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1da177e4 LT |
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/config.h> | |
14 | #include <linux/signal.h> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/errno.h> | |
18 | #include <linux/string.h> | |
19 | #include <linux/types.h> | |
20 | #include <linux/ptrace.h> | |
21 | #include <linux/mman.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/smp.h> | |
24 | #include <linux/smp_lock.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/console.h> | |
27 | #include <linux/module.h> | |
28 | #include <linux/hardirq.h> | |
29 | ||
30 | #include <asm/system.h> | |
31 | #include <asm/uaccess.h> | |
32 | #include <asm/pgtable.h> | |
33 | ||
34 | #ifndef CONFIG_ARCH_S390X | |
35 | #define __FAIL_ADDR_MASK 0x7ffff000 | |
36 | #define __FIXUP_MASK 0x7fffffff | |
37 | #define __SUBCODE_MASK 0x0200 | |
38 | #define __PF_RES_FIELD 0ULL | |
39 | #else /* CONFIG_ARCH_S390X */ | |
40 | #define __FAIL_ADDR_MASK -4096L | |
41 | #define __FIXUP_MASK ~0L | |
42 | #define __SUBCODE_MASK 0x0600 | |
43 | #define __PF_RES_FIELD 0x8000000000000000ULL | |
44 | #endif /* CONFIG_ARCH_S390X */ | |
45 | ||
46 | #ifdef CONFIG_SYSCTL | |
47 | extern int sysctl_userprocess_debug; | |
48 | #endif | |
49 | ||
50 | extern void die(const char *,struct pt_regs *,long); | |
51 | ||
52 | extern spinlock_t timerlist_lock; | |
53 | ||
54 | /* | |
55 | * Unlock any spinlocks which will prevent us from getting the | |
56 | * message out (timerlist_lock is acquired through the | |
57 | * console unblank code) | |
58 | */ | |
59 | void bust_spinlocks(int yes) | |
60 | { | |
61 | if (yes) { | |
62 | oops_in_progress = 1; | |
63 | } else { | |
64 | int loglevel_save = console_loglevel; | |
65 | console_unblank(); | |
66 | oops_in_progress = 0; | |
67 | /* | |
68 | * OK, the message is on the console. Now we call printk() | |
69 | * without oops_in_progress set so that printk will give klogd | |
70 | * a poke. Hold onto your hats... | |
71 | */ | |
72 | console_loglevel = 15; | |
73 | printk(" "); | |
74 | console_loglevel = loglevel_save; | |
75 | } | |
76 | } | |
77 | ||
78 | /* | |
79 | * Check which address space is addressed by the access | |
80 | * register in S390_lowcore.exc_access_id. | |
81 | * Returns 1 for user space and 0 for kernel space. | |
82 | */ | |
83 | static int __check_access_register(struct pt_regs *regs, int error_code) | |
84 | { | |
85 | int areg = S390_lowcore.exc_access_id; | |
86 | ||
87 | if (areg == 0) | |
88 | /* Access via access register 0 -> kernel address */ | |
89 | return 0; | |
90 | save_access_regs(current->thread.acrs); | |
91 | if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1) | |
92 | /* | |
93 | * access register contains 0 -> kernel address, | |
94 | * access register contains 1 -> user space address | |
95 | */ | |
96 | return current->thread.acrs[areg]; | |
97 | ||
98 | /* Something unhealthy was done with the access registers... */ | |
99 | die("page fault via unknown access register", regs, error_code); | |
100 | do_exit(SIGKILL); | |
101 | return 0; | |
102 | } | |
103 | ||
104 | /* | |
105 | * Check which address space the address belongs to. | |
106 | * Returns 1 for user space and 0 for kernel space. | |
107 | */ | |
108 | static inline int check_user_space(struct pt_regs *regs, int error_code) | |
109 | { | |
110 | /* | |
111 | * The lowest two bits of S390_lowcore.trans_exc_code indicate | |
112 | * which paging table was used: | |
113 | * 0: Primary Segment Table Descriptor | |
114 | * 1: STD determined via access register | |
115 | * 2: Secondary Segment Table Descriptor | |
116 | * 3: Home Segment Table Descriptor | |
117 | */ | |
118 | int descriptor = S390_lowcore.trans_exc_code & 3; | |
119 | if (unlikely(descriptor == 1)) | |
120 | return __check_access_register(regs, error_code); | |
121 | if (descriptor == 2) | |
122 | return current->thread.mm_segment.ar4; | |
123 | return descriptor != 0; | |
124 | } | |
125 | ||
126 | /* | |
127 | * Send SIGSEGV to task. This is an external routine | |
128 | * to keep the stack usage of do_page_fault small. | |
129 | */ | |
130 | static void do_sigsegv(struct pt_regs *regs, unsigned long error_code, | |
131 | int si_code, unsigned long address) | |
132 | { | |
133 | struct siginfo si; | |
134 | ||
135 | #if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG) | |
136 | #if defined(CONFIG_SYSCTL) | |
137 | if (sysctl_userprocess_debug) | |
138 | #endif | |
139 | { | |
140 | printk("User process fault: interruption code 0x%lX\n", | |
141 | error_code); | |
142 | printk("failing address: %lX\n", address); | |
143 | show_regs(regs); | |
144 | } | |
145 | #endif | |
146 | si.si_signo = SIGSEGV; | |
147 | si.si_code = si_code; | |
148 | si.si_addr = (void *) address; | |
149 | force_sig_info(SIGSEGV, &si, current); | |
150 | } | |
151 | ||
152 | /* | |
153 | * This routine handles page faults. It determines the address, | |
154 | * and the problem, and then passes it off to one of the appropriate | |
155 | * routines. | |
156 | * | |
157 | * error_code: | |
158 | * 04 Protection -> Write-Protection (suprression) | |
159 | * 10 Segment translation -> Not present (nullification) | |
160 | * 11 Page translation -> Not present (nullification) | |
161 | * 3b Region third trans. -> Not present (nullification) | |
162 | */ | |
163 | extern inline void | |
164 | do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) | |
165 | { | |
166 | struct task_struct *tsk; | |
167 | struct mm_struct *mm; | |
168 | struct vm_area_struct * vma; | |
169 | unsigned long address; | |
170 | int user_address; | |
171 | const struct exception_table_entry *fixup; | |
172 | int si_code = SEGV_MAPERR; | |
173 | ||
174 | tsk = current; | |
175 | mm = tsk->mm; | |
176 | ||
177 | /* | |
178 | * Check for low-address protection. This needs to be treated | |
179 | * as a special case because the translation exception code | |
180 | * field is not guaranteed to contain valid data in this case. | |
181 | */ | |
182 | if (is_protection && !(S390_lowcore.trans_exc_code & 4)) { | |
183 | ||
184 | /* Low-address protection hit in kernel mode means | |
185 | NULL pointer write access in kernel mode. */ | |
186 | if (!(regs->psw.mask & PSW_MASK_PSTATE)) { | |
187 | address = 0; | |
188 | user_address = 0; | |
189 | goto no_context; | |
190 | } | |
191 | ||
192 | /* Low-address protection hit in user mode 'cannot happen'. */ | |
193 | die ("Low-address protection", regs, error_code); | |
194 | do_exit(SIGKILL); | |
195 | } | |
196 | ||
197 | /* | |
198 | * get the failing address | |
199 | * more specific the segment and page table portion of | |
200 | * the address | |
201 | */ | |
202 | address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; | |
203 | user_address = check_user_space(regs, error_code); | |
204 | ||
205 | /* | |
206 | * Verify that the fault happened in user space, that | |
207 | * we are not in an interrupt and that there is a | |
208 | * user context. | |
209 | */ | |
595bf2aa | 210 | if (user_address == 0 || in_atomic() || !mm) |
1da177e4 LT |
211 | goto no_context; |
212 | ||
213 | /* | |
214 | * When we get here, the fault happened in the current | |
215 | * task's user address space, so we can switch on the | |
216 | * interrupts again and then search the VMAs | |
217 | */ | |
218 | local_irq_enable(); | |
219 | ||
220 | down_read(&mm->mmap_sem); | |
221 | ||
222 | vma = find_vma(mm, address); | |
223 | if (!vma) | |
224 | goto bad_area; | |
225 | if (vma->vm_start <= address) | |
226 | goto good_area; | |
227 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
228 | goto bad_area; | |
229 | if (expand_stack(vma, address)) | |
230 | goto bad_area; | |
231 | /* | |
232 | * Ok, we have a good vm_area for this memory access, so | |
233 | * we can handle it.. | |
234 | */ | |
235 | good_area: | |
236 | si_code = SEGV_ACCERR; | |
237 | if (!is_protection) { | |
238 | /* page not present, check vm flags */ | |
239 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
240 | goto bad_area; | |
241 | } else { | |
242 | if (!(vma->vm_flags & VM_WRITE)) | |
243 | goto bad_area; | |
244 | } | |
245 | ||
246 | survive: | |
247 | /* | |
248 | * If for any reason at all we couldn't handle the fault, | |
249 | * make sure we exit gracefully rather than endlessly redo | |
250 | * the fault. | |
251 | */ | |
252 | switch (handle_mm_fault(mm, vma, address, is_protection)) { | |
253 | case VM_FAULT_MINOR: | |
254 | tsk->min_flt++; | |
255 | break; | |
256 | case VM_FAULT_MAJOR: | |
257 | tsk->maj_flt++; | |
258 | break; | |
259 | case VM_FAULT_SIGBUS: | |
260 | goto do_sigbus; | |
261 | case VM_FAULT_OOM: | |
262 | goto out_of_memory; | |
263 | default: | |
264 | BUG(); | |
265 | } | |
266 | ||
267 | up_read(&mm->mmap_sem); | |
268 | /* | |
269 | * The instruction that caused the program check will | |
270 | * be repeated. Don't signal single step via SIGTRAP. | |
271 | */ | |
272 | clear_tsk_thread_flag(current, TIF_SINGLE_STEP); | |
273 | return; | |
274 | ||
275 | /* | |
276 | * Something tried to access memory that isn't in our memory map.. | |
277 | * Fix it, but check if it's kernel or user first.. | |
278 | */ | |
279 | bad_area: | |
280 | up_read(&mm->mmap_sem); | |
281 | ||
282 | /* User mode accesses just cause a SIGSEGV */ | |
283 | if (regs->psw.mask & PSW_MASK_PSTATE) { | |
284 | tsk->thread.prot_addr = address; | |
285 | tsk->thread.trap_no = error_code; | |
286 | do_sigsegv(regs, error_code, si_code, address); | |
287 | return; | |
288 | } | |
289 | ||
290 | no_context: | |
291 | /* Are we prepared to handle this kernel fault? */ | |
292 | fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); | |
293 | if (fixup) { | |
294 | regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; | |
295 | return; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Oops. The kernel tried to access some bad page. We'll have to | |
300 | * terminate things with extreme prejudice. | |
301 | */ | |
302 | if (user_address == 0) | |
303 | printk(KERN_ALERT "Unable to handle kernel pointer dereference" | |
304 | " at virtual kernel address %p\n", (void *)address); | |
305 | else | |
306 | printk(KERN_ALERT "Unable to handle kernel paging request" | |
307 | " at virtual user address %p\n", (void *)address); | |
308 | ||
309 | die("Oops", regs, error_code); | |
310 | do_exit(SIGKILL); | |
311 | ||
312 | ||
313 | /* | |
314 | * We ran out of memory, or some other thing happened to us that made | |
315 | * us unable to handle the page fault gracefully. | |
316 | */ | |
317 | out_of_memory: | |
318 | up_read(&mm->mmap_sem); | |
319 | if (tsk->pid == 1) { | |
320 | yield(); | |
321 | goto survive; | |
322 | } | |
323 | printk("VM: killing process %s\n", tsk->comm); | |
324 | if (regs->psw.mask & PSW_MASK_PSTATE) | |
325 | do_exit(SIGKILL); | |
326 | goto no_context; | |
327 | ||
328 | do_sigbus: | |
329 | up_read(&mm->mmap_sem); | |
330 | ||
331 | /* | |
332 | * Send a sigbus, regardless of whether we were in kernel | |
333 | * or user mode. | |
334 | */ | |
335 | tsk->thread.prot_addr = address; | |
336 | tsk->thread.trap_no = error_code; | |
337 | force_sig(SIGBUS, tsk); | |
338 | ||
339 | /* Kernel mode? Handle exceptions or die */ | |
340 | if (!(regs->psw.mask & PSW_MASK_PSTATE)) | |
341 | goto no_context; | |
342 | } | |
343 | ||
344 | void do_protection_exception(struct pt_regs *regs, unsigned long error_code) | |
345 | { | |
346 | regs->psw.addr -= (error_code >> 16); | |
347 | do_exception(regs, 4, 1); | |
348 | } | |
349 | ||
350 | void do_dat_exception(struct pt_regs *regs, unsigned long error_code) | |
351 | { | |
352 | do_exception(regs, error_code & 0xff, 0); | |
353 | } | |
354 | ||
355 | #ifndef CONFIG_ARCH_S390X | |
356 | ||
357 | typedef struct _pseudo_wait_t { | |
358 | struct _pseudo_wait_t *next; | |
359 | wait_queue_head_t queue; | |
360 | unsigned long address; | |
361 | int resolved; | |
362 | } pseudo_wait_t; | |
363 | ||
364 | static pseudo_wait_t *pseudo_lock_queue = NULL; | |
365 | static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */ | |
366 | ||
367 | /* | |
368 | * This routine handles 'pagex' pseudo page faults. | |
369 | */ | |
370 | asmlinkage void | |
371 | do_pseudo_page_fault(struct pt_regs *regs, unsigned long error_code) | |
372 | { | |
373 | pseudo_wait_t wait_struct; | |
374 | pseudo_wait_t *ptr, *last, *next; | |
375 | unsigned long address; | |
376 | ||
377 | /* | |
378 | * get the failing address | |
379 | * more specific the segment and page table portion of | |
380 | * the address | |
381 | */ | |
382 | address = S390_lowcore.trans_exc_code & 0xfffff000; | |
383 | ||
384 | if (address & 0x80000000) { | |
385 | /* high bit set -> a page has been swapped in by VM */ | |
386 | address &= 0x7fffffff; | |
387 | spin_lock(&pseudo_wait_spinlock); | |
388 | last = NULL; | |
389 | ptr = pseudo_lock_queue; | |
390 | while (ptr != NULL) { | |
391 | next = ptr->next; | |
392 | if (address == ptr->address) { | |
393 | /* | |
394 | * This is one of the processes waiting | |
395 | * for the page. Unchain from the queue. | |
396 | * There can be more than one process | |
397 | * waiting for the same page. VM presents | |
398 | * an initial and a completion interrupt for | |
399 | * every process that tries to access a | |
400 | * page swapped out by VM. | |
401 | */ | |
402 | if (last == NULL) | |
403 | pseudo_lock_queue = next; | |
404 | else | |
405 | last->next = next; | |
406 | /* now wake up the process */ | |
407 | ptr->resolved = 1; | |
408 | wake_up(&ptr->queue); | |
409 | } else | |
410 | last = ptr; | |
411 | ptr = next; | |
412 | } | |
413 | spin_unlock(&pseudo_wait_spinlock); | |
414 | } else { | |
415 | /* Pseudo page faults in kernel mode is a bad idea */ | |
416 | if (!(regs->psw.mask & PSW_MASK_PSTATE)) { | |
417 | /* | |
418 | * VM presents pseudo page faults if the interrupted | |
419 | * state was not disabled for interrupts. So we can | |
420 | * get pseudo page fault interrupts while running | |
421 | * in kernel mode. We simply access the page here | |
422 | * while we are running disabled. VM will then swap | |
423 | * in the page synchronously. | |
424 | */ | |
425 | if (check_user_space(regs, error_code) == 0) | |
426 | /* dereference a virtual kernel address */ | |
427 | __asm__ __volatile__ ( | |
428 | " ic 0,0(%0)" | |
429 | : : "a" (address) : "0"); | |
430 | else | |
431 | /* dereference a virtual user address */ | |
432 | __asm__ __volatile__ ( | |
433 | " la 2,0(%0)\n" | |
434 | " sacf 512\n" | |
435 | " ic 2,0(2)\n" | |
436 | "0:sacf 0\n" | |
437 | ".section __ex_table,\"a\"\n" | |
438 | " .align 4\n" | |
439 | " .long 0b,0b\n" | |
440 | ".previous" | |
441 | : : "a" (address) : "2" ); | |
442 | ||
443 | return; | |
444 | } | |
445 | /* initialize and add element to pseudo_lock_queue */ | |
446 | init_waitqueue_head (&wait_struct.queue); | |
447 | wait_struct.address = address; | |
448 | wait_struct.resolved = 0; | |
449 | spin_lock(&pseudo_wait_spinlock); | |
450 | wait_struct.next = pseudo_lock_queue; | |
451 | pseudo_lock_queue = &wait_struct; | |
452 | spin_unlock(&pseudo_wait_spinlock); | |
453 | /* | |
454 | * The instruction that caused the program check will | |
455 | * be repeated. Don't signal single step via SIGTRAP. | |
456 | */ | |
457 | clear_tsk_thread_flag(current, TIF_SINGLE_STEP); | |
458 | /* go to sleep */ | |
459 | wait_event(wait_struct.queue, wait_struct.resolved); | |
460 | } | |
461 | } | |
462 | #endif /* CONFIG_ARCH_S390X */ | |
463 | ||
464 | #ifdef CONFIG_PFAULT | |
465 | /* | |
466 | * 'pfault' pseudo page faults routines. | |
467 | */ | |
468 | static int pfault_disable = 0; | |
469 | ||
470 | static int __init nopfault(char *str) | |
471 | { | |
472 | pfault_disable = 1; | |
473 | return 1; | |
474 | } | |
475 | ||
476 | __setup("nopfault", nopfault); | |
477 | ||
478 | typedef struct { | |
479 | __u16 refdiagc; | |
480 | __u16 reffcode; | |
481 | __u16 refdwlen; | |
482 | __u16 refversn; | |
483 | __u64 refgaddr; | |
484 | __u64 refselmk; | |
485 | __u64 refcmpmk; | |
486 | __u64 reserved; | |
487 | } __attribute__ ((packed)) pfault_refbk_t; | |
488 | ||
489 | int pfault_init(void) | |
490 | { | |
491 | pfault_refbk_t refbk = | |
492 | { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48, | |
493 | __PF_RES_FIELD }; | |
494 | int rc; | |
495 | ||
496 | if (pfault_disable) | |
497 | return -1; | |
498 | __asm__ __volatile__( | |
499 | " diag %1,%0,0x258\n" | |
500 | "0: j 2f\n" | |
501 | "1: la %0,8\n" | |
502 | "2:\n" | |
503 | ".section __ex_table,\"a\"\n" | |
504 | " .align 4\n" | |
505 | #ifndef CONFIG_ARCH_S390X | |
506 | " .long 0b,1b\n" | |
507 | #else /* CONFIG_ARCH_S390X */ | |
508 | " .quad 0b,1b\n" | |
509 | #endif /* CONFIG_ARCH_S390X */ | |
510 | ".previous" | |
511 | : "=d" (rc) : "a" (&refbk) : "cc" ); | |
512 | __ctl_set_bit(0, 9); | |
513 | return rc; | |
514 | } | |
515 | ||
516 | void pfault_fini(void) | |
517 | { | |
518 | pfault_refbk_t refbk = | |
519 | { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; | |
520 | ||
521 | if (pfault_disable) | |
522 | return; | |
523 | __ctl_clear_bit(0,9); | |
524 | __asm__ __volatile__( | |
525 | " diag %0,0,0x258\n" | |
526 | "0:\n" | |
527 | ".section __ex_table,\"a\"\n" | |
528 | " .align 4\n" | |
529 | #ifndef CONFIG_ARCH_S390X | |
530 | " .long 0b,0b\n" | |
531 | #else /* CONFIG_ARCH_S390X */ | |
532 | " .quad 0b,0b\n" | |
533 | #endif /* CONFIG_ARCH_S390X */ | |
534 | ".previous" | |
535 | : : "a" (&refbk) : "cc" ); | |
536 | } | |
537 | ||
538 | asmlinkage void | |
539 | pfault_interrupt(struct pt_regs *regs, __u16 error_code) | |
540 | { | |
541 | struct task_struct *tsk; | |
542 | __u16 subcode; | |
543 | ||
544 | /* | |
545 | * Get the external interruption subcode & pfault | |
546 | * initial/completion signal bit. VM stores this | |
547 | * in the 'cpu address' field associated with the | |
548 | * external interrupt. | |
549 | */ | |
550 | subcode = S390_lowcore.cpu_addr; | |
551 | if ((subcode & 0xff00) != __SUBCODE_MASK) | |
552 | return; | |
553 | ||
554 | /* | |
555 | * Get the token (= address of the task structure of the affected task). | |
556 | */ | |
557 | tsk = *(struct task_struct **) __LC_PFAULT_INTPARM; | |
558 | ||
559 | if (subcode & 0x0080) { | |
560 | /* signal bit is set -> a page has been swapped in by VM */ | |
561 | if (xchg(&tsk->thread.pfault_wait, -1) != 0) { | |
562 | /* Initial interrupt was faster than the completion | |
563 | * interrupt. pfault_wait is valid. Set pfault_wait | |
564 | * back to zero and wake up the process. This can | |
565 | * safely be done because the task is still sleeping | |
b6d09449 | 566 | * and can't produce new pfaults. */ |
1da177e4 LT |
567 | tsk->thread.pfault_wait = 0; |
568 | wake_up_process(tsk); | |
b6d09449 | 569 | put_task_struct(tsk); |
1da177e4 LT |
570 | } |
571 | } else { | |
572 | /* signal bit not set -> a real page is missing. */ | |
b6d09449 | 573 | get_task_struct(tsk); |
1da177e4 LT |
574 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
575 | if (xchg(&tsk->thread.pfault_wait, 1) != 0) { | |
576 | /* Completion interrupt was faster than the initial | |
577 | * interrupt (swapped in a -1 for pfault_wait). Set | |
578 | * pfault_wait back to zero and exit. This can be | |
579 | * done safely because tsk is running in kernel | |
580 | * mode and can't produce new pfaults. */ | |
581 | tsk->thread.pfault_wait = 0; | |
582 | set_task_state(tsk, TASK_RUNNING); | |
b6d09449 | 583 | put_task_struct(tsk); |
1da177e4 LT |
584 | } else |
585 | set_tsk_need_resched(tsk); | |
586 | } | |
587 | } | |
588 | #endif | |
589 |