Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/arch/cris/mm/fault.c | |
3 | * | |
3e1fdc4e | 4 | * Copyright (C) 2000-2006 Axis Communications AB |
1da177e4 | 5 | * |
3e1fdc4e | 6 | * Authors: Bjorn Wesen |
1da177e4 LT |
7 | * |
8 | */ | |
9 | ||
10 | #include <linux/mm.h> | |
11 | #include <linux/interrupt.h> | |
12 | #include <linux/module.h> | |
13 | #include <asm/uaccess.h> | |
14 | ||
15 | extern int find_fixup_code(struct pt_regs *); | |
16 | extern void die_if_kernel(const char *, struct pt_regs *, long); | |
17 | ||
18 | /* debug of low-level TLB reload */ | |
19 | #undef DEBUG | |
20 | ||
21 | #ifdef DEBUG | |
22 | #define D(x) x | |
23 | #else | |
24 | #define D(x) | |
25 | #endif | |
26 | ||
27 | /* debug of higher-level faults */ | |
28 | #define DPG(x) | |
29 | ||
30 | /* current active page directory */ | |
31 | ||
fe87f94f | 32 | DEFINE_PER_CPU(pgd_t *, current_pgd); |
4f18cfbf | 33 | unsigned long cris_signal_return_page; |
1da177e4 LT |
34 | |
35 | /* | |
36 | * This routine handles page faults. It determines the address, | |
37 | * and the problem, and then passes it off to one of the appropriate | |
38 | * routines. | |
39 | * | |
40 | * Notice that the address we're given is aligned to the page the fault | |
41 | * occurred in, since we only get the PFN in R_MMU_CAUSE not the complete | |
42 | * address. | |
43 | * | |
44 | * error_code: | |
3e1fdc4e JN |
45 | * bit 0 == 0 means no page found, 1 means protection fault |
46 | * bit 1 == 0 means read, 1 means write | |
1da177e4 LT |
47 | * |
48 | * If this routine detects a bad access, it returns 1, otherwise it | |
49 | * returns 0. | |
50 | */ | |
51 | ||
52 | asmlinkage void | |
53 | do_page_fault(unsigned long address, struct pt_regs *regs, | |
54 | int protection, int writeaccess) | |
55 | { | |
56 | struct task_struct *tsk; | |
57 | struct mm_struct *mm; | |
58 | struct vm_area_struct * vma; | |
59 | siginfo_t info; | |
83c54070 | 60 | int fault; |
1da177e4 | 61 | |
3e1fdc4e JN |
62 | D(printk(KERN_DEBUG |
63 | "Page fault for %lX on %X at %lX, prot %d write %d\n", | |
64 | address, smp_processor_id(), instruction_pointer(regs), | |
65 | protection, writeaccess)); | |
1da177e4 LT |
66 | |
67 | tsk = current; | |
68 | ||
69 | /* | |
70 | * We fault-in kernel-space virtual memory on-demand. The | |
71 | * 'reference' page table is init_mm.pgd. | |
72 | * | |
73 | * NOTE! We MUST NOT take any locks for this case. We may | |
74 | * be in an interrupt or a critical region, and should | |
75 | * only copy the information from the master page table, | |
76 | * nothing more. | |
77 | * | |
78 | * NOTE2: This is done so that, when updating the vmalloc | |
79 | * mappings we don't have to walk all processes pgdirs and | |
80 | * add the high mappings all at once. Instead we do it as they | |
81 | * are used. However vmalloc'ed page entries have the PAGE_GLOBAL | |
82 | * bit set so sometimes the TLB can use a lingering entry. | |
83 | * | |
84 | * This verifies that the fault happens in kernel space | |
85 | * and that the fault was not a protection error (error_code & 1). | |
86 | */ | |
87 | ||
88 | if (address >= VMALLOC_START && | |
89 | !protection && | |
90 | !user_mode(regs)) | |
91 | goto vmalloc_fault; | |
92 | ||
4f18cfbf MS |
93 | /* When stack execution is not allowed we store the signal |
94 | * trampolines in the reserved cris_signal_return_page. | |
95 | * Handle this in the exact same way as vmalloc (we know | |
96 | * that the mapping is there and is valid so no need to | |
97 | * call handle_mm_fault). | |
98 | */ | |
99 | if (cris_signal_return_page && | |
100 | address == cris_signal_return_page && | |
101 | !protection && user_mode(regs)) | |
102 | goto vmalloc_fault; | |
103 | ||
1da177e4 | 104 | /* we can and should enable interrupts at this point */ |
4f18cfbf | 105 | local_irq_enable(); |
1da177e4 LT |
106 | |
107 | mm = tsk->mm; | |
108 | info.si_code = SEGV_MAPERR; | |
109 | ||
110 | /* | |
111 | * If we're in an interrupt or have no user | |
112 | * context, we must not take the fault.. | |
113 | */ | |
114 | ||
3e1fdc4e | 115 | if (in_interrupt() || !mm) |
1da177e4 LT |
116 | goto no_context; |
117 | ||
118 | down_read(&mm->mmap_sem); | |
119 | vma = find_vma(mm, address); | |
120 | if (!vma) | |
121 | goto bad_area; | |
122 | if (vma->vm_start <= address) | |
123 | goto good_area; | |
124 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
125 | goto bad_area; | |
126 | if (user_mode(regs)) { | |
127 | /* | |
128 | * accessing the stack below usp is always a bug. | |
129 | * we get page-aligned addresses so we can only check | |
130 | * if we're within a page from usp, but that might be | |
131 | * enough to catch brutal errors at least. | |
132 | */ | |
133 | if (address + PAGE_SIZE < rdusp()) | |
134 | goto bad_area; | |
135 | } | |
136 | if (expand_stack(vma, address)) | |
137 | goto bad_area; | |
138 | ||
139 | /* | |
140 | * Ok, we have a good vm_area for this memory access, so | |
141 | * we can handle it.. | |
142 | */ | |
143 | ||
144 | good_area: | |
145 | info.si_code = SEGV_ACCERR; | |
146 | ||
147 | /* first do some preliminary protection checks */ | |
148 | ||
4f18cfbf MS |
149 | if (writeaccess == 2){ |
150 | if (!(vma->vm_flags & VM_EXEC)) | |
151 | goto bad_area; | |
152 | } else if (writeaccess == 1) { | |
1da177e4 LT |
153 | if (!(vma->vm_flags & VM_WRITE)) |
154 | goto bad_area; | |
155 | } else { | |
156 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
157 | goto bad_area; | |
158 | } | |
159 | ||
160 | /* | |
161 | * If for any reason at all we couldn't handle the fault, | |
162 | * make sure we exit gracefully rather than endlessly redo | |
163 | * the fault. | |
164 | */ | |
165 | ||
d06063cc | 166 | fault = handle_mm_fault(mm, vma, address, (writeaccess & 1) ? FAULT_FLAG_WRITE : 0); |
83c54070 NP |
167 | if (unlikely(fault & VM_FAULT_ERROR)) { |
168 | if (fault & VM_FAULT_OOM) | |
169 | goto out_of_memory; | |
170 | else if (fault & VM_FAULT_SIGBUS) | |
171 | goto do_sigbus; | |
172 | BUG(); | |
1da177e4 | 173 | } |
83c54070 NP |
174 | if (fault & VM_FAULT_MAJOR) |
175 | tsk->maj_flt++; | |
176 | else | |
177 | tsk->min_flt++; | |
1da177e4 LT |
178 | |
179 | up_read(&mm->mmap_sem); | |
180 | return; | |
181 | ||
182 | /* | |
183 | * Something tried to access memory that isn't in our memory map.. | |
184 | * Fix it, but check if it's kernel or user first.. | |
185 | */ | |
186 | ||
187 | bad_area: | |
188 | up_read(&mm->mmap_sem); | |
189 | ||
190 | bad_area_nosemaphore: | |
191 | DPG(show_registers(regs)); | |
192 | ||
193 | /* User mode accesses just cause a SIGSEGV */ | |
194 | ||
195 | if (user_mode(regs)) { | |
196 | info.si_signo = SIGSEGV; | |
197 | info.si_errno = 0; | |
198 | /* info.si_code has been set above */ | |
199 | info.si_addr = (void *)address; | |
200 | force_sig_info(SIGSEGV, &info, tsk); | |
3e1fdc4e JN |
201 | printk(KERN_NOTICE "%s (pid %d) segfaults for page " |
202 | "address %08lx at pc %08lx\n", | |
203 | tsk->comm, tsk->pid, address, instruction_pointer(regs)); | |
1da177e4 LT |
204 | return; |
205 | } | |
206 | ||
207 | no_context: | |
208 | ||
209 | /* Are we prepared to handle this kernel fault? | |
210 | * | |
3e1fdc4e | 211 | * (The kernel has valid exception-points in the source |
af901ca1 | 212 | * when it accesses user-memory. When it fails in one |
1da177e4 LT |
213 | * of those points, we find it in a table and do a jump |
214 | * to some fixup code that loads an appropriate error | |
215 | * code) | |
216 | */ | |
217 | ||
218 | if (find_fixup_code(regs)) | |
219 | return; | |
220 | ||
221 | /* | |
222 | * Oops. The kernel tried to access some bad page. We'll have to | |
223 | * terminate things with extreme prejudice. | |
224 | */ | |
225 | ||
3e1fdc4e JN |
226 | if (!oops_in_progress) { |
227 | oops_in_progress = 1; | |
228 | if ((unsigned long) (address) < PAGE_SIZE) | |
229 | printk(KERN_ALERT "Unable to handle kernel NULL " | |
230 | "pointer dereference"); | |
231 | else | |
232 | printk(KERN_ALERT "Unable to handle kernel access" | |
233 | " at virtual address %08lx\n", address); | |
234 | ||
235 | die_if_kernel("Oops", regs, (writeaccess << 1) | protection); | |
236 | oops_in_progress = 0; | |
237 | } | |
1da177e4 LT |
238 | |
239 | do_exit(SIGKILL); | |
240 | ||
241 | /* | |
242 | * We ran out of memory, or some other thing happened to us that made | |
243 | * us unable to handle the page fault gracefully. | |
244 | */ | |
245 | ||
246 | out_of_memory: | |
247 | up_read(&mm->mmap_sem); | |
3648bdf7 JN |
248 | if (!user_mode(regs)) |
249 | goto no_context; | |
250 | pagefault_out_of_memory(); | |
251 | return; | |
1da177e4 LT |
252 | |
253 | do_sigbus: | |
254 | up_read(&mm->mmap_sem); | |
255 | ||
256 | /* | |
257 | * Send a sigbus, regardless of whether we were in kernel | |
258 | * or user mode. | |
259 | */ | |
260 | info.si_signo = SIGBUS; | |
261 | info.si_errno = 0; | |
262 | info.si_code = BUS_ADRERR; | |
263 | info.si_addr = (void *)address; | |
264 | force_sig_info(SIGBUS, &info, tsk); | |
265 | ||
266 | /* Kernel mode? Handle exceptions or die */ | |
267 | if (!user_mode(regs)) | |
268 | goto no_context; | |
269 | return; | |
270 | ||
271 | vmalloc_fault: | |
272 | { | |
273 | /* | |
274 | * Synchronize this task's top level page-table | |
275 | * with the 'reference' page table. | |
276 | * | |
277 | * Use current_pgd instead of tsk->active_mm->pgd | |
278 | * since the latter might be unavailable if this | |
279 | * code is executed in a misfortunately run irq | |
280 | * (like inside schedule() between switch_mm and | |
281 | * switch_to...). | |
282 | */ | |
283 | ||
284 | int offset = pgd_index(address); | |
285 | pgd_t *pgd, *pgd_k; | |
4f18cfbf | 286 | pud_t *pud, *pud_k; |
1da177e4 LT |
287 | pmd_t *pmd, *pmd_k; |
288 | pte_t *pte_k; | |
289 | ||
4f18cfbf | 290 | pgd = (pgd_t *)per_cpu(current_pgd, smp_processor_id()) + offset; |
1da177e4 LT |
291 | pgd_k = init_mm.pgd + offset; |
292 | ||
293 | /* Since we're two-level, we don't need to do both | |
294 | * set_pgd and set_pmd (they do the same thing). If | |
295 | * we go three-level at some point, do the right thing | |
3e1fdc4e JN |
296 | * with pgd_present and set_pgd here. |
297 | * | |
1da177e4 LT |
298 | * Also, since the vmalloc area is global, we don't |
299 | * need to copy individual PTE's, it is enough to | |
300 | * copy the pgd pointer into the pte page of the | |
301 | * root task. If that is there, we'll find our pte if | |
302 | * it exists. | |
303 | */ | |
304 | ||
4f18cfbf MS |
305 | pud = pud_offset(pgd, address); |
306 | pud_k = pud_offset(pgd_k, address); | |
307 | if (!pud_present(*pud_k)) | |
308 | goto no_context; | |
309 | ||
310 | pmd = pmd_offset(pud, address); | |
311 | pmd_k = pmd_offset(pud_k, address); | |
1da177e4 LT |
312 | |
313 | if (!pmd_present(*pmd_k)) | |
314 | goto bad_area_nosemaphore; | |
315 | ||
316 | set_pmd(pmd, *pmd_k); | |
317 | ||
318 | /* Make sure the actual PTE exists as well to | |
319 | * catch kernel vmalloc-area accesses to non-mapped | |
320 | * addresses. If we don't do this, this will just | |
321 | * silently loop forever. | |
322 | */ | |
323 | ||
324 | pte_k = pte_offset_kernel(pmd_k, address); | |
325 | if (!pte_present(*pte_k)) | |
326 | goto no_context; | |
327 | ||
328 | return; | |
329 | } | |
330 | } | |
4f18cfbf MS |
331 | |
332 | /* Find fixup code. */ | |
333 | int | |
334 | find_fixup_code(struct pt_regs *regs) | |
335 | { | |
336 | const struct exception_table_entry *fixup; | |
a90993c6 JN |
337 | /* in case of delay slot fault (v32) */ |
338 | unsigned long ip = (instruction_pointer(regs) & ~0x1); | |
4f18cfbf | 339 | |
a90993c6 JN |
340 | fixup = search_exception_tables(ip); |
341 | if (fixup != 0) { | |
4f18cfbf MS |
342 | /* Adjust the instruction pointer in the stackframe. */ |
343 | instruction_pointer(regs) = fixup->fixup; | |
344 | arch_fixup(regs); | |
345 | return 1; | |
346 | } | |
347 | ||
348 | return 0; | |
349 | } |