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