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1/*
2 * arch/s390/mm/fault.c
3 *
4 * S390 version
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Hartmut Penner (hp@de.ibm.com)
7 * Ulrich Weigand (uweigand@de.ibm.com)
8 *
9 * Derived from "arch/i386/mm/fault.c"
10 * Copyright (C) 1995 Linus Torvalds
11 */
12
13#include <linux/kernel_stat.h>
14#include <linux/perf_event.h>
15#include <linux/signal.h>
16#include <linux/sched.h>
17#include <linux/kernel.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/types.h>
21#include <linux/ptrace.h>
22#include <linux/mman.h>
23#include <linux/mm.h>
24#include <linux/compat.h>
25#include <linux/smp.h>
26#include <linux/kdebug.h>
27#include <linux/init.h>
28#include <linux/console.h>
29#include <linux/module.h>
30#include <linux/hardirq.h>
31#include <linux/kprobes.h>
32#include <linux/uaccess.h>
33#include <linux/hugetlb.h>
34#include <asm/asm-offsets.h>
35#include <asm/system.h>
36#include <asm/pgtable.h>
37#include <asm/irq.h>
38#include <asm/mmu_context.h>
39#include <asm/compat.h>
40#include "../kernel/entry.h"
41
42#ifndef CONFIG_64BIT
43#define __FAIL_ADDR_MASK 0x7ffff000
44#define __SUBCODE_MASK 0x0200
45#define __PF_RES_FIELD 0ULL
46#else /* CONFIG_64BIT */
47#define __FAIL_ADDR_MASK -4096L
48#define __SUBCODE_MASK 0x0600
49#define __PF_RES_FIELD 0x8000000000000000ULL
50#endif /* CONFIG_64BIT */
51
52#define VM_FAULT_BADCONTEXT 0x010000
53#define VM_FAULT_BADMAP 0x020000
54#define VM_FAULT_BADACCESS 0x040000
55
56static unsigned long store_indication;
57
58void fault_init(void)
59{
60 if (test_facility(2) && test_facility(75))
61 store_indication = 0xc00;
62}
63
64static inline int notify_page_fault(struct pt_regs *regs)
65{
66 int ret = 0;
67
68 /* kprobe_running() needs smp_processor_id() */
69 if (kprobes_built_in() && !user_mode(regs)) {
70 preempt_disable();
71 if (kprobe_running() && kprobe_fault_handler(regs, 14))
72 ret = 1;
73 preempt_enable();
74 }
75 return ret;
76}
77
78
79/*
80 * Unlock any spinlocks which will prevent us from getting the
81 * message out.
82 */
83void bust_spinlocks(int yes)
84{
85 if (yes) {
86 oops_in_progress = 1;
87 } else {
88 int loglevel_save = console_loglevel;
89 console_unblank();
90 oops_in_progress = 0;
91 /*
92 * OK, the message is on the console. Now we call printk()
93 * without oops_in_progress set so that printk will give klogd
94 * a poke. Hold onto your hats...
95 */
96 console_loglevel = 15;
97 printk(" ");
98 console_loglevel = loglevel_save;
99 }
100}
101
102/*
103 * Returns the address space associated with the fault.
104 * Returns 0 for kernel space and 1 for user space.
105 */
106static inline int user_space_fault(unsigned long trans_exc_code)
107{
108 /*
109 * The lowest two bits of the translation exception
110 * identification indicate which paging table was used.
111 */
112 trans_exc_code &= 3;
113 if (trans_exc_code == 2)
114 /* Access via secondary space, set_fs setting decides */
115 return current->thread.mm_segment.ar4;
116 if (user_mode == HOME_SPACE_MODE)
117 /* User space if the access has been done via home space. */
118 return trans_exc_code == 3;
119 /*
120 * If the user space is not the home space the kernel runs in home
121 * space. Access via secondary space has already been covered,
122 * access via primary space or access register is from user space
123 * and access via home space is from the kernel.
124 */
125 return trans_exc_code != 3;
126}
127
128static inline void report_user_fault(struct pt_regs *regs, long int_code,
129 int signr, unsigned long address)
130{
131 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
132 return;
133 if (!unhandled_signal(current, signr))
134 return;
135 if (!printk_ratelimit())
136 return;
137 printk("User process fault: interruption code 0x%lX ", int_code);
138 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
139 printk("\n");
140 printk("failing address: %lX\n", address);
141 show_regs(regs);
142}
143
144/*
145 * Send SIGSEGV to task. This is an external routine
146 * to keep the stack usage of do_page_fault small.
147 */
148static noinline void do_sigsegv(struct pt_regs *regs, long int_code,
149 int si_code, unsigned long trans_exc_code)
150{
151 struct siginfo si;
152 unsigned long address;
153
154 address = trans_exc_code & __FAIL_ADDR_MASK;
155 current->thread.prot_addr = address;
156 current->thread.trap_no = int_code;
157 report_user_fault(regs, int_code, SIGSEGV, address);
158 si.si_signo = SIGSEGV;
159 si.si_code = si_code;
160 si.si_addr = (void __user *) address;
161 force_sig_info(SIGSEGV, &si, current);
162}
163
164static noinline void do_no_context(struct pt_regs *regs, long int_code,
165 unsigned long trans_exc_code)
166{
167 const struct exception_table_entry *fixup;
168 unsigned long address;
169
170 /* Are we prepared to handle this kernel fault? */
171 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
172 if (fixup) {
173 regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
174 return;
175 }
176
177 /*
178 * Oops. The kernel tried to access some bad page. We'll have to
179 * terminate things with extreme prejudice.
180 */
181 address = trans_exc_code & __FAIL_ADDR_MASK;
182 if (!user_space_fault(trans_exc_code))
183 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
184 " at virtual kernel address %p\n", (void *)address);
185 else
186 printk(KERN_ALERT "Unable to handle kernel paging request"
187 " at virtual user address %p\n", (void *)address);
188
189 die("Oops", regs, int_code);
190 do_exit(SIGKILL);
191}
192
193static noinline void do_low_address(struct pt_regs *regs, long int_code,
194 unsigned long trans_exc_code)
195{
196 /* Low-address protection hit in kernel mode means
197 NULL pointer write access in kernel mode. */
198 if (regs->psw.mask & PSW_MASK_PSTATE) {
199 /* Low-address protection hit in user mode 'cannot happen'. */
200 die ("Low-address protection", regs, int_code);
201 do_exit(SIGKILL);
202 }
203
204 do_no_context(regs, int_code, trans_exc_code);
205}
206
207static noinline void do_sigbus(struct pt_regs *regs, long int_code,
208 unsigned long trans_exc_code)
209{
210 struct task_struct *tsk = current;
211 unsigned long address;
212 struct siginfo si;
213
214 /*
215 * Send a sigbus, regardless of whether we were in kernel
216 * or user mode.
217 */
218 address = trans_exc_code & __FAIL_ADDR_MASK;
219 tsk->thread.prot_addr = address;
220 tsk->thread.trap_no = int_code;
221 si.si_signo = SIGBUS;
222 si.si_errno = 0;
223 si.si_code = BUS_ADRERR;
224 si.si_addr = (void __user *) address;
225 force_sig_info(SIGBUS, &si, tsk);
226}
227
228static noinline void do_fault_error(struct pt_regs *regs, long int_code,
229 unsigned long trans_exc_code, int fault)
230{
231 int si_code;
232
233 switch (fault) {
234 case VM_FAULT_BADACCESS:
235 case VM_FAULT_BADMAP:
236 /* Bad memory access. Check if it is kernel or user space. */
237 if (regs->psw.mask & PSW_MASK_PSTATE) {
238 /* User mode accesses just cause a SIGSEGV */
239 si_code = (fault == VM_FAULT_BADMAP) ?
240 SEGV_MAPERR : SEGV_ACCERR;
241 do_sigsegv(regs, int_code, si_code, trans_exc_code);
242 return;
243 }
244 case VM_FAULT_BADCONTEXT:
245 do_no_context(regs, int_code, trans_exc_code);
246 break;
247 default: /* fault & VM_FAULT_ERROR */
248 if (fault & VM_FAULT_OOM) {
249 if (!(regs->psw.mask & PSW_MASK_PSTATE))
250 do_no_context(regs, int_code, trans_exc_code);
251 else
252 pagefault_out_of_memory();
253 } else if (fault & VM_FAULT_SIGBUS) {
254 /* Kernel mode? Handle exceptions or die */
255 if (!(regs->psw.mask & PSW_MASK_PSTATE))
256 do_no_context(regs, int_code, trans_exc_code);
257 else
258 do_sigbus(regs, int_code, trans_exc_code);
259 } else
260 BUG();
261 break;
262 }
263}
264
265/*
266 * This routine handles page faults. It determines the address,
267 * and the problem, and then passes it off to one of the appropriate
268 * routines.
269 *
270 * interruption code (int_code):
271 * 04 Protection -> Write-Protection (suprression)
272 * 10 Segment translation -> Not present (nullification)
273 * 11 Page translation -> Not present (nullification)
274 * 3b Region third trans. -> Not present (nullification)
275 */
276static inline int do_exception(struct pt_regs *regs, int access,
277 unsigned long trans_exc_code)
278{
279 struct task_struct *tsk;
280 struct mm_struct *mm;
281 struct vm_area_struct *vma;
282 unsigned long address;
283 unsigned int flags;
284 int fault;
285
286 if (notify_page_fault(regs))
287 return 0;
288
289 tsk = current;
290 mm = tsk->mm;
291
292 /*
293 * Verify that the fault happened in user space, that
294 * we are not in an interrupt and that there is a
295 * user context.
296 */
297 fault = VM_FAULT_BADCONTEXT;
298 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
299 goto out;
300
301 address = trans_exc_code & __FAIL_ADDR_MASK;
302 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
303 flags = FAULT_FLAG_ALLOW_RETRY;
304 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
305 flags |= FAULT_FLAG_WRITE;
306 down_read(&mm->mmap_sem);
307
308#ifdef CONFIG_PGSTE
309 if (test_tsk_thread_flag(current, TIF_SIE) && S390_lowcore.gmap) {
310 address = gmap_fault(address,
311 (struct gmap *) S390_lowcore.gmap);
312 if (address == -EFAULT) {
313 fault = VM_FAULT_BADMAP;
314 goto out_up;
315 }
316 if (address == -ENOMEM) {
317 fault = VM_FAULT_OOM;
318 goto out_up;
319 }
320 }
321#endif
322
323retry:
324 fault = VM_FAULT_BADMAP;
325 vma = find_vma(mm, address);
326 if (!vma)
327 goto out_up;
328
329 if (unlikely(vma->vm_start > address)) {
330 if (!(vma->vm_flags & VM_GROWSDOWN))
331 goto out_up;
332 if (expand_stack(vma, address))
333 goto out_up;
334 }
335
336 /*
337 * Ok, we have a good vm_area for this memory access, so
338 * we can handle it..
339 */
340 fault = VM_FAULT_BADACCESS;
341 if (unlikely(!(vma->vm_flags & access)))
342 goto out_up;
343
344 if (is_vm_hugetlb_page(vma))
345 address &= HPAGE_MASK;
346 /*
347 * If for any reason at all we couldn't handle the fault,
348 * make sure we exit gracefully rather than endlessly redo
349 * the fault.
350 */
351 fault = handle_mm_fault(mm, vma, address, flags);
352 if (unlikely(fault & VM_FAULT_ERROR))
353 goto out_up;
354
355 /*
356 * Major/minor page fault accounting is only done on the
357 * initial attempt. If we go through a retry, it is extremely
358 * likely that the page will be found in page cache at that point.
359 */
360 if (flags & FAULT_FLAG_ALLOW_RETRY) {
361 if (fault & VM_FAULT_MAJOR) {
362 tsk->maj_flt++;
363 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
364 regs, address);
365 } else {
366 tsk->min_flt++;
367 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
368 regs, address);
369 }
370 if (fault & VM_FAULT_RETRY) {
371 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
372 * of starvation. */
373 flags &= ~FAULT_FLAG_ALLOW_RETRY;
374 down_read(&mm->mmap_sem);
375 goto retry;
376 }
377 }
378 /*
379 * The instruction that caused the program check will
380 * be repeated. Don't signal single step via SIGTRAP.
381 */
382 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
383 fault = 0;
384out_up:
385 up_read(&mm->mmap_sem);
386out:
387 return fault;
388}
389
390void __kprobes do_protection_exception(struct pt_regs *regs, long pgm_int_code,
391 unsigned long trans_exc_code)
392{
393 int fault;
394
395 /* Protection exception is suppressing, decrement psw address. */
396 regs->psw.addr -= (pgm_int_code >> 16);
397 /*
398 * Check for low-address protection. This needs to be treated
399 * as a special case because the translation exception code
400 * field is not guaranteed to contain valid data in this case.
401 */
402 if (unlikely(!(trans_exc_code & 4))) {
403 do_low_address(regs, pgm_int_code, trans_exc_code);
404 return;
405 }
406 fault = do_exception(regs, VM_WRITE, trans_exc_code);
407 if (unlikely(fault))
408 do_fault_error(regs, 4, trans_exc_code, fault);
409}
410
411void __kprobes do_dat_exception(struct pt_regs *regs, long pgm_int_code,
412 unsigned long trans_exc_code)
413{
414 int access, fault;
415
416 access = VM_READ | VM_EXEC | VM_WRITE;
417 fault = do_exception(regs, access, trans_exc_code);
418 if (unlikely(fault))
419 do_fault_error(regs, pgm_int_code & 255, trans_exc_code, fault);
420}
421
422#ifdef CONFIG_64BIT
423void __kprobes do_asce_exception(struct pt_regs *regs, long pgm_int_code,
424 unsigned long trans_exc_code)
425{
426 struct mm_struct *mm = current->mm;
427 struct vm_area_struct *vma;
428
429 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
430 goto no_context;
431
432 down_read(&mm->mmap_sem);
433 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
434 up_read(&mm->mmap_sem);
435
436 if (vma) {
437 update_mm(mm, current);
438 return;
439 }
440
441 /* User mode accesses just cause a SIGSEGV */
442 if (regs->psw.mask & PSW_MASK_PSTATE) {
443 do_sigsegv(regs, pgm_int_code, SEGV_MAPERR, trans_exc_code);
444 return;
445 }
446
447no_context:
448 do_no_context(regs, pgm_int_code, trans_exc_code);
449}
450#endif
451
452int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
453{
454 struct pt_regs regs;
455 int access, fault;
456
457 regs.psw.mask = psw_kernel_bits;
458 if (!irqs_disabled())
459 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
460 regs.psw.addr = (unsigned long) __builtin_return_address(0);
461 regs.psw.addr |= PSW_ADDR_AMODE;
462 uaddr &= PAGE_MASK;
463 access = write ? VM_WRITE : VM_READ;
464 fault = do_exception(®s, access, uaddr | 2);
465 if (unlikely(fault)) {
466 if (fault & VM_FAULT_OOM)
467 return -EFAULT;
468 else if (fault & VM_FAULT_SIGBUS)
469 do_sigbus(®s, pgm_int_code, uaddr);
470 }
471 return fault ? -EFAULT : 0;
472}
473
474#ifdef CONFIG_PFAULT
475/*
476 * 'pfault' pseudo page faults routines.
477 */
478static int pfault_disable;
479
480static int __init nopfault(char *str)
481{
482 pfault_disable = 1;
483 return 1;
484}
485
486__setup("nopfault", nopfault);
487
488struct pfault_refbk {
489 u16 refdiagc;
490 u16 reffcode;
491 u16 refdwlen;
492 u16 refversn;
493 u64 refgaddr;
494 u64 refselmk;
495 u64 refcmpmk;
496 u64 reserved;
497} __attribute__ ((packed, aligned(8)));
498
499int pfault_init(void)
500{
501 struct pfault_refbk refbk = {
502 .refdiagc = 0x258,
503 .reffcode = 0,
504 .refdwlen = 5,
505 .refversn = 2,
506 .refgaddr = __LC_CURRENT_PID,
507 .refselmk = 1ULL << 48,
508 .refcmpmk = 1ULL << 48,
509 .reserved = __PF_RES_FIELD };
510 int rc;
511
512 if (!MACHINE_IS_VM || pfault_disable)
513 return -1;
514 asm volatile(
515 " diag %1,%0,0x258\n"
516 "0: j 2f\n"
517 "1: la %0,8\n"
518 "2:\n"
519 EX_TABLE(0b,1b)
520 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
521 return rc;
522}
523
524void pfault_fini(void)
525{
526 struct pfault_refbk refbk = {
527 .refdiagc = 0x258,
528 .reffcode = 1,
529 .refdwlen = 5,
530 .refversn = 2,
531 };
532
533 if (!MACHINE_IS_VM || pfault_disable)
534 return;
535 asm volatile(
536 " diag %0,0,0x258\n"
537 "0:\n"
538 EX_TABLE(0b,0b)
539 : : "a" (&refbk), "m" (refbk) : "cc");
540}
541
542static DEFINE_SPINLOCK(pfault_lock);
543static LIST_HEAD(pfault_list);
544
545static void pfault_interrupt(unsigned int ext_int_code,
546 unsigned int param32, unsigned long param64)
547{
548 struct task_struct *tsk;
549 __u16 subcode;
550 pid_t pid;
551
552 /*
553 * Get the external interruption subcode & pfault
554 * initial/completion signal bit. VM stores this
555 * in the 'cpu address' field associated with the
556 * external interrupt.
557 */
558 subcode = ext_int_code >> 16;
559 if ((subcode & 0xff00) != __SUBCODE_MASK)
560 return;
561 kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
562 if (subcode & 0x0080) {
563 /* Get the token (= pid of the affected task). */
564 pid = sizeof(void *) == 4 ? param32 : param64;
565 rcu_read_lock();
566 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
567 if (tsk)
568 get_task_struct(tsk);
569 rcu_read_unlock();
570 if (!tsk)
571 return;
572 } else {
573 tsk = current;
574 }
575 spin_lock(&pfault_lock);
576 if (subcode & 0x0080) {
577 /* signal bit is set -> a page has been swapped in by VM */
578 if (tsk->thread.pfault_wait == 1) {
579 /* Initial interrupt was faster than the completion
580 * interrupt. pfault_wait is valid. Set pfault_wait
581 * back to zero and wake up the process. This can
582 * safely be done because the task is still sleeping
583 * and can't produce new pfaults. */
584 tsk->thread.pfault_wait = 0;
585 list_del(&tsk->thread.list);
586 wake_up_process(tsk);
587 } else {
588 /* Completion interrupt was faster than initial
589 * interrupt. Set pfault_wait to -1 so the initial
590 * interrupt doesn't put the task to sleep. */
591 tsk->thread.pfault_wait = -1;
592 }
593 put_task_struct(tsk);
594 } else {
595 /* signal bit not set -> a real page is missing. */
596 if (tsk->thread.pfault_wait == -1) {
597 /* Completion interrupt was faster than the initial
598 * interrupt (pfault_wait == -1). Set pfault_wait
599 * back to zero and exit. */
600 tsk->thread.pfault_wait = 0;
601 } else {
602 /* Initial interrupt arrived before completion
603 * interrupt. Let the task sleep. */
604 tsk->thread.pfault_wait = 1;
605 list_add(&tsk->thread.list, &pfault_list);
606 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
607 set_tsk_need_resched(tsk);
608 }
609 }
610 spin_unlock(&pfault_lock);
611}
612
613static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
614 unsigned long action, void *hcpu)
615{
616 struct thread_struct *thread, *next;
617 struct task_struct *tsk;
618
619 switch (action) {
620 case CPU_DEAD:
621 case CPU_DEAD_FROZEN:
622 spin_lock_irq(&pfault_lock);
623 list_for_each_entry_safe(thread, next, &pfault_list, list) {
624 thread->pfault_wait = 0;
625 list_del(&thread->list);
626 tsk = container_of(thread, struct task_struct, thread);
627 wake_up_process(tsk);
628 }
629 spin_unlock_irq(&pfault_lock);
630 break;
631 default:
632 break;
633 }
634 return NOTIFY_OK;
635}
636
637static int __init pfault_irq_init(void)
638{
639 int rc;
640
641 if (!MACHINE_IS_VM)
642 return 0;
643 rc = register_external_interrupt(0x2603, pfault_interrupt);
644 if (rc)
645 goto out_extint;
646 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
647 if (rc)
648 goto out_pfault;
649 service_subclass_irq_register();
650 hotcpu_notifier(pfault_cpu_notify, 0);
651 return 0;
652
653out_pfault:
654 unregister_external_interrupt(0x2603, pfault_interrupt);
655out_extint:
656 pfault_disable = 1;
657 return rc;
658}
659early_initcall(pfault_irq_init);
660
661#endif /* CONFIG_PFAULT */
1/*
2 * arch/s390/mm/fault.c
3 *
4 * S390 version
5 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
6 * Author(s): Hartmut Penner (hp@de.ibm.com)
7 * Ulrich Weigand (uweigand@de.ibm.com)
8 *
9 * Derived from "arch/i386/mm/fault.c"
10 * Copyright (C) 1995 Linus Torvalds
11 */
12
13#include <linux/kernel_stat.h>
14#include <linux/perf_event.h>
15#include <linux/signal.h>
16#include <linux/sched.h>
17#include <linux/kernel.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/types.h>
21#include <linux/ptrace.h>
22#include <linux/mman.h>
23#include <linux/mm.h>
24#include <linux/compat.h>
25#include <linux/smp.h>
26#include <linux/kdebug.h>
27#include <linux/init.h>
28#include <linux/console.h>
29#include <linux/module.h>
30#include <linux/hardirq.h>
31#include <linux/kprobes.h>
32#include <linux/uaccess.h>
33#include <linux/hugetlb.h>
34#include <asm/asm-offsets.h>
35#include <asm/pgtable.h>
36#include <asm/irq.h>
37#include <asm/mmu_context.h>
38#include <asm/facility.h>
39#include "../kernel/entry.h"
40
41#ifndef CONFIG_64BIT
42#define __FAIL_ADDR_MASK 0x7ffff000
43#define __SUBCODE_MASK 0x0200
44#define __PF_RES_FIELD 0ULL
45#else /* CONFIG_64BIT */
46#define __FAIL_ADDR_MASK -4096L
47#define __SUBCODE_MASK 0x0600
48#define __PF_RES_FIELD 0x8000000000000000ULL
49#endif /* CONFIG_64BIT */
50
51#define VM_FAULT_BADCONTEXT 0x010000
52#define VM_FAULT_BADMAP 0x020000
53#define VM_FAULT_BADACCESS 0x040000
54
55static unsigned long store_indication;
56
57void fault_init(void)
58{
59 if (test_facility(2) && test_facility(75))
60 store_indication = 0xc00;
61}
62
63static inline int notify_page_fault(struct pt_regs *regs)
64{
65 int ret = 0;
66
67 /* kprobe_running() needs smp_processor_id() */
68 if (kprobes_built_in() && !user_mode(regs)) {
69 preempt_disable();
70 if (kprobe_running() && kprobe_fault_handler(regs, 14))
71 ret = 1;
72 preempt_enable();
73 }
74 return ret;
75}
76
77
78/*
79 * Unlock any spinlocks which will prevent us from getting the
80 * message out.
81 */
82void bust_spinlocks(int yes)
83{
84 if (yes) {
85 oops_in_progress = 1;
86 } else {
87 int loglevel_save = console_loglevel;
88 console_unblank();
89 oops_in_progress = 0;
90 /*
91 * OK, the message is on the console. Now we call printk()
92 * without oops_in_progress set so that printk will give klogd
93 * a poke. Hold onto your hats...
94 */
95 console_loglevel = 15;
96 printk(" ");
97 console_loglevel = loglevel_save;
98 }
99}
100
101/*
102 * Returns the address space associated with the fault.
103 * Returns 0 for kernel space and 1 for user space.
104 */
105static inline int user_space_fault(unsigned long trans_exc_code)
106{
107 /*
108 * The lowest two bits of the translation exception
109 * identification indicate which paging table was used.
110 */
111 trans_exc_code &= 3;
112 if (trans_exc_code == 2)
113 /* Access via secondary space, set_fs setting decides */
114 return current->thread.mm_segment.ar4;
115 if (user_mode == HOME_SPACE_MODE)
116 /* User space if the access has been done via home space. */
117 return trans_exc_code == 3;
118 /*
119 * If the user space is not the home space the kernel runs in home
120 * space. Access via secondary space has already been covered,
121 * access via primary space or access register is from user space
122 * and access via home space is from the kernel.
123 */
124 return trans_exc_code != 3;
125}
126
127static inline void report_user_fault(struct pt_regs *regs, long signr)
128{
129 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
130 return;
131 if (!unhandled_signal(current, signr))
132 return;
133 if (!printk_ratelimit())
134 return;
135 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
136 regs->int_code);
137 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
138 printk(KERN_CONT "\n");
139 printk(KERN_ALERT "failing address: %lX\n",
140 regs->int_parm_long & __FAIL_ADDR_MASK);
141 show_regs(regs);
142}
143
144/*
145 * Send SIGSEGV to task. This is an external routine
146 * to keep the stack usage of do_page_fault small.
147 */
148static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
149{
150 struct siginfo si;
151
152 report_user_fault(regs, SIGSEGV);
153 si.si_signo = SIGSEGV;
154 si.si_code = si_code;
155 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
156 force_sig_info(SIGSEGV, &si, current);
157}
158
159static noinline void do_no_context(struct pt_regs *regs)
160{
161 const struct exception_table_entry *fixup;
162 unsigned long address;
163
164 /* Are we prepared to handle this kernel fault? */
165 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
166 if (fixup) {
167 regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
168 return;
169 }
170
171 /*
172 * Oops. The kernel tried to access some bad page. We'll have to
173 * terminate things with extreme prejudice.
174 */
175 address = regs->int_parm_long & __FAIL_ADDR_MASK;
176 if (!user_space_fault(regs->int_parm_long))
177 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
178 " at virtual kernel address %p\n", (void *)address);
179 else
180 printk(KERN_ALERT "Unable to handle kernel paging request"
181 " at virtual user address %p\n", (void *)address);
182
183 die(regs, "Oops");
184 do_exit(SIGKILL);
185}
186
187static noinline void do_low_address(struct pt_regs *regs)
188{
189 /* Low-address protection hit in kernel mode means
190 NULL pointer write access in kernel mode. */
191 if (regs->psw.mask & PSW_MASK_PSTATE) {
192 /* Low-address protection hit in user mode 'cannot happen'. */
193 die (regs, "Low-address protection");
194 do_exit(SIGKILL);
195 }
196
197 do_no_context(regs);
198}
199
200static noinline void do_sigbus(struct pt_regs *regs)
201{
202 struct task_struct *tsk = current;
203 struct siginfo si;
204
205 /*
206 * Send a sigbus, regardless of whether we were in kernel
207 * or user mode.
208 */
209 si.si_signo = SIGBUS;
210 si.si_errno = 0;
211 si.si_code = BUS_ADRERR;
212 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
213 force_sig_info(SIGBUS, &si, tsk);
214}
215
216static noinline void do_fault_error(struct pt_regs *regs, int fault)
217{
218 int si_code;
219
220 switch (fault) {
221 case VM_FAULT_BADACCESS:
222 case VM_FAULT_BADMAP:
223 /* Bad memory access. Check if it is kernel or user space. */
224 if (regs->psw.mask & PSW_MASK_PSTATE) {
225 /* User mode accesses just cause a SIGSEGV */
226 si_code = (fault == VM_FAULT_BADMAP) ?
227 SEGV_MAPERR : SEGV_ACCERR;
228 do_sigsegv(regs, si_code);
229 return;
230 }
231 case VM_FAULT_BADCONTEXT:
232 do_no_context(regs);
233 break;
234 default: /* fault & VM_FAULT_ERROR */
235 if (fault & VM_FAULT_OOM) {
236 if (!(regs->psw.mask & PSW_MASK_PSTATE))
237 do_no_context(regs);
238 else
239 pagefault_out_of_memory();
240 } else if (fault & VM_FAULT_SIGBUS) {
241 /* Kernel mode? Handle exceptions or die */
242 if (!(regs->psw.mask & PSW_MASK_PSTATE))
243 do_no_context(regs);
244 else
245 do_sigbus(regs);
246 } else
247 BUG();
248 break;
249 }
250}
251
252/*
253 * This routine handles page faults. It determines the address,
254 * and the problem, and then passes it off to one of the appropriate
255 * routines.
256 *
257 * interruption code (int_code):
258 * 04 Protection -> Write-Protection (suprression)
259 * 10 Segment translation -> Not present (nullification)
260 * 11 Page translation -> Not present (nullification)
261 * 3b Region third trans. -> Not present (nullification)
262 */
263static inline int do_exception(struct pt_regs *regs, int access)
264{
265 struct task_struct *tsk;
266 struct mm_struct *mm;
267 struct vm_area_struct *vma;
268 unsigned long trans_exc_code;
269 unsigned long address;
270 unsigned int flags;
271 int fault;
272
273 if (notify_page_fault(regs))
274 return 0;
275
276 tsk = current;
277 mm = tsk->mm;
278 trans_exc_code = regs->int_parm_long;
279
280 /*
281 * Verify that the fault happened in user space, that
282 * we are not in an interrupt and that there is a
283 * user context.
284 */
285 fault = VM_FAULT_BADCONTEXT;
286 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
287 goto out;
288
289 address = trans_exc_code & __FAIL_ADDR_MASK;
290 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
291 flags = FAULT_FLAG_ALLOW_RETRY;
292 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
293 flags |= FAULT_FLAG_WRITE;
294 down_read(&mm->mmap_sem);
295
296#ifdef CONFIG_PGSTE
297 if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
298 address = __gmap_fault(address,
299 (struct gmap *) S390_lowcore.gmap);
300 if (address == -EFAULT) {
301 fault = VM_FAULT_BADMAP;
302 goto out_up;
303 }
304 if (address == -ENOMEM) {
305 fault = VM_FAULT_OOM;
306 goto out_up;
307 }
308 }
309#endif
310
311retry:
312 fault = VM_FAULT_BADMAP;
313 vma = find_vma(mm, address);
314 if (!vma)
315 goto out_up;
316
317 if (unlikely(vma->vm_start > address)) {
318 if (!(vma->vm_flags & VM_GROWSDOWN))
319 goto out_up;
320 if (expand_stack(vma, address))
321 goto out_up;
322 }
323
324 /*
325 * Ok, we have a good vm_area for this memory access, so
326 * we can handle it..
327 */
328 fault = VM_FAULT_BADACCESS;
329 if (unlikely(!(vma->vm_flags & access)))
330 goto out_up;
331
332 if (is_vm_hugetlb_page(vma))
333 address &= HPAGE_MASK;
334 /*
335 * If for any reason at all we couldn't handle the fault,
336 * make sure we exit gracefully rather than endlessly redo
337 * the fault.
338 */
339 fault = handle_mm_fault(mm, vma, address, flags);
340 if (unlikely(fault & VM_FAULT_ERROR))
341 goto out_up;
342
343 /*
344 * Major/minor page fault accounting is only done on the
345 * initial attempt. If we go through a retry, it is extremely
346 * likely that the page will be found in page cache at that point.
347 */
348 if (flags & FAULT_FLAG_ALLOW_RETRY) {
349 if (fault & VM_FAULT_MAJOR) {
350 tsk->maj_flt++;
351 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
352 regs, address);
353 } else {
354 tsk->min_flt++;
355 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
356 regs, address);
357 }
358 if (fault & VM_FAULT_RETRY) {
359 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
360 * of starvation. */
361 flags &= ~FAULT_FLAG_ALLOW_RETRY;
362 down_read(&mm->mmap_sem);
363 goto retry;
364 }
365 }
366 /*
367 * The instruction that caused the program check will
368 * be repeated. Don't signal single step via SIGTRAP.
369 */
370 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
371 fault = 0;
372out_up:
373 up_read(&mm->mmap_sem);
374out:
375 return fault;
376}
377
378void __kprobes do_protection_exception(struct pt_regs *regs)
379{
380 unsigned long trans_exc_code;
381 int fault;
382
383 trans_exc_code = regs->int_parm_long;
384 /* Protection exception is suppressing, decrement psw address. */
385 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
386 /*
387 * Check for low-address protection. This needs to be treated
388 * as a special case because the translation exception code
389 * field is not guaranteed to contain valid data in this case.
390 */
391 if (unlikely(!(trans_exc_code & 4))) {
392 do_low_address(regs);
393 return;
394 }
395 fault = do_exception(regs, VM_WRITE);
396 if (unlikely(fault))
397 do_fault_error(regs, fault);
398}
399
400void __kprobes do_dat_exception(struct pt_regs *regs)
401{
402 int access, fault;
403
404 access = VM_READ | VM_EXEC | VM_WRITE;
405 fault = do_exception(regs, access);
406 if (unlikely(fault))
407 do_fault_error(regs, fault);
408}
409
410#ifdef CONFIG_64BIT
411void __kprobes do_asce_exception(struct pt_regs *regs)
412{
413 struct mm_struct *mm = current->mm;
414 struct vm_area_struct *vma;
415 unsigned long trans_exc_code;
416
417 trans_exc_code = regs->int_parm_long;
418 if (unlikely(!user_space_fault(trans_exc_code) || in_atomic() || !mm))
419 goto no_context;
420
421 down_read(&mm->mmap_sem);
422 vma = find_vma(mm, trans_exc_code & __FAIL_ADDR_MASK);
423 up_read(&mm->mmap_sem);
424
425 if (vma) {
426 update_mm(mm, current);
427 return;
428 }
429
430 /* User mode accesses just cause a SIGSEGV */
431 if (regs->psw.mask & PSW_MASK_PSTATE) {
432 do_sigsegv(regs, SEGV_MAPERR);
433 return;
434 }
435
436no_context:
437 do_no_context(regs);
438}
439#endif
440
441int __handle_fault(unsigned long uaddr, unsigned long pgm_int_code, int write)
442{
443 struct pt_regs regs;
444 int access, fault;
445
446 /* Emulate a uaccess fault from kernel mode. */
447 regs.psw.mask = psw_kernel_bits | PSW_MASK_DAT | PSW_MASK_MCHECK;
448 if (!irqs_disabled())
449 regs.psw.mask |= PSW_MASK_IO | PSW_MASK_EXT;
450 regs.psw.addr = (unsigned long) __builtin_return_address(0);
451 regs.psw.addr |= PSW_ADDR_AMODE;
452 regs.int_code = pgm_int_code;
453 regs.int_parm_long = (uaddr & PAGE_MASK) | 2;
454 access = write ? VM_WRITE : VM_READ;
455 fault = do_exception(®s, access);
456 /*
457 * Since the fault happened in kernel mode while performing a uaccess
458 * all we need to do now is emulating a fixup in case "fault" is not
459 * zero.
460 * For the calling uaccess functions this results always in -EFAULT.
461 */
462 return fault ? -EFAULT : 0;
463}
464
465#ifdef CONFIG_PFAULT
466/*
467 * 'pfault' pseudo page faults routines.
468 */
469static int pfault_disable;
470
471static int __init nopfault(char *str)
472{
473 pfault_disable = 1;
474 return 1;
475}
476
477__setup("nopfault", nopfault);
478
479struct pfault_refbk {
480 u16 refdiagc;
481 u16 reffcode;
482 u16 refdwlen;
483 u16 refversn;
484 u64 refgaddr;
485 u64 refselmk;
486 u64 refcmpmk;
487 u64 reserved;
488} __attribute__ ((packed, aligned(8)));
489
490int pfault_init(void)
491{
492 struct pfault_refbk refbk = {
493 .refdiagc = 0x258,
494 .reffcode = 0,
495 .refdwlen = 5,
496 .refversn = 2,
497 .refgaddr = __LC_CURRENT_PID,
498 .refselmk = 1ULL << 48,
499 .refcmpmk = 1ULL << 48,
500 .reserved = __PF_RES_FIELD };
501 int rc;
502
503 if (pfault_disable)
504 return -1;
505 asm volatile(
506 " diag %1,%0,0x258\n"
507 "0: j 2f\n"
508 "1: la %0,8\n"
509 "2:\n"
510 EX_TABLE(0b,1b)
511 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
512 return rc;
513}
514
515void pfault_fini(void)
516{
517 struct pfault_refbk refbk = {
518 .refdiagc = 0x258,
519 .reffcode = 1,
520 .refdwlen = 5,
521 .refversn = 2,
522 };
523
524 if (pfault_disable)
525 return;
526 asm volatile(
527 " diag %0,0,0x258\n"
528 "0:\n"
529 EX_TABLE(0b,0b)
530 : : "a" (&refbk), "m" (refbk) : "cc");
531}
532
533static DEFINE_SPINLOCK(pfault_lock);
534static LIST_HEAD(pfault_list);
535
536static void pfault_interrupt(struct ext_code ext_code,
537 unsigned int param32, unsigned long param64)
538{
539 struct task_struct *tsk;
540 __u16 subcode;
541 pid_t pid;
542
543 /*
544 * Get the external interruption subcode & pfault
545 * initial/completion signal bit. VM stores this
546 * in the 'cpu address' field associated with the
547 * external interrupt.
548 */
549 subcode = ext_code.subcode;
550 if ((subcode & 0xff00) != __SUBCODE_MASK)
551 return;
552 kstat_cpu(smp_processor_id()).irqs[EXTINT_PFL]++;
553 /* Get the token (= pid of the affected task). */
554 pid = sizeof(void *) == 4 ? param32 : param64;
555 rcu_read_lock();
556 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
557 if (tsk)
558 get_task_struct(tsk);
559 rcu_read_unlock();
560 if (!tsk)
561 return;
562 spin_lock(&pfault_lock);
563 if (subcode & 0x0080) {
564 /* signal bit is set -> a page has been swapped in by VM */
565 if (tsk->thread.pfault_wait == 1) {
566 /* Initial interrupt was faster than the completion
567 * interrupt. pfault_wait is valid. Set pfault_wait
568 * back to zero and wake up the process. This can
569 * safely be done because the task is still sleeping
570 * and can't produce new pfaults. */
571 tsk->thread.pfault_wait = 0;
572 list_del(&tsk->thread.list);
573 wake_up_process(tsk);
574 put_task_struct(tsk);
575 } else {
576 /* Completion interrupt was faster than initial
577 * interrupt. Set pfault_wait to -1 so the initial
578 * interrupt doesn't put the task to sleep.
579 * If the task is not running, ignore the completion
580 * interrupt since it must be a leftover of a PFAULT
581 * CANCEL operation which didn't remove all pending
582 * completion interrupts. */
583 if (tsk->state == TASK_RUNNING)
584 tsk->thread.pfault_wait = -1;
585 }
586 } else {
587 /* signal bit not set -> a real page is missing. */
588 if (WARN_ON_ONCE(tsk != current))
589 goto out;
590 if (tsk->thread.pfault_wait == 1) {
591 /* Already on the list with a reference: put to sleep */
592 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
593 set_tsk_need_resched(tsk);
594 } else if (tsk->thread.pfault_wait == -1) {
595 /* Completion interrupt was faster than the initial
596 * interrupt (pfault_wait == -1). Set pfault_wait
597 * back to zero and exit. */
598 tsk->thread.pfault_wait = 0;
599 } else {
600 /* Initial interrupt arrived before completion
601 * interrupt. Let the task sleep.
602 * An extra task reference is needed since a different
603 * cpu may set the task state to TASK_RUNNING again
604 * before the scheduler is reached. */
605 get_task_struct(tsk);
606 tsk->thread.pfault_wait = 1;
607 list_add(&tsk->thread.list, &pfault_list);
608 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
609 set_tsk_need_resched(tsk);
610 }
611 }
612out:
613 spin_unlock(&pfault_lock);
614 put_task_struct(tsk);
615}
616
617static int __cpuinit pfault_cpu_notify(struct notifier_block *self,
618 unsigned long action, void *hcpu)
619{
620 struct thread_struct *thread, *next;
621 struct task_struct *tsk;
622
623 switch (action) {
624 case CPU_DEAD:
625 case CPU_DEAD_FROZEN:
626 spin_lock_irq(&pfault_lock);
627 list_for_each_entry_safe(thread, next, &pfault_list, list) {
628 thread->pfault_wait = 0;
629 list_del(&thread->list);
630 tsk = container_of(thread, struct task_struct, thread);
631 wake_up_process(tsk);
632 put_task_struct(tsk);
633 }
634 spin_unlock_irq(&pfault_lock);
635 break;
636 default:
637 break;
638 }
639 return NOTIFY_OK;
640}
641
642static int __init pfault_irq_init(void)
643{
644 int rc;
645
646 rc = register_external_interrupt(0x2603, pfault_interrupt);
647 if (rc)
648 goto out_extint;
649 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
650 if (rc)
651 goto out_pfault;
652 service_subclass_irq_register();
653 hotcpu_notifier(pfault_cpu_notify, 0);
654 return 0;
655
656out_pfault:
657 unregister_external_interrupt(0x2603, pfault_interrupt);
658out_extint:
659 pfault_disable = 1;
660 return rc;
661}
662early_initcall(pfault_irq_init);
663
664#endif /* CONFIG_PFAULT */