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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 * S390 version
3 * Copyright IBM Corp. 1999
4 * Author(s): Hartmut Penner (hp@de.ibm.com)
5 * Ulrich Weigand (uweigand@de.ibm.com)
6 *
7 * Derived from "arch/i386/mm/fault.c"
8 * Copyright (C) 1995 Linus Torvalds
9 */
10
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"
38
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 */
48
49#define VM_FAULT_BADCONTEXT 0x010000
50#define VM_FAULT_BADMAP 0x020000
51#define VM_FAULT_BADACCESS 0x040000
52#define VM_FAULT_SIGNAL 0x080000
53#define VM_FAULT_PFAULT 0x100000
54
55static unsigned long store_indication __read_mostly;
56
57#ifdef CONFIG_64BIT
58static int __init fault_init(void)
59{
60 if (test_facility(75))
61 store_indication = 0xc00;
62 return 0;
63}
64early_initcall(fault_init);
65#endif
66
67static inline int notify_page_fault(struct pt_regs *regs)
68{
69 int ret = 0;
70
71 /* kprobe_running() needs smp_processor_id() */
72 if (kprobes_built_in() && !user_mode(regs)) {
73 preempt_disable();
74 if (kprobe_running() && kprobe_fault_handler(regs, 14))
75 ret = 1;
76 preempt_enable();
77 }
78 return ret;
79}
80
81
82/*
83 * Unlock any spinlocks which will prevent us from getting the
84 * message out.
85 */
86void bust_spinlocks(int yes)
87{
88 if (yes) {
89 oops_in_progress = 1;
90 } else {
91 int loglevel_save = console_loglevel;
92 console_unblank();
93 oops_in_progress = 0;
94 /*
95 * OK, the message is on the console. Now we call printk()
96 * without oops_in_progress set so that printk will give klogd
97 * a poke. Hold onto your hats...
98 */
99 console_loglevel = 15;
100 printk(" ");
101 console_loglevel = loglevel_save;
102 }
103}
104
105/*
106 * Returns the address space associated with the fault.
107 * Returns 0 for kernel space and 1 for user space.
108 */
109static inline int user_space_fault(struct pt_regs *regs)
110{
111 unsigned long trans_exc_code;
112
113 /*
114 * The lowest two bits of the translation exception
115 * identification indicate which paging table was used.
116 */
117 trans_exc_code = regs->int_parm_long & 3;
118 if (trans_exc_code == 3) /* home space -> kernel */
119 return 0;
120 if (user_mode(regs))
121 return 1;
122 if (trans_exc_code == 2) /* secondary space -> set_fs */
123 return current->thread.mm_segment.ar4;
124 if (current->flags & PF_VCPU)
125 return 1;
126 return 0;
127}
128
129static int bad_address(void *p)
130{
131 unsigned long dummy;
132
133 return probe_kernel_address((unsigned long *)p, dummy);
134}
135
136#ifdef CONFIG_64BIT
137static void dump_pagetable(unsigned long asce, unsigned long address)
138{
139 unsigned long *table = __va(asce & PAGE_MASK);
140
141 pr_alert("AS:%016lx ", asce);
142 switch (asce & _ASCE_TYPE_MASK) {
143 case _ASCE_TYPE_REGION1:
144 table = table + ((address >> 53) & 0x7ff);
145 if (bad_address(table))
146 goto bad;
147 pr_cont("R1:%016lx ", *table);
148 if (*table & _REGION_ENTRY_INVALID)
149 goto out;
150 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
151 /* fallthrough */
152 case _ASCE_TYPE_REGION2:
153 table = table + ((address >> 42) & 0x7ff);
154 if (bad_address(table))
155 goto bad;
156 pr_cont("R2:%016lx ", *table);
157 if (*table & _REGION_ENTRY_INVALID)
158 goto out;
159 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
160 /* fallthrough */
161 case _ASCE_TYPE_REGION3:
162 table = table + ((address >> 31) & 0x7ff);
163 if (bad_address(table))
164 goto bad;
165 pr_cont("R3:%016lx ", *table);
166 if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
167 goto out;
168 table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
169 /* fallthrough */
170 case _ASCE_TYPE_SEGMENT:
171 table = table + ((address >> 20) & 0x7ff);
172 if (bad_address(table))
173 goto bad;
174 pr_cont(KERN_CONT "S:%016lx ", *table);
175 if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
176 goto out;
177 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
178 }
179 table = table + ((address >> 12) & 0xff);
180 if (bad_address(table))
181 goto bad;
182 pr_cont("P:%016lx ", *table);
183out:
184 pr_cont("\n");
185 return;
186bad:
187 pr_cont("BAD\n");
188}
189
190#else /* CONFIG_64BIT */
191
192static void dump_pagetable(unsigned long asce, unsigned long address)
193{
194 unsigned long *table = __va(asce & PAGE_MASK);
195
196 pr_alert("AS:%08lx ", asce);
197 table = table + ((address >> 20) & 0x7ff);
198 if (bad_address(table))
199 goto bad;
200 pr_cont("S:%08lx ", *table);
201 if (*table & _SEGMENT_ENTRY_INVALID)
202 goto out;
203 table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
204 table = table + ((address >> 12) & 0xff);
205 if (bad_address(table))
206 goto bad;
207 pr_cont("P:%08lx ", *table);
208out:
209 pr_cont("\n");
210 return;
211bad:
212 pr_cont("BAD\n");
213}
214
215#endif /* CONFIG_64BIT */
216
217static void dump_fault_info(struct pt_regs *regs)
218{
219 unsigned long asce;
220
221 pr_alert("Fault in ");
222 switch (regs->int_parm_long & 3) {
223 case 3:
224 pr_cont("home space ");
225 break;
226 case 2:
227 pr_cont("secondary space ");
228 break;
229 case 1:
230 pr_cont("access register ");
231 break;
232 case 0:
233 pr_cont("primary space ");
234 break;
235 }
236 pr_cont("mode while using ");
237 if (!user_space_fault(regs)) {
238 asce = S390_lowcore.kernel_asce;
239 pr_cont("kernel ");
240 }
241#ifdef CONFIG_PGSTE
242 else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
243 struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
244 asce = gmap->asce;
245 pr_cont("gmap ");
246 }
247#endif
248 else {
249 asce = S390_lowcore.user_asce;
250 pr_cont("user ");
251 }
252 pr_cont("ASCE.\n");
253 dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
254}
255
256static inline void report_user_fault(struct pt_regs *regs, long signr)
257{
258 if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
259 return;
260 if (!unhandled_signal(current, signr))
261 return;
262 if (!printk_ratelimit())
263 return;
264 printk(KERN_ALERT "User process fault: interruption code 0x%X ",
265 regs->int_code);
266 print_vma_addr(KERN_CONT "in ", regs->psw.addr & PSW_ADDR_INSN);
267 printk(KERN_CONT "\n");
268 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
269 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
270 dump_fault_info(regs);
271 show_regs(regs);
272}
273
274/*
275 * Send SIGSEGV to task. This is an external routine
276 * to keep the stack usage of do_page_fault small.
277 */
278static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
279{
280 struct siginfo si;
281
282 report_user_fault(regs, SIGSEGV);
283 si.si_signo = SIGSEGV;
284 si.si_code = si_code;
285 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
286 force_sig_info(SIGSEGV, &si, current);
287}
288
289static noinline void do_no_context(struct pt_regs *regs)
290{
291 const struct exception_table_entry *fixup;
292 unsigned long address;
293
294 /* Are we prepared to handle this kernel fault? */
295 fixup = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
296 if (fixup) {
297 regs->psw.addr = extable_fixup(fixup) | PSW_ADDR_AMODE;
298 return;
299 }
300
301 /*
302 * Oops. The kernel tried to access some bad page. We'll have to
303 * terminate things with extreme prejudice.
304 */
305 address = regs->int_parm_long & __FAIL_ADDR_MASK;
306 if (!user_space_fault(regs))
307 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
308 " in virtual kernel address space\n");
309 else
310 printk(KERN_ALERT "Unable to handle kernel paging request"
311 " in virtual user address space\n");
312 printk(KERN_ALERT "failing address: %016lx TEID: %016lx\n",
313 regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
314 dump_fault_info(regs);
315 die(regs, "Oops");
316 do_exit(SIGKILL);
317}
318
319static noinline void do_low_address(struct pt_regs *regs)
320{
321 /* Low-address protection hit in kernel mode means
322 NULL pointer write access in kernel mode. */
323 if (regs->psw.mask & PSW_MASK_PSTATE) {
324 /* Low-address protection hit in user mode 'cannot happen'. */
325 die (regs, "Low-address protection");
326 do_exit(SIGKILL);
327 }
328
329 do_no_context(regs);
330}
331
332static noinline void do_sigbus(struct pt_regs *regs)
333{
334 struct task_struct *tsk = current;
335 struct siginfo si;
336
337 /*
338 * Send a sigbus, regardless of whether we were in kernel
339 * or user mode.
340 */
341 si.si_signo = SIGBUS;
342 si.si_errno = 0;
343 si.si_code = BUS_ADRERR;
344 si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
345 force_sig_info(SIGBUS, &si, tsk);
346}
347
348static noinline void do_fault_error(struct pt_regs *regs, int fault)
349{
350 int si_code;
351
352 switch (fault) {
353 case VM_FAULT_BADACCESS:
354 case VM_FAULT_BADMAP:
355 /* Bad memory access. Check if it is kernel or user space. */
356 if (user_mode(regs)) {
357 /* User mode accesses just cause a SIGSEGV */
358 si_code = (fault == VM_FAULT_BADMAP) ?
359 SEGV_MAPERR : SEGV_ACCERR;
360 do_sigsegv(regs, si_code);
361 return;
362 }
363 case VM_FAULT_BADCONTEXT:
364 case VM_FAULT_PFAULT:
365 do_no_context(regs);
366 break;
367 case VM_FAULT_SIGNAL:
368 if (!user_mode(regs))
369 do_no_context(regs);
370 break;
371 default: /* fault & VM_FAULT_ERROR */
372 if (fault & VM_FAULT_OOM) {
373 if (!user_mode(regs))
374 do_no_context(regs);
375 else
376 pagefault_out_of_memory();
377 } else if (fault & VM_FAULT_SIGBUS) {
378 /* Kernel mode? Handle exceptions or die */
379 if (!user_mode(regs))
380 do_no_context(regs);
381 else
382 do_sigbus(regs);
383 } else
384 BUG();
385 break;
386 }
387}
388
389/*
390 * This routine handles page faults. It determines the address,
391 * and the problem, and then passes it off to one of the appropriate
392 * routines.
393 *
394 * interruption code (int_code):
395 * 04 Protection -> Write-Protection (suprression)
396 * 10 Segment translation -> Not present (nullification)
397 * 11 Page translation -> Not present (nullification)
398 * 3b Region third trans. -> Not present (nullification)
399 */
400static inline int do_exception(struct pt_regs *regs, int access)
401{
402#ifdef CONFIG_PGSTE
403 struct gmap *gmap;
404#endif
405 struct task_struct *tsk;
406 struct mm_struct *mm;
407 struct vm_area_struct *vma;
408 unsigned long trans_exc_code;
409 unsigned long address;
410 unsigned int flags;
411 int fault;
412
413 tsk = current;
414 /*
415 * The instruction that caused the program check has
416 * been nullified. Don't signal single step via SIGTRAP.
417 */
418 clear_tsk_thread_flag(tsk, TIF_PER_TRAP);
419
420 if (notify_page_fault(regs))
421 return 0;
422
423 mm = tsk->mm;
424 trans_exc_code = regs->int_parm_long;
425
426 /*
427 * Verify that the fault happened in user space, that
428 * we are not in an interrupt and that there is a
429 * user context.
430 */
431 fault = VM_FAULT_BADCONTEXT;
432 if (unlikely(!user_space_fault(regs) || in_atomic() || !mm))
433 goto out;
434
435 address = trans_exc_code & __FAIL_ADDR_MASK;
436 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
437 flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
438 if (user_mode(regs))
439 flags |= FAULT_FLAG_USER;
440 if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
441 flags |= FAULT_FLAG_WRITE;
442 down_read(&mm->mmap_sem);
443
444#ifdef CONFIG_PGSTE
445 gmap = (struct gmap *)
446 ((current->flags & PF_VCPU) ? S390_lowcore.gmap : 0);
447 if (gmap) {
448 address = __gmap_fault(address, gmap);
449 if (address == -EFAULT) {
450 fault = VM_FAULT_BADMAP;
451 goto out_up;
452 }
453 if (address == -ENOMEM) {
454 fault = VM_FAULT_OOM;
455 goto out_up;
456 }
457 if (gmap->pfault_enabled)
458 flags |= FAULT_FLAG_RETRY_NOWAIT;
459 }
460#endif
461
462retry:
463 fault = VM_FAULT_BADMAP;
464 vma = find_vma(mm, address);
465 if (!vma)
466 goto out_up;
467
468 if (unlikely(vma->vm_start > address)) {
469 if (!(vma->vm_flags & VM_GROWSDOWN))
470 goto out_up;
471 if (expand_stack(vma, address))
472 goto out_up;
473 }
474
475 /*
476 * Ok, we have a good vm_area for this memory access, so
477 * we can handle it..
478 */
479 fault = VM_FAULT_BADACCESS;
480 if (unlikely(!(vma->vm_flags & access)))
481 goto out_up;
482
483 if (is_vm_hugetlb_page(vma))
484 address &= HPAGE_MASK;
485 /*
486 * If for any reason at all we couldn't handle the fault,
487 * make sure we exit gracefully rather than endlessly redo
488 * the fault.
489 */
490 fault = handle_mm_fault(mm, vma, address, flags);
491 /* No reason to continue if interrupted by SIGKILL. */
492 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
493 fault = VM_FAULT_SIGNAL;
494 goto out;
495 }
496 if (unlikely(fault & VM_FAULT_ERROR))
497 goto out_up;
498
499 /*
500 * Major/minor page fault accounting is only done on the
501 * initial attempt. If we go through a retry, it is extremely
502 * likely that the page will be found in page cache at that point.
503 */
504 if (flags & FAULT_FLAG_ALLOW_RETRY) {
505 if (fault & VM_FAULT_MAJOR) {
506 tsk->maj_flt++;
507 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
508 regs, address);
509 } else {
510 tsk->min_flt++;
511 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
512 regs, address);
513 }
514 if (fault & VM_FAULT_RETRY) {
515#ifdef CONFIG_PGSTE
516 if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
517 /* FAULT_FLAG_RETRY_NOWAIT has been set,
518 * mmap_sem has not been released */
519 current->thread.gmap_pfault = 1;
520 fault = VM_FAULT_PFAULT;
521 goto out_up;
522 }
523#endif
524 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
525 * of starvation. */
526 flags &= ~(FAULT_FLAG_ALLOW_RETRY |
527 FAULT_FLAG_RETRY_NOWAIT);
528 flags |= FAULT_FLAG_TRIED;
529 down_read(&mm->mmap_sem);
530 goto retry;
531 }
532 }
533 fault = 0;
534out_up:
535 up_read(&mm->mmap_sem);
536out:
537 return fault;
538}
539
540void __kprobes do_protection_exception(struct pt_regs *regs)
541{
542 unsigned long trans_exc_code;
543 int fault;
544
545 trans_exc_code = regs->int_parm_long;
546 /*
547 * Protection exceptions are suppressing, decrement psw address.
548 * The exception to this rule are aborted transactions, for these
549 * the PSW already points to the correct location.
550 */
551 if (!(regs->int_code & 0x200))
552 regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
553 /*
554 * Check for low-address protection. This needs to be treated
555 * as a special case because the translation exception code
556 * field is not guaranteed to contain valid data in this case.
557 */
558 if (unlikely(!(trans_exc_code & 4))) {
559 do_low_address(regs);
560 return;
561 }
562 fault = do_exception(regs, VM_WRITE);
563 if (unlikely(fault))
564 do_fault_error(regs, fault);
565}
566
567void __kprobes do_dat_exception(struct pt_regs *regs)
568{
569 int access, fault;
570
571 access = VM_READ | VM_EXEC | VM_WRITE;
572 fault = do_exception(regs, access);
573 if (unlikely(fault))
574 do_fault_error(regs, fault);
575}
576
577#ifdef CONFIG_PFAULT
578/*
579 * 'pfault' pseudo page faults routines.
580 */
581static int pfault_disable;
582
583static int __init nopfault(char *str)
584{
585 pfault_disable = 1;
586 return 1;
587}
588
589__setup("nopfault", nopfault);
590
591struct pfault_refbk {
592 u16 refdiagc;
593 u16 reffcode;
594 u16 refdwlen;
595 u16 refversn;
596 u64 refgaddr;
597 u64 refselmk;
598 u64 refcmpmk;
599 u64 reserved;
600} __attribute__ ((packed, aligned(8)));
601
602int pfault_init(void)
603{
604 struct pfault_refbk refbk = {
605 .refdiagc = 0x258,
606 .reffcode = 0,
607 .refdwlen = 5,
608 .refversn = 2,
609 .refgaddr = __LC_CURRENT_PID,
610 .refselmk = 1ULL << 48,
611 .refcmpmk = 1ULL << 48,
612 .reserved = __PF_RES_FIELD };
613 int rc;
614
615 if (pfault_disable)
616 return -1;
617 asm volatile(
618 " diag %1,%0,0x258\n"
619 "0: j 2f\n"
620 "1: la %0,8\n"
621 "2:\n"
622 EX_TABLE(0b,1b)
623 : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
624 return rc;
625}
626
627void pfault_fini(void)
628{
629 struct pfault_refbk refbk = {
630 .refdiagc = 0x258,
631 .reffcode = 1,
632 .refdwlen = 5,
633 .refversn = 2,
634 };
635
636 if (pfault_disable)
637 return;
638 asm volatile(
639 " diag %0,0,0x258\n"
640 "0:\n"
641 EX_TABLE(0b,0b)
642 : : "a" (&refbk), "m" (refbk) : "cc");
643}
644
645static DEFINE_SPINLOCK(pfault_lock);
646static LIST_HEAD(pfault_list);
647
648static void pfault_interrupt(struct ext_code ext_code,
649 unsigned int param32, unsigned long param64)
650{
651 struct task_struct *tsk;
652 __u16 subcode;
653 pid_t pid;
654
655 /*
656 * Get the external interruption subcode & pfault
657 * initial/completion signal bit. VM stores this
658 * in the 'cpu address' field associated with the
659 * external interrupt.
660 */
661 subcode = ext_code.subcode;
662 if ((subcode & 0xff00) != __SUBCODE_MASK)
663 return;
664 inc_irq_stat(IRQEXT_PFL);
665 /* Get the token (= pid of the affected task). */
666 pid = sizeof(void *) == 4 ? param32 : param64;
667 rcu_read_lock();
668 tsk = find_task_by_pid_ns(pid, &init_pid_ns);
669 if (tsk)
670 get_task_struct(tsk);
671 rcu_read_unlock();
672 if (!tsk)
673 return;
674 spin_lock(&pfault_lock);
675 if (subcode & 0x0080) {
676 /* signal bit is set -> a page has been swapped in by VM */
677 if (tsk->thread.pfault_wait == 1) {
678 /* Initial interrupt was faster than the completion
679 * interrupt. pfault_wait is valid. Set pfault_wait
680 * back to zero and wake up the process. This can
681 * safely be done because the task is still sleeping
682 * and can't produce new pfaults. */
683 tsk->thread.pfault_wait = 0;
684 list_del(&tsk->thread.list);
685 wake_up_process(tsk);
686 put_task_struct(tsk);
687 } else {
688 /* Completion interrupt was faster than initial
689 * interrupt. Set pfault_wait to -1 so the initial
690 * interrupt doesn't put the task to sleep.
691 * If the task is not running, ignore the completion
692 * interrupt since it must be a leftover of a PFAULT
693 * CANCEL operation which didn't remove all pending
694 * completion interrupts. */
695 if (tsk->state == TASK_RUNNING)
696 tsk->thread.pfault_wait = -1;
697 }
698 } else {
699 /* signal bit not set -> a real page is missing. */
700 if (WARN_ON_ONCE(tsk != current))
701 goto out;
702 if (tsk->thread.pfault_wait == 1) {
703 /* Already on the list with a reference: put to sleep */
704 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
705 set_tsk_need_resched(tsk);
706 } else if (tsk->thread.pfault_wait == -1) {
707 /* Completion interrupt was faster than the initial
708 * interrupt (pfault_wait == -1). Set pfault_wait
709 * back to zero and exit. */
710 tsk->thread.pfault_wait = 0;
711 } else {
712 /* Initial interrupt arrived before completion
713 * interrupt. Let the task sleep.
714 * An extra task reference is needed since a different
715 * cpu may set the task state to TASK_RUNNING again
716 * before the scheduler is reached. */
717 get_task_struct(tsk);
718 tsk->thread.pfault_wait = 1;
719 list_add(&tsk->thread.list, &pfault_list);
720 __set_task_state(tsk, TASK_UNINTERRUPTIBLE);
721 set_tsk_need_resched(tsk);
722 }
723 }
724out:
725 spin_unlock(&pfault_lock);
726 put_task_struct(tsk);
727}
728
729static int pfault_cpu_notify(struct notifier_block *self, unsigned long action,
730 void *hcpu)
731{
732 struct thread_struct *thread, *next;
733 struct task_struct *tsk;
734
735 switch (action & ~CPU_TASKS_FROZEN) {
736 case CPU_DEAD:
737 spin_lock_irq(&pfault_lock);
738 list_for_each_entry_safe(thread, next, &pfault_list, list) {
739 thread->pfault_wait = 0;
740 list_del(&thread->list);
741 tsk = container_of(thread, struct task_struct, thread);
742 wake_up_process(tsk);
743 put_task_struct(tsk);
744 }
745 spin_unlock_irq(&pfault_lock);
746 break;
747 default:
748 break;
749 }
750 return NOTIFY_OK;
751}
752
753static int __init pfault_irq_init(void)
754{
755 int rc;
756
757 rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
758 if (rc)
759 goto out_extint;
760 rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
761 if (rc)
762 goto out_pfault;
763 irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
764 hotcpu_notifier(pfault_cpu_notify, 0);
765 return 0;
766
767out_pfault:
768 unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
769out_extint:
770 pfault_disable = 1;
771 return rc;
772}
773early_initcall(pfault_irq_init);
774
775#endif /* CONFIG_PFAULT */