Commit | Line | Data |
---|---|---|
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> | |
13 | #include <linux/mman.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/smp.h> | |
1da177e4 LT |
16 | #include <linux/interrupt.h> |
17 | #include <linux/init.h> | |
18 | #include <linux/tty.h> | |
19 | #include <linux/vt_kern.h> /* For unblank_screen() */ | |
20 | #include <linux/compiler.h> | |
c61e211d HH |
21 | #include <linux/highmem.h> |
22 | #include <linux/bootmem.h> /* for max_low_pfn */ | |
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> |
7c9f8861 | 28 | #include <linux/magic.h> |
1da177e4 LT |
29 | |
30 | #include <asm/system.h> | |
c61e211d HH |
31 | #include <asm/desc.h> |
32 | #include <asm/segment.h> | |
1da177e4 LT |
33 | #include <asm/pgalloc.h> |
34 | #include <asm/smp.h> | |
35 | #include <asm/tlbflush.h> | |
36 | #include <asm/proto.h> | |
1da177e4 | 37 | #include <asm-generic/sections.h> |
1da177e4 | 38 | |
33cb5243 HH |
39 | /* |
40 | * Page fault error code bits | |
41 | * bit 0 == 0 means no page found, 1 means protection fault | |
42 | * bit 1 == 0 means read, 1 means write | |
43 | * bit 2 == 0 means kernel, 1 means user-mode | |
44 | * bit 3 == 1 means use of reserved bit detected | |
45 | * bit 4 == 1 means fault was an instruction fetch | |
46 | */ | |
8a19da7b | 47 | #define PF_PROT (1<<0) |
66c58156 | 48 | #define PF_WRITE (1<<1) |
8a19da7b IM |
49 | #define PF_USER (1<<2) |
50 | #define PF_RSVD (1<<3) | |
66c58156 AK |
51 | #define PF_INSTR (1<<4) |
52 | ||
74a0b576 | 53 | static inline int notify_page_fault(struct pt_regs *regs) |
1bd858a5 | 54 | { |
33cb5243 | 55 | #ifdef CONFIG_KPROBES |
74a0b576 CH |
56 | int ret = 0; |
57 | ||
58 | /* kprobe_running() needs smp_processor_id() */ | |
f8c2ee22 HH |
59 | #ifdef CONFIG_X86_32 |
60 | if (!user_mode_vm(regs)) { | |
61 | #else | |
74a0b576 | 62 | if (!user_mode(regs)) { |
f8c2ee22 | 63 | #endif |
74a0b576 CH |
64 | preempt_disable(); |
65 | if (kprobe_running() && kprobe_fault_handler(regs, 14)) | |
66 | ret = 1; | |
67 | preempt_enable(); | |
68 | } | |
1bd858a5 | 69 | |
74a0b576 | 70 | return ret; |
74a0b576 | 71 | #else |
74a0b576 | 72 | return 0; |
74a0b576 | 73 | #endif |
33cb5243 | 74 | } |
1bd858a5 | 75 | |
1dc85be0 HH |
76 | /* |
77 | * X86_32 | |
78 | * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch. | |
79 | * Check that here and ignore it. | |
80 | * | |
81 | * X86_64 | |
82 | * Sometimes the CPU reports invalid exceptions on prefetch. | |
83 | * Check that here and ignore it. | |
84 | * | |
85 | * Opcode checker based on code by Richard Brunner | |
86 | */ | |
87 | static int is_prefetch(struct pt_regs *regs, unsigned long addr, | |
88 | unsigned long error_code) | |
33cb5243 | 89 | { |
ab2bf0c1 | 90 | unsigned char *instr; |
1da177e4 | 91 | int scan_more = 1; |
33cb5243 | 92 | int prefetch = 0; |
f1290ec9 | 93 | unsigned char *max_instr; |
1da177e4 | 94 | |
3085354d IM |
95 | /* |
96 | * If it was a exec (instruction fetch) fault on NX page, then | |
97 | * do not ignore the fault: | |
98 | */ | |
66c58156 | 99 | if (error_code & PF_INSTR) |
1da177e4 | 100 | return 0; |
1dc85be0 | 101 | |
f2857ce9 | 102 | instr = (unsigned char *)convert_ip_to_linear(current, regs); |
f1290ec9 | 103 | max_instr = instr + 15; |
1da177e4 | 104 | |
76381fee | 105 | if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE) |
1da177e4 LT |
106 | return 0; |
107 | ||
33cb5243 | 108 | while (scan_more && instr < max_instr) { |
1da177e4 LT |
109 | unsigned char opcode; |
110 | unsigned char instr_hi; | |
111 | unsigned char instr_lo; | |
112 | ||
ab2bf0c1 | 113 | if (probe_kernel_address(instr, opcode)) |
33cb5243 | 114 | break; |
1da177e4 | 115 | |
33cb5243 HH |
116 | instr_hi = opcode & 0xf0; |
117 | instr_lo = opcode & 0x0f; | |
1da177e4 LT |
118 | instr++; |
119 | ||
33cb5243 | 120 | switch (instr_hi) { |
1da177e4 LT |
121 | case 0x20: |
122 | case 0x30: | |
33cb5243 HH |
123 | /* |
124 | * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes. | |
125 | * In X86_64 long mode, the CPU will signal invalid | |
126 | * opcode if some of these prefixes are present so | |
127 | * X86_64 will never get here anyway | |
128 | */ | |
1da177e4 LT |
129 | scan_more = ((instr_lo & 7) == 0x6); |
130 | break; | |
33cb5243 | 131 | #ifdef CONFIG_X86_64 |
1da177e4 | 132 | case 0x40: |
33cb5243 HH |
133 | /* |
134 | * In AMD64 long mode 0x40..0x4F are valid REX prefixes | |
135 | * Need to figure out under what instruction mode the | |
136 | * instruction was issued. Could check the LDT for lm, | |
137 | * but for now it's good enough to assume that long | |
138 | * mode only uses well known segments or kernel. | |
139 | */ | |
76381fee | 140 | scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS); |
1da177e4 | 141 | break; |
33cb5243 | 142 | #endif |
1da177e4 LT |
143 | case 0x60: |
144 | /* 0x64 thru 0x67 are valid prefixes in all modes. */ | |
145 | scan_more = (instr_lo & 0xC) == 0x4; | |
33cb5243 | 146 | break; |
1da177e4 | 147 | case 0xF0: |
1dc85be0 | 148 | /* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */ |
1da177e4 | 149 | scan_more = !instr_lo || (instr_lo>>1) == 1; |
33cb5243 | 150 | break; |
1da177e4 LT |
151 | case 0x00: |
152 | /* Prefetch instruction is 0x0F0D or 0x0F18 */ | |
153 | scan_more = 0; | |
f2857ce9 | 154 | |
ab2bf0c1 | 155 | if (probe_kernel_address(instr, opcode)) |
1da177e4 LT |
156 | break; |
157 | prefetch = (instr_lo == 0xF) && | |
158 | (opcode == 0x0D || opcode == 0x18); | |
33cb5243 | 159 | break; |
1da177e4 LT |
160 | default: |
161 | scan_more = 0; | |
162 | break; | |
33cb5243 | 163 | } |
1da177e4 LT |
164 | } |
165 | return prefetch; | |
166 | } | |
167 | ||
c4aba4a8 HH |
168 | static void force_sig_info_fault(int si_signo, int si_code, |
169 | unsigned long address, struct task_struct *tsk) | |
170 | { | |
171 | siginfo_t info; | |
172 | ||
173 | info.si_signo = si_signo; | |
174 | info.si_errno = 0; | |
175 | info.si_code = si_code; | |
176 | info.si_addr = (void __user *)address; | |
177 | force_sig_info(si_signo, &info, tsk); | |
178 | } | |
179 | ||
1156e098 | 180 | #ifdef CONFIG_X86_64 |
33cb5243 HH |
181 | static int bad_address(void *p) |
182 | { | |
1da177e4 | 183 | unsigned long dummy; |
ab2bf0c1 | 184 | return probe_kernel_address((unsigned long *)p, dummy); |
33cb5243 | 185 | } |
1156e098 | 186 | #endif |
1da177e4 | 187 | |
cae30f82 | 188 | static void dump_pagetable(unsigned long address) |
1da177e4 | 189 | { |
1156e098 HH |
190 | #ifdef CONFIG_X86_32 |
191 | __typeof__(pte_val(__pte(0))) page; | |
192 | ||
193 | page = read_cr3(); | |
194 | page = ((__typeof__(page) *) __va(page))[address >> PGDIR_SHIFT]; | |
195 | #ifdef CONFIG_X86_PAE | |
196 | printk("*pdpt = %016Lx ", page); | |
197 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
198 | && page & _PAGE_PRESENT) { | |
199 | page &= PAGE_MASK; | |
200 | page = ((__typeof__(page) *) __va(page))[(address >> PMD_SHIFT) | |
201 | & (PTRS_PER_PMD - 1)]; | |
202 | printk(KERN_CONT "*pde = %016Lx ", page); | |
203 | page &= ~_PAGE_NX; | |
204 | } | |
205 | #else | |
206 | printk("*pde = %08lx ", page); | |
207 | #endif | |
208 | ||
209 | /* | |
210 | * We must not directly access the pte in the highpte | |
211 | * case if the page table is located in highmem. | |
212 | * And let's rather not kmap-atomic the pte, just in case | |
213 | * it's allocated already. | |
214 | */ | |
215 | if ((page >> PAGE_SHIFT) < max_low_pfn | |
216 | && (page & _PAGE_PRESENT) | |
217 | && !(page & _PAGE_PSE)) { | |
218 | page &= PAGE_MASK; | |
219 | page = ((__typeof__(page) *) __va(page))[(address >> PAGE_SHIFT) | |
220 | & (PTRS_PER_PTE - 1)]; | |
221 | printk("*pte = %0*Lx ", sizeof(page)*2, (u64)page); | |
222 | } | |
223 | ||
224 | printk("\n"); | |
225 | #else /* CONFIG_X86_64 */ | |
1da177e4 LT |
226 | pgd_t *pgd; |
227 | pud_t *pud; | |
228 | pmd_t *pmd; | |
229 | pte_t *pte; | |
230 | ||
f51c9452 | 231 | pgd = (pgd_t *)read_cr3(); |
1da177e4 | 232 | |
33cb5243 | 233 | pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); |
1da177e4 | 234 | pgd += pgd_index(address); |
1da177e4 | 235 | if (bad_address(pgd)) goto bad; |
d646bce4 | 236 | printk("PGD %lx ", pgd_val(*pgd)); |
33cb5243 | 237 | if (!pgd_present(*pgd)) goto ret; |
1da177e4 | 238 | |
d2ae5b5f | 239 | pud = pud_offset(pgd, address); |
1da177e4 LT |
240 | if (bad_address(pud)) goto bad; |
241 | printk("PUD %lx ", pud_val(*pud)); | |
b5360222 AK |
242 | if (!pud_present(*pud) || pud_large(*pud)) |
243 | goto ret; | |
1da177e4 LT |
244 | |
245 | pmd = pmd_offset(pud, address); | |
246 | if (bad_address(pmd)) goto bad; | |
247 | printk("PMD %lx ", pmd_val(*pmd)); | |
b1992df3 | 248 | if (!pmd_present(*pmd) || pmd_large(*pmd)) goto ret; |
1da177e4 LT |
249 | |
250 | pte = pte_offset_kernel(pmd, address); | |
251 | if (bad_address(pte)) goto bad; | |
33cb5243 | 252 | printk("PTE %lx", pte_val(*pte)); |
1da177e4 LT |
253 | ret: |
254 | printk("\n"); | |
255 | return; | |
256 | bad: | |
257 | printk("BAD\n"); | |
1156e098 HH |
258 | #endif |
259 | } | |
260 | ||
261 | #ifdef CONFIG_X86_32 | |
262 | static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address) | |
263 | { | |
264 | unsigned index = pgd_index(address); | |
265 | pgd_t *pgd_k; | |
266 | pud_t *pud, *pud_k; | |
267 | pmd_t *pmd, *pmd_k; | |
268 | ||
269 | pgd += index; | |
270 | pgd_k = init_mm.pgd + index; | |
271 | ||
272 | if (!pgd_present(*pgd_k)) | |
273 | return NULL; | |
274 | ||
275 | /* | |
276 | * set_pgd(pgd, *pgd_k); here would be useless on PAE | |
277 | * and redundant with the set_pmd() on non-PAE. As would | |
278 | * set_pud. | |
279 | */ | |
280 | ||
281 | pud = pud_offset(pgd, address); | |
282 | pud_k = pud_offset(pgd_k, address); | |
283 | if (!pud_present(*pud_k)) | |
284 | return NULL; | |
285 | ||
286 | pmd = pmd_offset(pud, address); | |
287 | pmd_k = pmd_offset(pud_k, address); | |
288 | if (!pmd_present(*pmd_k)) | |
289 | return NULL; | |
290 | if (!pmd_present(*pmd)) { | |
291 | set_pmd(pmd, *pmd_k); | |
292 | arch_flush_lazy_mmu_mode(); | |
293 | } else | |
294 | BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k)); | |
295 | return pmd_k; | |
1da177e4 | 296 | } |
1156e098 | 297 | #endif |
1da177e4 | 298 | |
1dc85be0 | 299 | #ifdef CONFIG_X86_64 |
33cb5243 | 300 | static const char errata93_warning[] = |
1da177e4 LT |
301 | KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n" |
302 | KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n" | |
303 | KERN_ERR "******* Please consider a BIOS update.\n" | |
304 | KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n"; | |
fdfe8aa8 | 305 | #endif |
1da177e4 LT |
306 | |
307 | /* Workaround for K8 erratum #93 & buggy BIOS. | |
308 | BIOS SMM functions are required to use a specific workaround | |
33cb5243 HH |
309 | to avoid corruption of the 64bit RIP register on C stepping K8. |
310 | A lot of BIOS that didn't get tested properly miss this. | |
1da177e4 LT |
311 | The OS sees this as a page fault with the upper 32bits of RIP cleared. |
312 | Try to work around it here. | |
fdfe8aa8 HH |
313 | Note we only handle faults in kernel here. |
314 | Does nothing for X86_32 | |
315 | */ | |
33cb5243 | 316 | static int is_errata93(struct pt_regs *regs, unsigned long address) |
1da177e4 | 317 | { |
fdfe8aa8 | 318 | #ifdef CONFIG_X86_64 |
1da177e4 | 319 | static int warned; |
65ea5b03 | 320 | if (address != regs->ip) |
1da177e4 | 321 | return 0; |
33cb5243 | 322 | if ((address >> 32) != 0) |
1da177e4 LT |
323 | return 0; |
324 | address |= 0xffffffffUL << 32; | |
33cb5243 HH |
325 | if ((address >= (u64)_stext && address <= (u64)_etext) || |
326 | (address >= MODULES_VADDR && address <= MODULES_END)) { | |
1da177e4 | 327 | if (!warned) { |
33cb5243 | 328 | printk(errata93_warning); |
1da177e4 LT |
329 | warned = 1; |
330 | } | |
65ea5b03 | 331 | regs->ip = address; |
1da177e4 LT |
332 | return 1; |
333 | } | |
fdfe8aa8 | 334 | #endif |
1da177e4 | 335 | return 0; |
33cb5243 | 336 | } |
1da177e4 | 337 | |
35f3266f HH |
338 | /* |
339 | * Work around K8 erratum #100 K8 in compat mode occasionally jumps to illegal | |
340 | * addresses >4GB. We catch this in the page fault handler because these | |
341 | * addresses are not reachable. Just detect this case and return. Any code | |
342 | * segment in LDT is compatibility mode. | |
343 | */ | |
344 | static int is_errata100(struct pt_regs *regs, unsigned long address) | |
345 | { | |
346 | #ifdef CONFIG_X86_64 | |
347 | if ((regs->cs == __USER32_CS || (regs->cs & (1<<2))) && | |
348 | (address >> 32)) | |
349 | return 1; | |
350 | #endif | |
351 | return 0; | |
352 | } | |
353 | ||
29caf2f9 HH |
354 | void do_invalid_op(struct pt_regs *, unsigned long); |
355 | ||
356 | static int is_f00f_bug(struct pt_regs *regs, unsigned long address) | |
357 | { | |
358 | #ifdef CONFIG_X86_F00F_BUG | |
359 | unsigned long nr; | |
360 | /* | |
361 | * Pentium F0 0F C7 C8 bug workaround. | |
362 | */ | |
363 | if (boot_cpu_data.f00f_bug) { | |
364 | nr = (address - idt_descr.address) >> 3; | |
365 | ||
366 | if (nr == 6) { | |
367 | do_invalid_op(regs, 0); | |
368 | return 1; | |
369 | } | |
370 | } | |
371 | #endif | |
372 | return 0; | |
373 | } | |
374 | ||
b3279c7f HH |
375 | static void show_fault_oops(struct pt_regs *regs, unsigned long error_code, |
376 | unsigned long address) | |
377 | { | |
1156e098 HH |
378 | #ifdef CONFIG_X86_32 |
379 | if (!oops_may_print()) | |
380 | return; | |
fd40d6e3 | 381 | #endif |
1156e098 HH |
382 | |
383 | #ifdef CONFIG_X86_PAE | |
384 | if (error_code & PF_INSTR) { | |
93809be8 | 385 | unsigned int level; |
1156e098 HH |
386 | pte_t *pte = lookup_address(address, &level); |
387 | ||
388 | if (pte && pte_present(*pte) && !pte_exec(*pte)) | |
389 | printk(KERN_CRIT "kernel tried to execute " | |
390 | "NX-protected page - exploit attempt? " | |
391 | "(uid: %d)\n", current->uid); | |
392 | } | |
393 | #endif | |
1156e098 | 394 | |
19f0dda9 | 395 | printk(KERN_ALERT "BUG: unable to handle kernel "); |
b3279c7f | 396 | if (address < PAGE_SIZE) |
19f0dda9 | 397 | printk(KERN_CONT "NULL pointer dereference"); |
b3279c7f | 398 | else |
19f0dda9 | 399 | printk(KERN_CONT "paging request"); |
fd40d6e3 HH |
400 | #ifdef CONFIG_X86_32 |
401 | printk(KERN_CONT " at %08lx\n", address); | |
402 | #else | |
19f0dda9 | 403 | printk(KERN_CONT " at %016lx\n", address); |
fd40d6e3 | 404 | #endif |
19f0dda9 | 405 | printk(KERN_ALERT "IP:"); |
b3279c7f HH |
406 | printk_address(regs->ip, 1); |
407 | dump_pagetable(address); | |
408 | } | |
409 | ||
1156e098 | 410 | #ifdef CONFIG_X86_64 |
1da177e4 LT |
411 | static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs, |
412 | unsigned long error_code) | |
413 | { | |
1209140c | 414 | unsigned long flags = oops_begin(); |
6e3f3617 | 415 | struct task_struct *tsk; |
1209140c | 416 | |
1da177e4 LT |
417 | printk(KERN_ALERT "%s: Corrupted page table at address %lx\n", |
418 | current->comm, address); | |
419 | dump_pagetable(address); | |
6e3f3617 JB |
420 | tsk = current; |
421 | tsk->thread.cr2 = address; | |
422 | tsk->thread.trap_no = 14; | |
423 | tsk->thread.error_code = error_code; | |
22f5991c JB |
424 | if (__die("Bad pagetable", regs, error_code)) |
425 | regs = NULL; | |
426 | oops_end(flags, regs, SIGKILL); | |
1da177e4 | 427 | } |
1156e098 | 428 | #endif |
1da177e4 | 429 | |
d8b57bb7 TG |
430 | static int spurious_fault_check(unsigned long error_code, pte_t *pte) |
431 | { | |
432 | if ((error_code & PF_WRITE) && !pte_write(*pte)) | |
433 | return 0; | |
434 | if ((error_code & PF_INSTR) && !pte_exec(*pte)) | |
435 | return 0; | |
436 | ||
437 | return 1; | |
438 | } | |
439 | ||
5b727a3b JF |
440 | /* |
441 | * Handle a spurious fault caused by a stale TLB entry. This allows | |
442 | * us to lazily refresh the TLB when increasing the permissions of a | |
443 | * kernel page (RO -> RW or NX -> X). Doing it eagerly is very | |
444 | * expensive since that implies doing a full cross-processor TLB | |
445 | * flush, even if no stale TLB entries exist on other processors. | |
446 | * There are no security implications to leaving a stale TLB when | |
447 | * increasing the permissions on a page. | |
448 | */ | |
449 | static int spurious_fault(unsigned long address, | |
450 | unsigned long error_code) | |
451 | { | |
452 | pgd_t *pgd; | |
453 | pud_t *pud; | |
454 | pmd_t *pmd; | |
455 | pte_t *pte; | |
456 | ||
457 | /* Reserved-bit violation or user access to kernel space? */ | |
458 | if (error_code & (PF_USER | PF_RSVD)) | |
459 | return 0; | |
460 | ||
461 | pgd = init_mm.pgd + pgd_index(address); | |
462 | if (!pgd_present(*pgd)) | |
463 | return 0; | |
464 | ||
465 | pud = pud_offset(pgd, address); | |
466 | if (!pud_present(*pud)) | |
467 | return 0; | |
468 | ||
d8b57bb7 TG |
469 | if (pud_large(*pud)) |
470 | return spurious_fault_check(error_code, (pte_t *) pud); | |
471 | ||
5b727a3b JF |
472 | pmd = pmd_offset(pud, address); |
473 | if (!pmd_present(*pmd)) | |
474 | return 0; | |
475 | ||
d8b57bb7 TG |
476 | if (pmd_large(*pmd)) |
477 | return spurious_fault_check(error_code, (pte_t *) pmd); | |
478 | ||
5b727a3b JF |
479 | pte = pte_offset_kernel(pmd, address); |
480 | if (!pte_present(*pte)) | |
481 | return 0; | |
482 | ||
d8b57bb7 | 483 | return spurious_fault_check(error_code, pte); |
5b727a3b JF |
484 | } |
485 | ||
1da177e4 | 486 | /* |
f8c2ee22 HH |
487 | * X86_32 |
488 | * Handle a fault on the vmalloc or module mapping area | |
489 | * | |
490 | * X86_64 | |
f95190b2 | 491 | * Handle a fault on the vmalloc area |
3b9ba4d5 AK |
492 | * |
493 | * This assumes no large pages in there. | |
1da177e4 LT |
494 | */ |
495 | static int vmalloc_fault(unsigned long address) | |
496 | { | |
fdfe8aa8 HH |
497 | #ifdef CONFIG_X86_32 |
498 | unsigned long pgd_paddr; | |
499 | pmd_t *pmd_k; | |
500 | pte_t *pte_k; | |
501 | /* | |
502 | * Synchronize this task's top level page-table | |
503 | * with the 'reference' page table. | |
504 | * | |
505 | * Do _not_ use "current" here. We might be inside | |
506 | * an interrupt in the middle of a task switch.. | |
507 | */ | |
508 | pgd_paddr = read_cr3(); | |
509 | pmd_k = vmalloc_sync_one(__va(pgd_paddr), address); | |
510 | if (!pmd_k) | |
511 | return -1; | |
512 | pte_k = pte_offset_kernel(pmd_k, address); | |
513 | if (!pte_present(*pte_k)) | |
514 | return -1; | |
515 | return 0; | |
516 | #else | |
1da177e4 LT |
517 | pgd_t *pgd, *pgd_ref; |
518 | pud_t *pud, *pud_ref; | |
519 | pmd_t *pmd, *pmd_ref; | |
520 | pte_t *pte, *pte_ref; | |
521 | ||
cf89ec92 HH |
522 | /* Make sure we are in vmalloc area */ |
523 | if (!(address >= VMALLOC_START && address < VMALLOC_END)) | |
524 | return -1; | |
525 | ||
1da177e4 LT |
526 | /* Copy kernel mappings over when needed. This can also |
527 | happen within a race in page table update. In the later | |
528 | case just flush. */ | |
529 | ||
530 | pgd = pgd_offset(current->mm ?: &init_mm, address); | |
531 | pgd_ref = pgd_offset_k(address); | |
532 | if (pgd_none(*pgd_ref)) | |
533 | return -1; | |
534 | if (pgd_none(*pgd)) | |
535 | set_pgd(pgd, *pgd_ref); | |
8c914cb7 | 536 | else |
46a82b2d | 537 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); |
1da177e4 LT |
538 | |
539 | /* Below here mismatches are bugs because these lower tables | |
540 | are shared */ | |
541 | ||
542 | pud = pud_offset(pgd, address); | |
543 | pud_ref = pud_offset(pgd_ref, address); | |
544 | if (pud_none(*pud_ref)) | |
545 | return -1; | |
46a82b2d | 546 | if (pud_none(*pud) || pud_page_vaddr(*pud) != pud_page_vaddr(*pud_ref)) |
1da177e4 LT |
547 | BUG(); |
548 | pmd = pmd_offset(pud, address); | |
549 | pmd_ref = pmd_offset(pud_ref, address); | |
550 | if (pmd_none(*pmd_ref)) | |
551 | return -1; | |
552 | if (pmd_none(*pmd) || pmd_page(*pmd) != pmd_page(*pmd_ref)) | |
553 | BUG(); | |
554 | pte_ref = pte_offset_kernel(pmd_ref, address); | |
555 | if (!pte_present(*pte_ref)) | |
556 | return -1; | |
557 | pte = pte_offset_kernel(pmd, address); | |
3b9ba4d5 AK |
558 | /* Don't use pte_page here, because the mappings can point |
559 | outside mem_map, and the NUMA hash lookup cannot handle | |
560 | that. */ | |
561 | if (!pte_present(*pte) || pte_pfn(*pte) != pte_pfn(*pte_ref)) | |
1da177e4 | 562 | BUG(); |
1da177e4 | 563 | return 0; |
fdfe8aa8 | 564 | #endif |
1da177e4 LT |
565 | } |
566 | ||
abd4f750 | 567 | int show_unhandled_signals = 1; |
1da177e4 LT |
568 | |
569 | /* | |
570 | * This routine handles page faults. It determines the address, | |
571 | * and the problem, and then passes it off to one of the appropriate | |
572 | * routines. | |
1da177e4 | 573 | */ |
f8c2ee22 HH |
574 | #ifdef CONFIG_X86_64 |
575 | asmlinkage | |
576 | #endif | |
577 | void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code) | |
1da177e4 LT |
578 | { |
579 | struct task_struct *tsk; | |
580 | struct mm_struct *mm; | |
33cb5243 | 581 | struct vm_area_struct *vma; |
1da177e4 | 582 | unsigned long address; |
f8c2ee22 HH |
583 | int write, si_code; |
584 | int fault; | |
7c9f8861 ES |
585 | unsigned long *stackend; |
586 | ||
f8c2ee22 | 587 | #ifdef CONFIG_X86_64 |
1209140c | 588 | unsigned long flags; |
f8c2ee22 | 589 | #endif |
1da177e4 | 590 | |
143a5d32 PZ |
591 | /* |
592 | * We can fault from pretty much anywhere, with unknown IRQ state. | |
593 | */ | |
594 | trace_hardirqs_fixup(); | |
595 | ||
a9ba9a3b AV |
596 | tsk = current; |
597 | mm = tsk->mm; | |
598 | prefetchw(&mm->mmap_sem); | |
599 | ||
1da177e4 | 600 | /* get the address */ |
f51c9452 | 601 | address = read_cr2(); |
1da177e4 | 602 | |
c4aba4a8 | 603 | si_code = SEGV_MAPERR; |
1da177e4 | 604 | |
608566b4 HH |
605 | if (notify_page_fault(regs)) |
606 | return; | |
1da177e4 LT |
607 | |
608 | /* | |
609 | * We fault-in kernel-space virtual memory on-demand. The | |
610 | * 'reference' page table is init_mm.pgd. | |
611 | * | |
612 | * NOTE! We MUST NOT take any locks for this case. We may | |
613 | * be in an interrupt or a critical region, and should | |
614 | * only copy the information from the master page table, | |
615 | * nothing more. | |
616 | * | |
617 | * This verifies that the fault happens in kernel space | |
618 | * (error_code & 4) == 0, and that the fault was not a | |
8b1bde93 | 619 | * protection error (error_code & 9) == 0. |
1da177e4 | 620 | */ |
f8c2ee22 HH |
621 | #ifdef CONFIG_X86_32 |
622 | if (unlikely(address >= TASK_SIZE)) { | |
cf89ec92 HH |
623 | #else |
624 | if (unlikely(address >= TASK_SIZE64)) { | |
625 | #endif | |
f8c2ee22 HH |
626 | if (!(error_code & (PF_RSVD|PF_USER|PF_PROT)) && |
627 | vmalloc_fault(address) >= 0) | |
628 | return; | |
5b727a3b JF |
629 | |
630 | /* Can handle a stale RO->RW TLB */ | |
631 | if (spurious_fault(address, error_code)) | |
632 | return; | |
633 | ||
f8c2ee22 HH |
634 | /* |
635 | * Don't take the mm semaphore here. If we fixup a prefetch | |
636 | * fault we could otherwise deadlock. | |
637 | */ | |
638 | goto bad_area_nosemaphore; | |
639 | } | |
640 | ||
cf89ec92 HH |
641 | |
642 | #ifdef CONFIG_X86_32 | |
f8c2ee22 HH |
643 | /* It's safe to allow irq's after cr2 has been saved and the vmalloc |
644 | fault has been handled. */ | |
6b6891f9 | 645 | if (regs->flags & (X86_EFLAGS_IF | X86_VM_MASK)) |
f8c2ee22 HH |
646 | local_irq_enable(); |
647 | ||
648 | /* | |
649 | * If we're in an interrupt, have no user context or are running in an | |
650 | * atomic region then we must not take the fault. | |
651 | */ | |
652 | if (in_atomic() || !mm) | |
653 | goto bad_area_nosemaphore; | |
654 | #else /* CONFIG_X86_64 */ | |
65ea5b03 | 655 | if (likely(regs->flags & X86_EFLAGS_IF)) |
8c914cb7 JB |
656 | local_irq_enable(); |
657 | ||
66c58156 | 658 | if (unlikely(error_code & PF_RSVD)) |
1da177e4 LT |
659 | pgtable_bad(address, regs, error_code); |
660 | ||
661 | /* | |
33cb5243 HH |
662 | * If we're in an interrupt, have no user context or are running in an |
663 | * atomic region then we must not take the fault. | |
1da177e4 LT |
664 | */ |
665 | if (unlikely(in_atomic() || !mm)) | |
666 | goto bad_area_nosemaphore; | |
667 | ||
dbe3ed1c LT |
668 | /* |
669 | * User-mode registers count as a user access even for any | |
670 | * potential system fault or CPU buglet. | |
671 | */ | |
672 | if (user_mode_vm(regs)) | |
673 | error_code |= PF_USER; | |
f8c2ee22 HH |
674 | again: |
675 | #endif | |
1da177e4 LT |
676 | /* When running in the kernel we expect faults to occur only to |
677 | * addresses in user space. All other faults represent errors in the | |
676b1855 | 678 | * kernel and should generate an OOPS. Unfortunately, in the case of an |
80f7228b | 679 | * erroneous fault occurring in a code path which already holds mmap_sem |
1da177e4 LT |
680 | * we will deadlock attempting to validate the fault against the |
681 | * address space. Luckily the kernel only validly references user | |
682 | * space from well defined areas of code, which are listed in the | |
683 | * exceptions table. | |
684 | * | |
685 | * As the vast majority of faults will be valid we will only perform | |
676b1855 | 686 | * the source reference check when there is a possibility of a deadlock. |
1da177e4 LT |
687 | * Attempt to lock the address space, if we cannot we then validate the |
688 | * source. If this is invalid we can skip the address space check, | |
689 | * thus avoiding the deadlock. | |
690 | */ | |
691 | if (!down_read_trylock(&mm->mmap_sem)) { | |
66c58156 | 692 | if ((error_code & PF_USER) == 0 && |
65ea5b03 | 693 | !search_exception_tables(regs->ip)) |
1da177e4 LT |
694 | goto bad_area_nosemaphore; |
695 | down_read(&mm->mmap_sem); | |
696 | } | |
697 | ||
698 | vma = find_vma(mm, address); | |
699 | if (!vma) | |
700 | goto bad_area; | |
f8c2ee22 | 701 | if (vma->vm_start <= address) |
1da177e4 LT |
702 | goto good_area; |
703 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
704 | goto bad_area; | |
33cb5243 | 705 | if (error_code & PF_USER) { |
6f4d368e HH |
706 | /* |
707 | * Accessing the stack below %sp is always a bug. | |
708 | * The large cushion allows instructions like enter | |
709 | * and pusha to work. ("enter $65535,$31" pushes | |
710 | * 32 pointers and then decrements %sp by 65535.) | |
03fdc2c2 | 711 | */ |
65ea5b03 | 712 | if (address + 65536 + 32 * sizeof(unsigned long) < regs->sp) |
1da177e4 LT |
713 | goto bad_area; |
714 | } | |
715 | if (expand_stack(vma, address)) | |
716 | goto bad_area; | |
717 | /* | |
718 | * Ok, we have a good vm_area for this memory access, so | |
719 | * we can handle it.. | |
720 | */ | |
721 | good_area: | |
c4aba4a8 | 722 | si_code = SEGV_ACCERR; |
1da177e4 | 723 | write = 0; |
66c58156 | 724 | switch (error_code & (PF_PROT|PF_WRITE)) { |
33cb5243 HH |
725 | default: /* 3: write, present */ |
726 | /* fall through */ | |
727 | case PF_WRITE: /* write, not present */ | |
728 | if (!(vma->vm_flags & VM_WRITE)) | |
729 | goto bad_area; | |
730 | write++; | |
731 | break; | |
732 | case PF_PROT: /* read, present */ | |
733 | goto bad_area; | |
734 | case 0: /* read, not present */ | |
735 | if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) | |
1da177e4 | 736 | goto bad_area; |
1da177e4 LT |
737 | } |
738 | ||
f8c2ee22 HH |
739 | #ifdef CONFIG_X86_32 |
740 | survive: | |
741 | #endif | |
1da177e4 LT |
742 | /* |
743 | * If for any reason at all we couldn't handle the fault, | |
744 | * make sure we exit gracefully rather than endlessly redo | |
745 | * the fault. | |
746 | */ | |
83c54070 NP |
747 | fault = handle_mm_fault(mm, vma, address, write); |
748 | if (unlikely(fault & VM_FAULT_ERROR)) { | |
749 | if (fault & VM_FAULT_OOM) | |
750 | goto out_of_memory; | |
751 | else if (fault & VM_FAULT_SIGBUS) | |
752 | goto do_sigbus; | |
753 | BUG(); | |
1da177e4 | 754 | } |
83c54070 NP |
755 | if (fault & VM_FAULT_MAJOR) |
756 | tsk->maj_flt++; | |
757 | else | |
758 | tsk->min_flt++; | |
d729ab35 HH |
759 | |
760 | #ifdef CONFIG_X86_32 | |
761 | /* | |
762 | * Did it hit the DOS screen memory VA from vm86 mode? | |
763 | */ | |
764 | if (v8086_mode(regs)) { | |
765 | unsigned long bit = (address - 0xA0000) >> PAGE_SHIFT; | |
766 | if (bit < 32) | |
767 | tsk->thread.screen_bitmap |= 1 << bit; | |
768 | } | |
769 | #endif | |
1da177e4 LT |
770 | up_read(&mm->mmap_sem); |
771 | return; | |
772 | ||
773 | /* | |
774 | * Something tried to access memory that isn't in our memory map.. | |
775 | * Fix it, but check if it's kernel or user first.. | |
776 | */ | |
777 | bad_area: | |
778 | up_read(&mm->mmap_sem); | |
779 | ||
780 | bad_area_nosemaphore: | |
1da177e4 | 781 | /* User mode accesses just cause a SIGSEGV */ |
66c58156 | 782 | if (error_code & PF_USER) { |
e5e3c84b SR |
783 | /* |
784 | * It's possible to have interrupts off here. | |
785 | */ | |
786 | local_irq_enable(); | |
787 | ||
1156e098 HH |
788 | /* |
789 | * Valid to do another page fault here because this one came | |
790 | * from user space. | |
791 | */ | |
1da177e4 LT |
792 | if (is_prefetch(regs, address, error_code)) |
793 | return; | |
794 | ||
35f3266f | 795 | if (is_errata100(regs, address)) |
1da177e4 LT |
796 | return; |
797 | ||
abd4f750 MAS |
798 | if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && |
799 | printk_ratelimit()) { | |
1da177e4 | 800 | printk( |
6f4d368e | 801 | #ifdef CONFIG_X86_32 |
edcd8119 | 802 | "%s%s[%d]: segfault at %lx ip %08lx sp %08lx error %lx", |
6f4d368e | 803 | #else |
03252919 | 804 | "%s%s[%d]: segfault at %lx ip %lx sp %lx error %lx", |
6f4d368e HH |
805 | #endif |
806 | task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, | |
807 | tsk->comm, task_pid_nr(tsk), address, regs->ip, | |
808 | regs->sp, error_code); | |
03252919 AK |
809 | print_vma_addr(" in ", regs->ip); |
810 | printk("\n"); | |
1da177e4 | 811 | } |
33cb5243 | 812 | |
1da177e4 LT |
813 | tsk->thread.cr2 = address; |
814 | /* Kernel addresses are always protection faults */ | |
815 | tsk->thread.error_code = error_code | (address >= TASK_SIZE); | |
816 | tsk->thread.trap_no = 14; | |
c4aba4a8 | 817 | force_sig_info_fault(SIGSEGV, si_code, address, tsk); |
1da177e4 LT |
818 | return; |
819 | } | |
820 | ||
29caf2f9 HH |
821 | if (is_f00f_bug(regs, address)) |
822 | return; | |
823 | ||
1da177e4 | 824 | no_context: |
1da177e4 | 825 | /* Are we prepared to handle this kernel fault? */ |
33cb5243 | 826 | if (fixup_exception(regs)) |
1da177e4 | 827 | return; |
1da177e4 | 828 | |
33cb5243 | 829 | /* |
f8c2ee22 HH |
830 | * X86_32 |
831 | * Valid to do another page fault here, because if this fault | |
832 | * had been triggered by is_prefetch fixup_exception would have | |
833 | * handled it. | |
834 | * | |
835 | * X86_64 | |
1da177e4 LT |
836 | * Hall of shame of CPU/BIOS bugs. |
837 | */ | |
33cb5243 HH |
838 | if (is_prefetch(regs, address, error_code)) |
839 | return; | |
1da177e4 LT |
840 | |
841 | if (is_errata93(regs, address)) | |
33cb5243 | 842 | return; |
1da177e4 LT |
843 | |
844 | /* | |
845 | * Oops. The kernel tried to access some bad page. We'll have to | |
846 | * terminate things with extreme prejudice. | |
847 | */ | |
f8c2ee22 HH |
848 | #ifdef CONFIG_X86_32 |
849 | bust_spinlocks(1); | |
fd40d6e3 HH |
850 | #else |
851 | flags = oops_begin(); | |
852 | #endif | |
f8c2ee22 HH |
853 | |
854 | show_fault_oops(regs, error_code, address); | |
1da177e4 | 855 | |
7c9f8861 ES |
856 | stackend = end_of_stack(tsk); |
857 | if (*stackend != STACK_END_MAGIC) | |
858 | printk(KERN_ALERT "Thread overran stack, or stack corrupted\n"); | |
859 | ||
f8c2ee22 HH |
860 | tsk->thread.cr2 = address; |
861 | tsk->thread.trap_no = 14; | |
862 | tsk->thread.error_code = error_code; | |
fd40d6e3 HH |
863 | |
864 | #ifdef CONFIG_X86_32 | |
f8c2ee22 HH |
865 | die("Oops", regs, error_code); |
866 | bust_spinlocks(0); | |
867 | do_exit(SIGKILL); | |
fd40d6e3 | 868 | #else |
22f5991c JB |
869 | if (__die("Oops", regs, error_code)) |
870 | regs = NULL; | |
1da177e4 LT |
871 | /* Executive summary in case the body of the oops scrolled away */ |
872 | printk(KERN_EMERG "CR2: %016lx\n", address); | |
22f5991c | 873 | oops_end(flags, regs, SIGKILL); |
f8c2ee22 | 874 | #endif |
1da177e4 LT |
875 | |
876 | /* | |
877 | * We ran out of memory, or some other thing happened to us that made | |
878 | * us unable to handle the page fault gracefully. | |
879 | */ | |
880 | out_of_memory: | |
881 | up_read(&mm->mmap_sem); | |
f8c2ee22 HH |
882 | if (is_global_init(tsk)) { |
883 | yield(); | |
fd40d6e3 | 884 | #ifdef CONFIG_X86_32 |
f8c2ee22 HH |
885 | down_read(&mm->mmap_sem); |
886 | goto survive; | |
f8c2ee22 | 887 | #else |
1da177e4 | 888 | goto again; |
f8c2ee22 | 889 | #endif |
fd40d6e3 HH |
890 | } |
891 | ||
1da177e4 | 892 | printk("VM: killing process %s\n", tsk->comm); |
318aa296 | 893 | if (error_code & PF_USER) |
021daae2 | 894 | do_group_exit(SIGKILL); |
1da177e4 LT |
895 | goto no_context; |
896 | ||
897 | do_sigbus: | |
898 | up_read(&mm->mmap_sem); | |
899 | ||
900 | /* Kernel mode? Handle exceptions or die */ | |
66c58156 | 901 | if (!(error_code & PF_USER)) |
1da177e4 | 902 | goto no_context; |
f8c2ee22 HH |
903 | #ifdef CONFIG_X86_32 |
904 | /* User space => ok to do another page fault */ | |
905 | if (is_prefetch(regs, address, error_code)) | |
906 | return; | |
907 | #endif | |
1da177e4 LT |
908 | tsk->thread.cr2 = address; |
909 | tsk->thread.error_code = error_code; | |
910 | tsk->thread.trap_no = 14; | |
c4aba4a8 | 911 | force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk); |
1da177e4 | 912 | } |
9e43e1b7 | 913 | |
8c914cb7 | 914 | DEFINE_SPINLOCK(pgd_lock); |
2bff7383 | 915 | LIST_HEAD(pgd_list); |
8c914cb7 JB |
916 | |
917 | void vmalloc_sync_all(void) | |
918 | { | |
1156e098 HH |
919 | #ifdef CONFIG_X86_32 |
920 | /* | |
921 | * Note that races in the updates of insync and start aren't | |
922 | * problematic: insync can only get set bits added, and updates to | |
923 | * start are only improving performance (without affecting correctness | |
924 | * if undone). | |
925 | */ | |
926 | static DECLARE_BITMAP(insync, PTRS_PER_PGD); | |
927 | static unsigned long start = TASK_SIZE; | |
928 | unsigned long address; | |
929 | ||
930 | if (SHARED_KERNEL_PMD) | |
931 | return; | |
932 | ||
933 | BUILD_BUG_ON(TASK_SIZE & ~PGDIR_MASK); | |
934 | for (address = start; address >= TASK_SIZE; address += PGDIR_SIZE) { | |
935 | if (!test_bit(pgd_index(address), insync)) { | |
936 | unsigned long flags; | |
937 | struct page *page; | |
938 | ||
939 | spin_lock_irqsave(&pgd_lock, flags); | |
e3ed910d | 940 | list_for_each_entry(page, &pgd_list, lru) { |
1156e098 | 941 | if (!vmalloc_sync_one(page_address(page), |
e3ed910d | 942 | address)) |
1156e098 | 943 | break; |
e3ed910d | 944 | } |
1156e098 HH |
945 | spin_unlock_irqrestore(&pgd_lock, flags); |
946 | if (!page) | |
947 | set_bit(pgd_index(address), insync); | |
948 | } | |
949 | if (address == start && test_bit(pgd_index(address), insync)) | |
950 | start = address + PGDIR_SIZE; | |
951 | } | |
952 | #else /* CONFIG_X86_64 */ | |
6f4d368e HH |
953 | /* |
954 | * Note that races in the updates of insync and start aren't | |
955 | * problematic: insync can only get set bits added, and updates to | |
956 | * start are only improving performance (without affecting correctness | |
957 | * if undone). | |
958 | */ | |
8c914cb7 JB |
959 | static DECLARE_BITMAP(insync, PTRS_PER_PGD); |
960 | static unsigned long start = VMALLOC_START & PGDIR_MASK; | |
961 | unsigned long address; | |
962 | ||
963 | for (address = start; address <= VMALLOC_END; address += PGDIR_SIZE) { | |
964 | if (!test_bit(pgd_index(address), insync)) { | |
965 | const pgd_t *pgd_ref = pgd_offset_k(address); | |
58d5d0d8 | 966 | unsigned long flags; |
8c914cb7 JB |
967 | struct page *page; |
968 | ||
969 | if (pgd_none(*pgd_ref)) | |
970 | continue; | |
58d5d0d8 | 971 | spin_lock_irqsave(&pgd_lock, flags); |
2bff7383 | 972 | list_for_each_entry(page, &pgd_list, lru) { |
8c914cb7 JB |
973 | pgd_t *pgd; |
974 | pgd = (pgd_t *)page_address(page) + pgd_index(address); | |
975 | if (pgd_none(*pgd)) | |
976 | set_pgd(pgd, *pgd_ref); | |
977 | else | |
46a82b2d | 978 | BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); |
8c914cb7 | 979 | } |
58d5d0d8 | 980 | spin_unlock_irqrestore(&pgd_lock, flags); |
8c914cb7 JB |
981 | set_bit(pgd_index(address), insync); |
982 | } | |
983 | if (address == start) | |
984 | start = address + PGDIR_SIZE; | |
985 | } | |
1156e098 | 986 | #endif |
8c914cb7 | 987 | } |