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[/] [test_project/] [trunk/] [linux_sd_driver/] [arch/] [s390/] [mm/] [fault.c] - Blame information for rev 63

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1 63 marcus.erl
/*
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/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/kdebug.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
#include <linux/kprobes.h>
30
#include <linux/uaccess.h>
31
 
32
#include <asm/system.h>
33
#include <asm/pgtable.h>
34
#include <asm/s390_ext.h>
35
 
36
#ifndef CONFIG_64BIT
37
#define __FAIL_ADDR_MASK 0x7ffff000
38
#define __FIXUP_MASK 0x7fffffff
39
#define __SUBCODE_MASK 0x0200
40
#define __PF_RES_FIELD 0ULL
41
#else /* CONFIG_64BIT */
42
#define __FAIL_ADDR_MASK -4096L
43
#define __FIXUP_MASK ~0L
44
#define __SUBCODE_MASK 0x0600
45
#define __PF_RES_FIELD 0x8000000000000000ULL
46
#endif /* CONFIG_64BIT */
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
 
54
#ifdef CONFIG_KPROBES
55
static inline int notify_page_fault(struct pt_regs *regs, long err)
56
{
57
        int ret = 0;
58
 
59
        /* kprobe_running() needs smp_processor_id() */
60
        if (!user_mode(regs)) {
61
                preempt_disable();
62
                if (kprobe_running() && kprobe_fault_handler(regs, 14))
63
                        ret = 1;
64
                preempt_enable();
65
        }
66
 
67
        return ret;
68
}
69
#else
70
static inline int notify_page_fault(struct pt_regs *regs, long err)
71
{
72
        return 0;
73
}
74
#endif
75
 
76
 
77
/*
78
 * Unlock any spinlocks which will prevent us from getting the
79
 * message out.
80
 */
81
void bust_spinlocks(int yes)
82
{
83
        if (yes) {
84
                oops_in_progress = 1;
85
        } else {
86
                int loglevel_save = console_loglevel;
87
                console_unblank();
88
                oops_in_progress = 0;
89
                /*
90
                 * OK, the message is on the console.  Now we call printk()
91
                 * without oops_in_progress set so that printk will give klogd
92
                 * a poke.  Hold onto your hats...
93
                 */
94
                console_loglevel = 15;
95
                printk(" ");
96
                console_loglevel = loglevel_save;
97
        }
98
}
99
 
100
/*
101
 * Returns the address space associated with the fault.
102
 * Returns 0 for kernel space, 1 for user space and
103
 * 2 for code execution in user space with noexec=on.
104
 */
105
static inline int check_space(struct task_struct *tsk)
106
{
107
        /*
108
         * The lowest two bits of S390_lowcore.trans_exc_code
109
         * indicate which paging table was used.
110
         */
111
        int desc = S390_lowcore.trans_exc_code & 3;
112
 
113
        if (desc == 3)  /* Home Segment Table Descriptor */
114
                return switch_amode == 0;
115
        if (desc == 2)  /* Secondary Segment Table Descriptor */
116
                return tsk->thread.mm_segment.ar4;
117
#ifdef CONFIG_S390_SWITCH_AMODE
118
        if (unlikely(desc == 1)) { /* STD determined via access register */
119
                /* %a0 always indicates primary space. */
120
                if (S390_lowcore.exc_access_id != 0) {
121
                        save_access_regs(tsk->thread.acrs);
122
                        /*
123
                         * An alet of 0 indicates primary space.
124
                         * An alet of 1 indicates secondary space.
125
                         * Any other alet values generate an
126
                         * alen-translation exception.
127
                         */
128
                        if (tsk->thread.acrs[S390_lowcore.exc_access_id])
129
                                return tsk->thread.mm_segment.ar4;
130
                }
131
        }
132
#endif
133
        /* Primary Segment Table Descriptor */
134
        return switch_amode << s390_noexec;
135
}
136
 
137
/*
138
 * Send SIGSEGV to task.  This is an external routine
139
 * to keep the stack usage of do_page_fault small.
140
 */
141
static void do_sigsegv(struct pt_regs *regs, unsigned long error_code,
142
                       int si_code, unsigned long address)
143
{
144
        struct siginfo si;
145
 
146
#if defined(CONFIG_SYSCTL) || defined(CONFIG_PROCESS_DEBUG)
147
#if defined(CONFIG_SYSCTL)
148
        if (sysctl_userprocess_debug)
149
#endif
150
        {
151
                printk("User process fault: interruption code 0x%lX\n",
152
                       error_code);
153
                printk("failing address: %lX\n", address);
154
                show_regs(regs);
155
        }
156
#endif
157
        si.si_signo = SIGSEGV;
158
        si.si_code = si_code;
159
        si.si_addr = (void __user *) address;
160
        force_sig_info(SIGSEGV, &si, current);
161
}
162
 
163
static void do_no_context(struct pt_regs *regs, unsigned long error_code,
164
                          unsigned long address)
165
{
166
        const struct exception_table_entry *fixup;
167
 
168
        /* Are we prepared to handle this kernel fault?  */
169
        fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK);
170
        if (fixup) {
171
                regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE;
172
                return;
173
        }
174
 
175
        /*
176
         * Oops. The kernel tried to access some bad page. We'll have to
177
         * terminate things with extreme prejudice.
178
         */
179
        if (check_space(current) == 0)
180
                printk(KERN_ALERT "Unable to handle kernel pointer dereference"
181
                       " at virtual kernel address %p\n", (void *)address);
182
        else
183
                printk(KERN_ALERT "Unable to handle kernel paging request"
184
                       " at virtual user address %p\n", (void *)address);
185
 
186
        die("Oops", regs, error_code);
187
        do_exit(SIGKILL);
188
}
189
 
190
static void do_low_address(struct pt_regs *regs, unsigned long error_code)
191
{
192
        /* Low-address protection hit in kernel mode means
193
           NULL pointer write access in kernel mode.  */
194
        if (regs->psw.mask & PSW_MASK_PSTATE) {
195
                /* Low-address protection hit in user mode 'cannot happen'. */
196
                die ("Low-address protection", regs, error_code);
197
                do_exit(SIGKILL);
198
        }
199
 
200
        do_no_context(regs, error_code, 0);
201
}
202
 
203
/*
204
 * We ran out of memory, or some other thing happened to us that made
205
 * us unable to handle the page fault gracefully.
206
 */
207
static int do_out_of_memory(struct pt_regs *regs, unsigned long error_code,
208
                            unsigned long address)
209
{
210
        struct task_struct *tsk = current;
211
        struct mm_struct *mm = tsk->mm;
212
 
213
        up_read(&mm->mmap_sem);
214
        if (is_global_init(tsk)) {
215
                yield();
216
                down_read(&mm->mmap_sem);
217
                return 1;
218
        }
219
        printk("VM: killing process %s\n", tsk->comm);
220
        if (regs->psw.mask & PSW_MASK_PSTATE)
221
                do_group_exit(SIGKILL);
222
        do_no_context(regs, error_code, address);
223
        return 0;
224
}
225
 
226
static void do_sigbus(struct pt_regs *regs, unsigned long error_code,
227
                      unsigned long address)
228
{
229
        struct task_struct *tsk = current;
230
        struct mm_struct *mm = tsk->mm;
231
 
232
        up_read(&mm->mmap_sem);
233
        /*
234
         * Send a sigbus, regardless of whether we were in kernel
235
         * or user mode.
236
         */
237
        tsk->thread.prot_addr = address;
238
        tsk->thread.trap_no = error_code;
239
        force_sig(SIGBUS, tsk);
240
 
241
        /* Kernel mode? Handle exceptions or die */
242
        if (!(regs->psw.mask & PSW_MASK_PSTATE))
243
                do_no_context(regs, error_code, address);
244
}
245
 
246
#ifdef CONFIG_S390_EXEC_PROTECT
247
extern long sys_sigreturn(struct pt_regs *regs);
248
extern long sys_rt_sigreturn(struct pt_regs *regs);
249
extern long sys32_sigreturn(struct pt_regs *regs);
250
extern long sys32_rt_sigreturn(struct pt_regs *regs);
251
 
252
static int signal_return(struct mm_struct *mm, struct pt_regs *regs,
253
                         unsigned long address, unsigned long error_code)
254
{
255
        u16 instruction;
256
        int rc;
257
#ifdef CONFIG_COMPAT
258
        int compat;
259
#endif
260
 
261
        pagefault_disable();
262
        rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
263
        pagefault_enable();
264
        if (rc)
265
                return -EFAULT;
266
 
267
        up_read(&mm->mmap_sem);
268
        clear_tsk_thread_flag(current, TIF_SINGLE_STEP);
269
#ifdef CONFIG_COMPAT
270
        compat = test_tsk_thread_flag(current, TIF_31BIT);
271
        if (compat && instruction == 0x0a77)
272
                sys32_sigreturn(regs);
273
        else if (compat && instruction == 0x0aad)
274
                sys32_rt_sigreturn(regs);
275
        else
276
#endif
277
        if (instruction == 0x0a77)
278
                sys_sigreturn(regs);
279
        else if (instruction == 0x0aad)
280
                sys_rt_sigreturn(regs);
281
        else {
282
                current->thread.prot_addr = address;
283
                current->thread.trap_no = error_code;
284
                do_sigsegv(regs, error_code, SEGV_MAPERR, address);
285
        }
286
        return 0;
287
}
288
#endif /* CONFIG_S390_EXEC_PROTECT */
289
 
290
/*
291
 * This routine handles page faults.  It determines the address,
292
 * and the problem, and then passes it off to one of the appropriate
293
 * routines.
294
 *
295
 * error_code:
296
 *   04       Protection           ->  Write-Protection  (suprression)
297
 *   10       Segment translation  ->  Not present       (nullification)
298
 *   11       Page translation     ->  Not present       (nullification)
299
 *   3b       Region third trans.  ->  Not present       (nullification)
300
 */
301
static inline void
302
do_exception(struct pt_regs *regs, unsigned long error_code, int write)
303
{
304
        struct task_struct *tsk;
305
        struct mm_struct *mm;
306
        struct vm_area_struct *vma;
307
        unsigned long address;
308
        int space;
309
        int si_code;
310
        int fault;
311
 
312
        if (notify_page_fault(regs, error_code))
313
                return;
314
 
315
        tsk = current;
316
        mm = tsk->mm;
317
 
318
        /* get the failing address and the affected space */
319
        address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK;
320
        space = check_space(tsk);
321
 
322
        /*
323
         * Verify that the fault happened in user space, that
324
         * we are not in an interrupt and that there is a
325
         * user context.
326
         */
327
        if (unlikely(space == 0 || in_atomic() || !mm))
328
                goto no_context;
329
 
330
        /*
331
         * When we get here, the fault happened in the current
332
         * task's user address space, so we can switch on the
333
         * interrupts again and then search the VMAs
334
         */
335
        local_irq_enable();
336
 
337
        down_read(&mm->mmap_sem);
338
 
339
        si_code = SEGV_MAPERR;
340
        vma = find_vma(mm, address);
341
        if (!vma)
342
                goto bad_area;
343
 
344
#ifdef CONFIG_S390_EXEC_PROTECT
345
        if (unlikely((space == 2) && !(vma->vm_flags & VM_EXEC)))
346
                if (!signal_return(mm, regs, address, error_code))
347
                        /*
348
                         * signal_return() has done an up_read(&mm->mmap_sem)
349
                         * if it returns 0.
350
                         */
351
                        return;
352
#endif
353
 
354
        if (vma->vm_start <= address)
355
                goto good_area;
356
        if (!(vma->vm_flags & VM_GROWSDOWN))
357
                goto bad_area;
358
        if (expand_stack(vma, address))
359
                goto bad_area;
360
/*
361
 * Ok, we have a good vm_area for this memory access, so
362
 * we can handle it..
363
 */
364
good_area:
365
        si_code = SEGV_ACCERR;
366
        if (!write) {
367
                /* page not present, check vm flags */
368
                if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
369
                        goto bad_area;
370
        } else {
371
                if (!(vma->vm_flags & VM_WRITE))
372
                        goto bad_area;
373
        }
374
 
375
survive:
376
        /*
377
         * If for any reason at all we couldn't handle the fault,
378
         * make sure we exit gracefully rather than endlessly redo
379
         * the fault.
380
         */
381
        fault = handle_mm_fault(mm, vma, address, write);
382
        if (unlikely(fault & VM_FAULT_ERROR)) {
383
                if (fault & VM_FAULT_OOM) {
384
                        if (do_out_of_memory(regs, error_code, address))
385
                                goto survive;
386
                        return;
387
                } else if (fault & VM_FAULT_SIGBUS) {
388
                        do_sigbus(regs, error_code, address);
389
                        return;
390
                }
391
                BUG();
392
        }
393
        if (fault & VM_FAULT_MAJOR)
394
                tsk->maj_flt++;
395
        else
396
                tsk->min_flt++;
397
 
398
        up_read(&mm->mmap_sem);
399
        /*
400
         * The instruction that caused the program check will
401
         * be repeated. Don't signal single step via SIGTRAP.
402
         */
403
        clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP);
404
        return;
405
 
406
/*
407
 * Something tried to access memory that isn't in our memory map..
408
 * Fix it, but check if it's kernel or user first..
409
 */
410
bad_area:
411
        up_read(&mm->mmap_sem);
412
 
413
        /* User mode accesses just cause a SIGSEGV */
414
        if (regs->psw.mask & PSW_MASK_PSTATE) {
415
                tsk->thread.prot_addr = address;
416
                tsk->thread.trap_no = error_code;
417
                do_sigsegv(regs, error_code, si_code, address);
418
                return;
419
        }
420
 
421
no_context:
422
        do_no_context(regs, error_code, address);
423
}
424
 
425
void __kprobes do_protection_exception(struct pt_regs *regs,
426
                                       unsigned long error_code)
427
{
428
        /* Protection exception is supressing, decrement psw address. */
429
        regs->psw.addr -= (error_code >> 16);
430
        /*
431
         * Check for low-address protection.  This needs to be treated
432
         * as a special case because the translation exception code
433
         * field is not guaranteed to contain valid data in this case.
434
         */
435
        if (unlikely(!(S390_lowcore.trans_exc_code & 4))) {
436
                do_low_address(regs, error_code);
437
                return;
438
        }
439
        do_exception(regs, 4, 1);
440
}
441
 
442
void __kprobes do_dat_exception(struct pt_regs *regs, unsigned long error_code)
443
{
444
        do_exception(regs, error_code & 0xff, 0);
445
}
446
 
447
#ifdef CONFIG_PFAULT 
448
/*
449
 * 'pfault' pseudo page faults routines.
450
 */
451
static ext_int_info_t ext_int_pfault;
452
static int pfault_disable = 0;
453
 
454
static int __init nopfault(char *str)
455
{
456
        pfault_disable = 1;
457
        return 1;
458
}
459
 
460
__setup("nopfault", nopfault);
461
 
462
typedef struct {
463
        __u16 refdiagc;
464
        __u16 reffcode;
465
        __u16 refdwlen;
466
        __u16 refversn;
467
        __u64 refgaddr;
468
        __u64 refselmk;
469
        __u64 refcmpmk;
470
        __u64 reserved;
471
} __attribute__ ((packed, aligned(8))) pfault_refbk_t;
472
 
473
int pfault_init(void)
474
{
475
        pfault_refbk_t refbk =
476
                { 0x258, 0, 5, 2, __LC_CURRENT, 1ULL << 48, 1ULL << 48,
477
                  __PF_RES_FIELD };
478
        int rc;
479
 
480
        if (!MACHINE_IS_VM || pfault_disable)
481
                return -1;
482
        asm volatile(
483
                "       diag    %1,%0,0x258\n"
484
                "0:     j       2f\n"
485
                "1:     la      %0,8\n"
486
                "2:\n"
487
                EX_TABLE(0b,1b)
488
                : "=d" (rc) : "a" (&refbk), "m" (refbk) : "cc");
489
        __ctl_set_bit(0, 9);
490
        return rc;
491
}
492
 
493
void pfault_fini(void)
494
{
495
        pfault_refbk_t refbk =
496
        { 0x258, 1, 5, 2, 0ULL, 0ULL, 0ULL, 0ULL };
497
 
498
        if (!MACHINE_IS_VM || pfault_disable)
499
                return;
500
        __ctl_clear_bit(0,9);
501
        asm volatile(
502
                "       diag    %0,0,0x258\n"
503
                "0:\n"
504
                EX_TABLE(0b,0b)
505
                : : "a" (&refbk), "m" (refbk) : "cc");
506
}
507
 
508
static void pfault_interrupt(__u16 error_code)
509
{
510
        struct task_struct *tsk;
511
        __u16 subcode;
512
 
513
        /*
514
         * Get the external interruption subcode & pfault
515
         * initial/completion signal bit. VM stores this
516
         * in the 'cpu address' field associated with the
517
         * external interrupt.
518
         */
519
        subcode = S390_lowcore.cpu_addr;
520
        if ((subcode & 0xff00) != __SUBCODE_MASK)
521
                return;
522
 
523
        /*
524
         * Get the token (= address of the task structure of the affected task).
525
         */
526
        tsk = *(struct task_struct **) __LC_PFAULT_INTPARM;
527
 
528
        if (subcode & 0x0080) {
529
                /* signal bit is set -> a page has been swapped in by VM */
530
                if (xchg(&tsk->thread.pfault_wait, -1) != 0) {
531
                        /* Initial interrupt was faster than the completion
532
                         * interrupt. pfault_wait is valid. Set pfault_wait
533
                         * back to zero and wake up the process. This can
534
                         * safely be done because the task is still sleeping
535
                         * and can't produce new pfaults. */
536
                        tsk->thread.pfault_wait = 0;
537
                        wake_up_process(tsk);
538
                        put_task_struct(tsk);
539
                }
540
        } else {
541
                /* signal bit not set -> a real page is missing. */
542
                get_task_struct(tsk);
543
                set_task_state(tsk, TASK_UNINTERRUPTIBLE);
544
                if (xchg(&tsk->thread.pfault_wait, 1) != 0) {
545
                        /* Completion interrupt was faster than the initial
546
                         * interrupt (swapped in a -1 for pfault_wait). Set
547
                         * pfault_wait back to zero and exit. This can be
548
                         * done safely because tsk is running in kernel
549
                         * mode and can't produce new pfaults. */
550
                        tsk->thread.pfault_wait = 0;
551
                        set_task_state(tsk, TASK_RUNNING);
552
                        put_task_struct(tsk);
553
                } else
554
                        set_tsk_need_resched(tsk);
555
        }
556
}
557
 
558
void __init pfault_irq_init(void)
559
{
560
        if (!MACHINE_IS_VM)
561
                return;
562
 
563
        /*
564
         * Try to get pfault pseudo page faults going.
565
         */
566
        if (register_early_external_interrupt(0x2603, pfault_interrupt,
567
                                              &ext_int_pfault) != 0)
568
                panic("Couldn't request external interrupt 0x2603");
569
 
570
        if (pfault_init() == 0)
571
                return;
572
 
573
        /* Tough luck, no pfault. */
574
        pfault_disable = 1;
575
        unregister_early_external_interrupt(0x2603, pfault_interrupt,
576
                                            &ext_int_pfault);
577
}
578
#endif

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