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1/*
2 * Page fault handler for SH with an MMU.
3 *
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2012 Paul Mundt
6 *
7 * Based on linux/arch/i386/mm/fault.c:
8 * Copyright (C) 1995 Linus Torvalds
9 *
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file "COPYING" in the main directory of this archive
12 * for more details.
13 */
14#include <linux/kernel.h>
15#include <linux/mm.h>
16#include <linux/sched/signal.h>
17#include <linux/hardirq.h>
18#include <linux/kprobes.h>
19#include <linux/perf_event.h>
20#include <linux/kdebug.h>
21#include <linux/uaccess.h>
22#include <asm/io_trapped.h>
23#include <asm/mmu_context.h>
24#include <asm/tlbflush.h>
25#include <asm/traps.h>
26
27static inline int notify_page_fault(struct pt_regs *regs, int trap)
28{
29 int ret = 0;
30
31 if (kprobes_built_in() && !user_mode(regs)) {
32 preempt_disable();
33 if (kprobe_running() && kprobe_fault_handler(regs, trap))
34 ret = 1;
35 preempt_enable();
36 }
37
38 return ret;
39}
40
41static void
42force_sig_info_fault(int si_signo, int si_code, unsigned long address,
43 struct task_struct *tsk)
44{
45 siginfo_t info;
46
47 info.si_signo = si_signo;
48 info.si_errno = 0;
49 info.si_code = si_code;
50 info.si_addr = (void __user *)address;
51
52 force_sig_info(si_signo, &info, tsk);
53}
54
55/*
56 * This is useful to dump out the page tables associated with
57 * 'addr' in mm 'mm'.
58 */
59static void show_pte(struct mm_struct *mm, unsigned long addr)
60{
61 pgd_t *pgd;
62
63 if (mm) {
64 pgd = mm->pgd;
65 } else {
66 pgd = get_TTB();
67
68 if (unlikely(!pgd))
69 pgd = swapper_pg_dir;
70 }
71
72 printk(KERN_ALERT "pgd = %p\n", pgd);
73 pgd += pgd_index(addr);
74 printk(KERN_ALERT "[%08lx] *pgd=%0*Lx", addr,
75 (u32)(sizeof(*pgd) * 2), (u64)pgd_val(*pgd));
76
77 do {
78 pud_t *pud;
79 pmd_t *pmd;
80 pte_t *pte;
81
82 if (pgd_none(*pgd))
83 break;
84
85 if (pgd_bad(*pgd)) {
86 printk("(bad)");
87 break;
88 }
89
90 pud = pud_offset(pgd, addr);
91 if (PTRS_PER_PUD != 1)
92 printk(", *pud=%0*Lx", (u32)(sizeof(*pud) * 2),
93 (u64)pud_val(*pud));
94
95 if (pud_none(*pud))
96 break;
97
98 if (pud_bad(*pud)) {
99 printk("(bad)");
100 break;
101 }
102
103 pmd = pmd_offset(pud, addr);
104 if (PTRS_PER_PMD != 1)
105 printk(", *pmd=%0*Lx", (u32)(sizeof(*pmd) * 2),
106 (u64)pmd_val(*pmd));
107
108 if (pmd_none(*pmd))
109 break;
110
111 if (pmd_bad(*pmd)) {
112 printk("(bad)");
113 break;
114 }
115
116 /* We must not map this if we have highmem enabled */
117 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
118 break;
119
120 pte = pte_offset_kernel(pmd, addr);
121 printk(", *pte=%0*Lx", (u32)(sizeof(*pte) * 2),
122 (u64)pte_val(*pte));
123 } while (0);
124
125 printk("\n");
126}
127
128static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
129{
130 unsigned index = pgd_index(address);
131 pgd_t *pgd_k;
132 pud_t *pud, *pud_k;
133 pmd_t *pmd, *pmd_k;
134
135 pgd += index;
136 pgd_k = init_mm.pgd + index;
137
138 if (!pgd_present(*pgd_k))
139 return NULL;
140
141 pud = pud_offset(pgd, address);
142 pud_k = pud_offset(pgd_k, address);
143 if (!pud_present(*pud_k))
144 return NULL;
145
146 if (!pud_present(*pud))
147 set_pud(pud, *pud_k);
148
149 pmd = pmd_offset(pud, address);
150 pmd_k = pmd_offset(pud_k, address);
151 if (!pmd_present(*pmd_k))
152 return NULL;
153
154 if (!pmd_present(*pmd))
155 set_pmd(pmd, *pmd_k);
156 else {
157 /*
158 * The page tables are fully synchronised so there must
159 * be another reason for the fault. Return NULL here to
160 * signal that we have not taken care of the fault.
161 */
162 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
163 return NULL;
164 }
165
166 return pmd_k;
167}
168
169#ifdef CONFIG_SH_STORE_QUEUES
170#define __FAULT_ADDR_LIMIT P3_ADDR_MAX
171#else
172#define __FAULT_ADDR_LIMIT VMALLOC_END
173#endif
174
175/*
176 * Handle a fault on the vmalloc or module mapping area
177 */
178static noinline int vmalloc_fault(unsigned long address)
179{
180 pgd_t *pgd_k;
181 pmd_t *pmd_k;
182 pte_t *pte_k;
183
184 /* Make sure we are in vmalloc/module/P3 area: */
185 if (!(address >= VMALLOC_START && address < __FAULT_ADDR_LIMIT))
186 return -1;
187
188 /*
189 * Synchronize this task's top level page-table
190 * with the 'reference' page table.
191 *
192 * Do _not_ use "current" here. We might be inside
193 * an interrupt in the middle of a task switch..
194 */
195 pgd_k = get_TTB();
196 pmd_k = vmalloc_sync_one(pgd_k, address);
197 if (!pmd_k)
198 return -1;
199
200 pte_k = pte_offset_kernel(pmd_k, address);
201 if (!pte_present(*pte_k))
202 return -1;
203
204 return 0;
205}
206
207static void
208show_fault_oops(struct pt_regs *regs, unsigned long address)
209{
210 if (!oops_may_print())
211 return;
212
213 printk(KERN_ALERT "BUG: unable to handle kernel ");
214 if (address < PAGE_SIZE)
215 printk(KERN_CONT "NULL pointer dereference");
216 else
217 printk(KERN_CONT "paging request");
218
219 printk(KERN_CONT " at %08lx\n", address);
220 printk(KERN_ALERT "PC:");
221 printk_address(regs->pc, 1);
222
223 show_pte(NULL, address);
224}
225
226static noinline void
227no_context(struct pt_regs *regs, unsigned long error_code,
228 unsigned long address)
229{
230 /* Are we prepared to handle this kernel fault? */
231 if (fixup_exception(regs))
232 return;
233
234 if (handle_trapped_io(regs, address))
235 return;
236
237 /*
238 * Oops. The kernel tried to access some bad page. We'll have to
239 * terminate things with extreme prejudice.
240 */
241 bust_spinlocks(1);
242
243 show_fault_oops(regs, address);
244
245 die("Oops", regs, error_code);
246 bust_spinlocks(0);
247 do_exit(SIGKILL);
248}
249
250static void
251__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
252 unsigned long address, int si_code)
253{
254 struct task_struct *tsk = current;
255
256 /* User mode accesses just cause a SIGSEGV */
257 if (user_mode(regs)) {
258 /*
259 * It's possible to have interrupts off here:
260 */
261 local_irq_enable();
262
263 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
264
265 return;
266 }
267
268 no_context(regs, error_code, address);
269}
270
271static noinline void
272bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
273 unsigned long address)
274{
275 __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
276}
277
278static void
279__bad_area(struct pt_regs *regs, unsigned long error_code,
280 unsigned long address, int si_code)
281{
282 struct mm_struct *mm = current->mm;
283
284 /*
285 * Something tried to access memory that isn't in our memory map..
286 * Fix it, but check if it's kernel or user first..
287 */
288 up_read(&mm->mmap_sem);
289
290 __bad_area_nosemaphore(regs, error_code, address, si_code);
291}
292
293static noinline void
294bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
295{
296 __bad_area(regs, error_code, address, SEGV_MAPERR);
297}
298
299static noinline void
300bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
301 unsigned long address)
302{
303 __bad_area(regs, error_code, address, SEGV_ACCERR);
304}
305
306static void
307do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
308{
309 struct task_struct *tsk = current;
310 struct mm_struct *mm = tsk->mm;
311
312 up_read(&mm->mmap_sem);
313
314 /* Kernel mode? Handle exceptions or die: */
315 if (!user_mode(regs))
316 no_context(regs, error_code, address);
317
318 force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
319}
320
321static noinline int
322mm_fault_error(struct pt_regs *regs, unsigned long error_code,
323 unsigned long address, unsigned int fault)
324{
325 /*
326 * Pagefault was interrupted by SIGKILL. We have no reason to
327 * continue pagefault.
328 */
329 if (fatal_signal_pending(current)) {
330 if (!(fault & VM_FAULT_RETRY))
331 up_read(¤t->mm->mmap_sem);
332 if (!user_mode(regs))
333 no_context(regs, error_code, address);
334 return 1;
335 }
336
337 if (!(fault & VM_FAULT_ERROR))
338 return 0;
339
340 if (fault & VM_FAULT_OOM) {
341 /* Kernel mode? Handle exceptions or die: */
342 if (!user_mode(regs)) {
343 up_read(¤t->mm->mmap_sem);
344 no_context(regs, error_code, address);
345 return 1;
346 }
347 up_read(¤t->mm->mmap_sem);
348
349 /*
350 * We ran out of memory, call the OOM killer, and return the
351 * userspace (which will retry the fault, or kill us if we got
352 * oom-killed):
353 */
354 pagefault_out_of_memory();
355 } else {
356 if (fault & VM_FAULT_SIGBUS)
357 do_sigbus(regs, error_code, address);
358 else if (fault & VM_FAULT_SIGSEGV)
359 bad_area(regs, error_code, address);
360 else
361 BUG();
362 }
363
364 return 1;
365}
366
367static inline int access_error(int error_code, struct vm_area_struct *vma)
368{
369 if (error_code & FAULT_CODE_WRITE) {
370 /* write, present and write, not present: */
371 if (unlikely(!(vma->vm_flags & VM_WRITE)))
372 return 1;
373 return 0;
374 }
375
376 /* ITLB miss on NX page */
377 if (unlikely((error_code & FAULT_CODE_ITLB) &&
378 !(vma->vm_flags & VM_EXEC)))
379 return 1;
380
381 /* read, not present: */
382 if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
383 return 1;
384
385 return 0;
386}
387
388static int fault_in_kernel_space(unsigned long address)
389{
390 return address >= TASK_SIZE;
391}
392
393/*
394 * This routine handles page faults. It determines the address,
395 * and the problem, and then passes it off to one of the appropriate
396 * routines.
397 */
398asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
399 unsigned long error_code,
400 unsigned long address)
401{
402 unsigned long vec;
403 struct task_struct *tsk;
404 struct mm_struct *mm;
405 struct vm_area_struct * vma;
406 int fault;
407 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
408
409 tsk = current;
410 mm = tsk->mm;
411 vec = lookup_exception_vector();
412
413 /*
414 * We fault-in kernel-space virtual memory on-demand. The
415 * 'reference' page table is init_mm.pgd.
416 *
417 * NOTE! We MUST NOT take any locks for this case. We may
418 * be in an interrupt or a critical region, and should
419 * only copy the information from the master page table,
420 * nothing more.
421 */
422 if (unlikely(fault_in_kernel_space(address))) {
423 if (vmalloc_fault(address) >= 0)
424 return;
425 if (notify_page_fault(regs, vec))
426 return;
427
428 bad_area_nosemaphore(regs, error_code, address);
429 return;
430 }
431
432 if (unlikely(notify_page_fault(regs, vec)))
433 return;
434
435 /* Only enable interrupts if they were on before the fault */
436 if ((regs->sr & SR_IMASK) != SR_IMASK)
437 local_irq_enable();
438
439 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
440
441 /*
442 * If we're in an interrupt, have no user context or are running
443 * with pagefaults disabled then we must not take the fault:
444 */
445 if (unlikely(faulthandler_disabled() || !mm)) {
446 bad_area_nosemaphore(regs, error_code, address);
447 return;
448 }
449
450retry:
451 down_read(&mm->mmap_sem);
452
453 vma = find_vma(mm, address);
454 if (unlikely(!vma)) {
455 bad_area(regs, error_code, address);
456 return;
457 }
458 if (likely(vma->vm_start <= address))
459 goto good_area;
460 if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
461 bad_area(regs, error_code, address);
462 return;
463 }
464 if (unlikely(expand_stack(vma, address))) {
465 bad_area(regs, error_code, address);
466 return;
467 }
468
469 /*
470 * Ok, we have a good vm_area for this memory access, so
471 * we can handle it..
472 */
473good_area:
474 if (unlikely(access_error(error_code, vma))) {
475 bad_area_access_error(regs, error_code, address);
476 return;
477 }
478
479 set_thread_fault_code(error_code);
480
481 if (user_mode(regs))
482 flags |= FAULT_FLAG_USER;
483 if (error_code & FAULT_CODE_WRITE)
484 flags |= FAULT_FLAG_WRITE;
485
486 /*
487 * If for any reason at all we couldn't handle the fault,
488 * make sure we exit gracefully rather than endlessly redo
489 * the fault.
490 */
491 fault = handle_mm_fault(vma, address, flags);
492
493 if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
494 if (mm_fault_error(regs, error_code, address, fault))
495 return;
496
497 if (flags & FAULT_FLAG_ALLOW_RETRY) {
498 if (fault & VM_FAULT_MAJOR) {
499 tsk->maj_flt++;
500 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
501 regs, address);
502 } else {
503 tsk->min_flt++;
504 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
505 regs, address);
506 }
507 if (fault & VM_FAULT_RETRY) {
508 flags &= ~FAULT_FLAG_ALLOW_RETRY;
509 flags |= FAULT_FLAG_TRIED;
510
511 /*
512 * No need to up_read(&mm->mmap_sem) as we would
513 * have already released it in __lock_page_or_retry
514 * in mm/filemap.c.
515 */
516 goto retry;
517 }
518 }
519
520 up_read(&mm->mmap_sem);
521}
1/*
2 * Page fault handler for SH with an MMU.
3 *
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2012 Paul Mundt
6 *
7 * Based on linux/arch/i386/mm/fault.c:
8 * Copyright (C) 1995 Linus Torvalds
9 *
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file "COPYING" in the main directory of this archive
12 * for more details.
13 */
14#include <linux/kernel.h>
15#include <linux/mm.h>
16#include <linux/hardirq.h>
17#include <linux/kprobes.h>
18#include <linux/perf_event.h>
19#include <linux/kdebug.h>
20#include <asm/io_trapped.h>
21#include <asm/mmu_context.h>
22#include <asm/tlbflush.h>
23#include <asm/traps.h>
24
25static inline int notify_page_fault(struct pt_regs *regs, int trap)
26{
27 int ret = 0;
28
29 if (kprobes_built_in() && !user_mode(regs)) {
30 preempt_disable();
31 if (kprobe_running() && kprobe_fault_handler(regs, trap))
32 ret = 1;
33 preempt_enable();
34 }
35
36 return ret;
37}
38
39static void
40force_sig_info_fault(int si_signo, int si_code, unsigned long address,
41 struct task_struct *tsk)
42{
43 siginfo_t info;
44
45 info.si_signo = si_signo;
46 info.si_errno = 0;
47 info.si_code = si_code;
48 info.si_addr = (void __user *)address;
49
50 force_sig_info(si_signo, &info, tsk);
51}
52
53/*
54 * This is useful to dump out the page tables associated with
55 * 'addr' in mm 'mm'.
56 */
57static void show_pte(struct mm_struct *mm, unsigned long addr)
58{
59 pgd_t *pgd;
60
61 if (mm) {
62 pgd = mm->pgd;
63 } else {
64 pgd = get_TTB();
65
66 if (unlikely(!pgd))
67 pgd = swapper_pg_dir;
68 }
69
70 printk(KERN_ALERT "pgd = %p\n", pgd);
71 pgd += pgd_index(addr);
72 printk(KERN_ALERT "[%08lx] *pgd=%0*Lx", addr,
73 (u32)(sizeof(*pgd) * 2), (u64)pgd_val(*pgd));
74
75 do {
76 pud_t *pud;
77 pmd_t *pmd;
78 pte_t *pte;
79
80 if (pgd_none(*pgd))
81 break;
82
83 if (pgd_bad(*pgd)) {
84 printk("(bad)");
85 break;
86 }
87
88 pud = pud_offset(pgd, addr);
89 if (PTRS_PER_PUD != 1)
90 printk(", *pud=%0*Lx", (u32)(sizeof(*pud) * 2),
91 (u64)pud_val(*pud));
92
93 if (pud_none(*pud))
94 break;
95
96 if (pud_bad(*pud)) {
97 printk("(bad)");
98 break;
99 }
100
101 pmd = pmd_offset(pud, addr);
102 if (PTRS_PER_PMD != 1)
103 printk(", *pmd=%0*Lx", (u32)(sizeof(*pmd) * 2),
104 (u64)pmd_val(*pmd));
105
106 if (pmd_none(*pmd))
107 break;
108
109 if (pmd_bad(*pmd)) {
110 printk("(bad)");
111 break;
112 }
113
114 /* We must not map this if we have highmem enabled */
115 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
116 break;
117
118 pte = pte_offset_kernel(pmd, addr);
119 printk(", *pte=%0*Lx", (u32)(sizeof(*pte) * 2),
120 (u64)pte_val(*pte));
121 } while (0);
122
123 printk("\n");
124}
125
126static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
127{
128 unsigned index = pgd_index(address);
129 pgd_t *pgd_k;
130 pud_t *pud, *pud_k;
131 pmd_t *pmd, *pmd_k;
132
133 pgd += index;
134 pgd_k = init_mm.pgd + index;
135
136 if (!pgd_present(*pgd_k))
137 return NULL;
138
139 pud = pud_offset(pgd, address);
140 pud_k = pud_offset(pgd_k, address);
141 if (!pud_present(*pud_k))
142 return NULL;
143
144 if (!pud_present(*pud))
145 set_pud(pud, *pud_k);
146
147 pmd = pmd_offset(pud, address);
148 pmd_k = pmd_offset(pud_k, address);
149 if (!pmd_present(*pmd_k))
150 return NULL;
151
152 if (!pmd_present(*pmd))
153 set_pmd(pmd, *pmd_k);
154 else {
155 /*
156 * The page tables are fully synchronised so there must
157 * be another reason for the fault. Return NULL here to
158 * signal that we have not taken care of the fault.
159 */
160 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
161 return NULL;
162 }
163
164 return pmd_k;
165}
166
167#ifdef CONFIG_SH_STORE_QUEUES
168#define __FAULT_ADDR_LIMIT P3_ADDR_MAX
169#else
170#define __FAULT_ADDR_LIMIT VMALLOC_END
171#endif
172
173/*
174 * Handle a fault on the vmalloc or module mapping area
175 */
176static noinline int vmalloc_fault(unsigned long address)
177{
178 pgd_t *pgd_k;
179 pmd_t *pmd_k;
180 pte_t *pte_k;
181
182 /* Make sure we are in vmalloc/module/P3 area: */
183 if (!(address >= VMALLOC_START && address < __FAULT_ADDR_LIMIT))
184 return -1;
185
186 /*
187 * Synchronize this task's top level page-table
188 * with the 'reference' page table.
189 *
190 * Do _not_ use "current" here. We might be inside
191 * an interrupt in the middle of a task switch..
192 */
193 pgd_k = get_TTB();
194 pmd_k = vmalloc_sync_one(pgd_k, address);
195 if (!pmd_k)
196 return -1;
197
198 pte_k = pte_offset_kernel(pmd_k, address);
199 if (!pte_present(*pte_k))
200 return -1;
201
202 return 0;
203}
204
205static void
206show_fault_oops(struct pt_regs *regs, unsigned long address)
207{
208 if (!oops_may_print())
209 return;
210
211 printk(KERN_ALERT "BUG: unable to handle kernel ");
212 if (address < PAGE_SIZE)
213 printk(KERN_CONT "NULL pointer dereference");
214 else
215 printk(KERN_CONT "paging request");
216
217 printk(KERN_CONT " at %08lx\n", address);
218 printk(KERN_ALERT "PC:");
219 printk_address(regs->pc, 1);
220
221 show_pte(NULL, address);
222}
223
224static noinline void
225no_context(struct pt_regs *regs, unsigned long error_code,
226 unsigned long address)
227{
228 /* Are we prepared to handle this kernel fault? */
229 if (fixup_exception(regs))
230 return;
231
232 if (handle_trapped_io(regs, address))
233 return;
234
235 /*
236 * Oops. The kernel tried to access some bad page. We'll have to
237 * terminate things with extreme prejudice.
238 */
239 bust_spinlocks(1);
240
241 show_fault_oops(regs, address);
242
243 die("Oops", regs, error_code);
244 bust_spinlocks(0);
245 do_exit(SIGKILL);
246}
247
248static void
249__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
250 unsigned long address, int si_code)
251{
252 struct task_struct *tsk = current;
253
254 /* User mode accesses just cause a SIGSEGV */
255 if (user_mode(regs)) {
256 /*
257 * It's possible to have interrupts off here:
258 */
259 local_irq_enable();
260
261 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
262
263 return;
264 }
265
266 no_context(regs, error_code, address);
267}
268
269static noinline void
270bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
271 unsigned long address)
272{
273 __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
274}
275
276static void
277__bad_area(struct pt_regs *regs, unsigned long error_code,
278 unsigned long address, int si_code)
279{
280 struct mm_struct *mm = current->mm;
281
282 /*
283 * Something tried to access memory that isn't in our memory map..
284 * Fix it, but check if it's kernel or user first..
285 */
286 up_read(&mm->mmap_sem);
287
288 __bad_area_nosemaphore(regs, error_code, address, si_code);
289}
290
291static noinline void
292bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
293{
294 __bad_area(regs, error_code, address, SEGV_MAPERR);
295}
296
297static noinline void
298bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
299 unsigned long address)
300{
301 __bad_area(regs, error_code, address, SEGV_ACCERR);
302}
303
304static void out_of_memory(void)
305{
306 /*
307 * We ran out of memory, call the OOM killer, and return the userspace
308 * (which will retry the fault, or kill us if we got oom-killed):
309 */
310 up_read(¤t->mm->mmap_sem);
311
312 pagefault_out_of_memory();
313}
314
315static void
316do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
317{
318 struct task_struct *tsk = current;
319 struct mm_struct *mm = tsk->mm;
320
321 up_read(&mm->mmap_sem);
322
323 /* Kernel mode? Handle exceptions or die: */
324 if (!user_mode(regs))
325 no_context(regs, error_code, address);
326
327 force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
328}
329
330static noinline int
331mm_fault_error(struct pt_regs *regs, unsigned long error_code,
332 unsigned long address, unsigned int fault)
333{
334 /*
335 * Pagefault was interrupted by SIGKILL. We have no reason to
336 * continue pagefault.
337 */
338 if (fatal_signal_pending(current)) {
339 if (!(fault & VM_FAULT_RETRY))
340 up_read(¤t->mm->mmap_sem);
341 if (!user_mode(regs))
342 no_context(regs, error_code, address);
343 return 1;
344 }
345
346 if (!(fault & VM_FAULT_ERROR))
347 return 0;
348
349 if (fault & VM_FAULT_OOM) {
350 /* Kernel mode? Handle exceptions or die: */
351 if (!user_mode(regs)) {
352 up_read(¤t->mm->mmap_sem);
353 no_context(regs, error_code, address);
354 return 1;
355 }
356
357 out_of_memory();
358 } else {
359 if (fault & VM_FAULT_SIGBUS)
360 do_sigbus(regs, error_code, address);
361 else
362 BUG();
363 }
364
365 return 1;
366}
367
368static inline int access_error(int error_code, struct vm_area_struct *vma)
369{
370 if (error_code & FAULT_CODE_WRITE) {
371 /* write, present and write, not present: */
372 if (unlikely(!(vma->vm_flags & VM_WRITE)))
373 return 1;
374 return 0;
375 }
376
377 /* ITLB miss on NX page */
378 if (unlikely((error_code & FAULT_CODE_ITLB) &&
379 !(vma->vm_flags & VM_EXEC)))
380 return 1;
381
382 /* read, not present: */
383 if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
384 return 1;
385
386 return 0;
387}
388
389static int fault_in_kernel_space(unsigned long address)
390{
391 return address >= TASK_SIZE;
392}
393
394/*
395 * This routine handles page faults. It determines the address,
396 * and the problem, and then passes it off to one of the appropriate
397 * routines.
398 */
399asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
400 unsigned long error_code,
401 unsigned long address)
402{
403 unsigned long vec;
404 struct task_struct *tsk;
405 struct mm_struct *mm;
406 struct vm_area_struct * vma;
407 int fault;
408 int write = error_code & FAULT_CODE_WRITE;
409 unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
410 (write ? FAULT_FLAG_WRITE : 0));
411
412 tsk = current;
413 mm = tsk->mm;
414 vec = lookup_exception_vector();
415
416 /*
417 * We fault-in kernel-space virtual memory on-demand. The
418 * 'reference' page table is init_mm.pgd.
419 *
420 * NOTE! We MUST NOT take any locks for this case. We may
421 * be in an interrupt or a critical region, and should
422 * only copy the information from the master page table,
423 * nothing more.
424 */
425 if (unlikely(fault_in_kernel_space(address))) {
426 if (vmalloc_fault(address) >= 0)
427 return;
428 if (notify_page_fault(regs, vec))
429 return;
430
431 bad_area_nosemaphore(regs, error_code, address);
432 return;
433 }
434
435 if (unlikely(notify_page_fault(regs, vec)))
436 return;
437
438 /* Only enable interrupts if they were on before the fault */
439 if ((regs->sr & SR_IMASK) != SR_IMASK)
440 local_irq_enable();
441
442 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
443
444 /*
445 * If we're in an interrupt, have no user context or are running
446 * in an atomic region then we must not take the fault:
447 */
448 if (unlikely(in_atomic() || !mm)) {
449 bad_area_nosemaphore(regs, error_code, address);
450 return;
451 }
452
453retry:
454 down_read(&mm->mmap_sem);
455
456 vma = find_vma(mm, address);
457 if (unlikely(!vma)) {
458 bad_area(regs, error_code, address);
459 return;
460 }
461 if (likely(vma->vm_start <= address))
462 goto good_area;
463 if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
464 bad_area(regs, error_code, address);
465 return;
466 }
467 if (unlikely(expand_stack(vma, address))) {
468 bad_area(regs, error_code, address);
469 return;
470 }
471
472 /*
473 * Ok, we have a good vm_area for this memory access, so
474 * we can handle it..
475 */
476good_area:
477 if (unlikely(access_error(error_code, vma))) {
478 bad_area_access_error(regs, error_code, address);
479 return;
480 }
481
482 set_thread_fault_code(error_code);
483
484 /*
485 * If for any reason at all we couldn't handle the fault,
486 * make sure we exit gracefully rather than endlessly redo
487 * the fault.
488 */
489 fault = handle_mm_fault(mm, vma, address, flags);
490
491 if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
492 if (mm_fault_error(regs, error_code, address, fault))
493 return;
494
495 if (flags & FAULT_FLAG_ALLOW_RETRY) {
496 if (fault & VM_FAULT_MAJOR) {
497 tsk->maj_flt++;
498 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
499 regs, address);
500 } else {
501 tsk->min_flt++;
502 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
503 regs, address);
504 }
505 if (fault & VM_FAULT_RETRY) {
506 flags &= ~FAULT_FLAG_ALLOW_RETRY;
507
508 /*
509 * No need to up_read(&mm->mmap_sem) as we would
510 * have already released it in __lock_page_or_retry
511 * in mm/filemap.c.
512 */
513 goto retry;
514 }
515 }
516
517 up_read(&mm->mmap_sem);
518}