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