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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/s390/mm/fault.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/s390/mm/fault.c')
-rw-r--r--arch/s390/mm/fault.c586
1 files changed, 586 insertions, 0 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
new file mode 100644
index 000000000000..80306bc8c799
--- /dev/null
+++ b/arch/s390/mm/fault.c
@@ -0,0 +1,586 @@
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
47extern int sysctl_userprocess_debug;
48#endif
49
50extern void die(const char *,struct pt_regs *,long);
51
52extern 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 */
59void 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 */
83static 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 */
108static 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 */
130static 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 */
163extern inline void
164do_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 */
210 if (user_address == 0 || in_interrupt() || !mm)
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 */
235good_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
246survive:
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 */
279bad_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
290no_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*/
317out_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
328do_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
344void 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
350void 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
357typedef 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
364static pseudo_wait_t *pseudo_lock_queue = NULL;
365static spinlock_t pseudo_wait_spinlock; /* spinlock to protect lock queue */
366
367/*
368 * This routine handles 'pagex' pseudo page faults.
369 */
370asmlinkage void
371do_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 */
468static int pfault_disable = 0;
469
470static int __init nopfault(char *str)
471{
472 pfault_disable = 1;
473 return 1;
474}
475
476__setup("nopfault", nopfault);
477
478typedef 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
489int 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
516void 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
538asmlinkage void
539pfault_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
566 * and can't procude new pfaults. */
567 tsk->thread.pfault_wait = 0;
568 wake_up_process(tsk);
569 }
570 } else {
571 /* signal bit not set -> a real page is missing. */
572 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
573 if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
574 /* Completion interrupt was faster than the initial
575 * interrupt (swapped in a -1 for pfault_wait). Set
576 * pfault_wait back to zero and exit. This can be
577 * done safely because tsk is running in kernel
578 * mode and can't produce new pfaults. */
579 tsk->thread.pfault_wait = 0;
580 set_task_state(tsk, TASK_RUNNING);
581 } else
582 set_tsk_need_resched(tsk);
583 }
584}
585#endif
586