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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 | 2 | * Copyright (C) 1995 Linus Torvalds |
2d4a7167 | 3 | * Copyright (C) 2001, 2002 Andi Kleen, SuSE Labs. |
f8eeb2e6 | 4 | * Copyright (C) 2008-2009, Red Hat Inc., Ingo Molnar |
1da177e4 | 5 | */ |
a2bcd473 IM |
6 | #include <linux/magic.h> /* STACK_END_MAGIC */ |
7 | #include <linux/sched.h> /* test_thread_flag(), ... */ | |
8 | #include <linux/kdebug.h> /* oops_begin/end, ... */ | |
9 | #include <linux/module.h> /* search_exception_table */ | |
10 | #include <linux/bootmem.h> /* max_low_pfn */ | |
11 | #include <linux/kprobes.h> /* __kprobes, ... */ | |
12 | #include <linux/mmiotrace.h> /* kmmio_handler, ... */ | |
940010c5 | 13 | #include <linux/perf_counter.h> /* perf_swcounter_event */ |
2d4a7167 | 14 | |
a2bcd473 IM |
15 | #include <asm/traps.h> /* dotraplinkage, ... */ |
16 | #include <asm/pgalloc.h> /* pgd_*(), ... */ | |
1da177e4 | 17 | |
33cb5243 | 18 | /* |
2d4a7167 IM |
19 | * Page fault error code bits: |
20 | * | |
21 | * bit 0 == 0: no page found 1: protection fault | |
22 | * bit 1 == 0: read access 1: write access | |
23 | * bit 2 == 0: kernel-mode access 1: user-mode access | |
24 | * bit 3 == 1: use of reserved bit detected | |
25 | * bit 4 == 1: fault was an instruction fetch | |
33cb5243 | 26 | */ |
2d4a7167 IM |
27 | enum x86_pf_error_code { |
28 | ||
29 | PF_PROT = 1 << 0, | |
30 | PF_WRITE = 1 << 1, | |
31 | PF_USER = 1 << 2, | |
32 | PF_RSVD = 1 << 3, | |
33 | PF_INSTR = 1 << 4, | |
34 | }; | |
66c58156 | 35 | |
b814d41f | 36 | /* |
b319eed0 IM |
37 | * Returns 0 if mmiotrace is disabled, or if the fault is not |
38 | * handled by mmiotrace: | |
b814d41f | 39 | */ |
0fd0e3da | 40 | static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr) |
86069782 | 41 | { |
0fd0e3da PP |
42 | if (unlikely(is_kmmio_active())) |
43 | if (kmmio_handler(regs, addr) == 1) | |
44 | return -1; | |
0fd0e3da | 45 | return 0; |
86069782 PP |
46 | } |
47 | ||
74a0b576 | 48 | static inline int notify_page_fault(struct pt_regs *regs) |
1bd858a5 | 49 | { |
74a0b576 CH |
50 | int ret = 0; |
51 | ||
52 | /* kprobe_running() needs smp_processor_id() */ | |
b1801812 | 53 | if (kprobes_built_in() && !user_mode_vm(regs)) { |
74a0b576 CH |
54 | preempt_disable(); |
55 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
56 | ret = 1; | |
57 | preempt_enable(); | |
58 | } | |
1bd858a5 | 59 | |
74a0b576 | 60 | return ret; |
33cb5243 | 61 | } |
1bd858a5 | 62 | |
1dc85be0 | 63 | /* |
2d4a7167 IM |
64 | * Prefetch quirks: |
65 | * | |
66 | * 32-bit mode: | |
67 | * | |
68 | * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. | |
69 | * Check that here and ignore it. | |
1dc85be0 | 70 | * |
2d4a7167 | 71 | * 64-bit mode: |
1dc85be0 | 72 | * |
2d4a7167 IM |
73 | * Sometimes the CPU reports invalid exceptions on prefetch. |
74 | * Check that here and ignore it. | |
75 | * | |
76 | * Opcode checker based on code by Richard Brunner. | |
1dc85be0 | 77 | */ |
107a0367 IM |
78 | static inline int |
79 | check_prefetch_opcode(struct pt_regs *regs, unsigned char *instr, | |
80 | unsigned char opcode, int *prefetch) | |
81 | { | |
82 | unsigned char instr_hi = opcode & 0xf0; | |
83 | unsigned char instr_lo = opcode & 0x0f; | |
84 | ||
85 | switch (instr_hi) { | |
86 | case 0x20: | |
87 | case 0x30: | |
88 | /* | |
89 | * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. | |
90 | * In X86_64 long mode, the CPU will signal invalid | |
91 | * opcode if some of these prefixes are present so | |
92 | * X86_64 will never get here anyway | |
93 | */ | |
94 | return ((instr_lo & 7) == 0x6); | |
95 | #ifdef CONFIG_X86_64 | |
96 | case 0x40: | |
97 | /* | |
98 | * In AMD64 long mode 0x40..0x4F are valid REX prefixes | |
99 | * Need to figure out under what instruction mode the | |
100 | * instruction was issued. Could check the LDT for lm, | |
101 | * but for now it's good enough to assume that long | |
102 | * mode only uses well known segments or kernel. | |
103 | */ | |
104 | return (!user_mode(regs)) || (regs->cs == __USER_CS); | |
105 | #endif | |
106 | case 0x60: | |
107 | /* 0x64 thru 0x67 are valid prefixes in all modes. */ | |
108 | return (instr_lo & 0xC) == 0x4; | |
109 | case 0xF0: | |
110 | /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ | |
111 | return !instr_lo || (instr_lo>>1) == 1; | |
112 | case 0x00: | |
113 | /* Prefetch instruction is 0x0F0D or 0x0F18 */ | |
114 | if (probe_kernel_address(instr, opcode)) | |
115 | return 0; | |
116 | ||
117 | *prefetch = (instr_lo == 0xF) && | |
118 | (opcode == 0x0D || opcode == 0x18); | |
119 | return 0; | |
120 | default: | |
121 | return 0; | |
122 | } | |
123 | } | |
124 | ||
2d4a7167 IM |
125 | static int |
126 | is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr) | |
33cb5243 | 127 | { |
2d4a7167 | 128 | unsigned char *max_instr; |
ab2bf0c1 | 129 | unsigned char *instr; |
33cb5243 | 130 | int prefetch = 0; |
1da177e4 | 131 | |
3085354d IM |
132 | /* |
133 | * If it was a exec (instruction fetch) fault on NX page, then | |
134 | * do not ignore the fault: | |
135 | */ | |
66c58156 | 136 | if (error_code & PF_INSTR) |
1da177e4 | 137 | return 0; |
1dc85be0 | 138 | |
107a0367 | 139 | instr = (void *)convert_ip_to_linear(current, regs); |
f1290ec9 | 140 | max_instr = instr + 15; |
1da177e4 | 141 | |
76381fee | 142 | if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) |
1da177e4 LT |
143 | return 0; |
144 | ||
107a0367 | 145 | while (instr < max_instr) { |
2d4a7167 | 146 | unsigned char opcode; |
1da177e4 | 147 | |
ab2bf0c1 | 148 | if (probe_kernel_address(instr, opcode)) |
33cb5243 | 149 | break; |
1da177e4 | 150 | |
1da177e4 LT |
151 | instr++; |
152 | ||
107a0367 | 153 | if (!check_prefetch_opcode(regs, instr, opcode, &prefetch)) |
1da177e4 | 154 | break; |
1da177e4 LT |
155 | } |
156 | return prefetch; | |
157 | } | |
158 | ||
2d4a7167 IM |
159 | static void |
160 | force_sig_info_fault(int si_signo, int si_code, unsigned long address, | |
161 | struct task_struct *tsk) | |
c4aba4a8 HH |
162 | { |
163 | siginfo_t info; | |
164 | ||
2d4a7167 IM |
165 | info.si_signo = si_signo; |
166 | info.si_errno = 0; | |
167 | info.si_code = si_code; | |
168 | info.si_addr = (void __user *)address; | |
169 | ||
c4aba4a8 HH |
170 | force_sig_info(si_signo, &info, tsk); |
171 | } | |
172 | ||
f2f13a85 IM |
173 | DEFINE_SPINLOCK(pgd_lock); |
174 | LIST_HEAD(pgd_list); | |
175 | ||
176 | #ifdef CONFIG_X86_32 | |
177 | static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) | |
33cb5243 | 178 | { |
f2f13a85 IM |
179 | unsigned index = pgd_index(address); |
180 | pgd_t *pgd_k; | |
181 | pud_t *pud, *pud_k; | |
182 | pmd_t *pmd, *pmd_k; | |
2d4a7167 | 183 | |
f2f13a85 IM |
184 | pgd += index; |
185 | pgd_k = init_mm.pgd + index; | |
186 | ||
187 | if (!pgd_present(*pgd_k)) | |
188 | return NULL; | |
189 | ||
190 | /* | |
191 | * set_pgd(pgd, *pgd_k); here would be useless on PAE | |
192 | * and redundant with the set_pmd() on non-PAE. As would | |
193 | * set_pud. | |
194 | */ | |
195 | pud = pud_offset(pgd, address); | |
196 | pud_k = pud_offset(pgd_k, address); | |
197 | if (!pud_present(*pud_k)) | |
198 | return NULL; | |
199 | ||
200 | pmd = pmd_offset(pud, address); | |
201 | pmd_k = pmd_offset(pud_k, address); | |
202 | if (!pmd_present(*pmd_k)) | |
203 | return NULL; | |
204 | ||
b8bcfe99 | 205 | if (!pmd_present(*pmd)) |
f2f13a85 | 206 | set_pmd(pmd, *pmd_k); |
b8bcfe99 | 207 | else |
f2f13a85 | 208 | BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); |
f2f13a85 IM |
209 | |
210 | return pmd_k; | |
211 | } | |
212 | ||
213 | void vmalloc_sync_all(void) | |
214 | { | |
215 | unsigned long address; | |
216 | ||
217 | if (SHARED_KERNEL_PMD) | |
218 | return; | |
219 | ||
220 | for (address = VMALLOC_START & PMD_MASK; | |
221 | address >= TASK_SIZE && address < FIXADDR_TOP; | |
222 | address += PMD_SIZE) { | |
223 | ||
224 | unsigned long flags; | |
225 | struct page *page; | |
226 | ||
227 | spin_lock_irqsave(&pgd_lock, flags); | |
228 | list_for_each_entry(page, &pgd_list, lru) { | |
229 | if (!vmalloc_sync_one(page_address(page), address)) | |
230 | break; | |
231 | } | |
232 | spin_unlock_irqrestore(&pgd_lock, flags); | |
233 | } | |
234 | } | |
235 | ||
236 | /* | |
237 | * 32-bit: | |
238 | * | |
239 | * Handle a fault on the vmalloc or module mapping area | |
240 | */ | |
241 | static noinline int vmalloc_fault(unsigned long address) | |
242 | { | |
243 | unsigned long pgd_paddr; | |
244 | pmd_t *pmd_k; | |
245 | pte_t *pte_k; | |
246 | ||
247 | /* Make sure we are in vmalloc area: */ | |
248 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
249 | return -1; | |
250 | ||
251 | /* | |
252 | * Synchronize this task's top level page-table | |
253 | * with the 'reference' page table. | |
254 | * | |
255 | * Do _not_ use "current" here. We might be inside | |
256 | * an interrupt in the middle of a task switch.. | |
257 | */ | |
258 | pgd_paddr = read_cr3(); | |
259 | pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); | |
260 | if (!pmd_k) | |
261 | return -1; | |
262 | ||
263 | pte_k = pte_offset_kernel(pmd_k, address); | |
264 | if (!pte_present(*pte_k)) | |
265 | return -1; | |
266 | ||
267 | return 0; | |
268 | } | |
269 | ||
270 | /* | |
271 | * Did it hit the DOS screen memory VA from vm86 mode? | |
272 | */ | |
273 | static inline void | |
274 | check_v8086_mode(struct pt_regs *regs, unsigned long address, | |
275 | struct task_struct *tsk) | |
276 | { | |
277 | unsigned long bit; | |
278 | ||
279 | if (!v8086_mode(regs)) | |
280 | return; | |
281 | ||
282 | bit = (address - 0xA0000) >> PAGE_SHIFT; | |
283 | if (bit < 32) | |
284 | tsk->thread.screen_bitmap |= 1 << bit; | |
33cb5243 | 285 | } |
1da177e4 | 286 | |
cae30f82 | 287 | static void dump_pagetable(unsigned long address) |
1da177e4 | 288 | { |
1156e098 HH |
289 | __typeof__(pte_val(__pte(0))) page; |
290 | ||
291 | page = read_cr3(); | |
292 | page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT]; | |
2d4a7167 | 293 | |
1156e098 HH |
294 | #ifdef CONFIG_X86_PAE |
295 | printk("*pdpt = %016Lx ", page); | |
296 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
297 | && page & _PAGE_PRESENT) { | |
298 | page &= PAGE_MASK; | |
299 | page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT) | |
2d4a7167 | 300 | & (PTRS_PER_PMD - 1)]; |
1156e098 HH |
301 | printk(KERN_CONT "*pde = %016Lx ", page); |
302 | page &= ~_PAGE_NX; | |
303 | } | |
304 | #else | |
305 | printk("*pde = %08lx ", page); | |
306 | #endif | |
307 | ||
308 | /* | |
309 | * We must not directly access the pte in the highpte | |
310 | * case if the page table is located in highmem. | |
311 | * And let's rather not kmap-atomic the pte, just in case | |
2d4a7167 | 312 | * it's allocated already: |
1156e098 HH |
313 | */ |
314 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
315 | && (page & _PAGE_PRESENT) | |
316 | && !(page & _PAGE_PSE)) { | |
2d4a7167 | 317 | |
1156e098 HH |
318 | page &= PAGE_MASK; |
319 | page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT) | |
2d4a7167 | 320 | & (PTRS_PER_PTE - 1)]; |
1156e098 HH |
321 | printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page); |
322 | } | |
323 | ||
324 | printk("\n"); | |
f2f13a85 IM |
325 | } |
326 | ||
327 | #else /* CONFIG_X86_64: */ | |
328 | ||
329 | void vmalloc_sync_all(void) | |
330 | { | |
331 | unsigned long address; | |
332 | ||
333 | for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END; | |
334 | address += PGDIR_SIZE) { | |
335 | ||
336 | const pgd_t *pgd_ref = pgd_offset_k(address); | |
337 | unsigned long flags; | |
338 | struct page *page; | |
339 | ||
340 | if (pgd_none(*pgd_ref)) | |
341 | continue; | |
342 | ||
343 | spin_lock_irqsave(&pgd_lock, flags); | |
344 | list_for_each_entry(page, &pgd_list, lru) { | |
345 | pgd_t *pgd; | |
346 | pgd = (pgd_t *)page_address(page) + pgd_index(address); | |
347 | if (pgd_none(*pgd)) | |
348 | set_pgd(pgd, *pgd_ref); | |
349 | else | |
350 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); | |
351 | } | |
352 | spin_unlock_irqrestore(&pgd_lock, flags); | |
353 | } | |
354 | } | |
355 | ||
356 | /* | |
357 | * 64-bit: | |
358 | * | |
359 | * Handle a fault on the vmalloc area | |
360 | * | |
361 | * This assumes no large pages in there. | |
362 | */ | |
363 | static noinline int vmalloc_fault(unsigned long address) | |
364 | { | |
365 | pgd_t *pgd, *pgd_ref; | |
366 | pud_t *pud, *pud_ref; | |
367 | pmd_t *pmd, *pmd_ref; | |
368 | pte_t *pte, *pte_ref; | |
369 | ||
370 | /* Make sure we are in vmalloc area: */ | |
371 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
372 | return -1; | |
373 | ||
374 | /* | |
375 | * Copy kernel mappings over when needed. This can also | |
376 | * happen within a race in page table update. In the later | |
377 | * case just flush: | |
378 | */ | |
379 | pgd = pgd_offset(current->active_mm, address); | |
380 | pgd_ref = pgd_offset_k(address); | |
381 | if (pgd_none(*pgd_ref)) | |
382 | return -1; | |
383 | ||
384 | if (pgd_none(*pgd)) | |
385 | set_pgd(pgd, *pgd_ref); | |
386 | else | |
387 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); | |
388 | ||
389 | /* | |
390 | * Below here mismatches are bugs because these lower tables | |
391 | * are shared: | |
392 | */ | |
393 | ||
394 | pud = pud_offset(pgd, address); | |
395 | pud_ref = pud_offset(pgd_ref, address); | |
396 | if (pud_none(*pud_ref)) | |
397 | return -1; | |
398 | ||
399 | if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) | |
400 | BUG(); | |
401 | ||
402 | pmd = pmd_offset(pud, address); | |
403 | pmd_ref = pmd_offset(pud_ref, address); | |
404 | if (pmd_none(*pmd_ref)) | |
405 | return -1; | |
406 | ||
407 | if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) | |
408 | BUG(); | |
409 | ||
410 | pte_ref = pte_offset_kernel(pmd_ref, address); | |
411 | if (!pte_present(*pte_ref)) | |
412 | return -1; | |
413 | ||
414 | pte = pte_offset_kernel(pmd, address); | |
415 | ||
416 | /* | |
417 | * Don't use pte_page here, because the mappings can point | |
418 | * outside mem_map, and the NUMA hash lookup cannot handle | |
419 | * that: | |
420 | */ | |
421 | if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) | |
422 | BUG(); | |
423 | ||
424 | return 0; | |
425 | } | |
426 | ||
427 | static const char errata93_warning[] = | |
428 | KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" | |
429 | KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n" | |
430 | KERN_ERR "******* Please consider a BIOS update.\n" | |
431 | KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; | |
432 | ||
433 | /* | |
434 | * No vm86 mode in 64-bit mode: | |
435 | */ | |
436 | static inline void | |
437 | check_v8086_mode(struct pt_regs *regs, unsigned long address, | |
438 | struct task_struct *tsk) | |
439 | { | |
440 | } | |
441 | ||
442 | static int bad_address(void *p) | |
443 | { | |
444 | unsigned long dummy; | |
445 | ||
446 | return probe_kernel_address((unsigned long *)p, dummy); | |
447 | } | |
448 | ||
449 | static void dump_pagetable(unsigned long address) | |
450 | { | |
1da177e4 LT |
451 | pgd_t *pgd; |
452 | pud_t *pud; | |
453 | pmd_t *pmd; | |
454 | pte_t *pte; | |
455 | ||
f51c9452 | 456 | pgd = (pgd_t *)read_cr3(); |
1da177e4 | 457 | |
33cb5243 | 458 | pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); |
2d4a7167 | 459 | |
1da177e4 | 460 | pgd += pgd_index(address); |
2d4a7167 IM |
461 | if (bad_address(pgd)) |
462 | goto bad; | |
463 | ||
d646bce4 | 464 | printk("PGD %lx ", pgd_val(*pgd)); |
2d4a7167 IM |
465 | |
466 | if (!pgd_present(*pgd)) | |
467 | goto out; | |
1da177e4 | 468 | |
d2ae5b5f | 469 | pud = pud_offset(pgd, address); |
2d4a7167 IM |
470 | if (bad_address(pud)) |
471 | goto bad; | |
472 | ||
1da177e4 | 473 | printk("PUD %lx ", pud_val(*pud)); |
b5360222 | 474 | if (!pud_present(*pud) || pud_large(*pud)) |
2d4a7167 | 475 | goto out; |
1da177e4 LT |
476 | |
477 | pmd = pmd_offset(pud, address); | |
2d4a7167 IM |
478 | if (bad_address(pmd)) |
479 | goto bad; | |
480 | ||
1da177e4 | 481 | printk("PMD %lx ", pmd_val(*pmd)); |
2d4a7167 IM |
482 | if (!pmd_present(*pmd) || pmd_large(*pmd)) |
483 | goto out; | |
1da177e4 LT |
484 | |
485 | pte = pte_offset_kernel(pmd, address); | |
2d4a7167 IM |
486 | if (bad_address(pte)) |
487 | goto bad; | |
488 | ||
33cb5243 | 489 | printk("PTE %lx", pte_val(*pte)); |
2d4a7167 | 490 | out: |
1da177e4 LT |
491 | printk("\n"); |
492 | return; | |
493 | bad: | |
494 | printk("BAD\n"); | |
8c938f9f IM |
495 | } |
496 | ||
f2f13a85 | 497 | #endif /* CONFIG_X86_64 */ |
1da177e4 | 498 | |
2d4a7167 IM |
499 | /* |
500 | * Workaround for K8 erratum #93 & buggy BIOS. | |
501 | * | |
502 | * BIOS SMM functions are required to use a specific workaround | |
503 | * to avoid corruption of the 64bit RIP register on C stepping K8. | |
504 | * | |
505 | * A lot of BIOS that didn't get tested properly miss this. | |
506 | * | |
507 | * The OS sees this as a page fault with the upper 32bits of RIP cleared. | |
508 | * Try to work around it here. | |
509 | * | |
510 | * Note we only handle faults in kernel here. | |
511 | * Does nothing on 32-bit. | |
fdfe8aa8 | 512 | */ |
33cb5243 | 513 | static int is_errata93(struct pt_regs *regs, unsigned long address) |
1da177e4 | 514 | { |
fdfe8aa8 | 515 | #ifdef CONFIG_X86_64 |
65ea5b03 | 516 | if (address != regs->ip) |
1da177e4 | 517 | return 0; |
2d4a7167 | 518 | |
33cb5243 | 519 | if ((address >> 32) != 0) |
1da177e4 | 520 | return 0; |
2d4a7167 | 521 | |
1da177e4 | 522 | address |= 0xffffffffUL << 32; |
33cb5243 HH |
523 | if ((address >= (u64)_stext && address <= (u64)_etext) || |
524 | (address >= MODULES_VADDR && address <= MODULES_END)) { | |
a454ab31 | 525 | printk_once(errata93_warning); |
65ea5b03 | 526 | regs->ip = address; |
1da177e4 LT |
527 | return 1; |
528 | } | |
fdfe8aa8 | 529 | #endif |
1da177e4 | 530 | return 0; |
33cb5243 | 531 | } |
1da177e4 | 532 | |
35f3266f | 533 | /* |
2d4a7167 IM |
534 | * Work around K8 erratum #100 K8 in compat mode occasionally jumps |
535 | * to illegal addresses >4GB. | |
536 | * | |
537 | * We catch this in the page fault handler because these addresses | |
538 | * are not reachable. Just detect this case and return. Any code | |
35f3266f HH |
539 | * segment in LDT is compatibility mode. |
540 | */ | |
541 | static int is_errata100(struct pt_regs *regs, unsigned long address) | |
542 | { | |
543 | #ifdef CONFIG_X86_64 | |
2d4a7167 | 544 | if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32)) |
35f3266f HH |
545 | return 1; |
546 | #endif | |
547 | return 0; | |
548 | } | |
549 | ||
29caf2f9 HH |
550 | static int is_f00f_bug(struct pt_regs *regs, unsigned long address) |
551 | { | |
552 | #ifdef CONFIG_X86_F00F_BUG | |
553 | unsigned long nr; | |
2d4a7167 | 554 | |
29caf2f9 | 555 | /* |
2d4a7167 | 556 | * Pentium F0 0F C7 C8 bug workaround: |
29caf2f9 HH |
557 | */ |
558 | if (boot_cpu_data.f00f_bug) { | |
559 | nr = (address - idt_descr.address) >> 3; | |
560 | ||
561 | if (nr == 6) { | |
562 | do_invalid_op(regs, 0); | |
563 | return 1; | |
564 | } | |
565 | } | |
566 | #endif | |
567 | return 0; | |
568 | } | |
569 | ||
8f766149 IM |
570 | static const char nx_warning[] = KERN_CRIT |
571 | "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n"; | |
572 | ||
2d4a7167 IM |
573 | static void |
574 | show_fault_oops(struct pt_regs *regs, unsigned long error_code, | |
575 | unsigned long address) | |
b3279c7f | 576 | { |
1156e098 HH |
577 | if (!oops_may_print()) |
578 | return; | |
579 | ||
1156e098 | 580 | if (error_code & PF_INSTR) { |
93809be8 | 581 | unsigned int level; |
2d4a7167 | 582 | |
1156e098 HH |
583 | pte_t *pte = lookup_address(address, &level); |
584 | ||
8f766149 IM |
585 | if (pte && pte_present(*pte) && !pte_exec(*pte)) |
586 | printk(nx_warning, current_uid()); | |
1156e098 | 587 | } |
1156e098 | 588 | |
19f0dda9 | 589 | printk(KERN_ALERT "BUG: unable to handle kernel "); |
b3279c7f | 590 | if (address < PAGE_SIZE) |
19f0dda9 | 591 | printk(KERN_CONT "NULL pointer dereference"); |
b3279c7f | 592 | else |
19f0dda9 | 593 | printk(KERN_CONT "paging request"); |
2d4a7167 | 594 | |
f294a8ce | 595 | printk(KERN_CONT " at %p\n", (void *) address); |
19f0dda9 | 596 | printk(KERN_ALERT "IP:"); |
b3279c7f | 597 | printk_address(regs->ip, 1); |
2d4a7167 | 598 | |
b3279c7f HH |
599 | dump_pagetable(address); |
600 | } | |
601 | ||
2d4a7167 IM |
602 | static noinline void |
603 | pgtable_bad(struct pt_regs *regs, unsigned long error_code, | |
604 | unsigned long address) | |
1da177e4 | 605 | { |
2d4a7167 IM |
606 | struct task_struct *tsk; |
607 | unsigned long flags; | |
608 | int sig; | |
609 | ||
610 | flags = oops_begin(); | |
611 | tsk = current; | |
612 | sig = SIGKILL; | |
1209140c | 613 | |
1da177e4 | 614 | printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
92181f19 | 615 | tsk->comm, address); |
1da177e4 | 616 | dump_pagetable(address); |
2d4a7167 IM |
617 | |
618 | tsk->thread.cr2 = address; | |
619 | tsk->thread.trap_no = 14; | |
620 | tsk->thread.error_code = error_code; | |
621 | ||
22f5991c | 622 | if (__die("Bad pagetable", regs, error_code)) |
874d93d1 | 623 | sig = 0; |
2d4a7167 | 624 | |
874d93d1 | 625 | oops_end(flags, regs, sig); |
1da177e4 LT |
626 | } |
627 | ||
2d4a7167 IM |
628 | static noinline void |
629 | no_context(struct pt_regs *regs, unsigned long error_code, | |
630 | unsigned long address) | |
92181f19 NP |
631 | { |
632 | struct task_struct *tsk = current; | |
19803078 | 633 | unsigned long *stackend; |
92181f19 NP |
634 | unsigned long flags; |
635 | int sig; | |
92181f19 | 636 | |
2d4a7167 | 637 | /* Are we prepared to handle this kernel fault? */ |
92181f19 NP |
638 | if (fixup_exception(regs)) |
639 | return; | |
640 | ||
641 | /* | |
2d4a7167 IM |
642 | * 32-bit: |
643 | * | |
644 | * Valid to do another page fault here, because if this fault | |
645 | * had been triggered by is_prefetch fixup_exception would have | |
646 | * handled it. | |
647 | * | |
648 | * 64-bit: | |
92181f19 | 649 | * |
2d4a7167 | 650 | * Hall of shame of CPU/BIOS bugs. |
92181f19 NP |
651 | */ |
652 | if (is_prefetch(regs, error_code, address)) | |
653 | return; | |
654 | ||
655 | if (is_errata93(regs, address)) | |
656 | return; | |
657 | ||
658 | /* | |
659 | * Oops. The kernel tried to access some bad page. We'll have to | |
2d4a7167 | 660 | * terminate things with extreme prejudice: |
92181f19 | 661 | */ |
92181f19 | 662 | flags = oops_begin(); |
92181f19 NP |
663 | |
664 | show_fault_oops(regs, error_code, address); | |
665 | ||
2d4a7167 | 666 | stackend = end_of_stack(tsk); |
19803078 IM |
667 | if (*stackend != STACK_END_MAGIC) |
668 | printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); | |
669 | ||
1cc99544 IM |
670 | tsk->thread.cr2 = address; |
671 | tsk->thread.trap_no = 14; | |
672 | tsk->thread.error_code = error_code; | |
92181f19 | 673 | |
92181f19 NP |
674 | sig = SIGKILL; |
675 | if (__die("Oops", regs, error_code)) | |
676 | sig = 0; | |
2d4a7167 | 677 | |
92181f19 NP |
678 | /* Executive summary in case the body of the oops scrolled away */ |
679 | printk(KERN_EMERG "CR2: %016lx\n", address); | |
2d4a7167 | 680 | |
92181f19 | 681 | oops_end(flags, regs, sig); |
92181f19 NP |
682 | } |
683 | ||
2d4a7167 IM |
684 | /* |
685 | * Print out info about fatal segfaults, if the show_unhandled_signals | |
686 | * sysctl is set: | |
687 | */ | |
688 | static inline void | |
689 | show_signal_msg(struct pt_regs *regs, unsigned long error_code, | |
690 | unsigned long address, struct task_struct *tsk) | |
691 | { | |
692 | if (!unhandled_signal(tsk, SIGSEGV)) | |
693 | return; | |
694 | ||
695 | if (!printk_ratelimit()) | |
696 | return; | |
697 | ||
698 | printk(KERN_CONT "%s%s[%d]: segfault at %lx ip %p sp %p error %lx", | |
699 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, | |
700 | tsk->comm, task_pid_nr(tsk), address, | |
701 | (void *)regs->ip, (void *)regs->sp, error_code); | |
702 | ||
703 | print_vma_addr(KERN_CONT " in ", regs->ip); | |
704 | ||
705 | printk(KERN_CONT "\n"); | |
706 | } | |
707 | ||
708 | static void | |
709 | __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, | |
710 | unsigned long address, int si_code) | |
92181f19 NP |
711 | { |
712 | struct task_struct *tsk = current; | |
713 | ||
714 | /* User mode accesses just cause a SIGSEGV */ | |
715 | if (error_code & PF_USER) { | |
716 | /* | |
2d4a7167 | 717 | * It's possible to have interrupts off here: |
92181f19 NP |
718 | */ |
719 | local_irq_enable(); | |
720 | ||
721 | /* | |
722 | * Valid to do another page fault here because this one came | |
2d4a7167 | 723 | * from user space: |
92181f19 NP |
724 | */ |
725 | if (is_prefetch(regs, error_code, address)) | |
726 | return; | |
727 | ||
728 | if (is_errata100(regs, address)) | |
729 | return; | |
730 | ||
2d4a7167 IM |
731 | if (unlikely(show_unhandled_signals)) |
732 | show_signal_msg(regs, error_code, address, tsk); | |
733 | ||
734 | /* Kernel addresses are always protection faults: */ | |
735 | tsk->thread.cr2 = address; | |
736 | tsk->thread.error_code = error_code | (address >= TASK_SIZE); | |
737 | tsk->thread.trap_no = 14; | |
92181f19 | 738 | |
92181f19 | 739 | force_sig_info_fault(SIGSEGV, si_code, address, tsk); |
2d4a7167 | 740 | |
92181f19 NP |
741 | return; |
742 | } | |
743 | ||
744 | if (is_f00f_bug(regs, address)) | |
745 | return; | |
746 | ||
747 | no_context(regs, error_code, address); | |
748 | } | |
749 | ||
2d4a7167 IM |
750 | static noinline void |
751 | bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, | |
752 | unsigned long address) | |
92181f19 NP |
753 | { |
754 | __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR); | |
755 | } | |
756 | ||
2d4a7167 IM |
757 | static void |
758 | __bad_area(struct pt_regs *regs, unsigned long error_code, | |
759 | unsigned long address, int si_code) | |
92181f19 NP |
760 | { |
761 | struct mm_struct *mm = current->mm; | |
762 | ||
763 | /* | |
764 | * Something tried to access memory that isn't in our memory map.. | |
765 | * Fix it, but check if it's kernel or user first.. | |
766 | */ | |
767 | up_read(&mm->mmap_sem); | |
768 | ||
769 | __bad_area_nosemaphore(regs, error_code, address, si_code); | |
770 | } | |
771 | ||
2d4a7167 IM |
772 | static noinline void |
773 | bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address) | |
92181f19 NP |
774 | { |
775 | __bad_area(regs, error_code, address, SEGV_MAPERR); | |
776 | } | |
777 | ||
2d4a7167 IM |
778 | static noinline void |
779 | bad_area_access_error(struct pt_regs *regs, unsigned long error_code, | |
780 | unsigned long address) | |
92181f19 NP |
781 | { |
782 | __bad_area(regs, error_code, address, SEGV_ACCERR); | |
783 | } | |
784 | ||
785 | /* TODO: fixup for "mm-invoke-oom-killer-from-page-fault.patch" */ | |
2d4a7167 IM |
786 | static void |
787 | out_of_memory(struct pt_regs *regs, unsigned long error_code, | |
788 | unsigned long address) | |
92181f19 NP |
789 | { |
790 | /* | |
791 | * We ran out of memory, call the OOM killer, and return the userspace | |
2d4a7167 | 792 | * (which will retry the fault, or kill us if we got oom-killed): |
92181f19 NP |
793 | */ |
794 | up_read(¤t->mm->mmap_sem); | |
2d4a7167 | 795 | |
92181f19 NP |
796 | pagefault_out_of_memory(); |
797 | } | |
798 | ||
2d4a7167 IM |
799 | static void |
800 | do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address) | |
92181f19 NP |
801 | { |
802 | struct task_struct *tsk = current; | |
803 | struct mm_struct *mm = tsk->mm; | |
804 | ||
805 | up_read(&mm->mmap_sem); | |
806 | ||
2d4a7167 | 807 | /* Kernel mode? Handle exceptions or die: */ |
92181f19 NP |
808 | if (!(error_code & PF_USER)) |
809 | no_context(regs, error_code, address); | |
2d4a7167 | 810 | |
cd1b68f0 | 811 | /* User-space => ok to do another page fault: */ |
92181f19 NP |
812 | if (is_prefetch(regs, error_code, address)) |
813 | return; | |
2d4a7167 IM |
814 | |
815 | tsk->thread.cr2 = address; | |
816 | tsk->thread.error_code = error_code; | |
817 | tsk->thread.trap_no = 14; | |
818 | ||
92181f19 NP |
819 | force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk); |
820 | } | |
821 | ||
2d4a7167 IM |
822 | static noinline void |
823 | mm_fault_error(struct pt_regs *regs, unsigned long error_code, | |
824 | unsigned long address, unsigned int fault) | |
92181f19 | 825 | { |
2d4a7167 | 826 | if (fault & VM_FAULT_OOM) { |
92181f19 | 827 | out_of_memory(regs, error_code, address); |
2d4a7167 IM |
828 | } else { |
829 | if (fault & VM_FAULT_SIGBUS) | |
830 | do_sigbus(regs, error_code, address); | |
831 | else | |
832 | BUG(); | |
833 | } | |
92181f19 NP |
834 | } |
835 | ||
d8b57bb7 TG |
836 | static int spurious_fault_check(unsigned long error_code, pte_t *pte) |
837 | { | |
838 | if ((error_code & PF_WRITE) && !pte_write(*pte)) | |
839 | return 0; | |
2d4a7167 | 840 | |
d8b57bb7 TG |
841 | if ((error_code & PF_INSTR) && !pte_exec(*pte)) |
842 | return 0; | |
843 | ||
844 | return 1; | |
845 | } | |
846 | ||
5b727a3b | 847 | /* |
2d4a7167 IM |
848 | * Handle a spurious fault caused by a stale TLB entry. |
849 | * | |
850 | * This allows us to lazily refresh the TLB when increasing the | |
851 | * permissions of a kernel page (RO -> RW or NX -> X). Doing it | |
852 | * eagerly is very expensive since that implies doing a full | |
853 | * cross-processor TLB flush, even if no stale TLB entries exist | |
854 | * on other processors. | |
855 | * | |
5b727a3b JF |
856 | * There are no security implications to leaving a stale TLB when |
857 | * increasing the permissions on a page. | |
858 | */ | |
2d4a7167 IM |
859 | static noinline int |
860 | spurious_fault(unsigned long error_code, unsigned long address) | |
5b727a3b JF |
861 | { |
862 | pgd_t *pgd; | |
863 | pud_t *pud; | |
864 | pmd_t *pmd; | |
865 | pte_t *pte; | |
3c3e5694 | 866 | int ret; |
5b727a3b JF |
867 | |
868 | /* Reserved-bit violation or user access to kernel space? */ | |
869 | if (error_code & (PF_USER | PF_RSVD)) | |
870 | return 0; | |
871 | ||
872 | pgd = init_mm.pgd + pgd_index(address); | |
873 | if (!pgd_present(*pgd)) | |
874 | return 0; | |
875 | ||
876 | pud = pud_offset(pgd, address); | |
877 | if (!pud_present(*pud)) | |
878 | return 0; | |
879 | ||
d8b57bb7 TG |
880 | if (pud_large(*pud)) |
881 | return spurious_fault_check(error_code, (pte_t *) pud); | |
882 | ||
5b727a3b JF |
883 | pmd = pmd_offset(pud, address); |
884 | if (!pmd_present(*pmd)) | |
885 | return 0; | |
886 | ||
d8b57bb7 TG |
887 | if (pmd_large(*pmd)) |
888 | return spurious_fault_check(error_code, (pte_t *) pmd); | |
889 | ||
5b727a3b JF |
890 | pte = pte_offset_kernel(pmd, address); |
891 | if (!pte_present(*pte)) | |
892 | return 0; | |
893 | ||
3c3e5694 SR |
894 | ret = spurious_fault_check(error_code, pte); |
895 | if (!ret) | |
896 | return 0; | |
897 | ||
898 | /* | |
2d4a7167 IM |
899 | * Make sure we have permissions in PMD. |
900 | * If not, then there's a bug in the page tables: | |
3c3e5694 SR |
901 | */ |
902 | ret = spurious_fault_check(error_code, (pte_t *) pmd); | |
903 | WARN_ONCE(!ret, "PMD has incorrect permission bits\n"); | |
2d4a7167 | 904 | |
3c3e5694 | 905 | return ret; |
5b727a3b JF |
906 | } |
907 | ||
abd4f750 | 908 | int show_unhandled_signals = 1; |
1da177e4 | 909 | |
2d4a7167 IM |
910 | static inline int |
911 | access_error(unsigned long error_code, int write, struct vm_area_struct *vma) | |
92181f19 NP |
912 | { |
913 | if (write) { | |
2d4a7167 | 914 | /* write, present and write, not present: */ |
92181f19 NP |
915 | if (unlikely(!(vma->vm_flags & VM_WRITE))) |
916 | return 1; | |
2d4a7167 | 917 | return 0; |
92181f19 NP |
918 | } |
919 | ||
2d4a7167 IM |
920 | /* read, present: */ |
921 | if (unlikely(error_code & PF_PROT)) | |
922 | return 1; | |
923 | ||
924 | /* read, not present: */ | |
925 | if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))) | |
926 | return 1; | |
927 | ||
92181f19 NP |
928 | return 0; |
929 | } | |
930 | ||
0973a06c HS |
931 | static int fault_in_kernel_space(unsigned long address) |
932 | { | |
d9517346 | 933 | return address >= TASK_SIZE_MAX; |
0973a06c HS |
934 | } |
935 | ||
1da177e4 LT |
936 | /* |
937 | * This routine handles page faults. It determines the address, | |
938 | * and the problem, and then passes it off to one of the appropriate | |
939 | * routines. | |
1da177e4 | 940 | */ |
c3731c68 IM |
941 | dotraplinkage void __kprobes |
942 | do_page_fault(struct pt_regs *regs, unsigned long error_code) | |
1da177e4 | 943 | { |
2d4a7167 | 944 | struct vm_area_struct *vma; |
1da177e4 | 945 | struct task_struct *tsk; |
2d4a7167 | 946 | unsigned long address; |
1da177e4 | 947 | struct mm_struct *mm; |
92181f19 | 948 | int write; |
f8c2ee22 | 949 | int fault; |
1da177e4 | 950 | |
a9ba9a3b AV |
951 | tsk = current; |
952 | mm = tsk->mm; | |
2d4a7167 | 953 | |
a9ba9a3b AV |
954 | prefetchw(&mm->mmap_sem); |
955 | ||
2d4a7167 | 956 | /* Get the faulting address: */ |
f51c9452 | 957 | address = read_cr2(); |
1da177e4 | 958 | |
0fd0e3da | 959 | if (unlikely(kmmio_fault(regs, address))) |
86069782 | 960 | return; |
1da177e4 LT |
961 | |
962 | /* | |
963 | * We fault-in kernel-space virtual memory on-demand. The | |
964 | * 'reference' page table is init_mm.pgd. | |
965 | * | |
966 | * NOTE! We MUST NOT take any locks for this case. We may | |
967 | * be in an interrupt or a critical region, and should | |
968 | * only copy the information from the master page table, | |
969 | * nothing more. | |
970 | * | |
971 | * This verifies that the fault happens in kernel space | |
972 | * (error_code & 4) == 0, and that the fault was not a | |
8b1bde93 | 973 | * protection error (error_code & 9) == 0. |
1da177e4 | 974 | */ |
0973a06c | 975 | if (unlikely(fault_in_kernel_space(address))) { |
f8c2ee22 HH |
976 | if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && |
977 | vmalloc_fault(address) >= 0) | |
978 | return; | |
5b727a3b | 979 | |
2d4a7167 | 980 | /* Can handle a stale RO->RW TLB: */ |
92181f19 | 981 | if (spurious_fault(error_code, address)) |
5b727a3b JF |
982 | return; |
983 | ||
2d4a7167 | 984 | /* kprobes don't want to hook the spurious faults: */ |
9be260a6 MH |
985 | if (notify_page_fault(regs)) |
986 | return; | |
f8c2ee22 HH |
987 | /* |
988 | * Don't take the mm semaphore here. If we fixup a prefetch | |
2d4a7167 | 989 | * fault we could otherwise deadlock: |
f8c2ee22 | 990 | */ |
92181f19 | 991 | bad_area_nosemaphore(regs, error_code, address); |
2d4a7167 | 992 | |
92181f19 | 993 | return; |
f8c2ee22 HH |
994 | } |
995 | ||
2d4a7167 | 996 | /* kprobes don't want to hook the spurious faults: */ |
f8a6b2b9 | 997 | if (unlikely(notify_page_fault(regs))) |
9be260a6 | 998 | return; |
f8c2ee22 | 999 | /* |
891cffbd LT |
1000 | * It's safe to allow irq's after cr2 has been saved and the |
1001 | * vmalloc fault has been handled. | |
1002 | * | |
1003 | * User-mode registers count as a user access even for any | |
2d4a7167 | 1004 | * potential system fault or CPU buglet: |
f8c2ee22 | 1005 | */ |
891cffbd LT |
1006 | if (user_mode_vm(regs)) { |
1007 | local_irq_enable(); | |
1008 | error_code |= PF_USER; | |
2d4a7167 IM |
1009 | } else { |
1010 | if (regs->flags & X86_EFLAGS_IF) | |
1011 | local_irq_enable(); | |
1012 | } | |
8c914cb7 | 1013 | |
66c58156 | 1014 | if (unlikely(error_code & PF_RSVD)) |
92181f19 | 1015 | pgtable_bad(regs, error_code, address); |
1da177e4 | 1016 | |
f4dbfa8f | 1017 | perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address); |
7dd1fcc2 | 1018 | |
1da177e4 | 1019 | /* |
2d4a7167 IM |
1020 | * If we're in an interrupt, have no user context or are running |
1021 | * in an atomic region then we must not take the fault: | |
1da177e4 | 1022 | */ |
92181f19 NP |
1023 | if (unlikely(in_atomic() || !mm)) { |
1024 | bad_area_nosemaphore(regs, error_code, address); | |
1025 | return; | |
1026 | } | |
1da177e4 | 1027 | |
3a1dfe6e IM |
1028 | /* |
1029 | * When running in the kernel we expect faults to occur only to | |
2d4a7167 IM |
1030 | * addresses in user space. All other faults represent errors in |
1031 | * the kernel and should generate an OOPS. Unfortunately, in the | |
1032 | * case of an erroneous fault occurring in a code path which already | |
1033 | * holds mmap_sem we will deadlock attempting to validate the fault | |
1034 | * against the address space. Luckily the kernel only validly | |
1035 | * references user space from well defined areas of code, which are | |
1036 | * listed in the exceptions table. | |
1da177e4 LT |
1037 | * |
1038 | * As the vast majority of faults will be valid we will only perform | |
2d4a7167 IM |
1039 | * the source reference check when there is a possibility of a |
1040 | * deadlock. Attempt to lock the address space, if we cannot we then | |
1041 | * validate the source. If this is invalid we can skip the address | |
1042 | * space check, thus avoiding the deadlock: | |
1da177e4 | 1043 | */ |
92181f19 | 1044 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) { |
66c58156 | 1045 | if ((error_code & PF_USER) == 0 && |
92181f19 NP |
1046 | !search_exception_tables(regs->ip)) { |
1047 | bad_area_nosemaphore(regs, error_code, address); | |
1048 | return; | |
1049 | } | |
1da177e4 | 1050 | down_read(&mm->mmap_sem); |
01006074 PZ |
1051 | } else { |
1052 | /* | |
2d4a7167 IM |
1053 | * The above down_read_trylock() might have succeeded in |
1054 | * which case we'll have missed the might_sleep() from | |
1055 | * down_read(): | |
01006074 PZ |
1056 | */ |
1057 | might_sleep(); | |
1da177e4 LT |
1058 | } |
1059 | ||
1060 | vma = find_vma(mm, address); | |
92181f19 NP |
1061 | if (unlikely(!vma)) { |
1062 | bad_area(regs, error_code, address); | |
1063 | return; | |
1064 | } | |
1065 | if (likely(vma->vm_start <= address)) | |
1da177e4 | 1066 | goto good_area; |
92181f19 NP |
1067 | if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) { |
1068 | bad_area(regs, error_code, address); | |
1069 | return; | |
1070 | } | |
33cb5243 | 1071 | if (error_code & PF_USER) { |
6f4d368e HH |
1072 | /* |
1073 | * Accessing the stack below %sp is always a bug. | |
1074 | * The large cushion allows instructions like enter | |
2d4a7167 | 1075 | * and pusha to work. ("enter $65535, $31" pushes |
6f4d368e | 1076 | * 32 pointers and then decrements %sp by 65535.) |
03fdc2c2 | 1077 | */ |
92181f19 NP |
1078 | if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) { |
1079 | bad_area(regs, error_code, address); | |
1080 | return; | |
1081 | } | |
1da177e4 | 1082 | } |
92181f19 NP |
1083 | if (unlikely(expand_stack(vma, address))) { |
1084 | bad_area(regs, error_code, address); | |
1085 | return; | |
1086 | } | |
1087 | ||
1088 | /* | |
1089 | * Ok, we have a good vm_area for this memory access, so | |
1090 | * we can handle it.. | |
1091 | */ | |
1da177e4 | 1092 | good_area: |
92181f19 | 1093 | write = error_code & PF_WRITE; |
2d4a7167 | 1094 | |
92181f19 NP |
1095 | if (unlikely(access_error(error_code, write, vma))) { |
1096 | bad_area_access_error(regs, error_code, address); | |
1097 | return; | |
1da177e4 LT |
1098 | } |
1099 | ||
1100 | /* | |
1101 | * If for any reason at all we couldn't handle the fault, | |
1102 | * make sure we exit gracefully rather than endlessly redo | |
2d4a7167 | 1103 | * the fault: |
1da177e4 | 1104 | */ |
83c54070 | 1105 | fault = handle_mm_fault(mm, vma, address, write); |
2d4a7167 | 1106 | |
83c54070 | 1107 | if (unlikely(fault & VM_FAULT_ERROR)) { |
92181f19 NP |
1108 | mm_fault_error(regs, error_code, address, fault); |
1109 | return; | |
1da177e4 | 1110 | } |
2d4a7167 | 1111 | |
ac17dc8e | 1112 | if (fault & VM_FAULT_MAJOR) { |
83c54070 | 1113 | tsk->maj_flt++; |
f4dbfa8f | 1114 | perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0, |
78f13e95 | 1115 | regs, address); |
ac17dc8e | 1116 | } else { |
83c54070 | 1117 | tsk->min_flt++; |
f4dbfa8f | 1118 | perf_swcounter_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0, |
78f13e95 | 1119 | regs, address); |
ac17dc8e | 1120 | } |
d729ab35 | 1121 | |
8c938f9f IM |
1122 | check_v8086_mode(regs, address, tsk); |
1123 | ||
1da177e4 | 1124 | up_read(&mm->mmap_sem); |
1da177e4 | 1125 | } |