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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 | ||
1da177e4 LT |
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/smp.h> | |
23 | #include <linux/smp_lock.h> | |
24 | #include <linux/init.h> | |
25 | #include <linux/console.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/hardirq.h> | |
4ba069b8 | 28 | #include <linux/kprobes.h> |
1da177e4 LT |
29 | |
30 | #include <asm/system.h> | |
31 | #include <asm/uaccess.h> | |
32 | #include <asm/pgtable.h> | |
4ba069b8 | 33 | #include <asm/kdebug.h> |
29b08d2b | 34 | #include <asm/s390_ext.h> |
1da177e4 | 35 | |
347a8dc3 | 36 | #ifndef CONFIG_64BIT |
1da177e4 LT |
37 | #define __FAIL_ADDR_MASK 0x7ffff000 |
38 | #define __FIXUP_MASK 0x7fffffff | |
39 | #define __SUBCODE_MASK 0x0200 | |
40 | #define __PF_RES_FIELD 0ULL | |
347a8dc3 | 41 | #else /* CONFIG_64BIT */ |
1da177e4 LT |
42 | #define __FAIL_ADDR_MASK -4096L |
43 | #define __FIXUP_MASK ~0L | |
44 | #define __SUBCODE_MASK 0x0600 | |
45 | #define __PF_RES_FIELD 0x8000000000000000ULL | |
347a8dc3 | 46 | #endif /* CONFIG_64BIT */ |
1da177e4 LT |
47 | |
48 | #ifdef CONFIG_SYSCTL | |
49 | extern int sysctl_userprocess_debug; | |
50 | #endif | |
51 | ||
52 | extern void die(const char *,struct pt_regs *,long); | |
53 | ||
4ba069b8 | 54 | #ifdef CONFIG_KPROBES |
2b67fc46 | 55 | static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); |
4ba069b8 MG |
56 | int register_page_fault_notifier(struct notifier_block *nb) |
57 | { | |
58 | return atomic_notifier_chain_register(¬ify_page_fault_chain, nb); | |
59 | } | |
60 | ||
61 | int unregister_page_fault_notifier(struct notifier_block *nb) | |
62 | { | |
63 | return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); | |
64 | } | |
65 | ||
66 | static inline int notify_page_fault(enum die_val val, const char *str, | |
67 | struct pt_regs *regs, long err, int trap, int sig) | |
68 | { | |
69 | struct die_args args = { | |
70 | .regs = regs, | |
71 | .str = str, | |
72 | .err = err, | |
73 | .trapnr = trap, | |
74 | .signr = sig | |
75 | }; | |
76 | return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args); | |
77 | } | |
78 | #else | |
79 | static inline int notify_page_fault(enum die_val val, const char *str, | |
80 | struct pt_regs *regs, long err, int trap, int sig) | |
81 | { | |
82 | return NOTIFY_DONE; | |
83 | } | |
84 | #endif | |
85 | ||
1da177e4 LT |
86 | extern spinlock_t timerlist_lock; |
87 | ||
88 | /* | |
89 | * Unlock any spinlocks which will prevent us from getting the | |
90 | * message out (timerlist_lock is acquired through the | |
91 | * console unblank code) | |
92 | */ | |
93 | void bust_spinlocks(int yes) | |
94 | { | |
95 | if (yes) { | |
96 | oops_in_progress = 1; | |
97 | } else { | |
98 | int loglevel_save = console_loglevel; | |
99 | console_unblank(); | |
100 | oops_in_progress = 0; | |
101 | /* | |
102 | * OK, the message is on the console. Now we call printk() | |
103 | * without oops_in_progress set so that printk will give klogd | |
104 | * a poke. Hold onto your hats... | |
105 | */ | |
106 | console_loglevel = 15; | |
107 | printk(" "); | |
108 | console_loglevel = loglevel_save; | |
109 | } | |
110 | } | |
111 | ||
112 | /* | |
113 | * Check which address space is addressed by the access | |
114 | * register in S390_lowcore.exc_access_id. | |
115 | * Returns 1 for user space and 0 for kernel space. | |
116 | */ | |
117 | static int __check_access_register(struct pt_regs *regs, int error_code) | |
118 | { | |
119 | int areg = S390_lowcore.exc_access_id; | |
120 | ||
121 | if (areg == 0) | |
122 | /* Access via access register 0 -> kernel address */ | |
123 | return 0; | |
124 | save_access_regs(current->thread.acrs); | |
125 | if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1) | |
126 | /* | |
127 | * access register contains 0 -> kernel address, | |
128 | * access register contains 1 -> user space address | |
129 | */ | |
130 | return current->thread.acrs[areg]; | |
131 | ||
132 | /* Something unhealthy was done with the access registers... */ | |
133 | die("page fault via unknown access register", regs, error_code); | |
134 | do_exit(SIGKILL); | |
135 | return 0; | |
136 | } | |
137 | ||
138 | /* | |
139 | * Check which address space the address belongs to. | |
140 | * Returns 1 for user space and 0 for kernel space. | |
141 | */ | |
142 | static inline int check_user_space(struct pt_regs *regs, int error_code) | |
143 | { | |
144 | /* | |
145 | * The lowest two bits of S390_lowcore.trans_exc_code indicate | |
146 | * which paging table was used: | |
147 | * 0: Primary Segment Table Descriptor | |
148 | * 1: STD determined via access register | |
149 | * 2: Secondary Segment Table Descriptor | |
150 | * 3: Home Segment Table Descriptor | |
151 | */ | |
152 | int descriptor = S390_lowcore.trans_exc_code & 3; | |
153 | if (unlikely(descriptor == 1)) | |
154 | return __check_access_register(regs, error_code); | |
155 | if (descriptor == 2) | |
156 | return current->thread.mm_segment.ar4; | |
157 | return descriptor != 0; | |
158 | } | |
159 | ||
160 | /* | |
161 | * Send SIGSEGV to task. This is an external routine | |
162 | * to keep the stack usage of do_page_fault small. | |
163 | */ | |
164 | static void do_sigsegv(struct pt_regs *regs, unsigned long error_code, | |
165 | int si_code, unsigned long address) | |
166 | { | |
167 | struct siginfo si; | |
168 | ||
169 | #if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG) | |
170 | #if defined(CONFIG_SYSCTL) | |
171 | if (sysctl_userprocess_debug) | |
172 | #endif | |
173 | { | |
174 | printk("User process fault: interruption code 0x%lX\n", | |
175 | error_code); | |
176 | printk("failing address: %lX\n", address); | |
177 | show_regs(regs); | |
178 | } | |
179 | #endif | |
180 | si.si_signo = SIGSEGV; | |
181 | si.si_code = si_code; | |
d2c993d8 | 182 | si.si_addr = (void __user *) address; |
1da177e4 LT |
183 | force_sig_info(SIGSEGV, &si, current); |
184 | } | |
185 | ||
186 | /* | |
187 | * This routine handles page faults. It determines the address, | |
188 | * and the problem, and then passes it off to one of the appropriate | |
189 | * routines. | |
190 | * | |
191 | * error_code: | |
192 | * 04 Protection -> Write-Protection (suprression) | |
193 | * 10 Segment translation -> Not present (nullification) | |
194 | * 11 Page translation -> Not present (nullification) | |
195 | * 3b Region third trans. -> Not present (nullification) | |
196 | */ | |
4ba069b8 | 197 | static inline void __kprobes |
1da177e4 LT |
198 | do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) |
199 | { | |
200 | struct task_struct *tsk; | |
201 | struct mm_struct *mm; | |
202 | struct vm_area_struct * vma; | |
203 | unsigned long address; | |
204 | int user_address; | |
205 | const struct exception_table_entry *fixup; | |
206 | int si_code = SEGV_MAPERR; | |
207 | ||
208 | tsk = current; | |
209 | mm = tsk->mm; | |
210 | ||
4ba069b8 MG |
211 | if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, |
212 | SIGSEGV) == NOTIFY_STOP) | |
213 | return; | |
214 | ||
1da177e4 LT |
215 | /* |
216 | * Check for low-address protection. This needs to be treated | |
217 | * as a special case because the translation exception code | |
218 | * field is not guaranteed to contain valid data in this case. | |
219 | */ | |
220 | if (is_protection && !(S390_lowcore.trans_exc_code & 4)) { | |
221 | ||
222 | /* Low-address protection hit in kernel mode means | |
223 | NULL pointer write access in kernel mode. */ | |
224 | if (!(regs->psw.mask & PSW_MASK_PSTATE)) { | |
225 | address = 0; | |
226 | user_address = 0; | |
227 | goto no_context; | |
228 | } | |
229 | ||
230 | /* Low-address protection hit in user mode 'cannot happen'. */ | |
231 | die ("Low-address protection", regs, error_code); | |
232 | do_exit(SIGKILL); | |
233 | } | |
234 | ||
235 | /* | |
236 | * get the failing address | |
237 | * more specific the segment and page table portion of | |
238 | * the address | |
239 | */ | |
240 | address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; | |
241 | user_address = check_user_space(regs, error_code); | |
242 | ||
243 | /* | |
244 | * Verify that the fault happened in user space, that | |
245 | * we are not in an interrupt and that there is a | |
246 | * user context. | |
247 | */ | |
595bf2aa | 248 | if (user_address == 0 || in_atomic() || !mm) |
1da177e4 LT |
249 | goto no_context; |
250 | ||
251 | /* | |
252 | * When we get here, the fault happened in the current | |
253 | * task's user address space, so we can switch on the | |
254 | * interrupts again and then search the VMAs | |
255 | */ | |
256 | local_irq_enable(); | |
257 | ||
258 | down_read(&mm->mmap_sem); | |
259 | ||
260 | vma = find_vma(mm, address); | |
261 | if (!vma) | |
262 | goto bad_area; | |
263 | if (vma->vm_start <= address) | |
264 | goto good_area; | |
265 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
266 | goto bad_area; | |
267 | if (expand_stack(vma, address)) | |
268 | goto bad_area; | |
269 | /* | |
270 | * Ok, we have a good vm_area for this memory access, so | |
271 | * we can handle it.. | |
272 | */ | |
273 | good_area: | |
274 | si_code = SEGV_ACCERR; | |
275 | if (!is_protection) { | |
276 | /* page not present, check vm flags */ | |
277 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
278 | goto bad_area; | |
279 | } else { | |
280 | if (!(vma->vm_flags & VM_WRITE)) | |
281 | goto bad_area; | |
282 | } | |
283 | ||
284 | survive: | |
285 | /* | |
286 | * If for any reason at all we couldn't handle the fault, | |
287 | * make sure we exit gracefully rather than endlessly redo | |
288 | * the fault. | |
289 | */ | |
290 | switch (handle_mm_fault(mm, vma, address, is_protection)) { | |
291 | case VM_FAULT_MINOR: | |
292 | tsk->min_flt++; | |
293 | break; | |
294 | case VM_FAULT_MAJOR: | |
295 | tsk->maj_flt++; | |
296 | break; | |
297 | case VM_FAULT_SIGBUS: | |
298 | goto do_sigbus; | |
299 | case VM_FAULT_OOM: | |
300 | goto out_of_memory; | |
301 | default: | |
302 | BUG(); | |
303 | } | |
304 | ||
305 | up_read(&mm->mmap_sem); | |
306 | /* | |
307 | * The instruction that caused the program check will | |
308 | * be repeated. Don't signal single step via SIGTRAP. | |
309 | */ | |
310 | clear_tsk_thread_flag(current, TIF_SINGLE_STEP); | |
311 | return; | |
312 | ||
313 | /* | |
314 | * Something tried to access memory that isn't in our memory map.. | |
315 | * Fix it, but check if it's kernel or user first.. | |
316 | */ | |
317 | bad_area: | |
318 | up_read(&mm->mmap_sem); | |
319 | ||
320 | /* User mode accesses just cause a SIGSEGV */ | |
321 | if (regs->psw.mask & PSW_MASK_PSTATE) { | |
322 | tsk->thread.prot_addr = address; | |
323 | tsk->thread.trap_no = error_code; | |
324 | do_sigsegv(regs, error_code, si_code, address); | |
325 | return; | |
326 | } | |
327 | ||
328 | no_context: | |
329 | /* Are we prepared to handle this kernel fault? */ | |
330 | fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); | |
331 | if (fixup) { | |
332 | regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; | |
333 | return; | |
334 | } | |
335 | ||
336 | /* | |
337 | * Oops. The kernel tried to access some bad page. We'll have to | |
338 | * terminate things with extreme prejudice. | |
339 | */ | |
340 | if (user_address == 0) | |
341 | printk(KERN_ALERT "Unable to handle kernel pointer dereference" | |
342 | " at virtual kernel address %p\n", (void *)address); | |
343 | else | |
344 | printk(KERN_ALERT "Unable to handle kernel paging request" | |
345 | " at virtual user address %p\n", (void *)address); | |
346 | ||
347 | die("Oops", regs, error_code); | |
348 | do_exit(SIGKILL); | |
349 | ||
350 | ||
351 | /* | |
352 | * We ran out of memory, or some other thing happened to us that made | |
353 | * us unable to handle the page fault gracefully. | |
354 | */ | |
355 | out_of_memory: | |
356 | up_read(&mm->mmap_sem); | |
f400e198 | 357 | if (is_init(tsk)) { |
1da177e4 | 358 | yield(); |
bac9c66c | 359 | down_read(&mm->mmap_sem); |
1da177e4 LT |
360 | goto survive; |
361 | } | |
362 | printk("VM: killing process %s\n", tsk->comm); | |
363 | if (regs->psw.mask & PSW_MASK_PSTATE) | |
364 | do_exit(SIGKILL); | |
365 | goto no_context; | |
366 | ||
367 | do_sigbus: | |
368 | up_read(&mm->mmap_sem); | |
369 | ||
370 | /* | |
371 | * Send a sigbus, regardless of whether we were in kernel | |
372 | * or user mode. | |
373 | */ | |
374 | tsk->thread.prot_addr = address; | |
375 | tsk->thread.trap_no = error_code; | |
376 | force_sig(SIGBUS, tsk); | |
377 | ||
378 | /* Kernel mode? Handle exceptions or die */ | |
379 | if (!(regs->psw.mask & PSW_MASK_PSTATE)) | |
380 | goto no_context; | |
381 | } | |
382 | ||
383 | void do_protection_exception(struct pt_regs *regs, unsigned long error_code) | |
384 | { | |
385 | regs->psw.addr -= (error_code >> 16); | |
386 | do_exception(regs, 4, 1); | |
387 | } | |
388 | ||
389 | void do_dat_exception(struct pt_regs *regs, unsigned long error_code) | |
390 | { | |
391 | do_exception(regs, error_code & 0xff, 0); | |
392 | } | |
393 | ||
1da177e4 LT |
394 | #ifdef CONFIG_PFAULT |
395 | /* | |
396 | * 'pfault' pseudo page faults routines. | |
397 | */ | |
29b08d2b | 398 | static ext_int_info_t ext_int_pfault; |
1da177e4 LT |
399 | static int pfault_disable = 0; |
400 | ||
401 | static int __init nopfault(char *str) | |
402 | { | |
403 | pfault_disable = 1; | |
404 | return 1; | |
405 | } | |
406 | ||
407 | __setup("nopfault", nopfault); | |
408 | ||
409 | typedef struct { | |
410 | __u16 refdiagc; | |
411 | __u16 reffcode; | |
412 | __u16 refdwlen; | |
413 | __u16 refversn; | |
414 | __u64 refgaddr; | |
415 | __u64 refselmk; | |
416 | __u64 refcmpmk; | |
417 | __u64 reserved; | |
418 | } __attribute__ ((packed)) pfault_refbk_t; | |
419 | ||
420 | int pfault_init(void) | |
421 | { | |
422 | pfault_refbk_t refbk = | |
423 | { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48, | |
424 | __PF_RES_FIELD }; | |
425 | int rc; | |
426 | ||
29b08d2b | 427 | if (!MACHINE_IS_VM || pfault_disable) |
1da177e4 | 428 | return -1; |
94c12cc7 MS |
429 | asm volatile( |
430 | " diag %1,%0,0x258\n" | |
431 | "0: j 2f\n" | |
432 | "1: la %0,8\n" | |
1da177e4 | 433 | "2:\n" |
94c12cc7 MS |
434 | EX_TABLE(0b,1b) |
435 | : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
436 | __ctl_set_bit(0, 9); |
437 | return rc; | |
438 | } | |
439 | ||
440 | void pfault_fini(void) | |
441 | { | |
442 | pfault_refbk_t refbk = | |
443 | { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL }; | |
444 | ||
29b08d2b | 445 | if (!MACHINE_IS_VM || pfault_disable) |
1da177e4 LT |
446 | return; |
447 | __ctl_clear_bit(0,9); | |
94c12cc7 MS |
448 | asm volatile( |
449 | " diag %0,0,0x258\n" | |
1da177e4 | 450 | "0:\n" |
94c12cc7 MS |
451 | EX_TABLE(0b,0b) |
452 | : : "a" (&refbk), "m" (refbk) : "cc"); | |
1da177e4 LT |
453 | } |
454 | ||
2b67fc46 | 455 | static void pfault_interrupt(__u16 error_code) |
1da177e4 LT |
456 | { |
457 | struct task_struct *tsk; | |
458 | __u16 subcode; | |
459 | ||
460 | /* | |
461 | * Get the external interruption subcode & pfault | |
462 | * initial/completion signal bit. VM stores this | |
463 | * in the 'cpu address' field associated with the | |
464 | * external interrupt. | |
465 | */ | |
466 | subcode = S390_lowcore.cpu_addr; | |
467 | if ((subcode & 0xff00) != __SUBCODE_MASK) | |
468 | return; | |
469 | ||
470 | /* | |
471 | * Get the token (= address of the task structure of the affected task). | |
472 | */ | |
473 | tsk = *(struct task_struct **) __LC_PFAULT_INTPARM; | |
474 | ||
475 | if (subcode & 0x0080) { | |
476 | /* signal bit is set -> a page has been swapped in by VM */ | |
477 | if (xchg(&tsk->thread.pfault_wait, -1) != 0) { | |
478 | /* Initial interrupt was faster than the completion | |
479 | * interrupt. pfault_wait is valid. Set pfault_wait | |
480 | * back to zero and wake up the process. This can | |
481 | * safely be done because the task is still sleeping | |
b6d09449 | 482 | * and can't produce new pfaults. */ |
1da177e4 LT |
483 | tsk->thread.pfault_wait = 0; |
484 | wake_up_process(tsk); | |
b6d09449 | 485 | put_task_struct(tsk); |
1da177e4 LT |
486 | } |
487 | } else { | |
488 | /* signal bit not set -> a real page is missing. */ | |
b6d09449 | 489 | get_task_struct(tsk); |
1da177e4 LT |
490 | set_task_state(tsk, TASK_UNINTERRUPTIBLE); |
491 | if (xchg(&tsk->thread.pfault_wait, 1) != 0) { | |
492 | /* Completion interrupt was faster than the initial | |
493 | * interrupt (swapped in a -1 for pfault_wait). Set | |
494 | * pfault_wait back to zero and exit. This can be | |
495 | * done safely because tsk is running in kernel | |
496 | * mode and can't produce new pfaults. */ | |
497 | tsk->thread.pfault_wait = 0; | |
498 | set_task_state(tsk, TASK_RUNNING); | |
b6d09449 | 499 | put_task_struct(tsk); |
1da177e4 LT |
500 | } else |
501 | set_tsk_need_resched(tsk); | |
502 | } | |
503 | } | |
1da177e4 | 504 | |
29b08d2b HC |
505 | void __init pfault_irq_init(void) |
506 | { | |
507 | if (!MACHINE_IS_VM) | |
508 | return; | |
509 | ||
510 | /* | |
511 | * Try to get pfault pseudo page faults going. | |
512 | */ | |
513 | if (register_early_external_interrupt(0x2603, pfault_interrupt, | |
514 | &ext_int_pfault) != 0) | |
515 | panic("Couldn't request external interrupt 0x2603"); | |
516 | ||
517 | if (pfault_init() == 0) | |
518 | return; | |
519 | ||
520 | /* Tough luck, no pfault. */ | |
521 | pfault_disable = 1; | |
522 | unregister_early_external_interrupt(0x2603, pfault_interrupt, | |
523 | &ext_int_pfault); | |
524 | } | |
525 | #endif |