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Commit | Line | Data |
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1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Copyright (C) 1995 Linus Torvalds |
3 | * Copyright (C) 2001,2002 Andi Kleen, SuSE Labs. | |
4 | */ | |
5 | ||
1da177e4 LT |
6 | #include <linux/signal.h> |
7 | #include <linux/sched.h> | |
8 | #include <linux/kernel.h> | |
9 | #include <linux/errno.h> | |
10 | #include <linux/string.h> | |
11 | #include <linux/types.h> | |
12 | #include <linux/ptrace.h> | |
0fd0e3da | 13 | #include <linux/mmiotrace.h> |
1da177e4 LT |
14 | #include <linux/mman.h> |
15 | #include <linux/mm.h> | |
16 | #include <linux/smp.h> | |
1da177e4 LT |
17 | #include <linux/interrupt.h> |
18 | #include <linux/init.h> | |
19 | #include <linux/tty.h> | |
20 | #include <linux/vt_kern.h> /* For unblank_screen() */ | |
21 | #include <linux/compiler.h> | |
c61e211d HH |
22 | #include <linux/highmem.h> |
23 | #include <linux/bootmem.h> /* for max_low_pfn */ | |
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> |
7c9f8861 | 29 | #include <linux/magic.h> |
1da177e4 LT |
30 | |
31 | #include <asm/system.h> | |
c61e211d HH |
32 | #include <asm/desc.h> |
33 | #include <asm/segment.h> | |
1da177e4 LT |
34 | #include <asm/pgalloc.h> |
35 | #include <asm/smp.h> | |
36 | #include <asm/tlbflush.h> | |
37 | #include <asm/proto.h> | |
1da177e4 | 38 | #include <asm-generic/sections.h> |
70ef5641 | 39 | #include <asm/traps.h> |
1da177e4 | 40 | |
33cb5243 HH |
41 | /* |
42 | * Page fault error code bits | |
43 | * bit 0 == 0 means no page found, 1 means protection fault | |
44 | * bit 1 == 0 means read, 1 means write | |
45 | * bit 2 == 0 means kernel, 1 means user-mode | |
46 | * bit 3 == 1 means use of reserved bit detected | |
47 | * bit 4 == 1 means fault was an instruction fetch | |
48 | */ | |
8a19da7b | 49 | #define PF_PROT (1<<0) |
66c58156 | 50 | #define PF_WRITE (1<<1) |
8a19da7b IM |
51 | #define PF_USER (1<<2) |
52 | #define PF_RSVD (1<<3) | |
66c58156 AK |
53 | #define PF_INSTR (1<<4) |
54 | ||
0fd0e3da | 55 | static inline int kmmio_fault(struct pt_regs *regs, unsigned long addr) |
86069782 | 56 | { |
fd3fdf11 | 57 | #ifdef CONFIG_MMIOTRACE |
0fd0e3da PP |
58 | if (unlikely(is_kmmio_active())) |
59 | if (kmmio_handler(regs, addr) == 1) | |
60 | return -1; | |
86069782 | 61 | #endif |
0fd0e3da | 62 | return 0; |
86069782 PP |
63 | } |
64 | ||
74a0b576 | 65 | static inline int notify_page_fault(struct pt_regs *regs) |
1bd858a5 | 66 | { |
33cb5243 | 67 | #ifdef CONFIG_KPROBES |
74a0b576 CH |
68 | int ret = 0; |
69 | ||
70 | /* kprobe_running() needs smp_processor_id() */ | |
f8c2ee22 | 71 | if (!user_mode_vm(regs)) { |
74a0b576 CH |
72 | preempt_disable(); |
73 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
74 | ret = 1; | |
75 | preempt_enable(); | |
76 | } | |
1bd858a5 | 77 | |
74a0b576 | 78 | return ret; |
74a0b576 | 79 | #else |
74a0b576 | 80 | return 0; |
74a0b576 | 81 | #endif |
33cb5243 | 82 | } |
1bd858a5 | 83 | |
1dc85be0 HH |
84 | /* |
85 | * X86_32 | |
86 | * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. | |
87 | * Check that here and ignore it. | |
88 | * | |
89 | * X86_64 | |
90 | * Sometimes the CPU reports invalid exceptions on prefetch. | |
91 | * Check that here and ignore it. | |
92 | * | |
93 | * Opcode checker based on code by Richard Brunner | |
94 | */ | |
92181f19 NP |
95 | static int is_prefetch(struct pt_regs *regs, unsigned long error_code, |
96 | unsigned long addr) | |
33cb5243 | 97 | { |
ab2bf0c1 | 98 | unsigned char *instr; |
1da177e4 | 99 | int scan_more = 1; |
33cb5243 | 100 | int prefetch = 0; |
f1290ec9 | 101 | unsigned char *max_instr; |
1da177e4 | 102 | |
3085354d IM |
103 | /* |
104 | * If it was a exec (instruction fetch) fault on NX page, then | |
105 | * do not ignore the fault: | |
106 | */ | |
66c58156 | 107 | if (error_code & PF_INSTR) |
1da177e4 | 108 | return 0; |
1dc85be0 | 109 | |
f2857ce9 | 110 | instr = (unsigned char *)convert_ip_to_linear(current, regs); |
f1290ec9 | 111 | max_instr = instr + 15; |
1da177e4 | 112 | |
76381fee | 113 | if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) |
1da177e4 LT |
114 | return 0; |
115 | ||
33cb5243 | 116 | while (scan_more && instr < max_instr) { |
1da177e4 LT |
117 | unsigned char opcode; |
118 | unsigned char instr_hi; | |
119 | unsigned char instr_lo; | |
120 | ||
ab2bf0c1 | 121 | if (probe_kernel_address(instr, opcode)) |
33cb5243 | 122 | break; |
1da177e4 | 123 | |
33cb5243 HH |
124 | instr_hi = opcode & 0xf0; |
125 | instr_lo = opcode & 0x0f; | |
1da177e4 LT |
126 | instr++; |
127 | ||
33cb5243 | 128 | switch (instr_hi) { |
1da177e4 LT |
129 | case 0x20: |
130 | case 0x30: | |
33cb5243 HH |
131 | /* |
132 | * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. | |
133 | * In X86_64 long mode, the CPU will signal invalid | |
134 | * opcode if some of these prefixes are present so | |
135 | * X86_64 will never get here anyway | |
136 | */ | |
1da177e4 LT |
137 | scan_more = ((instr_lo & 7) == 0x6); |
138 | break; | |
33cb5243 | 139 | #ifdef CONFIG_X86_64 |
1da177e4 | 140 | case 0x40: |
33cb5243 HH |
141 | /* |
142 | * In AMD64 long mode 0x40..0x4F are valid REX prefixes | |
143 | * Need to figure out under what instruction mode the | |
144 | * instruction was issued. Could check the LDT for lm, | |
145 | * but for now it's good enough to assume that long | |
146 | * mode only uses well known segments or kernel. | |
147 | */ | |
76381fee | 148 | scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS); |
1da177e4 | 149 | break; |
33cb5243 | 150 | #endif |
1da177e4 LT |
151 | case 0x60: |
152 | /* 0x64 thru 0x67 are valid prefixes in all modes. */ | |
153 | scan_more = (instr_lo & 0xC) == 0x4; | |
33cb5243 | 154 | break; |
1da177e4 | 155 | case 0xF0: |
1dc85be0 | 156 | /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ |
1da177e4 | 157 | scan_more = !instr_lo || (instr_lo>>1) == 1; |
33cb5243 | 158 | break; |
1da177e4 LT |
159 | case 0x00: |
160 | /* Prefetch instruction is 0x0F0D or 0x0F18 */ | |
161 | scan_more = 0; | |
f2857ce9 | 162 | |
ab2bf0c1 | 163 | if (probe_kernel_address(instr, opcode)) |
1da177e4 LT |
164 | break; |
165 | prefetch = (instr_lo == 0xF) && | |
166 | (opcode == 0x0D || opcode == 0x18); | |
33cb5243 | 167 | break; |
1da177e4 LT |
168 | default: |
169 | scan_more = 0; | |
170 | break; | |
33cb5243 | 171 | } |
1da177e4 LT |
172 | } |
173 | return prefetch; | |
174 | } | |
175 | ||
c4aba4a8 HH |
176 | static void force_sig_info_fault(int si_signo, int si_code, |
177 | unsigned long address, struct task_struct *tsk) | |
178 | { | |
179 | siginfo_t info; | |
180 | ||
181 | info.si_signo = si_signo; | |
182 | info.si_errno = 0; | |
183 | info.si_code = si_code; | |
184 | info.si_addr = (void __user *)address; | |
185 | force_sig_info(si_signo, &info, tsk); | |
186 | } | |
187 | ||
1156e098 | 188 | #ifdef CONFIG_X86_64 |
33cb5243 HH |
189 | static int bad_address(void *p) |
190 | { | |
1da177e4 | 191 | unsigned long dummy; |
ab2bf0c1 | 192 | return probe_kernel_address((unsigned long *)p, dummy); |
33cb5243 | 193 | } |
1156e098 | 194 | #endif |
1da177e4 | 195 | |
cae30f82 | 196 | static void dump_pagetable(unsigned long address) |
1da177e4 | 197 | { |
1156e098 HH |
198 | #ifdef CONFIG_X86_32 |
199 | __typeof__(pte_val(__pte(0))) page; | |
200 | ||
201 | page = read_cr3(); | |
202 | page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT]; | |
203 | #ifdef CONFIG_X86_PAE | |
204 | printk("*pdpt = %016Lx ", page); | |
205 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
206 | && page & _PAGE_PRESENT) { | |
207 | page &= PAGE_MASK; | |
208 | page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT) | |
209 | & (PTRS_PER_PMD - 1)]; | |
210 | printk(KERN_CONT "*pde = %016Lx ", page); | |
211 | page &= ~_PAGE_NX; | |
212 | } | |
213 | #else | |
214 | printk("*pde = %08lx ", page); | |
215 | #endif | |
216 | ||
217 | /* | |
218 | * We must not directly access the pte in the highpte | |
219 | * case if the page table is located in highmem. | |
220 | * And let's rather not kmap-atomic the pte, just in case | |
221 | * it's allocated already. | |
222 | */ | |
223 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
224 | && (page & _PAGE_PRESENT) | |
225 | && !(page & _PAGE_PSE)) { | |
226 | page &= PAGE_MASK; | |
227 | page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT) | |
228 | & (PTRS_PER_PTE - 1)]; | |
229 | printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page); | |
230 | } | |
231 | ||
232 | printk("\n"); | |
233 | #else /* CONFIG_X86_64 */ | |
1da177e4 LT |
234 | pgd_t *pgd; |
235 | pud_t *pud; | |
236 | pmd_t *pmd; | |
237 | pte_t *pte; | |
238 | ||
f51c9452 | 239 | pgd = (pgd_t *)read_cr3(); |
1da177e4 | 240 | |
33cb5243 | 241 | pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); |
1da177e4 | 242 | pgd += pgd_index(address); |
1da177e4 | 243 | if (bad_address(pgd)) goto bad; |
d646bce4 | 244 | printk("PGD %lx ", pgd_val(*pgd)); |
33cb5243 | 245 | if (!pgd_present(*pgd)) goto ret; |
1da177e4 | 246 | |
d2ae5b5f | 247 | pud = pud_offset(pgd, address); |
1da177e4 LT |
248 | if (bad_address(pud)) goto bad; |
249 | printk("PUD %lx ", pud_val(*pud)); | |
b5360222 AK |
250 | if (!pud_present(*pud) || pud_large(*pud)) |
251 | goto ret; | |
1da177e4 LT |
252 | |
253 | pmd = pmd_offset(pud, address); | |
254 | if (bad_address(pmd)) goto bad; | |
255 | printk("PMD %lx ", pmd_val(*pmd)); | |
b1992df3 | 256 | if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret; |
1da177e4 LT |
257 | |
258 | pte = pte_offset_kernel(pmd, address); | |
259 | if (bad_address(pte)) goto bad; | |
33cb5243 | 260 | printk("PTE %lx", pte_val(*pte)); |
1da177e4 LT |
261 | ret: |
262 | printk("\n"); | |
263 | return; | |
264 | bad: | |
265 | printk("BAD\n"); | |
1156e098 HH |
266 | #endif |
267 | } | |
268 | ||
269 | #ifdef CONFIG_X86_32 | |
270 | static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) | |
271 | { | |
272 | unsigned index = pgd_index(address); | |
273 | pgd_t *pgd_k; | |
274 | pud_t *pud, *pud_k; | |
275 | pmd_t *pmd, *pmd_k; | |
276 | ||
277 | pgd += index; | |
278 | pgd_k = init_mm.pgd + index; | |
279 | ||
280 | if (!pgd_present(*pgd_k)) | |
281 | return NULL; | |
282 | ||
283 | /* | |
284 | * set_pgd(pgd, *pgd_k); here would be useless on PAE | |
285 | * and redundant with the set_pmd() on non-PAE. As would | |
286 | * set_pud. | |
287 | */ | |
288 | ||
289 | pud = pud_offset(pgd, address); | |
290 | pud_k = pud_offset(pgd_k, address); | |
291 | if (!pud_present(*pud_k)) | |
292 | return NULL; | |
293 | ||
294 | pmd = pmd_offset(pud, address); | |
295 | pmd_k = pmd_offset(pud_k, address); | |
296 | if (!pmd_present(*pmd_k)) | |
297 | return NULL; | |
298 | if (!pmd_present(*pmd)) { | |
299 | set_pmd(pmd, *pmd_k); | |
300 | arch_flush_lazy_mmu_mode(); | |
301 | } else | |
302 | BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); | |
303 | return pmd_k; | |
1da177e4 | 304 | } |
1156e098 | 305 | #endif |
1da177e4 | 306 | |
1dc85be0 | 307 | #ifdef CONFIG_X86_64 |
33cb5243 | 308 | static const char errata93_warning[] = |
1da177e4 LT |
309 | KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" |
310 | KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n" | |
311 | KERN_ERR "******* Please consider a BIOS update.\n" | |
312 | KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; | |
fdfe8aa8 | 313 | #endif |
1da177e4 LT |
314 | |
315 | /* Workaround for K8 erratum #93 & buggy BIOS. | |
316 | BIOS SMM functions are required to use a specific workaround | |
33cb5243 HH |
317 | to avoid corruption of the 64bit RIP register on C stepping K8. |
318 | A lot of BIOS that didn't get tested properly miss this. | |
1da177e4 LT |
319 | The OS sees this as a page fault with the upper 32bits of RIP cleared. |
320 | Try to work around it here. | |
fdfe8aa8 HH |
321 | Note we only handle faults in kernel here. |
322 | Does nothing for X86_32 | |
323 | */ | |
33cb5243 | 324 | static int is_errata93(struct pt_regs *regs, unsigned long address) |
1da177e4 | 325 | { |
fdfe8aa8 | 326 | #ifdef CONFIG_X86_64 |
1da177e4 | 327 | static int warned; |
65ea5b03 | 328 | if (address != regs->ip) |
1da177e4 | 329 | return 0; |
33cb5243 | 330 | if ((address >> 32) != 0) |
1da177e4 LT |
331 | return 0; |
332 | address |= 0xffffffffUL << 32; | |
33cb5243 HH |
333 | if ((address >= (u64)_stext && address <= (u64)_etext) || |
334 | (address >= MODULES_VADDR && address <= MODULES_END)) { | |
1da177e4 | 335 | if (!warned) { |
33cb5243 | 336 | printk(errata93_warning); |
1da177e4 LT |
337 | warned = 1; |
338 | } | |
65ea5b03 | 339 | regs->ip = address; |
1da177e4 LT |
340 | return 1; |
341 | } | |
fdfe8aa8 | 342 | #endif |
1da177e4 | 343 | return 0; |
33cb5243 | 344 | } |
1da177e4 | 345 | |
35f3266f HH |
346 | /* |
347 | * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal | |
348 | * addresses >4GB. We catch this in the page fault handler because these | |
349 | * addresses are not reachable. Just detect this case and return. Any code | |
350 | * segment in LDT is compatibility mode. | |
351 | */ | |
352 | static int is_errata100(struct pt_regs *regs, unsigned long address) | |
353 | { | |
354 | #ifdef CONFIG_X86_64 | |
355 | if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && | |
356 | (address >> 32)) | |
357 | return 1; | |
358 | #endif | |
359 | return 0; | |
360 | } | |
361 | ||
29caf2f9 HH |
362 | static int is_f00f_bug(struct pt_regs *regs, unsigned long address) |
363 | { | |
364 | #ifdef CONFIG_X86_F00F_BUG | |
365 | unsigned long nr; | |
366 | /* | |
367 | * Pentium F0 0F C7 C8 bug workaround. | |
368 | */ | |
369 | if (boot_cpu_data.f00f_bug) { | |
370 | nr = (address - idt_descr.address) >> 3; | |
371 | ||
372 | if (nr == 6) { | |
373 | do_invalid_op(regs, 0); | |
374 | return 1; | |
375 | } | |
376 | } | |
377 | #endif | |
378 | return 0; | |
379 | } | |
380 | ||
b3279c7f HH |
381 | static void show_fault_oops(struct pt_regs *regs, unsigned long error_code, |
382 | unsigned long address) | |
383 | { | |
1156e098 HH |
384 | #ifdef CONFIG_X86_32 |
385 | if (!oops_may_print()) | |
386 | return; | |
fd40d6e3 | 387 | #endif |
1156e098 HH |
388 | |
389 | #ifdef CONFIG_X86_PAE | |
390 | if (error_code & PF_INSTR) { | |
93809be8 | 391 | unsigned int level; |
1156e098 HH |
392 | pte_t *pte = lookup_address(address, &level); |
393 | ||
394 | if (pte && pte_present(*pte) && !pte_exec(*pte)) | |
395 | printk(KERN_CRIT "kernel tried to execute " | |
396 | "NX-protected page - exploit attempt? " | |
350b4da7 | 397 | "(uid: %d)\n", current_uid()); |
1156e098 HH |
398 | } |
399 | #endif | |
1156e098 | 400 | |
19f0dda9 | 401 | printk(KERN_ALERT "BUG: unable to handle kernel "); |
b3279c7f | 402 | if (address < PAGE_SIZE) |
19f0dda9 | 403 | printk(KERN_CONT "NULL pointer dereference"); |
b3279c7f | 404 | else |
19f0dda9 | 405 | printk(KERN_CONT "paging request"); |
f294a8ce | 406 | printk(KERN_CONT " at %p\n", (void *) address); |
19f0dda9 | 407 | printk(KERN_ALERT "IP:"); |
b3279c7f HH |
408 | printk_address(regs->ip, 1); |
409 | dump_pagetable(address); | |
410 | } | |
411 | ||
1156e098 | 412 | #ifdef CONFIG_X86_64 |
92181f19 NP |
413 | static noinline void pgtable_bad(struct pt_regs *regs, |
414 | unsigned long error_code, unsigned long address) | |
1da177e4 | 415 | { |
1209140c | 416 | unsigned long flags = oops_begin(); |
874d93d1 | 417 | int sig = SIGKILL; |
92181f19 | 418 | struct task_struct *tsk = current; |
1209140c | 419 | |
1da177e4 | 420 | printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
92181f19 | 421 | tsk->comm, address); |
1da177e4 | 422 | dump_pagetable(address); |
6e3f3617 JB |
423 | tsk->thread.cr2 = address; |
424 | tsk->thread.trap_no = 14; | |
425 | tsk->thread.error_code = error_code; | |
22f5991c | 426 | if (__die("Bad pagetable", regs, error_code)) |
874d93d1 AH |
427 | sig = 0; |
428 | oops_end(flags, regs, sig); | |
1da177e4 | 429 | } |
1156e098 | 430 | #endif |
1da177e4 | 431 | |
92181f19 NP |
432 | static noinline void no_context(struct pt_regs *regs, |
433 | unsigned long error_code, unsigned long address) | |
434 | { | |
435 | struct task_struct *tsk = current; | |
19803078 IM |
436 | unsigned long *stackend; |
437 | ||
92181f19 NP |
438 | #ifdef CONFIG_X86_64 |
439 | unsigned long flags; | |
440 | int sig; | |
441 | #endif | |
442 | ||
443 | /* Are we prepared to handle this kernel fault? */ | |
444 | if (fixup_exception(regs)) | |
445 | return; | |
446 | ||
447 | /* | |
448 | * X86_32 | |
449 | * Valid to do another page fault here, because if this fault | |
450 | * had been triggered by is_prefetch fixup_exception would have | |
451 | * handled it. | |
452 | * | |
453 | * X86_64 | |
454 | * Hall of shame of CPU/BIOS bugs. | |
455 | */ | |
456 | if (is_prefetch(regs, error_code, address)) | |
457 | return; | |
458 | ||
459 | if (is_errata93(regs, address)) | |
460 | return; | |
461 | ||
462 | /* | |
463 | * Oops. The kernel tried to access some bad page. We'll have to | |
464 | * terminate things with extreme prejudice. | |
465 | */ | |
466 | #ifdef CONFIG_X86_32 | |
467 | bust_spinlocks(1); | |
468 | #else | |
469 | flags = oops_begin(); | |
470 | #endif | |
471 | ||
472 | show_fault_oops(regs, error_code, address); | |
473 | ||
19803078 IM |
474 | stackend = end_of_stack(tsk); |
475 | if (*stackend != STACK_END_MAGIC) | |
476 | printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); | |
477 | ||
92181f19 NP |
478 | tsk->thread.cr2 = address; |
479 | tsk->thread.trap_no = 14; | |
480 | tsk->thread.error_code = error_code; | |
481 | ||
482 | #ifdef CONFIG_X86_32 | |
483 | die("Oops", regs, error_code); | |
484 | bust_spinlocks(0); | |
485 | do_exit(SIGKILL); | |
486 | #else | |
487 | sig = SIGKILL; | |
488 | if (__die("Oops", regs, error_code)) | |
489 | sig = 0; | |
490 | /* Executive summary in case the body of the oops scrolled away */ | |
491 | printk(KERN_EMERG "CR2: %016lx\n", address); | |
492 | oops_end(flags, regs, sig); | |
493 | #endif | |
494 | } | |
495 | ||
496 | static void __bad_area_nosemaphore(struct pt_regs *regs, | |
497 | unsigned long error_code, unsigned long address, | |
498 | int si_code) | |
499 | { | |
500 | struct task_struct *tsk = current; | |
501 | ||
502 | /* User mode accesses just cause a SIGSEGV */ | |
503 | if (error_code & PF_USER) { | |
504 | /* | |
505 | * It's possible to have interrupts off here. | |
506 | */ | |
507 | local_irq_enable(); | |
508 | ||
509 | /* | |
510 | * Valid to do another page fault here because this one came | |
511 | * from user space. | |
512 | */ | |
513 | if (is_prefetch(regs, error_code, address)) | |
514 | return; | |
515 | ||
516 | if (is_errata100(regs, address)) | |
517 | return; | |
518 | ||
519 | if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && | |
520 | printk_ratelimit()) { | |
521 | printk( | |
522 | "%s%s[%d]: segfault at %lx ip %p sp %p error %lx", | |
523 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, | |
524 | tsk->comm, task_pid_nr(tsk), address, | |
525 | (void *) regs->ip, (void *) regs->sp, error_code); | |
526 | print_vma_addr(" in ", regs->ip); | |
527 | printk("\n"); | |
528 | } | |
529 | ||
530 | tsk->thread.cr2 = address; | |
531 | /* Kernel addresses are always protection faults */ | |
532 | tsk->thread.error_code = error_code | (address >= TASK_SIZE); | |
533 | tsk->thread.trap_no = 14; | |
534 | force_sig_info_fault(SIGSEGV, si_code, address, tsk); | |
535 | return; | |
536 | } | |
537 | ||
538 | if (is_f00f_bug(regs, address)) | |
539 | return; | |
540 | ||
541 | no_context(regs, error_code, address); | |
542 | } | |
543 | ||
544 | static noinline void bad_area_nosemaphore(struct pt_regs *regs, | |
545 | unsigned long error_code, unsigned long address) | |
546 | { | |
547 | __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR); | |
548 | } | |
549 | ||
550 | static void __bad_area(struct pt_regs *regs, | |
551 | unsigned long error_code, unsigned long address, | |
552 | int si_code) | |
553 | { | |
554 | struct mm_struct *mm = current->mm; | |
555 | ||
556 | /* | |
557 | * Something tried to access memory that isn't in our memory map.. | |
558 | * Fix it, but check if it's kernel or user first.. | |
559 | */ | |
560 | up_read(&mm->mmap_sem); | |
561 | ||
562 | __bad_area_nosemaphore(regs, error_code, address, si_code); | |
563 | } | |
564 | ||
565 | static noinline void bad_area(struct pt_regs *regs, | |
566 | unsigned long error_code, unsigned long address) | |
567 | { | |
568 | __bad_area(regs, error_code, address, SEGV_MAPERR); | |
569 | } | |
570 | ||
571 | static noinline void bad_area_access_error(struct pt_regs *regs, | |
572 | unsigned long error_code, unsigned long address) | |
573 | { | |
574 | __bad_area(regs, error_code, address, SEGV_ACCERR); | |
575 | } | |
576 | ||
577 | /* TODO: fixup for "mm-invoke-oom-killer-from-page-fault.patch" */ | |
578 | static void out_of_memory(struct pt_regs *regs, | |
579 | unsigned long error_code, unsigned long address) | |
580 | { | |
581 | /* | |
582 | * We ran out of memory, call the OOM killer, and return the userspace | |
583 | * (which will retry the fault, or kill us if we got oom-killed). | |
584 | */ | |
585 | up_read(¤t->mm->mmap_sem); | |
586 | pagefault_out_of_memory(); | |
587 | } | |
588 | ||
589 | static void do_sigbus(struct pt_regs *regs, | |
590 | unsigned long error_code, unsigned long address) | |
591 | { | |
592 | struct task_struct *tsk = current; | |
593 | struct mm_struct *mm = tsk->mm; | |
594 | ||
595 | up_read(&mm->mmap_sem); | |
596 | ||
597 | /* Kernel mode? Handle exceptions or die */ | |
598 | if (!(error_code & PF_USER)) | |
599 | no_context(regs, error_code, address); | |
600 | #ifdef CONFIG_X86_32 | |
601 | /* User space => ok to do another page fault */ | |
602 | if (is_prefetch(regs, error_code, address)) | |
603 | return; | |
604 | #endif | |
605 | tsk->thread.cr2 = address; | |
606 | tsk->thread.error_code = error_code; | |
607 | tsk->thread.trap_no = 14; | |
608 | force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk); | |
609 | } | |
610 | ||
611 | static noinline void mm_fault_error(struct pt_regs *regs, | |
612 | unsigned long error_code, unsigned long address, unsigned int fault) | |
613 | { | |
614 | if (fault & VM_FAULT_OOM) | |
615 | out_of_memory(regs, error_code, address); | |
616 | else if (fault & VM_FAULT_SIGBUS) | |
617 | do_sigbus(regs, error_code, address); | |
618 | else | |
619 | BUG(); | |
620 | } | |
621 | ||
d8b57bb7 TG |
622 | static int spurious_fault_check(unsigned long error_code, pte_t *pte) |
623 | { | |
624 | if ((error_code & PF_WRITE) && !pte_write(*pte)) | |
625 | return 0; | |
626 | if ((error_code & PF_INSTR) && !pte_exec(*pte)) | |
627 | return 0; | |
628 | ||
629 | return 1; | |
630 | } | |
631 | ||
5b727a3b JF |
632 | /* |
633 | * Handle a spurious fault caused by a stale TLB entry. This allows | |
634 | * us to lazily refresh the TLB when increasing the permissions of a | |
635 | * kernel page (RO -> RW or NX -> X). Doing it eagerly is very | |
636 | * expensive since that implies doing a full cross-processor TLB | |
637 | * flush, even if no stale TLB entries exist on other processors. | |
638 | * There are no security implications to leaving a stale TLB when | |
639 | * increasing the permissions on a page. | |
640 | */ | |
92181f19 NP |
641 | static noinline int spurious_fault(unsigned long error_code, |
642 | unsigned long address) | |
5b727a3b JF |
643 | { |
644 | pgd_t *pgd; | |
645 | pud_t *pud; | |
646 | pmd_t *pmd; | |
647 | pte_t *pte; | |
648 | ||
649 | /* Reserved-bit violation or user access to kernel space? */ | |
650 | if (error_code & (PF_USER | PF_RSVD)) | |
651 | return 0; | |
652 | ||
653 | pgd = init_mm.pgd + pgd_index(address); | |
654 | if (!pgd_present(*pgd)) | |
655 | return 0; | |
656 | ||
657 | pud = pud_offset(pgd, address); | |
658 | if (!pud_present(*pud)) | |
659 | return 0; | |
660 | ||
d8b57bb7 TG |
661 | if (pud_large(*pud)) |
662 | return spurious_fault_check(error_code, (pte_t *) pud); | |
663 | ||
5b727a3b JF |
664 | pmd = pmd_offset(pud, address); |
665 | if (!pmd_present(*pmd)) | |
666 | return 0; | |
667 | ||
d8b57bb7 TG |
668 | if (pmd_large(*pmd)) |
669 | return spurious_fault_check(error_code, (pte_t *) pmd); | |
670 | ||
5b727a3b JF |
671 | pte = pte_offset_kernel(pmd, address); |
672 | if (!pte_present(*pte)) | |
673 | return 0; | |
674 | ||
d8b57bb7 | 675 | return spurious_fault_check(error_code, pte); |
5b727a3b JF |
676 | } |
677 | ||
1da177e4 | 678 | /* |
f8c2ee22 HH |
679 | * X86_32 |
680 | * Handle a fault on the vmalloc or module mapping area | |
681 | * | |
682 | * X86_64 | |
f95190b2 | 683 | * Handle a fault on the vmalloc area |
3b9ba4d5 AK |
684 | * |
685 | * This assumes no large pages in there. | |
1da177e4 | 686 | */ |
92181f19 | 687 | static noinline int vmalloc_fault(unsigned long address) |
1da177e4 | 688 | { |
fdfe8aa8 HH |
689 | #ifdef CONFIG_X86_32 |
690 | unsigned long pgd_paddr; | |
691 | pmd_t *pmd_k; | |
692 | pte_t *pte_k; | |
b29c701d HN |
693 | |
694 | /* Make sure we are in vmalloc area */ | |
695 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
696 | return -1; | |
697 | ||
fdfe8aa8 HH |
698 | /* |
699 | * Synchronize this task's top level page-table | |
700 | * with the 'reference' page table. | |
701 | * | |
702 | * Do _not_ use "current" here. We might be inside | |
703 | * an interrupt in the middle of a task switch.. | |
704 | */ | |
705 | pgd_paddr = read_cr3(); | |
706 | pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); | |
707 | if (!pmd_k) | |
708 | return -1; | |
709 | pte_k = pte_offset_kernel(pmd_k, address); | |
710 | if (!pte_present(*pte_k)) | |
711 | return -1; | |
712 | return 0; | |
713 | #else | |
1da177e4 LT |
714 | pgd_t *pgd, *pgd_ref; |
715 | pud_t *pud, *pud_ref; | |
716 | pmd_t *pmd, *pmd_ref; | |
717 | pte_t *pte, *pte_ref; | |
718 | ||
cf89ec92 HH |
719 | /* Make sure we are in vmalloc area */ |
720 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
721 | return -1; | |
722 | ||
1da177e4 LT |
723 | /* Copy kernel mappings over when needed. This can also |
724 | happen within a race in page table update. In the later | |
725 | case just flush. */ | |
726 | ||
f313e123 | 727 | pgd = pgd_offset(current->active_mm, address); |
1da177e4 LT |
728 | pgd_ref = pgd_offset_k(address); |
729 | if (pgd_none(*pgd_ref)) | |
730 | return -1; | |
731 | if (pgd_none(*pgd)) | |
732 | set_pgd(pgd, *pgd_ref); | |
8c914cb7 | 733 | else |
46a82b2d | 734 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); |
1da177e4 LT |
735 | |
736 | /* Below here mismatches are bugs because these lower tables | |
737 | are shared */ | |
738 | ||
739 | pud = pud_offset(pgd, address); | |
740 | pud_ref = pud_offset(pgd_ref, address); | |
741 | if (pud_none(*pud_ref)) | |
742 | return -1; | |
46a82b2d | 743 | if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) |
1da177e4 LT |
744 | BUG(); |
745 | pmd = pmd_offset(pud, address); | |
746 | pmd_ref = pmd_offset(pud_ref, address); | |
747 | if (pmd_none(*pmd_ref)) | |
748 | return -1; | |
749 | if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) | |
750 | BUG(); | |
751 | pte_ref = pte_offset_kernel(pmd_ref, address); | |
752 | if (!pte_present(*pte_ref)) | |
753 | return -1; | |
754 | pte = pte_offset_kernel(pmd, address); | |
3b9ba4d5 AK |
755 | /* Don't use pte_page here, because the mappings can point |
756 | outside mem_map, and the NUMA hash lookup cannot handle | |
757 | that. */ | |
758 | if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) | |
1da177e4 | 759 | BUG(); |
1da177e4 | 760 | return 0; |
fdfe8aa8 | 761 | #endif |
1da177e4 LT |
762 | } |
763 | ||
abd4f750 | 764 | int show_unhandled_signals = 1; |
1da177e4 | 765 | |
92181f19 NP |
766 | static inline int access_error(unsigned long error_code, int write, |
767 | struct vm_area_struct *vma) | |
768 | { | |
769 | if (write) { | |
770 | /* write, present and write, not present */ | |
771 | if (unlikely(!(vma->vm_flags & VM_WRITE))) | |
772 | return 1; | |
773 | } else if (unlikely(error_code & PF_PROT)) { | |
774 | /* read, present */ | |
775 | return 1; | |
776 | } else { | |
777 | /* read, not present */ | |
778 | if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))) | |
779 | return 1; | |
780 | } | |
781 | ||
782 | return 0; | |
783 | } | |
784 | ||
1da177e4 LT |
785 | /* |
786 | * This routine handles page faults. It determines the address, | |
787 | * and the problem, and then passes it off to one of the appropriate | |
788 | * routines. | |
1da177e4 | 789 | */ |
f8c2ee22 HH |
790 | #ifdef CONFIG_X86_64 |
791 | asmlinkage | |
792 | #endif | |
793 | void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) | |
1da177e4 | 794 | { |
92181f19 | 795 | unsigned long address; |
1da177e4 LT |
796 | struct task_struct *tsk; |
797 | struct mm_struct *mm; | |
33cb5243 | 798 | struct vm_area_struct *vma; |
92181f19 | 799 | int write; |
f8c2ee22 | 800 | int fault; |
1da177e4 | 801 | |
a9ba9a3b AV |
802 | tsk = current; |
803 | mm = tsk->mm; | |
804 | prefetchw(&mm->mmap_sem); | |
805 | ||
1da177e4 | 806 | /* get the address */ |
f51c9452 | 807 | address = read_cr2(); |
1da177e4 | 808 | |
92181f19 | 809 | if (unlikely(notify_page_fault(regs))) |
608566b4 | 810 | return; |
0fd0e3da | 811 | if (unlikely(kmmio_fault(regs, address))) |
86069782 | 812 | return; |
1da177e4 LT |
813 | |
814 | /* | |
815 | * We fault-in kernel-space virtual memory on-demand. The | |
816 | * 'reference' page table is init_mm.pgd. | |
817 | * | |
818 | * NOTE! We MUST NOT take any locks for this case. We may | |
819 | * be in an interrupt or a critical region, and should | |
820 | * only copy the information from the master page table, | |
821 | * nothing more. | |
822 | * | |
823 | * This verifies that the fault happens in kernel space | |
824 | * (error_code & 4) == 0, and that the fault was not a | |
8b1bde93 | 825 | * protection error (error_code & 9) == 0. |
1da177e4 | 826 | */ |
f8c2ee22 HH |
827 | #ifdef CONFIG_X86_32 |
828 | if (unlikely(address >= TASK_SIZE)) { | |
cf89ec92 HH |
829 | #else |
830 | if (unlikely(address >= TASK_SIZE64)) { | |
831 | #endif | |
f8c2ee22 HH |
832 | if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && |
833 | vmalloc_fault(address) >= 0) | |
834 | return; | |
5b727a3b JF |
835 | |
836 | /* Can handle a stale RO->RW TLB */ | |
92181f19 | 837 | if (spurious_fault(error_code, address)) |
5b727a3b JF |
838 | return; |
839 | ||
f8c2ee22 HH |
840 | /* |
841 | * Don't take the mm semaphore here. If we fixup a prefetch | |
842 | * fault we could otherwise deadlock. | |
843 | */ | |
92181f19 NP |
844 | bad_area_nosemaphore(regs, error_code, address); |
845 | return; | |
f8c2ee22 HH |
846 | } |
847 | ||
f8c2ee22 | 848 | /* |
891cffbd LT |
849 | * It's safe to allow irq's after cr2 has been saved and the |
850 | * vmalloc fault has been handled. | |
851 | * | |
852 | * User-mode registers count as a user access even for any | |
853 | * potential system fault or CPU buglet. | |
f8c2ee22 | 854 | */ |
891cffbd LT |
855 | if (user_mode_vm(regs)) { |
856 | local_irq_enable(); | |
857 | error_code |= PF_USER; | |
858 | } else if (regs->flags & X86_EFLAGS_IF) | |
8c914cb7 JB |
859 | local_irq_enable(); |
860 | ||
891cffbd | 861 | #ifdef CONFIG_X86_64 |
66c58156 | 862 | if (unlikely(error_code & PF_RSVD)) |
92181f19 | 863 | pgtable_bad(regs, error_code, address); |
891cffbd | 864 | #endif |
1da177e4 LT |
865 | |
866 | /* | |
33cb5243 HH |
867 | * If we're in an interrupt, have no user context or are running in an |
868 | * atomic region then we must not take the fault. | |
1da177e4 | 869 | */ |
92181f19 NP |
870 | if (unlikely(in_atomic() || !mm)) { |
871 | bad_area_nosemaphore(regs, error_code, address); | |
872 | return; | |
873 | } | |
1da177e4 | 874 | |
3a1dfe6e IM |
875 | /* |
876 | * When running in the kernel we expect faults to occur only to | |
1da177e4 | 877 | * addresses in user space. All other faults represent errors in the |
676b1855 | 878 | * kernel and should generate an OOPS. Unfortunately, in the case of an |
80f7228b | 879 | * erroneous fault occurring in a code path which already holds mmap_sem |
1da177e4 LT |
880 | * we will deadlock attempting to validate the fault against the |
881 | * address space. Luckily the kernel only validly references user | |
882 | * space from well defined areas of code, which are listed in the | |
883 | * exceptions table. | |
884 | * | |
885 | * As the vast majority of faults will be valid we will only perform | |
676b1855 | 886 | * the source reference check when there is a possibility of a deadlock. |
1da177e4 LT |
887 | * Attempt to lock the address space, if we cannot we then validate the |
888 | * source. If this is invalid we can skip the address space check, | |
889 | * thus avoiding the deadlock. | |
890 | */ | |
92181f19 | 891 | if (unlikely(!down_read_trylock(&mm->mmap_sem))) { |
66c58156 | 892 | if ((error_code & PF_USER) == 0 && |
92181f19 NP |
893 | !search_exception_tables(regs->ip)) { |
894 | bad_area_nosemaphore(regs, error_code, address); | |
895 | return; | |
896 | } | |
1da177e4 LT |
897 | down_read(&mm->mmap_sem); |
898 | } | |
899 | ||
900 | vma = find_vma(mm, address); | |
92181f19 NP |
901 | if (unlikely(!vma)) { |
902 | bad_area(regs, error_code, address); | |
903 | return; | |
904 | } | |
905 | if (likely(vma->vm_start <= address)) | |
1da177e4 | 906 | goto good_area; |
92181f19 NP |
907 | if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) { |
908 | bad_area(regs, error_code, address); | |
909 | return; | |
910 | } | |
33cb5243 | 911 | if (error_code & PF_USER) { |
6f4d368e HH |
912 | /* |
913 | * Accessing the stack below %sp is always a bug. | |
914 | * The large cushion allows instructions like enter | |
915 | * and pusha to work. ("enter $65535,$31" pushes | |
916 | * 32 pointers and then decrements %sp by 65535.) | |
03fdc2c2 | 917 | */ |
92181f19 NP |
918 | if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) { |
919 | bad_area(regs, error_code, address); | |
920 | return; | |
921 | } | |
1da177e4 | 922 | } |
92181f19 NP |
923 | if (unlikely(expand_stack(vma, address))) { |
924 | bad_area(regs, error_code, address); | |
925 | return; | |
926 | } | |
927 | ||
928 | /* | |
929 | * Ok, we have a good vm_area for this memory access, so | |
930 | * we can handle it.. | |
931 | */ | |
1da177e4 | 932 | good_area: |
92181f19 NP |
933 | write = error_code & PF_WRITE; |
934 | if (unlikely(access_error(error_code, write, vma))) { | |
935 | bad_area_access_error(regs, error_code, address); | |
936 | return; | |
1da177e4 LT |
937 | } |
938 | ||
939 | /* | |
940 | * If for any reason at all we couldn't handle the fault, | |
941 | * make sure we exit gracefully rather than endlessly redo | |
942 | * the fault. | |
943 | */ | |
83c54070 NP |
944 | fault = handle_mm_fault(mm, vma, address, write); |
945 | if (unlikely(fault & VM_FAULT_ERROR)) { | |
92181f19 NP |
946 | mm_fault_error(regs, error_code, address, fault); |
947 | return; | |
1da177e4 | 948 | } |
83c54070 NP |
949 | if (fault & VM_FAULT_MAJOR) |
950 | tsk->maj_flt++; | |
951 | else | |
952 | tsk->min_flt++; | |
d729ab35 HH |
953 | |
954 | #ifdef CONFIG_X86_32 | |
955 | /* | |
956 | * Did it hit the DOS screen memory VA from vm86 mode? | |
957 | */ | |
958 | if (v8086_mode(regs)) { | |
959 | unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT; | |
960 | if (bit < 32) | |
961 | tsk->thread.screen_bitmap |= 1 << bit; | |
962 | } | |
963 | #endif | |
1da177e4 | 964 | up_read(&mm->mmap_sem); |
1da177e4 | 965 | } |
9e43e1b7 | 966 | |
8c914cb7 | 967 | DEFINE_SPINLOCK(pgd_lock); |
2bff7383 | 968 | LIST_HEAD(pgd_list); |
8c914cb7 JB |
969 | |
970 | void vmalloc_sync_all(void) | |
971 | { | |
1156e098 HH |
972 | unsigned long address; |
973 | ||
cc643d46 | 974 | #ifdef CONFIG_X86_32 |
1156e098 HH |
975 | if (SHARED_KERNEL_PMD) |
976 | return; | |
977 | ||
cc643d46 JB |
978 | for (address = VMALLOC_START & PMD_MASK; |
979 | address >= TASK_SIZE && address < FIXADDR_TOP; | |
980 | address += PMD_SIZE) { | |
67350a5c JF |
981 | unsigned long flags; |
982 | struct page *page; | |
983 | ||
984 | spin_lock_irqsave(&pgd_lock, flags); | |
985 | list_for_each_entry(page, &pgd_list, lru) { | |
986 | if (!vmalloc_sync_one(page_address(page), | |
987 | address)) | |
988 | break; | |
1156e098 | 989 | } |
67350a5c | 990 | spin_unlock_irqrestore(&pgd_lock, flags); |
1156e098 HH |
991 | } |
992 | #else /* CONFIG_X86_64 */ | |
cc643d46 JB |
993 | for (address = VMALLOC_START & PGDIR_MASK; address <= VMALLOC_END; |
994 | address += PGDIR_SIZE) { | |
67350a5c JF |
995 | const pgd_t *pgd_ref = pgd_offset_k(address); |
996 | unsigned long flags; | |
997 | struct page *page; | |
998 | ||
999 | if (pgd_none(*pgd_ref)) | |
1000 | continue; | |
1001 | spin_lock_irqsave(&pgd_lock, flags); | |
1002 | list_for_each_entry(page, &pgd_list, lru) { | |
1003 | pgd_t *pgd; | |
1004 | pgd = (pgd_t *)page_address(page) + pgd_index(address); | |
1005 | if (pgd_none(*pgd)) | |
1006 | set_pgd(pgd, *pgd_ref); | |
1007 | else | |
1008 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); | |
8c914cb7 | 1009 | } |
67350a5c | 1010 | spin_unlock_irqrestore(&pgd_lock, flags); |
8c914cb7 | 1011 | } |
1156e098 | 1012 | #endif |
8c914cb7 | 1013 | } |