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