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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/arch/x86-64/mm/fault.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. | |
6 | */ | |
7 | ||
1da177e4 LT |
8 | #include <linux/signal.h> |
9 | #include <linux/sched.h> | |
10 | #include <linux/kernel.h> | |
11 | #include <linux/errno.h> | |
12 | #include <linux/string.h> | |
13 | #include <linux/types.h> | |
14 | #include <linux/ptrace.h> | |
15 | #include <linux/mman.h> | |
16 | #include <linux/mm.h> | |
17 | #include <linux/smp.h> | |
1da177e4 LT |
18 | #include <linux/interrupt.h> |
19 | #include <linux/init.h> | |
20 | #include <linux/tty.h> | |
21 | #include <linux/vt_kern.h> /* For unblank_screen() */ | |
22 | #include <linux/compiler.h> | |
1eeb66a1 | 23 | #include <linux/vmalloc.h> |
1da177e4 | 24 | #include <linux/module.h> |
0f2fbdcb | 25 | #include <linux/kprobes.h> |
ab2bf0c1 | 26 | #include <linux/uaccess.h> |
1eeb66a1 | 27 | #include <linux/kdebug.h> |
1da177e4 LT |
28 | |
29 | #include <asm/system.h> | |
1da177e4 LT |
30 | #include <asm/pgalloc.h> |
31 | #include <asm/smp.h> | |
32 | #include <asm/tlbflush.h> | |
33 | #include <asm/proto.h> | |
1da177e4 | 34 | #include <asm-generic/sections.h> |
1da177e4 | 35 | |
66c58156 AK |
36 | /* Page fault error code bits */ |
37 | #define PF_PROT (1<<0) /* or no page found */ | |
38 | #define PF_WRITE (1<<1) | |
39 | #define PF_USER (1<<2) | |
40 | #define PF_RSVD (1<<3) | |
41 | #define PF_INSTR (1<<4) | |
42 | ||
273819a2 | 43 | static ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain); |
1bd858a5 AK |
44 | |
45 | /* Hook to register for page fault notifications */ | |
46 | int register_page_fault_notifier(struct notifier_block *nb) | |
47 | { | |
48 | vmalloc_sync_all(); | |
49 | return atomic_notifier_chain_register(¬ify_page_fault_chain, nb); | |
50 | } | |
273819a2 | 51 | EXPORT_SYMBOL_GPL(register_page_fault_notifier); |
1bd858a5 AK |
52 | |
53 | int unregister_page_fault_notifier(struct notifier_block *nb) | |
54 | { | |
55 | return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); | |
56 | } | |
273819a2 | 57 | EXPORT_SYMBOL_GPL(unregister_page_fault_notifier); |
1bd858a5 | 58 | |
9b355897 | 59 | static inline int notify_page_fault(struct pt_regs *regs, long err) |
1bd858a5 AK |
60 | { |
61 | struct die_args args = { | |
62 | .regs = regs, | |
9b355897 | 63 | .str = "page fault", |
1bd858a5 | 64 | .err = err, |
9b355897 JB |
65 | .trapnr = 14, |
66 | .signr = SIGSEGV | |
1bd858a5 | 67 | }; |
9b355897 JB |
68 | return atomic_notifier_call_chain(¬ify_page_fault_chain, |
69 | DIE_PAGE_FAULT, &args); | |
1bd858a5 | 70 | } |
1bd858a5 | 71 | |
1da177e4 LT |
72 | /* Sometimes the CPU reports invalid exceptions on prefetch. |
73 | Check that here and ignore. | |
74 | Opcode checker based on code by Richard Brunner */ | |
75 | static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr, | |
76 | unsigned long error_code) | |
77 | { | |
ab2bf0c1 | 78 | unsigned char *instr; |
1da177e4 LT |
79 | int scan_more = 1; |
80 | int prefetch = 0; | |
f1290ec9 | 81 | unsigned char *max_instr; |
1da177e4 LT |
82 | |
83 | /* If it was a exec fault ignore */ | |
66c58156 | 84 | if (error_code & PF_INSTR) |
1da177e4 LT |
85 | return 0; |
86 | ||
dd2994f6 | 87 | instr = (unsigned char __user *)convert_rip_to_linear(current, regs); |
f1290ec9 | 88 | max_instr = instr + 15; |
1da177e4 | 89 | |
76381fee | 90 | if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) |
1da177e4 LT |
91 | return 0; |
92 | ||
93 | while (scan_more && instr < max_instr) { | |
94 | unsigned char opcode; | |
95 | unsigned char instr_hi; | |
96 | unsigned char instr_lo; | |
97 | ||
ab2bf0c1 | 98 | if (probe_kernel_address(instr, opcode)) |
1da177e4 LT |
99 | break; |
100 | ||
101 | instr_hi = opcode & 0xf0; | |
102 | instr_lo = opcode & 0x0f; | |
103 | instr++; | |
104 | ||
105 | switch (instr_hi) { | |
106 | case 0x20: | |
107 | case 0x30: | |
108 | /* Values 0x26,0x2E,0x36,0x3E are valid x86 | |
109 | prefixes. In long mode, the CPU will signal | |
110 | invalid opcode if some of these prefixes are | |
111 | present so we will never get here anyway */ | |
112 | scan_more = ((instr_lo & 7) == 0x6); | |
113 | break; | |
114 | ||
115 | case 0x40: | |
116 | /* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes | |
117 | Need to figure out under what instruction mode the | |
118 | instruction was issued ... */ | |
119 | /* Could check the LDT for lm, but for now it's good | |
120 | enough to assume that long mode only uses well known | |
121 | segments or kernel. */ | |
76381fee | 122 | scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS); |
1da177e4 LT |
123 | break; |
124 | ||
125 | case 0x60: | |
126 | /* 0x64 thru 0x67 are valid prefixes in all modes. */ | |
127 | scan_more = (instr_lo & 0xC) == 0x4; | |
128 | break; | |
129 | case 0xF0: | |
130 | /* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */ | |
131 | scan_more = !instr_lo || (instr_lo>>1) == 1; | |
132 | break; | |
133 | case 0x00: | |
134 | /* Prefetch instruction is 0x0F0D or 0x0F18 */ | |
135 | scan_more = 0; | |
ab2bf0c1 | 136 | if (probe_kernel_address(instr, opcode)) |
1da177e4 LT |
137 | break; |
138 | prefetch = (instr_lo == 0xF) && | |
139 | (opcode == 0x0D || opcode == 0x18); | |
140 | break; | |
141 | default: | |
142 | scan_more = 0; | |
143 | break; | |
144 | } | |
145 | } | |
146 | return prefetch; | |
147 | } | |
148 | ||
149 | static int bad_address(void *p) | |
150 | { | |
151 | unsigned long dummy; | |
ab2bf0c1 | 152 | return probe_kernel_address((unsigned long *)p, dummy); |
1da177e4 LT |
153 | } |
154 | ||
155 | void dump_pagetable(unsigned long address) | |
156 | { | |
157 | pgd_t *pgd; | |
158 | pud_t *pud; | |
159 | pmd_t *pmd; | |
160 | pte_t *pte; | |
161 | ||
162 | asm("movq %%cr3,%0" : "=r" (pgd)); | |
163 | ||
164 | pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); | |
165 | pgd += pgd_index(address); | |
1da177e4 | 166 | if (bad_address(pgd)) goto bad; |
d646bce4 | 167 | printk("PGD %lx ", pgd_val(*pgd)); |
1da177e4 LT |
168 | if (!pgd_present(*pgd)) goto ret; |
169 | ||
d2ae5b5f | 170 | pud = pud_offset(pgd, address); |
1da177e4 LT |
171 | if (bad_address(pud)) goto bad; |
172 | printk("PUD %lx ", pud_val(*pud)); | |
173 | if (!pud_present(*pud)) goto ret; | |
174 | ||
175 | pmd = pmd_offset(pud, address); | |
176 | if (bad_address(pmd)) goto bad; | |
177 | printk("PMD %lx ", pmd_val(*pmd)); | |
178 | if (!pmd_present(*pmd)) goto ret; | |
179 | ||
180 | pte = pte_offset_kernel(pmd, address); | |
181 | if (bad_address(pte)) goto bad; | |
182 | printk("PTE %lx", pte_val(*pte)); | |
183 | ret: | |
184 | printk("\n"); | |
185 | return; | |
186 | bad: | |
187 | printk("BAD\n"); | |
188 | } | |
189 | ||
190 | static const char errata93_warning[] = | |
191 | KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" | |
192 | KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n" | |
193 | KERN_ERR "******* Please consider a BIOS update.\n" | |
194 | KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; | |
195 | ||
196 | /* Workaround for K8 erratum #93 & buggy BIOS. | |
197 | BIOS SMM functions are required to use a specific workaround | |
198 | to avoid corruption of the 64bit RIP register on C stepping K8. | |
199 | A lot of BIOS that didn't get tested properly miss this. | |
200 | The OS sees this as a page fault with the upper 32bits of RIP cleared. | |
201 | Try to work around it here. | |
202 | Note we only handle faults in kernel here. */ | |
203 | ||
204 | static int is_errata93(struct pt_regs *regs, unsigned long address) | |
205 | { | |
206 | static int warned; | |
207 | if (address != regs->rip) | |
208 | return 0; | |
209 | if ((address >> 32) != 0) | |
210 | return 0; | |
211 | address |= 0xffffffffUL << 32; | |
212 | if ((address >= (u64)_stext && address <= (u64)_etext) || | |
213 | (address >= MODULES_VADDR && address <= MODULES_END)) { | |
214 | if (!warned) { | |
215 | printk(errata93_warning); | |
216 | warned = 1; | |
217 | } | |
218 | regs->rip = address; | |
219 | return 1; | |
220 | } | |
221 | return 0; | |
222 | } | |
223 | ||
224 | int unhandled_signal(struct task_struct *tsk, int sig) | |
225 | { | |
f400e198 | 226 | if (is_init(tsk)) |
1da177e4 | 227 | return 1; |
5e5ec104 | 228 | if (tsk->ptrace & PT_PTRACED) |
1da177e4 LT |
229 | return 0; |
230 | return (tsk->sighand->action[sig-1].sa.sa_handler == SIG_IGN) || | |
231 | (tsk->sighand->action[sig-1].sa.sa_handler == SIG_DFL); | |
232 | } | |
233 | ||
234 | static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, | |
235 | unsigned long error_code) | |
236 | { | |
1209140c | 237 | unsigned long flags = oops_begin(); |
6e3f3617 | 238 | struct task_struct *tsk; |
1209140c | 239 | |
1da177e4 LT |
240 | printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
241 | current->comm, address); | |
242 | dump_pagetable(address); | |
6e3f3617 JB |
243 | tsk = current; |
244 | tsk->thread.cr2 = address; | |
245 | tsk->thread.trap_no = 14; | |
246 | tsk->thread.error_code = error_code; | |
1da177e4 | 247 | __die("Bad pagetable", regs, error_code); |
1209140c | 248 | oops_end(flags); |
1da177e4 LT |
249 | do_exit(SIGKILL); |
250 | } | |
251 | ||
252 | /* | |
f95190b2 | 253 | * Handle a fault on the vmalloc area |
3b9ba4d5 AK |
254 | * |
255 | * This assumes no large pages in there. | |
1da177e4 LT |
256 | */ |
257 | static int vmalloc_fault(unsigned long address) | |
258 | { | |
259 | pgd_t *pgd, *pgd_ref; | |
260 | pud_t *pud, *pud_ref; | |
261 | pmd_t *pmd, *pmd_ref; | |
262 | pte_t *pte, *pte_ref; | |
263 | ||
264 | /* Copy kernel mappings over when needed. This can also | |
265 | happen within a race in page table update. In the later | |
266 | case just flush. */ | |
267 | ||
268 | pgd = pgd_offset(current->mm ?: &init_mm, address); | |
269 | pgd_ref = pgd_offset_k(address); | |
270 | if (pgd_none(*pgd_ref)) | |
271 | return -1; | |
272 | if (pgd_none(*pgd)) | |
273 | set_pgd(pgd, *pgd_ref); | |
8c914cb7 | 274 | else |
46a82b2d | 275 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); |
1da177e4 LT |
276 | |
277 | /* Below here mismatches are bugs because these lower tables | |
278 | are shared */ | |
279 | ||
280 | pud = pud_offset(pgd, address); | |
281 | pud_ref = pud_offset(pgd_ref, address); | |
282 | if (pud_none(*pud_ref)) | |
283 | return -1; | |
46a82b2d | 284 | if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) |
1da177e4 LT |
285 | BUG(); |
286 | pmd = pmd_offset(pud, address); | |
287 | pmd_ref = pmd_offset(pud_ref, address); | |
288 | if (pmd_none(*pmd_ref)) | |
289 | return -1; | |
290 | if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) | |
291 | BUG(); | |
292 | pte_ref = pte_offset_kernel(pmd_ref, address); | |
293 | if (!pte_present(*pte_ref)) | |
294 | return -1; | |
295 | pte = pte_offset_kernel(pmd, address); | |
3b9ba4d5 AK |
296 | /* Don't use pte_page here, because the mappings can point |
297 | outside mem_map, and the NUMA hash lookup cannot handle | |
298 | that. */ | |
299 | if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) | |
1da177e4 | 300 | BUG(); |
1da177e4 LT |
301 | return 0; |
302 | } | |
303 | ||
304 | int page_fault_trace = 0; | |
305 | int exception_trace = 1; | |
306 | ||
307 | /* | |
308 | * This routine handles page faults. It determines the address, | |
309 | * and the problem, and then passes it off to one of the appropriate | |
310 | * routines. | |
1da177e4 | 311 | */ |
0f2fbdcb PP |
312 | asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, |
313 | unsigned long error_code) | |
1da177e4 LT |
314 | { |
315 | struct task_struct *tsk; | |
316 | struct mm_struct *mm; | |
317 | struct vm_area_struct * vma; | |
318 | unsigned long address; | |
319 | const struct exception_table_entry *fixup; | |
320 | int write; | |
1209140c | 321 | unsigned long flags; |
1da177e4 LT |
322 | siginfo_t info; |
323 | ||
a9ba9a3b AV |
324 | tsk = current; |
325 | mm = tsk->mm; | |
326 | prefetchw(&mm->mmap_sem); | |
327 | ||
1da177e4 LT |
328 | /* get the address */ |
329 | __asm__("movq %%cr2,%0":"=r" (address)); | |
1da177e4 | 330 | |
1da177e4 LT |
331 | info.si_code = SEGV_MAPERR; |
332 | ||
333 | ||
334 | /* | |
335 | * We fault-in kernel-space virtual memory on-demand. The | |
336 | * 'reference' page table is init_mm.pgd. | |
337 | * | |
338 | * NOTE! We MUST NOT take any locks for this case. We may | |
339 | * be in an interrupt or a critical region, and should | |
340 | * only copy the information from the master page table, | |
341 | * nothing more. | |
342 | * | |
343 | * This verifies that the fault happens in kernel space | |
344 | * (error_code & 4) == 0, and that the fault was not a | |
8b1bde93 | 345 | * protection error (error_code & 9) == 0. |
1da177e4 | 346 | */ |
84929801 | 347 | if (unlikely(address >= TASK_SIZE64)) { |
f95190b2 AK |
348 | /* |
349 | * Don't check for the module range here: its PML4 | |
350 | * is always initialized because it's shared with the main | |
351 | * kernel text. Only vmalloc may need PML4 syncups. | |
352 | */ | |
66c58156 | 353 | if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && |
f95190b2 | 354 | ((address >= VMALLOC_START && address < VMALLOC_END))) { |
8c914cb7 JB |
355 | if (vmalloc_fault(address) >= 0) |
356 | return; | |
1da177e4 | 357 | } |
9b355897 | 358 | if (notify_page_fault(regs, error_code) == NOTIFY_STOP) |
8c914cb7 | 359 | return; |
1da177e4 LT |
360 | /* |
361 | * Don't take the mm semaphore here. If we fixup a prefetch | |
362 | * fault we could otherwise deadlock. | |
363 | */ | |
364 | goto bad_area_nosemaphore; | |
365 | } | |
366 | ||
9b355897 | 367 | if (notify_page_fault(regs, error_code) == NOTIFY_STOP) |
8c914cb7 JB |
368 | return; |
369 | ||
370 | if (likely(regs->eflags & X86_EFLAGS_IF)) | |
371 | local_irq_enable(); | |
372 | ||
373 | if (unlikely(page_fault_trace)) | |
374 | printk("pagefault rip:%lx rsp:%lx cs:%lu ss:%lu address %lx error %lx\n", | |
375 | regs->rip,regs->rsp,regs->cs,regs->ss,address,error_code); | |
376 | ||
66c58156 | 377 | if (unlikely(error_code & PF_RSVD)) |
1da177e4 LT |
378 | pgtable_bad(address, regs, error_code); |
379 | ||
380 | /* | |
381 | * If we're in an interrupt or have no user | |
382 | * context, we must not take the fault.. | |
383 | */ | |
384 | if (unlikely(in_atomic() || !mm)) | |
385 | goto bad_area_nosemaphore; | |
386 | ||
387 | again: | |
388 | /* When running in the kernel we expect faults to occur only to | |
389 | * addresses in user space. All other faults represent errors in the | |
390 | * kernel and should generate an OOPS. Unfortunatly, in the case of an | |
80f7228b | 391 | * erroneous fault occurring in a code path which already holds mmap_sem |
1da177e4 LT |
392 | * we will deadlock attempting to validate the fault against the |
393 | * address space. Luckily the kernel only validly references user | |
394 | * space from well defined areas of code, which are listed in the | |
395 | * exceptions table. | |
396 | * | |
397 | * As the vast majority of faults will be valid we will only perform | |
398 | * the source reference check when there is a possibilty of a deadlock. | |
399 | * Attempt to lock the address space, if we cannot we then validate the | |
400 | * source. If this is invalid we can skip the address space check, | |
401 | * thus avoiding the deadlock. | |
402 | */ | |
403 | if (!down_read_trylock(&mm->mmap_sem)) { | |
66c58156 | 404 | if ((error_code & PF_USER) == 0 && |
1da177e4 LT |
405 | !search_exception_tables(regs->rip)) |
406 | goto bad_area_nosemaphore; | |
407 | down_read(&mm->mmap_sem); | |
408 | } | |
409 | ||
410 | vma = find_vma(mm, address); | |
411 | if (!vma) | |
412 | goto bad_area; | |
413 | if (likely(vma->vm_start <= address)) | |
414 | goto good_area; | |
415 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
416 | goto bad_area; | |
417 | if (error_code & 4) { | |
03fdc2c2 CE |
418 | /* Allow userspace just enough access below the stack pointer |
419 | * to let the 'enter' instruction work. | |
420 | */ | |
421 | if (address + 65536 + 32 * sizeof(unsigned long) < regs->rsp) | |
1da177e4 LT |
422 | goto bad_area; |
423 | } | |
424 | if (expand_stack(vma, address)) | |
425 | goto bad_area; | |
426 | /* | |
427 | * Ok, we have a good vm_area for this memory access, so | |
428 | * we can handle it.. | |
429 | */ | |
430 | good_area: | |
431 | info.si_code = SEGV_ACCERR; | |
432 | write = 0; | |
66c58156 | 433 | switch (error_code & (PF_PROT|PF_WRITE)) { |
1da177e4 LT |
434 | default: /* 3: write, present */ |
435 | /* fall through */ | |
66c58156 | 436 | case PF_WRITE: /* write, not present */ |
1da177e4 LT |
437 | if (!(vma->vm_flags & VM_WRITE)) |
438 | goto bad_area; | |
439 | write++; | |
440 | break; | |
66c58156 | 441 | case PF_PROT: /* read, present */ |
1da177e4 | 442 | goto bad_area; |
66c58156 | 443 | case 0: /* read, not present */ |
df67b3da | 444 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
1da177e4 LT |
445 | goto bad_area; |
446 | } | |
447 | ||
448 | /* | |
449 | * If for any reason at all we couldn't handle the fault, | |
450 | * make sure we exit gracefully rather than endlessly redo | |
451 | * the fault. | |
452 | */ | |
453 | switch (handle_mm_fault(mm, vma, address, write)) { | |
96800216 | 454 | case VM_FAULT_MINOR: |
1da177e4 LT |
455 | tsk->min_flt++; |
456 | break; | |
96800216 | 457 | case VM_FAULT_MAJOR: |
1da177e4 LT |
458 | tsk->maj_flt++; |
459 | break; | |
96800216 | 460 | case VM_FAULT_SIGBUS: |
1da177e4 LT |
461 | goto do_sigbus; |
462 | default: | |
463 | goto out_of_memory; | |
464 | } | |
465 | ||
466 | up_read(&mm->mmap_sem); | |
467 | return; | |
468 | ||
469 | /* | |
470 | * Something tried to access memory that isn't in our memory map.. | |
471 | * Fix it, but check if it's kernel or user first.. | |
472 | */ | |
473 | bad_area: | |
474 | up_read(&mm->mmap_sem); | |
475 | ||
476 | bad_area_nosemaphore: | |
1da177e4 | 477 | /* User mode accesses just cause a SIGSEGV */ |
66c58156 | 478 | if (error_code & PF_USER) { |
1da177e4 LT |
479 | if (is_prefetch(regs, address, error_code)) |
480 | return; | |
481 | ||
482 | /* Work around K8 erratum #100 K8 in compat mode | |
483 | occasionally jumps to illegal addresses >4GB. We | |
484 | catch this here in the page fault handler because | |
485 | these addresses are not reachable. Just detect this | |
486 | case and return. Any code segment in LDT is | |
487 | compatibility mode. */ | |
488 | if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && | |
489 | (address >> 32)) | |
490 | return; | |
491 | ||
492 | if (exception_trace && unhandled_signal(tsk, SIGSEGV)) { | |
493 | printk( | |
494 | "%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n", | |
495 | tsk->pid > 1 ? KERN_INFO : KERN_EMERG, | |
496 | tsk->comm, tsk->pid, address, regs->rip, | |
497 | regs->rsp, error_code); | |
498 | } | |
499 | ||
500 | tsk->thread.cr2 = address; | |
501 | /* Kernel addresses are always protection faults */ | |
502 | tsk->thread.error_code = error_code | (address >= TASK_SIZE); | |
503 | tsk->thread.trap_no = 14; | |
504 | info.si_signo = SIGSEGV; | |
505 | info.si_errno = 0; | |
506 | /* info.si_code has been set above */ | |
507 | info.si_addr = (void __user *)address; | |
508 | force_sig_info(SIGSEGV, &info, tsk); | |
509 | return; | |
510 | } | |
511 | ||
512 | no_context: | |
513 | ||
514 | /* Are we prepared to handle this kernel fault? */ | |
515 | fixup = search_exception_tables(regs->rip); | |
516 | if (fixup) { | |
517 | regs->rip = fixup->fixup; | |
518 | return; | |
519 | } | |
520 | ||
521 | /* | |
522 | * Hall of shame of CPU/BIOS bugs. | |
523 | */ | |
524 | ||
525 | if (is_prefetch(regs, address, error_code)) | |
526 | return; | |
527 | ||
528 | if (is_errata93(regs, address)) | |
529 | return; | |
530 | ||
531 | /* | |
532 | * Oops. The kernel tried to access some bad page. We'll have to | |
533 | * terminate things with extreme prejudice. | |
534 | */ | |
535 | ||
1209140c | 536 | flags = oops_begin(); |
1da177e4 LT |
537 | |
538 | if (address < PAGE_SIZE) | |
539 | printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); | |
540 | else | |
541 | printk(KERN_ALERT "Unable to handle kernel paging request"); | |
542 | printk(" at %016lx RIP: \n" KERN_ALERT,address); | |
543 | printk_address(regs->rip); | |
1da177e4 | 544 | dump_pagetable(address); |
6e3f3617 JB |
545 | tsk->thread.cr2 = address; |
546 | tsk->thread.trap_no = 14; | |
547 | tsk->thread.error_code = error_code; | |
1da177e4 LT |
548 | __die("Oops", regs, error_code); |
549 | /* Executive summary in case the body of the oops scrolled away */ | |
550 | printk(KERN_EMERG "CR2: %016lx\n", address); | |
1209140c | 551 | oops_end(flags); |
1da177e4 LT |
552 | do_exit(SIGKILL); |
553 | ||
554 | /* | |
555 | * We ran out of memory, or some other thing happened to us that made | |
556 | * us unable to handle the page fault gracefully. | |
557 | */ | |
558 | out_of_memory: | |
559 | up_read(&mm->mmap_sem); | |
f400e198 | 560 | if (is_init(current)) { |
1da177e4 LT |
561 | yield(); |
562 | goto again; | |
563 | } | |
564 | printk("VM: killing process %s\n", tsk->comm); | |
565 | if (error_code & 4) | |
566 | do_exit(SIGKILL); | |
567 | goto no_context; | |
568 | ||
569 | do_sigbus: | |
570 | up_read(&mm->mmap_sem); | |
571 | ||
572 | /* Kernel mode? Handle exceptions or die */ | |
66c58156 | 573 | if (!(error_code & PF_USER)) |
1da177e4 LT |
574 | goto no_context; |
575 | ||
576 | tsk->thread.cr2 = address; | |
577 | tsk->thread.error_code = error_code; | |
578 | tsk->thread.trap_no = 14; | |
579 | info.si_signo = SIGBUS; | |
580 | info.si_errno = 0; | |
581 | info.si_code = BUS_ADRERR; | |
582 | info.si_addr = (void __user *)address; | |
583 | force_sig_info(SIGBUS, &info, tsk); | |
584 | return; | |
585 | } | |
9e43e1b7 | 586 | |
8c914cb7 | 587 | DEFINE_SPINLOCK(pgd_lock); |
2bff7383 | 588 | LIST_HEAD(pgd_list); |
8c914cb7 JB |
589 | |
590 | void vmalloc_sync_all(void) | |
591 | { | |
592 | /* Note that races in the updates of insync and start aren't | |
593 | problematic: | |
594 | insync can only get set bits added, and updates to start are only | |
595 | improving performance (without affecting correctness if undone). */ | |
596 | static DECLARE_BITMAP(insync, PTRS_PER_PGD); | |
597 | static unsigned long start = VMALLOC_START & PGDIR_MASK; | |
598 | unsigned long address; | |
599 | ||
600 | for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) { | |
601 | if (!test_bit(pgd_index(address), insync)) { | |
602 | const pgd_t *pgd_ref = pgd_offset_k(address); | |
603 | struct page *page; | |
604 | ||
605 | if (pgd_none(*pgd_ref)) | |
606 | continue; | |
607 | spin_lock(&pgd_lock); | |
2bff7383 | 608 | list_for_each_entry(page, &pgd_list, lru) { |
8c914cb7 JB |
609 | pgd_t *pgd; |
610 | pgd = (pgd_t *)page_address(page) + pgd_index(address); | |
611 | if (pgd_none(*pgd)) | |
612 | set_pgd(pgd, *pgd_ref); | |
613 | else | |
46a82b2d | 614 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); |
8c914cb7 JB |
615 | } |
616 | spin_unlock(&pgd_lock); | |
617 | set_bit(pgd_index(address), insync); | |
618 | } | |
619 | if (address == start) | |
620 | start = address + PGDIR_SIZE; | |
621 | } | |
622 | /* Check that there is no need to do the same for the modules area. */ | |
623 | BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL)); | |
624 | BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == | |
625 | (__START_KERNEL & PGDIR_MASK))); | |
626 | } | |
627 | ||
9e43e1b7 AK |
628 | static int __init enable_pagefaulttrace(char *str) |
629 | { | |
630 | page_fault_trace = 1; | |
9b41046c | 631 | return 1; |
9e43e1b7 AK |
632 | } |
633 | __setup("pagefaulttrace", enable_pagefaulttrace); |