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Commit | Line | Data |
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1da177e4 | 1 | /* |
028c1f68 | 2 | * arch/cris/mm/fault.c |
1da177e4 | 3 | * |
028c1f68 | 4 | * Copyright (C) 2000-2010 Axis Communications AB |
1da177e4 LT |
5 | */ |
6 | ||
7 | #include <linux/mm.h> | |
8 | #include <linux/interrupt.h> | |
9 | #include <linux/module.h> | |
b4e8a181 | 10 | #include <linux/wait.h> |
1da177e4 LT |
11 | #include <asm/uaccess.h> |
12 | ||
13 | extern int find_fixup_code(struct pt_regs *); | |
14 | extern void die_if_kernel(const char *, struct pt_regs *, long); | |
2d495ebc | 15 | extern void show_registers(struct pt_regs *regs); |
1da177e4 LT |
16 | |
17 | /* debug of low-level TLB reload */ | |
18 | #undef DEBUG | |
19 | ||
20 | #ifdef DEBUG | |
21 | #define D(x) x | |
22 | #else | |
23 | #define D(x) | |
24 | #endif | |
25 | ||
26 | /* debug of higher-level faults */ | |
27 | #define DPG(x) | |
28 | ||
29 | /* current active page directory */ | |
30 | ||
fe87f94f | 31 | DEFINE_PER_CPU(pgd_t *, current_pgd); |
4f18cfbf | 32 | unsigned long cris_signal_return_page; |
1da177e4 LT |
33 | |
34 | /* | |
35 | * This routine handles page faults. It determines the address, | |
36 | * and the problem, and then passes it off to one of the appropriate | |
37 | * routines. | |
38 | * | |
39 | * Notice that the address we're given is aligned to the page the fault | |
40 | * occurred in, since we only get the PFN in R_MMU_CAUSE not the complete | |
41 | * address. | |
42 | * | |
43 | * error_code: | |
3e1fdc4e JN |
44 | * bit 0 == 0 means no page found, 1 means protection fault |
45 | * bit 1 == 0 means read, 1 means write | |
1da177e4 LT |
46 | * |
47 | * If this routine detects a bad access, it returns 1, otherwise it | |
48 | * returns 0. | |
49 | */ | |
50 | ||
51 | asmlinkage void | |
52 | do_page_fault(unsigned long address, struct pt_regs *regs, | |
53 | int protection, int writeaccess) | |
54 | { | |
55 | struct task_struct *tsk; | |
56 | struct mm_struct *mm; | |
57 | struct vm_area_struct * vma; | |
58 | siginfo_t info; | |
83c54070 | 59 | int fault; |
1da177e4 | 60 | |
3e1fdc4e JN |
61 | D(printk(KERN_DEBUG |
62 | "Page fault for %lX on %X at %lX, prot %d write %d\n", | |
63 | address, smp_processor_id(), instruction_pointer(regs), | |
64 | protection, writeaccess)); | |
1da177e4 LT |
65 | |
66 | tsk = current; | |
67 | ||
68 | /* | |
69 | * We fault-in kernel-space virtual memory on-demand. The | |
70 | * 'reference' page table is init_mm.pgd. | |
71 | * | |
72 | * NOTE! We MUST NOT take any locks for this case. We may | |
73 | * be in an interrupt or a critical region, and should | |
74 | * only copy the information from the master page table, | |
75 | * nothing more. | |
76 | * | |
77 | * NOTE2: This is done so that, when updating the vmalloc | |
78 | * mappings we don't have to walk all processes pgdirs and | |
79 | * add the high mappings all at once. Instead we do it as they | |
80 | * are used. However vmalloc'ed page entries have the PAGE_GLOBAL | |
81 | * bit set so sometimes the TLB can use a lingering entry. | |
82 | * | |
83 | * This verifies that the fault happens in kernel space | |
84 | * and that the fault was not a protection error (error_code & 1). | |
85 | */ | |
86 | ||
87 | if (address >= VMALLOC_START && | |
88 | !protection && | |
89 | !user_mode(regs)) | |
90 | goto vmalloc_fault; | |
91 | ||
4f18cfbf MS |
92 | /* When stack execution is not allowed we store the signal |
93 | * trampolines in the reserved cris_signal_return_page. | |
94 | * Handle this in the exact same way as vmalloc (we know | |
95 | * that the mapping is there and is valid so no need to | |
96 | * call handle_mm_fault). | |
97 | */ | |
98 | if (cris_signal_return_page && | |
99 | address == cris_signal_return_page && | |
100 | !protection && user_mode(regs)) | |
101 | goto vmalloc_fault; | |
102 | ||
1da177e4 | 103 | /* we can and should enable interrupts at this point */ |
4f18cfbf | 104 | local_irq_enable(); |
1da177e4 LT |
105 | |
106 | mm = tsk->mm; | |
107 | info.si_code = SEGV_MAPERR; | |
108 | ||
109 | /* | |
028c1f68 JN |
110 | * If we're in an interrupt or "atomic" operation or have no |
111 | * user context, we must not take the fault. | |
1da177e4 LT |
112 | */ |
113 | ||
028c1f68 | 114 | if (in_atomic() || !mm) |
1da177e4 LT |
115 | goto no_context; |
116 | ||
117 | down_read(&mm->mmap_sem); | |
118 | vma = find_vma(mm, address); | |
119 | if (!vma) | |
120 | goto bad_area; | |
121 | if (vma->vm_start <= address) | |
122 | goto good_area; | |
123 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
124 | goto bad_area; | |
125 | if (user_mode(regs)) { | |
126 | /* | |
127 | * accessing the stack below usp is always a bug. | |
128 | * we get page-aligned addresses so we can only check | |
129 | * if we're within a page from usp, but that might be | |
130 | * enough to catch brutal errors at least. | |
131 | */ | |
132 | if (address + PAGE_SIZE < rdusp()) | |
133 | goto bad_area; | |
134 | } | |
135 | if (expand_stack(vma, address)) | |
136 | goto bad_area; | |
137 | ||
138 | /* | |
139 | * Ok, we have a good vm_area for this memory access, so | |
140 | * we can handle it.. | |
141 | */ | |
142 | ||
143 | good_area: | |
144 | info.si_code = SEGV_ACCERR; | |
145 | ||
146 | /* first do some preliminary protection checks */ | |
147 | ||
4f18cfbf MS |
148 | if (writeaccess == 2){ |
149 | if (!(vma->vm_flags & VM_EXEC)) | |
150 | goto bad_area; | |
151 | } else if (writeaccess == 1) { | |
1da177e4 LT |
152 | if (!(vma->vm_flags & VM_WRITE)) |
153 | goto bad_area; | |
154 | } else { | |
155 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
156 | goto bad_area; | |
157 | } | |
158 | ||
159 | /* | |
160 | * If for any reason at all we couldn't handle the fault, | |
161 | * make sure we exit gracefully rather than endlessly redo | |
162 | * the fault. | |
163 | */ | |
164 | ||
d06063cc | 165 | fault = handle_mm_fault(mm, vma, address, (writeaccess & 1) ? FAULT_FLAG_WRITE : 0); |
83c54070 NP |
166 | if (unlikely(fault & VM_FAULT_ERROR)) { |
167 | if (fault & VM_FAULT_OOM) | |
168 | goto out_of_memory; | |
169 | else if (fault & VM_FAULT_SIGBUS) | |
170 | goto do_sigbus; | |
171 | BUG(); | |
1da177e4 | 172 | } |
83c54070 NP |
173 | if (fault & VM_FAULT_MAJOR) |
174 | tsk->maj_flt++; | |
175 | else | |
176 | tsk->min_flt++; | |
1da177e4 LT |
177 | |
178 | up_read(&mm->mmap_sem); | |
179 | return; | |
180 | ||
181 | /* | |
182 | * Something tried to access memory that isn't in our memory map.. | |
183 | * Fix it, but check if it's kernel or user first.. | |
184 | */ | |
185 | ||
186 | bad_area: | |
187 | up_read(&mm->mmap_sem); | |
188 | ||
189 | bad_area_nosemaphore: | |
190 | DPG(show_registers(regs)); | |
191 | ||
192 | /* User mode accesses just cause a SIGSEGV */ | |
193 | ||
194 | if (user_mode(regs)) { | |
b4e8a181 JN |
195 | printk(KERN_NOTICE "%s (pid %d) segfaults for page " |
196 | "address %08lx at pc %08lx\n", | |
197 | tsk->comm, tsk->pid, | |
198 | address, instruction_pointer(regs)); | |
2d495ebc JN |
199 | |
200 | /* With DPG on, we've already dumped registers above. */ | |
201 | DPG(if (0)) | |
202 | show_registers(regs); | |
203 | ||
b4e8a181 JN |
204 | #ifdef CONFIG_NO_SEGFAULT_TERMINATION |
205 | DECLARE_WAIT_QUEUE_HEAD(wq); | |
206 | wait_event_interruptible(wq, 0 == 1); | |
207 | #else | |
1da177e4 LT |
208 | info.si_signo = SIGSEGV; |
209 | info.si_errno = 0; | |
210 | /* info.si_code has been set above */ | |
211 | info.si_addr = (void *)address; | |
212 | force_sig_info(SIGSEGV, &info, tsk); | |
b4e8a181 | 213 | #endif |
1da177e4 LT |
214 | return; |
215 | } | |
216 | ||
217 | no_context: | |
218 | ||
219 | /* Are we prepared to handle this kernel fault? | |
220 | * | |
3e1fdc4e | 221 | * (The kernel has valid exception-points in the source |
af901ca1 | 222 | * when it accesses user-memory. When it fails in one |
1da177e4 LT |
223 | * of those points, we find it in a table and do a jump |
224 | * to some fixup code that loads an appropriate error | |
225 | * code) | |
226 | */ | |
227 | ||
228 | if (find_fixup_code(regs)) | |
229 | return; | |
230 | ||
231 | /* | |
232 | * Oops. The kernel tried to access some bad page. We'll have to | |
233 | * terminate things with extreme prejudice. | |
234 | */ | |
235 | ||
3e1fdc4e JN |
236 | if (!oops_in_progress) { |
237 | oops_in_progress = 1; | |
238 | if ((unsigned long) (address) < PAGE_SIZE) | |
239 | printk(KERN_ALERT "Unable to handle kernel NULL " | |
240 | "pointer dereference"); | |
241 | else | |
242 | printk(KERN_ALERT "Unable to handle kernel access" | |
243 | " at virtual address %08lx\n", address); | |
244 | ||
245 | die_if_kernel("Oops", regs, (writeaccess << 1) | protection); | |
246 | oops_in_progress = 0; | |
247 | } | |
1da177e4 LT |
248 | |
249 | do_exit(SIGKILL); | |
250 | ||
251 | /* | |
252 | * We ran out of memory, or some other thing happened to us that made | |
253 | * us unable to handle the page fault gracefully. | |
254 | */ | |
255 | ||
256 | out_of_memory: | |
257 | up_read(&mm->mmap_sem); | |
3648bdf7 JN |
258 | if (!user_mode(regs)) |
259 | goto no_context; | |
260 | pagefault_out_of_memory(); | |
261 | return; | |
1da177e4 LT |
262 | |
263 | do_sigbus: | |
264 | up_read(&mm->mmap_sem); | |
265 | ||
266 | /* | |
267 | * Send a sigbus, regardless of whether we were in kernel | |
268 | * or user mode. | |
269 | */ | |
270 | info.si_signo = SIGBUS; | |
271 | info.si_errno = 0; | |
272 | info.si_code = BUS_ADRERR; | |
273 | info.si_addr = (void *)address; | |
274 | force_sig_info(SIGBUS, &info, tsk); | |
275 | ||
276 | /* Kernel mode? Handle exceptions or die */ | |
277 | if (!user_mode(regs)) | |
278 | goto no_context; | |
279 | return; | |
280 | ||
281 | vmalloc_fault: | |
282 | { | |
283 | /* | |
284 | * Synchronize this task's top level page-table | |
285 | * with the 'reference' page table. | |
286 | * | |
287 | * Use current_pgd instead of tsk->active_mm->pgd | |
288 | * since the latter might be unavailable if this | |
289 | * code is executed in a misfortunately run irq | |
290 | * (like inside schedule() between switch_mm and | |
291 | * switch_to...). | |
292 | */ | |
293 | ||
294 | int offset = pgd_index(address); | |
295 | pgd_t *pgd, *pgd_k; | |
4f18cfbf | 296 | pud_t *pud, *pud_k; |
1da177e4 LT |
297 | pmd_t *pmd, *pmd_k; |
298 | pte_t *pte_k; | |
299 | ||
4f18cfbf | 300 | pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset; |
1da177e4 LT |
301 | pgd_k = init_mm.pgd + offset; |
302 | ||
303 | /* Since we're two-level, we don't need to do both | |
304 | * set_pgd and set_pmd (they do the same thing). If | |
305 | * we go three-level at some point, do the right thing | |
3e1fdc4e JN |
306 | * with pgd_present and set_pgd here. |
307 | * | |
1da177e4 LT |
308 | * Also, since the vmalloc area is global, we don't |
309 | * need to copy individual PTE's, it is enough to | |
310 | * copy the pgd pointer into the pte page of the | |
311 | * root task. If that is there, we'll find our pte if | |
312 | * it exists. | |
313 | */ | |
314 | ||
4f18cfbf MS |
315 | pud = pud_offset(pgd, address); |
316 | pud_k = pud_offset(pgd_k, address); | |
317 | if (!pud_present(*pud_k)) | |
318 | goto no_context; | |
319 | ||
320 | pmd = pmd_offset(pud, address); | |
321 | pmd_k = pmd_offset(pud_k, address); | |
1da177e4 LT |
322 | |
323 | if (!pmd_present(*pmd_k)) | |
324 | goto bad_area_nosemaphore; | |
325 | ||
326 | set_pmd(pmd, *pmd_k); | |
327 | ||
328 | /* Make sure the actual PTE exists as well to | |
329 | * catch kernel vmalloc-area accesses to non-mapped | |
330 | * addresses. If we don't do this, this will just | |
331 | * silently loop forever. | |
332 | */ | |
333 | ||
334 | pte_k = pte_offset_kernel(pmd_k, address); | |
335 | if (!pte_present(*pte_k)) | |
336 | goto no_context; | |
337 | ||
338 | return; | |
339 | } | |
340 | } | |
4f18cfbf MS |
341 | |
342 | /* Find fixup code. */ | |
343 | int | |
344 | find_fixup_code(struct pt_regs *regs) | |
345 | { | |
346 | const struct exception_table_entry *fixup; | |
a90993c6 JN |
347 | /* in case of delay slot fault (v32) */ |
348 | unsigned long ip = (instruction_pointer(regs) & ~0x1); | |
4f18cfbf | 349 | |
a90993c6 JN |
350 | fixup = search_exception_tables(ip); |
351 | if (fixup != 0) { | |
4f18cfbf MS |
352 | /* Adjust the instruction pointer in the stackframe. */ |
353 | instruction_pointer(regs) = fixup->fixup; | |
354 | arch_fixup(regs); | |
355 | return 1; | |
356 | } | |
357 | ||
358 | return 0; | |
359 | } |