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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 <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(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}