Low-address protection hit in user mode 'cannot happen'. */
196 die (regs, "Low-address protection");
197 do_exit(SIGKILL);
200 do_no_context(regs);
203 static noinline void do_sigbus(struct pt_regs *regs)
205 struct task_struct *tsk = current;
206 struct siginfo si;
209 * Send a sigbus, regardless of whether we were in kernel
210 * or user mode.
212 si.si_signo = SIGBUS;
213 si.si_errno = 0;
214 si.si_code = BUS_ADRERR;
215 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
216 force_sig_info(SIGBUS, &si, tsk);
219 static noinline void do_fault_error(struct pt_regs *regs, int fault)
221 int si_code;
223 switch (fault) {
224 case VM_FAULT_BADACCESS:
225 case VM_FAULT_BADMAP:
226 /* Bad memory access. Check if it is kernel or user space. */
227 if (user_mode(regs)) {
228 /* User mode accesses just cause a SIGSEGV */
229 si_code = (fault == VM_FAULT_BADMAP) ?
230 SEGV_MAPERR : SEGV_ACCERR;
231 do_sigsegv(regs, si_code);
232 return;
234 case VM_FAULT_BADCONTEXT:
235 do_no_context(regs);
236 break;
237 case VM_FAULT_SIGNAL:
238 if (!user_mode(regs))
239 do_no_context(regs);
240 break;
241 default: /* fault & VM_FAULT_ERROR */
242 if (fault & VM_FAULT_OOM) {
243 if (!user_mode(regs))
244 do_no_context(regs);
245 else
246 pagefault_out_of_memory();
247 } else if (fault & VM_FAULT_SIGBUS) {
248 /* Kernel mode? Handle exceptions or die */
249 if (!user_mode(regs))
250 do_no_context(regs);
251 else
252 do_sigbus(regs);
253 } else
254 BUG();
255 break;
260 * This routine handles page faults. It determines the address,
261 * and the problem, and then passes it off to one of the appropriate
262 * routines.
264 * interruption code (int_code):
265 * 04 Protection -> Write-Protection (suprression)
266 * 10 Segment translation -> Not present (nullification)
267 * 11 Page translation -> Not present (nullification)
268 * 3b Region third trans. -> Not present (nullification)
270 static inline int do_exception(struct pt_regs *regs, int access)
272 struct task_struct *tsk;
273 struct mm_struct *mm;
274 struct vm_area_struct *vma;
275 unsigned long trans_exc_code;
276 unsigned long address;
277 unsigned int flags;
278 int fault;
280 tsk = current;
282 * The instruction that caused the program check has
283 * been nullified. Don't signal single step via SIGTRAP.
285 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
287 if (notify_page_fault(regs))
288 return 0;
290 mm = tsk->mm;
291 trans_exc_code = regs->int_parm_long;
294 * Verify that the fault happened in user space, that
295 * we are not in an interrupt and that there is a
296 * user context.
298 fault = VM_FAULT_BADCONTEXT;
299 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
300 goto out;
302 address = trans_exc_code & __FAIL_ADDR_MASK;
303 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
304 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
305 if (user_mode(regs))
306 flags |= FAULT_FLAG_USER;
307 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
308 flags |= FAULT_FLAG_WRITE;
309 down_read(&mm->mmap_sem);
311 #ifdef CONFIG_PGSTE
312 if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
313 address = __gmap_fault(address,
314 (struct gmap *) S390_lowcore.gmap);
315 if (address == -EFAULT) {
316 fault = VM_FAULT_BADMAP;
317 goto out_up;
319 if (address == -ENOMEM) {
320 fault = VM_FAULT_OOM;
321 goto out_up;
324 #endif
326 retry:
327 fault = VM_FAULT_BADMAP;
328 vma = find_vma(mm, address);
329 if (!vma)
330 goto out_up;
332 if (unlikely(vma->vm_start > address)) {
333 if (!(vma->vm_flags & VM_GROWSDOWN))
334 goto out_up;
335 if (expand_stack(vma, address))
336 goto out_up;
340 * Ok, we have a good vm_area for this memory access, so
341 * we can handle it..
343 fault = VM_FAULT_BADACCESS;
344 if (unlikely(!(vma->vm_flags & access)))
345 goto out_up;
347 if (is_vm_hugetlb_page(vma))
348 address &= HPAGE_MASK;
350 * If for any reason at all we couldn't handle the fault,
351 * make sure we exit gracefully rather than endlessly redo
352 * the fault.
354 fault = handle_mm_fault(mm, vma, address, flags);
355 /* No reason to continue if interrupted by SIGKILL. */
356 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
357 fault = VM_FAULT_SIGNAL;
358 goto out;
360 if (unlikely(fault & VM_FAULT_ERROR))
361 goto out_up;
364 * Major/minor page fault accounting is only done on the
365 * initial attempt. If we go through a retry, it is extremely
366 * likely that the page will be found in page cache at that point.
368 if (flags & FAULT_FLAG_ALLOW_RETRY) {
369 if (fault & VM_FAULT_MAJOR) {
370 tsk->maj_flt++;
371 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
372 regs, address);
373 } else {
374 tsk->min_flt++;
375 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
376 regs, address);
378 if (fault & VM_FAULT_RETRY) {
379 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
380 * of starvation. */
381 flags &= ~FAULT_FLAG_ALLOW_RETRY;
382 flags |= FAULT_FLAG_TRIED;
383 down_read(&mm->mmap_sem);
384 goto retry;
387 fault = 0;
388 out_up:
389 up_read(&mm->mmap_sem);
390 out:
391 return fault;
394 void __kprobes do_protection_exception(struct pt_regs *regs)
396 unsigned long trans_exc_code;
397 int fault;
399 trans_exc_code = regs->int_parm_long;
401 * Protection exceptions are suppressing, decrement psw address.
402 * The exception to this rule are aborted transactions, for these
403 * the PSW already points to the correct location.
405 if (!(regs->int_code & 0x200))
406 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
408 * Check for low-address protection. This needs to be treated
409 * as a special case because the translation exception code
410 * field is not guaranteed to contain valid data in this case.
412 if (unlikely(!(trans_exc_code & 4))) {
413 do_low_address(regs);
414 return;
416 fault = do_exception(regs, VM_WRITE);
417 if (unlikely(fault))
418 do_fault_error(regs, fault);
421 void __kprobes do_dat_exception(struct pt_regs *regs)
423 int access, fault;
425 access = VM_READ | VM_EXEC | VM_WRITE;
426 fault = do_exception(regs, access);
427 if (unlikely(fault))
428 do_fault_error(regs, fault);
431 #ifdef CONFIG_64BIT
432 void __kprobes do_asce_exception(struct pt_regs *regs)
434 struct mm_struct *mm = current->mm;
435 struct vm_area_struct *vma;
436 unsigned long trans_exc_code;
439 * The instruction that caused the program check has
440 * been nullified. Don't signal single step via SIGTRAP.
442 clear_tsk_thread_flag(current, TIF_PER_TRAP);
444 trans_exc_code = regs->int_parm_long;
445 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
446 goto no_context;
448 down_read(&mm->mmap_sem);
449 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
450 up_read(&mm->mmap_sem);
452 if (vma) {
453 update_mm(mm, current);
454 return;
457 /* User mode accesses just cause a SIGSEGV */
458 if (user_mode(regs)) {
459 do_sigsegv(regs, SEGV_MAPERR);
460 return;
463 no_context:
464 do_no_context(regs);
466 #endif
468 int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
470 struct pt_regs regs;
471 int access, fault;
473 /* Emulate a uaccess fault from kernel mode. */
474 regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
475 if (!irqs_disabled())
476 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
477 regs.psw.addr = (unsigned long) __builtin_return_address(0);
478 regs.psw.addr |= PSW_ADDR_AMODE;
479 regs.int_code = pgm_int_code;
480 regs.int_parm_long = (uaddr & PAGE_MASK) | 2;
481 access = write ? VM_WRITE : VM_READ;
482 fault = do_exception(&regs, access);
484 * Since the fault happened in kernel mode while performing a uaccess
485 * all we need to do now is emulating a fixup in case "fault" is not
486 * zero.
487 * For the calling uaccess functions this results always in -EFAULT.
489 return fault ? -EFAULT : 0;
492 #ifdef CONFIG_PFAULT
494 * 'pfault' pseudo page faults routines.
496 static int pfault_disable;
498 static int __init nopfault(char *str)
500 pfault_disable = 1;
501 return 1;
504 __setup("nopfault", nopfault);
506 struct pfault_refbk {
507 u16 refdiagc;
508 u16 reffcode;
509 u16 refdwlen;
510 u16 refversn;
511 u64 refgaddr;
512 u64 refselmk;
513 u64 refcmpmk;
514 u64 reserved;
515 } __attribute__ ((packed, aligned(8)));
517 int pfault_init(void)
519 struct pfault_refbk refbk = {
520 .refdiagc = 0x258,
521 .reffcode = 0,
522 .refdwlen = 5,
523 .refversn = 2,
524 .refgaddr = __LC_CURRENT_PID,
525 .refselmk = 1ULL << 48,
526 .refcmpmk = 1ULL << 48,
527 .reserved = __PF_RES_FIELD };
528 int rc;
530 if (pfault_disable)
531 return -1;
532 asm volatile(
533 " diag %1,%0,0x258\n"
534 "0: j 2f\n"
535 "1: la %0,8\n"
536 "2:\n"
537 EX_TABLE(0b,1b)
538 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
539 return rc;
542 void pfault_fini(void)
544 struct pfault_refbk refbk = {
545 .refdiagc = 0x258,
546 .reffcode = 1,
547 .refdwlen = 5,
548 .refversn = 2,
551 if (pfault_disable)
552 return;
553 asm volatile(
554 " diag %0,0,0x258\n"
555 "0:\n"
556 EX_TABLE(0b,0b)
557 : : "a" (&refbk), "m" (refbk) : "cc");
560 static DEFINE_SPINLOCK(pfault_lock);
561 static LIST_HEAD(pfault_list);
563 static void pfault_interrupt(struct ext_code ext_code,
564 unsigned int param32, unsigned long param64)
566 struct task_struct *tsk;
567 __u16 subcode;
568 pid_t pid;
571 * Get the external interruption subcode & pfault
572 * initial/completion signal bit. VM stores this
573 * in the 'cpu address' field associated with the
574 * external interrupt.
576 subcode = ext_code.subcode;
577 if ((subcode & 0xff00) != __SUBCODE_MASK)
578 return;
579 inc_irq_stat(IRQEXT_PFL);
580 /* Get the token (= pid of the affected task). */
581 pid = sizeof(void *) == 4 ? param32 : param64;
582 rcu_read_lock();
583 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
584 if (tsk)
585 get_task_struct(tsk);
586 rcu_read_unlock();
587 if (!tsk)
588 return;
589 spin_lock(&pfault_lock);
590 if (subcode & 0x0080) {
591 /* signal bit is set -> a page has been swapped in by VM */
592 if (tsk->thread.pfault_wait == 1) {
593 /* Initial interrupt was faster than the completion
594 * interrupt. pfault_wait is valid. Set pfault_wait
595 * back to zero and wake up the process. This can
596 * safely be done because the task is still sleeping
597 * and can't produce new pfaults. */
598 tsk->thread.pfault_wait = 0;
599 list_del(&tsk->thread.list);
600 wake_up_process(tsk);
601 put_task_struct(tsk);
602 } else {
603 /* Completion interrupt was faster than initial
604 * interrupt. Set pfault_wait to -1 so the initial
605 * interrupt doesn't put the task to sleep.
606 * If the task is not running, ignore the completion
607 * interrupt since it must be a leftover of a PFAULT
608 * CANCEL operation which didn't remove all pending
609 * completion interrupts. */
610 if (tsk->state == TASK_RUNNING)
611 tsk->thread.pfault_wait = -1;
613 } else {
614 /* signal bit not set -> a real page is missing. */
615 if (WARN_ON_ONCE(tsk != current))
616 goto out;
617 if (tsk->thread.pfault_wait == 1) {
618 /* Already on the list with a reference: put to sleep */
619 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
620 set_tsk_need_resched(tsk);
621 } else if (tsk->thread.pfault_wait == -1) {
622 /* Completion interrupt was faster than the initial
623 * interrupt (pfault_wait == -1). Set pfault_wait
624 * back to zero and exit. */
625 tsk->thread.pfault_wait = 0;
626 } else {
627 /* Initial interrupt arrived before completion
628 * interrupt. Let the task sleep.
629 * An extra task reference is needed since a different
630 * cpu may set the task state to TASK_RUNNING again
631 * before the scheduler is reached. */
632 get_task_struct(tsk);
633 tsk->thread.pfault_wait = 1;
634 list_add(&tsk->thread.list, &pfault_list);
635 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
636 set_tsk_need_resched(tsk);
639 out:
640 spin_unlock(&pfault_lock);
641 put_task_struct(tsk);
644 static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
645 void *hcpu)
647 struct thread_struct *thread, *next;
648 struct task_struct *tsk;
650 switch (action & ~CPU_TASKS_FROZEN) {
651 case CPU_DEAD:
652 spin_lock_irq(&pfault_lock);
653 list_for_each_entry_safe(thread, next, &pfault_list, list) {
654 thread->pfault_wait = 0;
655 list_del(&thread->list);
656 tsk = container_of(thread, struct task_struct, thread);
657 wake_up_process(tsk);
658 put_task_struct(tsk);
660 spin_unlock_irq(&pfault_lock);
661 break;
662 default:
663 break;
665 return NOTIFY_OK;
668 static int __init pfault_irq_init(void)
670 int rc;
672 rc = register_external_interrupt(0x2603, pfault_interrupt);
673 if (rc)
674 goto out_extint;
675 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
676 if (rc)
677 goto out_pfault;
678 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
679 hotcpu_notifier(pfault_cpu_notify, 0);
680 return 0;
682 out_pfault:
683 unregister_external_interrupt(0x2603, pfault_interrupt);
684 out_extint:
685 pfault_disable = 1;
686 return rc;
688 early_initcall(pfault_irq_init);
690 #endif /* CONFIG_PFAULT */