1
2
3
4#include <linux/extable.h>
5#include <linux/module.h>
6#include <linux/signal.h>
7#include <linux/ptrace.h>
8#include <linux/mm.h>
9#include <linux/init.h>
10#include <linux/hardirq.h>
11#include <linux/uaccess.h>
12#include <linux/perf_event.h>
13
14#include <asm/pgtable.h>
15#include <asm/tlbflush.h>
16
17extern void die(const char *str, struct pt_regs *regs, long err);
18
19
20
21
22
23void show_pte(struct mm_struct *mm, unsigned long addr)
24{
25 pgd_t *pgd;
26 if (!mm)
27 mm = &init_mm;
28
29 pr_alert("pgd = %p\n", mm->pgd);
30 pgd = pgd_offset(mm, addr);
31 pr_alert("[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
32
33 do {
34 p4d_t *p4d;
35 pud_t *pud;
36 pmd_t *pmd;
37
38 if (pgd_none(*pgd))
39 break;
40
41 if (pgd_bad(*pgd)) {
42 pr_alert("(bad)");
43 break;
44 }
45
46 p4d = p4d_offset(pgd, addr);
47 pud = pud_offset(p4d, addr);
48 pmd = pmd_offset(pud, addr);
49#if PTRS_PER_PMD != 1
50 pr_alert(", *pmd=%08lx", pmd_val(*pmd));
51#endif
52
53 if (pmd_none(*pmd))
54 break;
55
56 if (pmd_bad(*pmd)) {
57 pr_alert("(bad)");
58 break;
59 }
60
61 if (IS_ENABLED(CONFIG_HIGHMEM))
62 {
63 pte_t *pte;
64
65 pte = pte_offset_map(pmd, addr);
66 pr_alert(", *pte=%08lx", pte_val(*pte));
67 pte_unmap(pte);
68 }
69 } while (0);
70
71 pr_alert("\n");
72}
73
74void do_page_fault(unsigned long entry, unsigned long addr,
75 unsigned int error_code, struct pt_regs *regs)
76{
77 struct task_struct *tsk;
78 struct mm_struct *mm;
79 struct vm_area_struct *vma;
80 int si_code;
81 vm_fault_t fault;
82 unsigned int mask = VM_ACCESS_FLAGS;
83 unsigned int flags = FAULT_FLAG_DEFAULT;
84
85 error_code = error_code & (ITYPE_mskINST | ITYPE_mskETYPE);
86 tsk = current;
87 mm = tsk->mm;
88 si_code = SEGV_MAPERR;
89
90
91
92
93
94
95
96
97
98 if (addr >= TASK_SIZE) {
99 if (user_mode(regs))
100 goto bad_area_nosemaphore;
101
102 if (addr >= TASK_SIZE && addr < VMALLOC_END
103 && (entry == ENTRY_PTE_NOT_PRESENT))
104 goto vmalloc_fault;
105 else
106 goto no_context;
107 }
108
109
110 if (entry == ENTRY_GENERAL_EXCPETION
111 && error_code == ETYPE_ALIGNMENT_CHECK) {
112 if (user_mode(regs))
113 goto bad_area_nosemaphore;
114 else
115 goto no_context;
116 }
117
118
119
120
121
122 if (unlikely(faulthandler_disabled() || !mm))
123 goto no_context;
124
125
126
127
128
129
130 if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
131 if (!user_mode(regs) &&
132 !search_exception_tables(instruction_pointer(regs)))
133 goto no_context;
134retry:
135 down_read(&mm->mmap_sem);
136 } else {
137
138
139
140
141 might_sleep();
142 if (IS_ENABLED(CONFIG_DEBUG_VM)) {
143 if (!user_mode(regs) &&
144 !search_exception_tables(instruction_pointer(regs)))
145 goto no_context;
146 }
147 }
148
149 vma = find_vma(mm, addr);
150
151 if (unlikely(!vma))
152 goto bad_area;
153
154 if (vma->vm_start <= addr)
155 goto good_area;
156
157 if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
158 goto bad_area;
159
160 if (unlikely(expand_stack(vma, addr)))
161 goto bad_area;
162
163
164
165
166
167
168good_area:
169 si_code = SEGV_ACCERR;
170
171
172 if (entry == ENTRY_PTE_NOT_PRESENT) {
173 if (error_code & ITYPE_mskINST)
174 mask = VM_EXEC;
175 else {
176 mask = VM_READ | VM_WRITE;
177 }
178 } else if (entry == ENTRY_TLB_MISC) {
179 switch (error_code & ITYPE_mskETYPE) {
180 case RD_PROT:
181 mask = VM_READ;
182 break;
183 case WRT_PROT:
184 mask = VM_WRITE;
185 flags |= FAULT_FLAG_WRITE;
186 break;
187 case NOEXEC:
188 mask = VM_EXEC;
189 break;
190 case PAGE_MODIFY:
191 mask = VM_WRITE;
192 flags |= FAULT_FLAG_WRITE;
193 break;
194 case ACC_BIT:
195 BUG();
196 default:
197 break;
198 }
199
200 }
201 if (!(vma->vm_flags & mask))
202 goto bad_area;
203
204
205
206
207
208
209
210 fault = handle_mm_fault(vma, addr, flags);
211
212
213
214
215
216
217 if (fault_signal_pending(fault, regs)) {
218 if (!user_mode(regs))
219 goto no_context;
220 return;
221 }
222
223 if (unlikely(fault & VM_FAULT_ERROR)) {
224 if (fault & VM_FAULT_OOM)
225 goto out_of_memory;
226 else if (fault & VM_FAULT_SIGBUS)
227 goto do_sigbus;
228 else
229 goto bad_area;
230 }
231
232
233
234
235
236
237 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
238 if (flags & FAULT_FLAG_ALLOW_RETRY) {
239 if (fault & VM_FAULT_MAJOR) {
240 tsk->maj_flt++;
241 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
242 1, regs, addr);
243 } else {
244 tsk->min_flt++;
245 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
246 1, regs, addr);
247 }
248 if (fault & VM_FAULT_RETRY) {
249 flags |= FAULT_FLAG_TRIED;
250
251
252
253
254
255 goto retry;
256 }
257 }
258
259 up_read(&mm->mmap_sem);
260 return;
261
262
263
264
265
266bad_area:
267 up_read(&mm->mmap_sem);
268
269bad_area_nosemaphore:
270
271
272
273 if (user_mode(regs)) {
274 tsk->thread.address = addr;
275 tsk->thread.error_code = error_code;
276 tsk->thread.trap_no = entry;
277 force_sig_fault(SIGSEGV, si_code, (void __user *)addr);
278 return;
279 }
280
281no_context:
282
283
284
285
286
287
288
289
290
291
292 {
293 const struct exception_table_entry *entry;
294
295 if ((entry =
296 search_exception_tables(instruction_pointer(regs))) !=
297 NULL) {
298
299 instruction_pointer(regs) = entry->fixup;
300 return;
301 }
302 }
303
304
305
306
307
308
309 bust_spinlocks(1);
310 pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
311 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
312 "paging request", addr);
313
314 show_pte(mm, addr);
315 die("Oops", regs, error_code);
316 bust_spinlocks(0);
317 do_exit(SIGKILL);
318
319 return;
320
321
322
323
324
325
326out_of_memory:
327 up_read(&mm->mmap_sem);
328 if (!user_mode(regs))
329 goto no_context;
330 pagefault_out_of_memory();
331 return;
332
333do_sigbus:
334 up_read(&mm->mmap_sem);
335
336
337 if (!user_mode(regs))
338 goto no_context;
339
340
341
342
343 tsk->thread.address = addr;
344 tsk->thread.error_code = error_code;
345 tsk->thread.trap_no = entry;
346 force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)addr);
347
348 return;
349
350vmalloc_fault:
351 {
352
353
354
355
356
357
358
359
360
361
362
363 unsigned int index = pgd_index(addr);
364 pgd_t *pgd, *pgd_k;
365 p4d_t *p4d, *p4d_k;
366 pud_t *pud, *pud_k;
367 pmd_t *pmd, *pmd_k;
368 pte_t *pte_k;
369
370 pgd = (pgd_t *) __va(__nds32__mfsr(NDS32_SR_L1_PPTB)) + index;
371 pgd_k = init_mm.pgd + index;
372
373 if (!pgd_present(*pgd_k))
374 goto no_context;
375
376 p4d = p4d_offset(pgd, addr);
377 p4d_k = p4d_offset(pgd_k, addr);
378 if (!p4d_present(*p4d_k))
379 goto no_context;
380
381 pud = pud_offset(p4d, addr);
382 pud_k = pud_offset(p4d_k, addr);
383 if (!pud_present(*pud_k))
384 goto no_context;
385
386 pmd = pmd_offset(pud, addr);
387 pmd_k = pmd_offset(pud_k, addr);
388 if (!pmd_present(*pmd_k))
389 goto no_context;
390
391 if (!pmd_present(*pmd))
392 set_pmd(pmd, *pmd_k);
393 else
394 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410 pte_k = pte_offset_kernel(pmd_k, addr);
411 if (!pte_present(*pte_k))
412 goto no_context;
413
414 return;
415 }
416}
417