Commit | Line | Data |
---|---|---|
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, ... */ | |
cdd6c482 | 13 | #include <linux/perf_event.h> /* perf_sw_event */ |
2d4a7167 | 14 | |
a2bcd473 IM |
15 | #include <asm/traps.h> /* dotraplinkage, ... */ |
16 | #include <asm/pgalloc.h> /* pgd_*(), ... */ | |
f8561296 | 17 | #include <asm/kmemcheck.h> /* kmemcheck_*(), ... */ |
1da177e4 | 18 | |
33cb5243 | 19 | /* |
2d4a7167 IM |
20 | * Page fault error code bits: |
21 | * | |
22 | * bit 0 == 0: no page found 1: protection fault | |
23 | * bit 1 == 0: read access 1: write access | |
24 | * bit 2 == 0: kernel-mode access 1: user-mode access | |
25 | * bit 3 == 1: use of reserved bit detected | |
26 | * bit 4 == 1: fault was an instruction fetch | |
33cb5243 | 27 | */ |
2d4a7167 IM |
28 | enum x86_pf_error_code { |
29 | ||
30 | PF_PROT = 1 << 0, | |
31 | PF_WRITE = 1 << 1, | |
32 | PF_USER = 1 << 2, | |
33 | PF_RSVD = 1 << 3, | |
34 | PF_INSTR = 1 << 4, | |
35 | }; | |
66c58156 | 36 | |
b814d41f | 37 | /* |
b319eed0 IM |
38 | * Returns 0 if mmiotrace is disabled, or if the fault is not |
39 | * handled by mmiotrace: | |
b814d41f | 40 | */ |
62c9295f MH |
41 | static inline int __kprobes |
42 | kmmio_fault(struct pt_regs *regs, unsigned long addr) | |
86069782 | 43 | { |
0fd0e3da PP |
44 | if (unlikely(is_kmmio_active())) |
45 | if (kmmio_handler(regs, addr) == 1) | |
46 | return -1; | |
0fd0e3da | 47 | return 0; |
86069782 PP |
48 | } |
49 | ||
62c9295f | 50 | static inline int __kprobes notify_page_fault(struct pt_regs *regs) |
1bd858a5 | 51 | { |
74a0b576 CH |
52 | int ret = 0; |
53 | ||
54 | /* kprobe_running() needs smp_processor_id() */ | |
b1801812 | 55 | if (kprobes_built_in() && !user_mode_vm(regs)) { |
74a0b576 CH |
56 | preempt_disable(); |
57 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
58 | ret = 1; | |
59 | preempt_enable(); | |
60 | } | |
1bd858a5 | 61 | |
74a0b576 | 62 | return ret; |
33cb5243 | 63 | } |
1bd858a5 | 64 | |
1dc85be0 | 65 | /* |
2d4a7167 IM |
66 | * Prefetch quirks: |
67 | * | |
68 | * 32-bit mode: | |
69 | * | |
70 | * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. | |
71 | * Check that here and ignore it. | |
1dc85be0 | 72 | * |
2d4a7167 | 73 | * 64-bit mode: |
1dc85be0 | 74 | * |
2d4a7167 IM |
75 | * Sometimes the CPU reports invalid exceptions on prefetch. |
76 | * Check that here and ignore it. | |
77 | * | |
78 | * Opcode checker based on code by Richard Brunner. | |
1dc85be0 | 79 | */ |
107a0367 IM |
80 | static inline int |
81 | check_prefetch_opcode(struct pt_regs *regs, unsigned char *instr, | |
82 | unsigned char opcode, int *prefetch) | |
83 | { | |
84 | unsigned char instr_hi = opcode & 0xf0; | |
85 | unsigned char instr_lo = opcode & 0x0f; | |
86 | ||
87 | switch (instr_hi) { | |
88 | case 0x20: | |
89 | case 0x30: | |
90 | /* | |
91 | * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. | |
92 | * In X86_64 long mode, the CPU will signal invalid | |
93 | * opcode if some of these prefixes are present so | |
94 | * X86_64 will never get here anyway | |
95 | */ | |
96 | return ((instr_lo & 7) == 0x6); | |
97 | #ifdef CONFIG_X86_64 | |
98 | case 0x40: | |
99 | /* | |
100 | * In AMD64 long mode 0x40..0x4F are valid REX prefixes | |
101 | * Need to figure out under what instruction mode the | |
102 | * instruction was issued. Could check the LDT for lm, | |
103 | * but for now it's good enough to assume that long | |
104 | * mode only uses well known segments or kernel. | |
105 | */ | |
106 | return (!user_mode(regs)) || (regs->cs == __USER_CS); | |
107 | #endif | |
108 | case 0x60: | |
109 | /* 0x64 thru 0x67 are valid prefixes in all modes. */ | |
110 | return (instr_lo & 0xC) == 0x4; | |
111 | case 0xF0: | |
112 | /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ | |
113 | return !instr_lo || (instr_lo>>1) == 1; | |
114 | case 0x00: | |
115 | /* Prefetch instruction is 0x0F0D or 0x0F18 */ | |
116 | if (probe_kernel_address(instr, opcode)) | |
117 | return 0; | |
118 | ||
119 | *prefetch = (instr_lo == 0xF) && | |
120 | (opcode == 0x0D || opcode == 0x18); | |
121 | return 0; | |
122 | default: | |
123 | return 0; | |
124 | } | |
125 | } | |
126 | ||
2d4a7167 IM |
127 | static int |
128 | is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr) | |
33cb5243 | 129 | { |
2d4a7167 | 130 | unsigned char *max_instr; |
ab2bf0c1 | 131 | unsigned char *instr; |
33cb5243 | 132 | int prefetch = 0; |
1da177e4 | 133 | |
3085354d IM |
134 | /* |
135 | * If it was a exec (instruction fetch) fault on NX page, then | |
136 | * do not ignore the fault: | |
137 | */ | |
66c58156 | 138 | if (error_code & PF_INSTR) |
1da177e4 | 139 | return 0; |
1dc85be0 | 140 | |
107a0367 | 141 | instr = (void *)convert_ip_to_linear(current, regs); |
f1290ec9 | 142 | max_instr = instr + 15; |
1da177e4 | 143 | |
76381fee | 144 | if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) |
1da177e4 LT |
145 | return 0; |
146 | ||
107a0367 | 147 | while (instr < max_instr) { |
2d4a7167 | 148 | unsigned char opcode; |
1da177e4 | 149 | |
ab2bf0c1 | 150 | if (probe_kernel_address(instr, opcode)) |
33cb5243 | 151 | break; |
1da177e4 | 152 | |
1da177e4 LT |
153 | instr++; |
154 | ||
107a0367 | 155 | if (!check_prefetch_opcode(regs, instr, opcode, &prefetch)) |
1da177e4 | 156 | break; |
1da177e4 LT |
157 | } |
158 | return prefetch; | |
159 | } | |
160 | ||
2d4a7167 IM |
161 | static void |
162 | force_sig_info_fault(int si_signo, int si_code, unsigned long address, | |
163 | struct task_struct *tsk) | |
c4aba4a8 HH |
164 | { |
165 | siginfo_t info; | |
166 | ||
2d4a7167 IM |
167 | info.si_signo = si_signo; |
168 | info.si_errno = 0; | |
169 | info.si_code = si_code; | |
170 | info.si_addr = (void __user *)address; | |
a6e04aa9 | 171 | info.si_addr_lsb = si_code == BUS_MCEERR_AR ? PAGE_SHIFT : 0; |
2d4a7167 | 172 | |
c4aba4a8 HH |
173 | force_sig_info(si_signo, &info, tsk); |
174 | } | |
175 | ||
f2f13a85 IM |
176 | DEFINE_SPINLOCK(pgd_lock); |
177 | LIST_HEAD(pgd_list); | |
178 | ||
179 | #ifdef CONFIG_X86_32 | |
180 | static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) | |
33cb5243 | 181 | { |
f2f13a85 IM |
182 | unsigned index = pgd_index(address); |
183 | pgd_t *pgd_k; | |
184 | pud_t *pud, *pud_k; | |
185 | pmd_t *pmd, *pmd_k; | |
2d4a7167 | 186 | |
f2f13a85 IM |
187 | pgd += index; |
188 | pgd_k = init_mm.pgd + index; | |
189 | ||
190 | if (!pgd_present(*pgd_k)) | |
191 | return NULL; | |
192 | ||
193 | /* | |
194 | * set_pgd(pgd, *pgd_k); here would be useless on PAE | |
195 | * and redundant with the set_pmd() on non-PAE. As would | |
196 | * set_pud. | |
197 | */ | |
198 | pud = pud_offset(pgd, address); | |
199 | pud_k = pud_offset(pgd_k, address); | |
200 | if (!pud_present(*pud_k)) | |
201 | return NULL; | |
202 | ||
203 | pmd = pmd_offset(pud, address); | |
204 | pmd_k = pmd_offset(pud_k, address); | |
205 | if (!pmd_present(*pmd_k)) | |
206 | return NULL; | |
207 | ||
b8bcfe99 | 208 | if (!pmd_present(*pmd)) |
f2f13a85 | 209 | set_pmd(pmd, *pmd_k); |
b8bcfe99 | 210 | else |
f2f13a85 | 211 | BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); |
f2f13a85 IM |
212 | |
213 | return pmd_k; | |
214 | } | |
215 | ||
216 | void vmalloc_sync_all(void) | |
217 | { | |
218 | unsigned long address; | |
219 | ||
220 | if (SHARED_KERNEL_PMD) | |
221 | return; | |
222 | ||
223 | for (address = VMALLOC_START & PMD_MASK; | |
224 | address >= TASK_SIZE && address < FIXADDR_TOP; | |
225 | address += PMD_SIZE) { | |
226 | ||
227 | unsigned long flags; | |
228 | struct page *page; | |
229 | ||
230 | spin_lock_irqsave(&pgd_lock, flags); | |
231 | list_for_each_entry(page, &pgd_list, lru) { | |
232 | if (!vmalloc_sync_one(page_address(page), address)) | |
233 | break; | |
234 | } | |
235 | spin_unlock_irqrestore(&pgd_lock, flags); | |
236 | } | |
237 | } | |
238 | ||
239 | /* | |
240 | * 32-bit: | |
241 | * | |
242 | * Handle a fault on the vmalloc or module mapping area | |
243 | */ | |
62c9295f | 244 | static noinline __kprobes int vmalloc_fault(unsigned long address) |
f2f13a85 IM |
245 | { |
246 | unsigned long pgd_paddr; | |
247 | pmd_t *pmd_k; | |
248 | pte_t *pte_k; | |
249 | ||
250 | /* Make sure we are in vmalloc area: */ | |
251 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
252 | return -1; | |
253 | ||
254 | /* | |
255 | * Synchronize this task's top level page-table | |
256 | * with the 'reference' page table. | |
257 | * | |
258 | * Do _not_ use "current" here. We might be inside | |
259 | * an interrupt in the middle of a task switch.. | |
260 | */ | |
261 | pgd_paddr = read_cr3(); | |
262 | pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); | |
263 | if (!pmd_k) | |
264 | return -1; | |
265 | ||
266 | pte_k = pte_offset_kernel(pmd_k, address); | |
267 | if (!pte_present(*pte_k)) | |
268 | return -1; | |
269 | ||
270 | return 0; | |
271 | } | |
272 | ||
273 | /* | |
274 | * Did it hit the DOS screen memory VA from vm86 mode? | |
275 | */ | |
276 | static inline void | |
277 | check_v8086_mode(struct pt_regs *regs, unsigned long address, | |
278 | struct task_struct *tsk) | |
279 | { | |
280 | unsigned long bit; | |
281 | ||
282 | if (!v8086_mode(regs)) | |
283 | return; | |
284 | ||
285 | bit = (address - 0xA0000) >> PAGE_SHIFT; | |
286 | if (bit < 32) | |
287 | tsk->thread.screen_bitmap |= 1 << bit; | |
33cb5243 | 288 | } |
1da177e4 | 289 | |
087975b0 | 290 | static bool low_pfn(unsigned long pfn) |
1da177e4 | 291 | { |
087975b0 AM |
292 | return pfn < max_low_pfn; |
293 | } | |
1156e098 | 294 | |
087975b0 AM |
295 | static void dump_pagetable(unsigned long address) |
296 | { | |
297 | pgd_t *base = __va(read_cr3()); | |
298 | pgd_t *pgd = &base[pgd_index(address)]; | |
299 | pmd_t *pmd; | |
300 | pte_t *pte; | |
2d4a7167 | 301 | |
1156e098 | 302 | #ifdef CONFIG_X86_PAE |
087975b0 AM |
303 | printk("*pdpt = %016Lx ", pgd_val(*pgd)); |
304 | if (!low_pfn(pgd_val(*pgd) >> PAGE_SHIFT) || !pgd_present(*pgd)) | |
305 | goto out; | |
1156e098 | 306 | #endif |
087975b0 AM |
307 | pmd = pmd_offset(pud_offset(pgd, address), address); |
308 | printk(KERN_CONT "*pde = %0*Lx ", sizeof(*pmd) * 2, (u64)pmd_val(*pmd)); | |
1156e098 HH |
309 | |
310 | /* | |
311 | * We must not directly access the pte in the highpte | |
312 | * case if the page table is located in highmem. | |
313 | * And let's rather not kmap-atomic the pte, just in case | |
2d4a7167 | 314 | * it's allocated already: |
1156e098 | 315 | */ |
087975b0 AM |
316 | if (!low_pfn(pmd_pfn(*pmd)) || !pmd_present(*pmd) || pmd_large(*pmd)) |
317 | goto out; | |
1156e098 | 318 | |
087975b0 AM |
319 | pte = pte_offset_kernel(pmd, address); |
320 | printk("*pte = %0*Lx ", sizeof(*pte) * 2, (u64)pte_val(*pte)); | |
321 | out: | |
1156e098 | 322 | printk("\n"); |
f2f13a85 IM |
323 | } |
324 | ||
325 | #else /* CONFIG_X86_64: */ | |
326 | ||
327 | void vmalloc_sync_all(void) | |
328 | { | |
329 | unsigned long address; | |
330 | ||
331 | for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END; | |
332 | address += PGDIR_SIZE) { | |
333 | ||
334 | const pgd_t *pgd_ref = pgd_offset_k(address); | |
335 | unsigned long flags; | |
336 | struct page *page; | |
337 | ||
338 | if (pgd_none(*pgd_ref)) | |
339 | continue; | |
340 | ||
341 | spin_lock_irqsave(&pgd_lock, flags); | |
342 | list_for_each_entry(page, &pgd_list, lru) { | |
343 | pgd_t *pgd; | |
344 | pgd = (pgd_t *)page_address(page) + pgd_index(address); | |
345 | if (pgd_none(*pgd)) | |
346 | set_pgd(pgd, *pgd_ref); | |
347 | else | |
348 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); | |
349 | } | |
350 | spin_unlock_irqrestore(&pgd_lock, flags); | |
351 | } | |
352 | } | |
353 | ||
354 | /* | |
355 | * 64-bit: | |
356 | * | |
357 | * Handle a fault on the vmalloc area | |
358 | * | |
359 | * This assumes no large pages in there. | |
360 | */ | |
62c9295f | 361 | static noinline __kprobes int vmalloc_fault(unsigned long address) |
f2f13a85 IM |
362 | { |
363 | pgd_t *pgd, *pgd_ref; | |
364 | pud_t *pud, *pud_ref; | |
365 | pmd_t *pmd, *pmd_ref; | |
366 | pte_t *pte, *pte_ref; | |
367 | ||
368 | /* Make sure we are in vmalloc area: */ | |
369 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
370 | return -1; | |
371 | ||
372 | /* | |
373 | * Copy kernel mappings over when needed. This can also | |
374 | * happen within a race in page table update. In the later | |
375 | * case just flush: | |
376 | */ | |
377 | pgd = pgd_offset(current->active_mm, address); | |
378 | pgd_ref = pgd_offset_k(address); | |
379 | if (pgd_none(*pgd_ref)) | |
380 | return -1; | |
381 | ||
382 | if (pgd_none(*pgd)) | |
383 | set_pgd(pgd, *pgd_ref); | |
384 | else | |
385 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); | |
386 | ||
387 | /* | |
388 | * Below here mismatches are bugs because these lower tables | |
389 | * are shared: | |
390 | */ | |
391 | ||
392 | pud = pud_offset(pgd, address); | |
393 | pud_ref = pud_offset(pgd_ref, address); | |
394 | if (pud_none(*pud_ref)) | |
395 | return -1; | |
396 | ||
397 | if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) | |
398 | BUG(); | |
399 | ||
400 | pmd = pmd_offset(pud, address); | |
401 | pmd_ref = pmd_offset(pud_ref, address); | |
402 | if (pmd_none(*pmd_ref)) | |
403 | return -1; | |
404 | ||
405 | if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) | |
406 | BUG(); | |
407 | ||
408 | pte_ref = pte_offset_kernel(pmd_ref, address); | |
409 | if (!pte_present(*pte_ref)) | |
410 | return -1; | |
411 | ||
412 | pte = pte_offset_kernel(pmd, address); | |
413 | ||
414 | /* | |
415 | * Don't use pte_page here, because the mappings can point | |
416 | * outside mem_map, and the NUMA hash lookup cannot handle | |
417 | * that: | |
418 | */ | |
419 | if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) | |
420 | BUG(); | |
421 | ||
422 | return 0; | |
423 | } | |
424 | ||
425 | static const char errata93_warning[] = | |
ad361c98 JP |
426 | KERN_ERR |
427 | "******* Your BIOS seems to not contain a fix for K8 errata #93\n" | |
428 | "******* Working around it, but it may cause SEGVs or burn power.\n" | |
429 | "******* Please consider a BIOS update.\n" | |
430 | "******* Disabling USB legacy in the BIOS may also help.\n"; | |
f2f13a85 IM |
431 | |
432 | /* | |
433 | * No vm86 mode in 64-bit mode: | |
434 | */ | |
435 | static inline void | |
436 | check_v8086_mode(struct pt_regs *regs, unsigned long address, | |
437 | struct task_struct *tsk) | |
438 | { | |
439 | } | |
440 | ||
441 | static int bad_address(void *p) | |
442 | { | |
443 | unsigned long dummy; | |
444 | ||
445 | return probe_kernel_address((unsigned long *)p, dummy); | |
446 | } | |
447 | ||
448 | static void dump_pagetable(unsigned long address) | |
449 | { | |
087975b0 AM |
450 | pgd_t *base = __va(read_cr3() & PHYSICAL_PAGE_MASK); |
451 | pgd_t *pgd = base + pgd_index(address); | |
1da177e4 LT |
452 | pud_t *pud; |
453 | pmd_t *pmd; | |
454 | pte_t *pte; | |
455 | ||
2d4a7167 IM |
456 | if (bad_address(pgd)) |
457 | goto bad; | |
458 | ||
d646bce4 | 459 | printk("PGD %lx ", pgd_val(*pgd)); |
2d4a7167 IM |
460 | |
461 | if (!pgd_present(*pgd)) | |
462 | goto out; | |
1da177e4 | 463 | |
d2ae5b5f | 464 | pud = pud_offset(pgd, address); |
2d4a7167 IM |
465 | if (bad_address(pud)) |
466 | goto bad; | |
467 | ||
1da177e4 | 468 | printk("PUD %lx ", pud_val(*pud)); |
b5360222 | 469 | if (!pud_present(*pud) || pud_large(*pud)) |
2d4a7167 | 470 | goto out; |
1da177e4 LT |
471 | |
472 | pmd = pmd_offset(pud, address); | |
2d4a7167 IM |
473 | if (bad_address(pmd)) |
474 | goto bad; | |
475 | ||
1da177e4 | 476 | printk("PMD %lx ", pmd_val(*pmd)); |
2d4a7167 IM |
477 | if (!pmd_present(*pmd) || pmd_large(*pmd)) |
478 | goto out; | |
1da177e4 LT |
479 | |
480 | pte = pte_offset_kernel(pmd, address); | |
2d4a7167 IM |
481 | if (bad_address(pte)) |
482 | goto bad; | |
483 | ||
33cb5243 | 484 | printk("PTE %lx", pte_val(*pte)); |
2d4a7167 | 485 | out: |
1da177e4 LT |
486 | printk("\n"); |
487 | return; | |
488 | bad: | |
489 | printk("BAD\n"); | |
8c938f9f IM |
490 | } |
491 | ||
f2f13a85 | 492 | #endif /* CONFIG_X86_64 */ |
1da177e4 | 493 | |
2d4a7167 IM |
494 | /* |
495 | * Workaround for K8 erratum #93 & buggy BIOS. | |
496 | * | |
497 | * BIOS SMM functions are required to use a specific workaround | |
498 | * to avoid corruption of the 64bit RIP register on C stepping K8. | |
499 | * | |
500 | * A lot of BIOS that didn't get tested properly miss this. | |
501 | * | |
502 | * The OS sees this as a page fault with the upper 32bits of RIP cleared. | |
503 | * Try to work around it here. | |
504 | * | |
505 | * Note we only handle faults in kernel here. | |
506 | * Does nothing on 32-bit. | |
fdfe8aa8 | 507 | */ |
33cb5243 | 508 | static int is_errata93(struct pt_regs *regs, unsigned long address) |
1da177e4 | 509 | { |
fdfe8aa8 | 510 | #ifdef CONFIG_X86_64 |
65ea5b03 | 511 | if (address != regs->ip) |
1da177e4 | 512 | return 0; |
2d4a7167 | 513 | |
33cb5243 | 514 | if ((address >> 32) != 0) |
1da177e4 | 515 | return 0; |
2d4a7167 | 516 | |
1da177e4 | 517 | address |= 0xffffffffUL << 32; |
33cb5243 HH |
518 | if ((address >= (u64)_stext && address <= (u64)_etext) || |
519 | (address >= MODULES_VADDR && address <= MODULES_END)) { | |
a454ab31 | 520 | printk_once(errata93_warning); |
65ea5b03 | 521 | regs->ip = address; |
1da177e4 LT |
522 | return 1; |
523 | } | |
fdfe8aa8 | 524 | #endif |
1da177e4 | 525 | return 0; |
33cb5243 | 526 | } |
1da177e4 | 527 | |
35f3266f | 528 | /* |
2d4a7167 IM |
529 | * Work around K8 erratum #100 K8 in compat mode occasionally jumps |
530 | * to illegal addresses >4GB. | |
531 | * | |
532 | * We catch this in the page fault handler because these addresses | |
533 | * are not reachable. Just detect this case and return. Any code | |
35f3266f HH |
534 | * segment in LDT is compatibility mode. |
535 | */ | |
536 | static int is_errata100(struct pt_regs *regs, unsigned long address) | |
537 | { | |
538 | #ifdef CONFIG_X86_64 | |
2d4a7167 | 539 | if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && (address >> 32)) |
35f3266f HH |
540 | return 1; |
541 | #endif | |
542 | return 0; | |
543 | } | |
544 | ||
29caf2f9 HH |
545 | static int is_f00f_bug(struct pt_regs *regs, unsigned long address) |
546 | { | |
547 | #ifdef CONFIG_X86_F00F_BUG | |
548 | unsigned long nr; | |
2d4a7167 | 549 | |
29caf2f9 | 550 | /* |
2d4a7167 | 551 | * Pentium F0 0F C7 C8 bug workaround: |
29caf2f9 HH |
552 | */ |
553 | if (boot_cpu_data.f00f_bug) { | |
554 | nr = (address - idt_descr.address) >> 3; | |
555 | ||
556 | if (nr == 6) { | |
557 | do_invalid_op(regs, 0); | |
558 | return 1; | |
559 | } | |
560 | } | |
561 | #endif | |
562 | return 0; | |
563 | } | |
564 | ||
8f766149 IM |
565 | static const char nx_warning[] = KERN_CRIT |
566 | "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n"; | |
567 | ||
2d4a7167 IM |
568 | static void |
569 | show_fault_oops(struct pt_regs *regs, unsigned long error_code, | |
570 | unsigned long address) | |
b3279c7f | 571 | { |
1156e098 HH |
572 | if (!oops_may_print()) |
573 | return; | |
574 | ||
1156e098 | 575 | if (error_code & PF_INSTR) { |
93809be8 | 576 | unsigned int level; |
2d4a7167 | 577 | |
1156e098 HH |
578 | pte_t *pte = lookup_address(address, &level); |
579 | ||
8f766149 IM |
580 | if (pte && pte_present(*pte) && !pte_exec(*pte)) |
581 | printk(nx_warning, current_uid()); | |
1156e098 | 582 | } |
1156e098 | 583 | |
19f0dda9 | 584 | printk(KERN_ALERT "BUG: unable to handle kernel "); |
b3279c7f | 585 | if (address < PAGE_SIZE) |
19f0dda9 | 586 | printk(KERN_CONT "NULL pointer dereference"); |
b3279c7f | 587 | else |
19f0dda9 | 588 | printk(KERN_CONT "paging request"); |
2d4a7167 | 589 | |
f294a8ce | 590 | printk(KERN_CONT " at %p\n", (void *) address); |
19f0dda9 | 591 | printk(KERN_ALERT "IP:"); |
b3279c7f | 592 | printk_address(regs->ip, 1); |
2d4a7167 | 593 | |
b3279c7f HH |
594 | dump_pagetable(address); |
595 | } | |
596 | ||
2d4a7167 IM |
597 | static noinline void |
598 | pgtable_bad(struct pt_regs *regs, unsigned long error_code, | |
599 | unsigned long address) | |
1da177e4 | 600 | { |
2d4a7167 IM |
601 | struct task_struct *tsk; |
602 | unsigned long flags; | |
603 | int sig; | |
604 | ||
605 | flags = oops_begin(); | |
606 | tsk = current; | |
607 | sig = SIGKILL; | |
1209140c | 608 | |
1da177e4 | 609 | printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
92181f19 | 610 | tsk->comm, address); |
1da177e4 | 611 | dump_pagetable(address); |
2d4a7167 IM |
612 | |
613 | tsk->thread.cr2 = address; | |
614 | tsk->thread.trap_no = 14; | |
615 | tsk->thread.error_code = error_code; | |
616 | ||
22f5991c | 617 | if (__die("Bad pagetable", regs, error_code)) |
874d93d1 | 618 | sig = 0; |
2d4a7167 | 619 | |
874d93d1 | 620 | oops_end(flags, regs, sig); |
1da177e4 LT |
621 | } |
622 | ||
2d4a7167 IM |
623 | static noinline void |
624 | no_context(struct pt_regs *regs, unsigned long error_code, | |
625 | unsigned long address) | |
92181f19 NP |
626 | { |
627 | struct task_struct *tsk = current; | |
19803078 | 628 | unsigned long *stackend; |
92181f19 NP |
629 | unsigned long flags; |
630 | int sig; | |
92181f19 | 631 | |
2d4a7167 | 632 | /* Are we prepared to handle this kernel fault? */ |
92181f19 NP |
633 | if (fixup_exception(regs)) |
634 | return; | |
635 | ||
636 | /* | |
2d4a7167 IM |
637 | * 32-bit: |
638 | * | |
639 | * Valid to do another page fault here, because if this fault | |
640 | * had been triggered by is_prefetch fixup_exception would have | |
641 | * handled it. | |
642 | * | |
643 | * 64-bit: | |
92181f19 | 644 | * |
2d4a7167 | 645 | * Hall of shame of CPU/BIOS bugs. |
92181f19 NP |
646 | */ |
647 | if (is_prefetch(regs, error_code, address)) | |
648 | return; | |
649 | ||
650 | if (is_errata93(regs, address)) | |
651 | return; | |
652 | ||
653 | /* | |
654 | * Oops. The kernel tried to access some bad page. We'll have to | |
2d4a7167 | 655 | * terminate things with extreme prejudice: |
92181f19 | 656 | */ |
92181f19 | 657 | flags = oops_begin(); |
92181f19 NP |
658 | |
659 | show_fault_oops(regs, error_code, address); | |
660 | ||
2d4a7167 | 661 | stackend = end_of_stack(tsk); |
0e7810be | 662 | if (tsk != &init_task && *stackend != STACK_END_MAGIC) |
19803078 IM |
663 | printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); |
664 | ||
1cc99544 IM |
665 | tsk->thread.cr2 = address; |
666 | tsk->thread.trap_no = 14; | |
667 | tsk->thread.error_code = error_code; | |
92181f19 | 668 | |
92181f19 NP |
669 | sig = SIGKILL; |
670 | if (__die("Oops", regs, error_code)) | |
671 | sig = 0; | |
2d4a7167 | 672 | |
92181f19 NP |
673 | /* Executive summary in case the body of the oops scrolled away */ |
674 | printk(KERN_EMERG "CR2: %016lx\n", address); | |
2d4a7167 | 675 | |
92181f19 | 676 | oops_end(flags, regs, sig); |
92181f19 NP |
677 | } |
678 | ||
2d4a7167 IM |
679 | /* |
680 | * Print out info about fatal segfaults, if the show_unhandled_signals | |
681 | * sysctl is set: | |
682 | */ | |
683 | static inline void | |
684 | show_signal_msg(struct pt_regs *regs, unsigned long error_code, | |
685 | unsigned long address, struct task_struct *tsk) | |
686 | { | |
687 | if (!unhandled_signal(tsk, SIGSEGV)) | |
688 | return; | |
689 | ||
690 | if (!printk_ratelimit()) | |
691 | return; | |
692 | ||
a1a08d1c | 693 | printk("%s%s[%d]: segfault at %lx ip %p sp %p error %lx", |
2d4a7167 IM |
694 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, |
695 | tsk->comm, task_pid_nr(tsk), address, | |
696 | (void *)regs->ip, (void *)regs->sp, error_code); | |
697 | ||
698 | print_vma_addr(KERN_CONT " in ", regs->ip); | |
699 | ||
700 | printk(KERN_CONT "\n"); | |
701 | } | |
702 | ||
703 | static void | |
704 | __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, | |
705 | unsigned long address, int si_code) | |
92181f19 NP |
706 | { |
707 | struct task_struct *tsk = current; | |
708 | ||
709 | /* User mode accesses just cause a SIGSEGV */ | |
710 | if (error_code & PF_USER) { | |
711 | /* | |
2d4a7167 | 712 | * It's possible to have interrupts off here: |
92181f19 NP |
713 | */ |
714 | local_irq_enable(); | |
715 | ||
716 | /* | |
717 | * Valid to do another page fault here because this one came | |
2d4a7167 | 718 | * from user space: |
92181f19 NP |
719 | */ |
720 | if (is_prefetch(regs, error_code, address)) | |
721 | return; | |
722 | ||
723 | if (is_errata100(regs, address)) | |
724 | return; | |
725 | ||
2d4a7167 IM |
726 | if (unlikely(show_unhandled_signals)) |
727 | show_signal_msg(regs, error_code, address, tsk); | |
728 | ||
729 | /* Kernel addresses are always protection faults: */ | |
730 | tsk->thread.cr2 = address; | |
731 | tsk->thread.error_code = error_code | (address >= TASK_SIZE); | |
732 | tsk->thread.trap_no = 14; | |
92181f19 | 733 | |
92181f19 | 734 | force_sig_info_fault(SIGSEGV, si_code, address, tsk); |
2d4a7167 | 735 | |
92181f19 NP |
736 | return; |
737 | } | |
738 | ||
739 | if (is_f00f_bug(regs, address)) | |
740 | return; | |
741 | ||
742 | no_context(regs, error_code, address); | |
743 | } | |
744 | ||
2d4a7167 IM |
745 | static noinline void |
746 | bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, | |
747 | unsigned long address) | |
92181f19 NP |
748 | { |
749 | __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR); | |
750 | } | |
751 | ||
2d4a7167 IM |
752 | static void |
753 | __bad_area(struct pt_regs *regs, unsigned long error_code, | |
754 | unsigned long address, int si_code) | |
92181f19 NP |
755 | { |
756 | struct mm_struct *mm = current->mm; | |
757 | ||
758 | /* | |
759 | * Something tried to access memory that isn't in our memory map.. | |
760 | * Fix it, but check if it's kernel or user first.. | |
761 | */ | |
762 | up_read(&mm->mmap_sem); | |
763 | ||
764 | __bad_area_nosemaphore(regs, error_code, address, si_code); | |
765 | } | |
766 | ||
2d4a7167 IM |
767 | static noinline void |
768 | bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address) | |
92181f19 NP |
769 | { |
770 | __bad_area(regs, error_code, address, SEGV_MAPERR); | |
771 | } | |
772 | ||
2d4a7167 IM |
773 | static noinline void |
774 | bad_area_access_error(struct pt_regs *regs, unsigned long error_code, | |
775 | unsigned long address) | |
92181f19 NP |
776 | { |
777 | __bad_area(regs, error_code, address, SEGV_ACCERR); | |
778 | } | |
779 | ||
780 | /* TODO: fixup for "mm-invoke-oom-killer-from-page-fault.patch" */ | |
2d4a7167 IM |
781 | static void |
782 | out_of_memory(struct pt_regs *regs, unsigned long error_code, | |
783 | unsigned long address) | |
92181f19 NP |
784 | { |
785 | /* | |
786 | * We ran out of memory, call the OOM killer, and return the userspace | |
2d4a7167 | 787 | * (which will retry the fault, or kill us if we got oom-killed): |
92181f19 NP |
788 | */ |
789 | up_read(¤t->mm->mmap_sem); | |
2d4a7167 | 790 | |
92181f19 NP |
791 | pagefault_out_of_memory(); |
792 | } | |
793 | ||
2d4a7167 | 794 | static void |
a6e04aa9 AK |
795 | do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, |
796 | unsigned int fault) | |
92181f19 NP |
797 | { |
798 | struct task_struct *tsk = current; | |
799 | struct mm_struct *mm = tsk->mm; | |
a6e04aa9 | 800 | int code = BUS_ADRERR; |
92181f19 NP |
801 | |
802 | up_read(&mm->mmap_sem); | |
803 | ||
2d4a7167 | 804 | /* Kernel mode? Handle exceptions or die: */ |
96054569 | 805 | if (!(error_code & PF_USER)) { |
92181f19 | 806 | no_context(regs, error_code, address); |
96054569 LT |
807 | return; |
808 | } | |
2d4a7167 | 809 | |
cd1b68f0 | 810 | /* User-space => ok to do another page fault: */ |
92181f19 NP |
811 | if (is_prefetch(regs, error_code, address)) |
812 | return; | |
2d4a7167 IM |
813 | |
814 | tsk->thread.cr2 = address; | |
815 | tsk->thread.error_code = error_code; | |
816 | tsk->thread.trap_no = 14; | |
817 | ||
a6e04aa9 AK |
818 | #ifdef CONFIG_MEMORY_FAILURE |
819 | if (fault & VM_FAULT_HWPOISON) { | |
820 | printk(KERN_ERR | |
821 | "MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n", | |
822 | tsk->comm, tsk->pid, address); | |
823 | code = BUS_MCEERR_AR; | |
824 | } | |
825 | #endif | |
826 | force_sig_info_fault(SIGBUS, code, address, tsk); | |
92181f19 NP |
827 | } |
828 | ||
2d4a7167 IM |
829 | static noinline void |
830 | mm_fault_error(struct pt_regs *regs, unsigned long error_code, | |
831 | unsigned long address, unsigned int fault) | |
92181f19 | 832 | { |
2d4a7167 | 833 | if (fault & VM_FAULT_OOM) { |
92181f19 | 834 | out_of_memory(regs, error_code, address); |
2d4a7167 | 835 | } else { |
a6e04aa9 AK |
836 | if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON)) |
837 | do_sigbus(regs, error_code, address, fault); | |
2d4a7167 IM |
838 | else |
839 | BUG(); | |
840 | } | |
92181f19 NP |
841 | } |
842 | ||
d8b57bb7 TG |
843 | static int spurious_fault_check(unsigned long error_code, pte_t *pte) |
844 | { | |
845 | if ((error_code & PF_WRITE) && !pte_write(*pte)) | |
846 | return 0; | |
2d4a7167 | 847 | |
d8b57bb7 TG |
848 | if ((error_code & PF_INSTR) && !pte_exec(*pte)) |
849 | return 0; | |
850 | ||
851 | return 1; | |
852 | } | |
853 | ||
5b727a3b | 854 | /* |
2d4a7167 IM |
855 | * Handle a spurious fault caused by a stale TLB entry. |
856 | * | |
857 | * This allows us to lazily refresh the TLB when increasing the | |
858 | * permissions of a kernel page (RO -> RW or NX -> X). Doing it | |
859 | * eagerly is very expensive since that implies doing a full | |
860 | * cross-processor TLB flush, even if no stale TLB entries exist | |
861 | * on other processors. | |
862 | * | |
5b727a3b JF |
863 | * There are no security implications to leaving a stale TLB when |
864 | * increasing the permissions on a page. | |
865 | */ | |
62c9295f | 866 | static noinline __kprobes int |
2d4a7167 | 867 | spurious_fault(unsigned long error_code, unsigned long address) |
5b727a3b JF |
868 | { |
869 | pgd_t *pgd; | |
870 | pud_t *pud; | |
871 | pmd_t *pmd; | |
872 | pte_t *pte; | |
3c3e5694 | 873 | int ret; |
5b727a3b JF |
874 | |
875 | /* Reserved-bit violation or user access to kernel space? */ | |
876 | if (error_code & (PF_USER | PF_RSVD)) | |
877 | return 0; | |
878 | ||
879 | pgd = init_mm.pgd + pgd_index(address); | |
880 | if (!pgd_present(*pgd)) | |
881 | return 0; | |
882 | ||
883 | pud = pud_offset(pgd, address); | |
884 | if (!pud_present(*pud)) | |
885 | return 0; | |
886 | ||
d8b57bb7 TG |
887 | if (pud_large(*pud)) |
888 | return spurious_fault_check(error_code, (pte_t *) pud); | |
889 | ||
5b727a3b JF |
890 | pmd = pmd_offset(pud, address); |
891 | if (!pmd_present(*pmd)) | |
892 | return 0; | |
893 | ||
d8b57bb7 TG |
894 | if (pmd_large(*pmd)) |
895 | return spurious_fault_check(error_code, (pte_t *) pmd); | |
896 | ||
5b727a3b JF |
897 | pte = pte_offset_kernel(pmd, address); |
898 | if (!pte_present(*pte)) | |
899 | return 0; | |
900 | ||
3c3e5694 SR |
901 | ret = spurious_fault_check(error_code, pte); |
902 | if (!ret) | |
903 | return 0; | |
904 | ||
905 | /* | |
2d4a7167 IM |
906 | * Make sure we have permissions in PMD. |
907 | * If not, then there's a bug in the page tables: | |
3c3e5694 SR |
908 | */ |
909 | ret = spurious_fault_check(error_code, (pte_t *) pmd); | |
910 | WARN_ONCE(!ret, "PMD has incorrect permission bits\n"); | |
2d4a7167 | 911 | |
3c3e5694 | 912 | return ret; |
5b727a3b JF |
913 | } |
914 | ||
abd4f750 | 915 | int show_unhandled_signals = 1; |
1da177e4 | 916 | |
2d4a7167 IM |
917 | static inline int |
918 | access_error(unsigned long error_code, int write, struct vm_area_struct *vma) | |
92181f19 NP |
919 | { |
920 | if (write) { | |
2d4a7167 | 921 | /* write, present and write, not present: */ |
92181f19 NP |
922 | if (unlikely(!(vma->vm_flags & VM_WRITE))) |
923 | return 1; | |
2d4a7167 | 924 | return 0; |
92181f19 NP |
925 | } |
926 | ||
2d4a7167 IM |
927 | /* read, present: */ |
928 | if (unlikely(error_code & PF_PROT)) | |
929 | return 1; | |
930 | ||
931 | /* read, not present: */ | |
932 | if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))) | |
933 | return 1; | |
934 | ||
92181f19 NP |
935 | return 0; |
936 | } | |
937 | ||
0973a06c HS |
938 | static int fault_in_kernel_space(unsigned long address) |
939 | { | |
d9517346 | 940 | return address >= TASK_SIZE_MAX; |
0973a06c HS |
941 | } |
942 | ||
1da177e4 LT |
943 | /* |
944 | * This routine handles page faults. It determines the address, | |
945 | * and the problem, and then passes it off to one of the appropriate | |
946 | * routines. | |
1da177e4 | 947 | */ |
c3731c68 IM |
948 | dotraplinkage void __kprobes |
949 | do_page_fault(struct pt_regs *regs, unsigned long error_code) | |
1da177e4 | 950 | { |
2d4a7167 | 951 | struct vm_area_struct *vma; |
1da177e4 | 952 | struct task_struct *tsk; |
2d4a7167 | 953 | unsigned long address; |
1da177e4 | 954 | struct mm_struct *mm; |
92181f19 | 955 | int write; |
f8c2ee22 | 956 | int fault; |
1da177e4 | 957 | |
a9ba9a3b AV |
958 | tsk = current; |
959 | mm = tsk->mm; | |
2d4a7167 | 960 | |
2d4a7167 | 961 | /* Get the faulting address: */ |
f51c9452 | 962 | address = read_cr2(); |
1da177e4 | 963 | |
f8561296 VN |
964 | /* |
965 | * Detect and handle instructions that would cause a page fault for | |
966 | * both a tracked kernel page and a userspace page. | |
967 | */ | |
968 | if (kmemcheck_active(regs)) | |
969 | kmemcheck_hide(regs); | |
5dfaf90f | 970 | prefetchw(&mm->mmap_sem); |
f8561296 | 971 | |
0fd0e3da | 972 | if (unlikely(kmmio_fault(regs, address))) |
86069782 | 973 | return; |
1da177e4 LT |
974 | |
975 | /* | |
976 | * We fault-in kernel-space virtual memory on-demand. The | |
977 | * 'reference' page table is init_mm.pgd. | |
978 | * | |
979 | * NOTE! We MUST NOT take any locks for this case. We may | |
980 | * be in an interrupt or a critical region, and should | |
981 | * only copy the information from the master page table, | |
982 | * nothing more. | |
983 | * | |
984 | * This verifies that the fault happens in kernel space | |
985 | * (error_code & 4) == 0, and that the fault was not a | |
8b1bde93 | 986 | * protection error (error_code & 9) == 0. |
1da177e4 | 987 | */ |
0973a06c | 988 | if (unlikely(fault_in_kernel_space(address))) { |
f8561296 VN |
989 | if (!(error_code & (PF_RSVD | PF_USER | PF_PROT))) { |
990 | if (vmalloc_fault(address) >= 0) | |
991 | return; | |
992 | ||
993 | if (kmemcheck_fault(regs, address, error_code)) | |
994 | return; | |
995 | } | |
5b727a3b | 996 | |
2d4a7167 | 997 | /* Can handle a stale RO->RW TLB: */ |
92181f19 | 998 | if (spurious_fault(error_code, address)) |
5b727a3b JF |
999 | return; |
1000 | ||
2d4a7167 | 1001 | /* kprobes don't want to hook the spurious faults: */ |
9be260a6 MH |
1002 | if (notify_page_fault(regs)) |
1003 | return; | |
f8c2ee22 HH |
1004 | /* |
1005 | * Don't take the mm semaphore here. If we fixup a prefetch | |
2d4a7167 | 1006 | * fault we could otherwise deadlock: |
f8c2ee22 | 1007 | */ |
92181f19 | 1008 | bad_area_nosemaphore(regs, error_code, address); |
2d4a7167 | 1009 | |
92181f19 | 1010 | return; |
f8c2ee22 HH |
1011 | } |
1012 | ||
2d4a7167 | 1013 | /* kprobes don't want to hook the spurious faults: */ |
f8a6b2b9 | 1014 | if (unlikely(notify_page_fault(regs))) |
9be260a6 | 1015 | return; |
f8c2ee22 | 1016 | /* |
891cffbd LT |
1017 | * It's safe to allow irq's after cr2 has been saved and the |
1018 | * vmalloc fault has been handled. | |
1019 | * | |
1020 | * User-mode registers count as a user access even for any | |
2d4a7167 | 1021 | * potential system fault or CPU buglet: |
f8c2ee22 | 1022 | */ |
891cffbd LT |
1023 | if (user_mode_vm(regs)) { |
1024 | local_irq_enable(); | |
1025 | error_code |= PF_USER; | |
2d4a7167 IM |
1026 | } else { |
1027 | if (regs->flags & X86_EFLAGS_IF) | |
1028 | local_irq_enable(); | |
1029 | } | |
8c914cb7 | 1030 | |
66c58156 | 1031 | if (unlikely(error_code & PF_RSVD)) |
92181f19 | 1032 | pgtable_bad(regs, error_code, address); |
1da177e4 | 1033 | |
cdd6c482 | 1034 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, 0, regs, address); |
7dd1fcc2 | 1035 | |
1da177e4 | 1036 | /* |
2d4a7167 IM |
1037 | * If we're in an interrupt, have no user context or are running |
1038 | * in an atomic region then we must not take the fault: | |
1da177e4 | 1039 | */ |
92181f19 NP |
1040 | if (unlikely(in_atomic() || !mm)) { |
1041 | bad_area_nosemaphore(regs, error_code, address); | |
1042 | return; | |
1043 | } | |
1da177e4 | 1044 | |
3a1dfe6e IM |
1045 | /* |
1046 | * When running in the kernel we expect faults to occur only to | |
2d4a7167 IM |
1047 | * addresses in user space. All other faults represent errors in |
1048 | * the kernel and should generate an OOPS. Unfortunately, in the | |
1049 | * case of an erroneous fault occurring in a code path which already | |
1050 | * holds mmap_sem we will deadlock attempting to validate the fault | |
1051 | * against the address space. Luckily the kernel only validly | |
1052 | * references user space from well defined areas of code, which are | |
1053 | * listed in the exceptions table. | |
1da177e4 LT |
1054 | * |
1055 | * As the vast majority of faults will be valid we will only perform | |
2d4a7167 IM |
1056 | * the source reference check when there is a possibility of a |
1057 | * deadlock. Attempt to lock the address space, if we cannot we then | |
1058 | * validate the source. If this is invalid we can skip the address | |
1059 | * space check, thus avoiding the deadlock: | |
1da177e4 | 1060 | */ |
92181f19 | 1061 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) { |
66c58156 | 1062 | if ((error_code & PF_USER) == 0 && |
92181f19 NP |
1063 | !search_exception_tables(regs->ip)) { |
1064 | bad_area_nosemaphore(regs, error_code, address); | |
1065 | return; | |
1066 | } | |
1da177e4 | 1067 | down_read(&mm->mmap_sem); |
01006074 PZ |
1068 | } else { |
1069 | /* | |
2d4a7167 IM |
1070 | * The above down_read_trylock() might have succeeded in |
1071 | * which case we'll have missed the might_sleep() from | |
1072 | * down_read(): | |
01006074 PZ |
1073 | */ |
1074 | might_sleep(); | |
1da177e4 LT |
1075 | } |
1076 | ||
1077 | vma = find_vma(mm, address); | |
92181f19 NP |
1078 | if (unlikely(!vma)) { |
1079 | bad_area(regs, error_code, address); | |
1080 | return; | |
1081 | } | |
1082 | if (likely(vma->vm_start <= address)) | |
1da177e4 | 1083 | goto good_area; |
92181f19 NP |
1084 | if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) { |
1085 | bad_area(regs, error_code, address); | |
1086 | return; | |
1087 | } | |
33cb5243 | 1088 | if (error_code & PF_USER) { |
6f4d368e HH |
1089 | /* |
1090 | * Accessing the stack below %sp is always a bug. | |
1091 | * The large cushion allows instructions like enter | |
2d4a7167 | 1092 | * and pusha to work. ("enter $65535, $31" pushes |
6f4d368e | 1093 | * 32 pointers and then decrements %sp by 65535.) |
03fdc2c2 | 1094 | */ |
92181f19 NP |
1095 | if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) { |
1096 | bad_area(regs, error_code, address); | |
1097 | return; | |
1098 | } | |
1da177e4 | 1099 | } |
92181f19 NP |
1100 | if (unlikely(expand_stack(vma, address))) { |
1101 | bad_area(regs, error_code, address); | |
1102 | return; | |
1103 | } | |
1104 | ||
1105 | /* | |
1106 | * Ok, we have a good vm_area for this memory access, so | |
1107 | * we can handle it.. | |
1108 | */ | |
1da177e4 | 1109 | good_area: |
92181f19 | 1110 | write = error_code & PF_WRITE; |
2d4a7167 | 1111 | |
92181f19 NP |
1112 | if (unlikely(access_error(error_code, write, vma))) { |
1113 | bad_area_access_error(regs, error_code, address); | |
1114 | return; | |
1da177e4 LT |
1115 | } |
1116 | ||
1117 | /* | |
1118 | * If for any reason at all we couldn't handle the fault, | |
1119 | * make sure we exit gracefully rather than endlessly redo | |
2d4a7167 | 1120 | * the fault: |
1da177e4 | 1121 | */ |
d06063cc | 1122 | fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); |
2d4a7167 | 1123 | |
83c54070 | 1124 | if (unlikely(fault & VM_FAULT_ERROR)) { |
92181f19 NP |
1125 | mm_fault_error(regs, error_code, address, fault); |
1126 | return; | |
1da177e4 | 1127 | } |
2d4a7167 | 1128 | |
ac17dc8e | 1129 | if (fault & VM_FAULT_MAJOR) { |
83c54070 | 1130 | tsk->maj_flt++; |
cdd6c482 | 1131 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0, |
78f13e95 | 1132 | regs, address); |
ac17dc8e | 1133 | } else { |
83c54070 | 1134 | tsk->min_flt++; |
cdd6c482 | 1135 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0, |
78f13e95 | 1136 | regs, address); |
ac17dc8e | 1137 | } |
d729ab35 | 1138 | |
8c938f9f IM |
1139 | check_v8086_mode(regs, address, tsk); |
1140 | ||
1da177e4 | 1141 | up_read(&mm->mmap_sem); |
1da177e4 | 1142 | } |