Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm/mm/fault.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | * Modifications for ARM processor (c) 1995-2004 Russell King | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | #include <linux/config.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/signal.h> | |
14 | #include <linux/ptrace.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/init.h> | |
17 | ||
18 | #include <asm/system.h> | |
19 | #include <asm/pgtable.h> | |
20 | #include <asm/tlbflush.h> | |
21 | #include <asm/uaccess.h> | |
22 | ||
23 | #include "fault.h" | |
24 | ||
25 | /* | |
26 | * This is useful to dump out the page tables associated with | |
27 | * 'addr' in mm 'mm'. | |
28 | */ | |
29 | void show_pte(struct mm_struct *mm, unsigned long addr) | |
30 | { | |
31 | pgd_t *pgd; | |
32 | ||
33 | if (!mm) | |
34 | mm = &init_mm; | |
35 | ||
36 | printk(KERN_ALERT "pgd = %p\n", mm->pgd); | |
37 | pgd = pgd_offset(mm, addr); | |
38 | printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd)); | |
39 | ||
40 | do { | |
41 | pmd_t *pmd; | |
42 | pte_t *pte; | |
43 | ||
44 | if (pgd_none(*pgd)) | |
45 | break; | |
46 | ||
47 | if (pgd_bad(*pgd)) { | |
48 | printk("(bad)"); | |
49 | break; | |
50 | } | |
51 | ||
52 | pmd = pmd_offset(pgd, addr); | |
53 | #if PTRS_PER_PMD != 1 | |
54 | printk(", *pmd=%08lx", pmd_val(*pmd)); | |
55 | #endif | |
56 | ||
57 | if (pmd_none(*pmd)) | |
58 | break; | |
59 | ||
60 | if (pmd_bad(*pmd)) { | |
61 | printk("(bad)"); | |
62 | break; | |
63 | } | |
64 | ||
65 | #ifndef CONFIG_HIGHMEM | |
66 | /* We must not map this if we have highmem enabled */ | |
67 | pte = pte_offset_map(pmd, addr); | |
68 | printk(", *pte=%08lx", pte_val(*pte)); | |
69 | printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE])); | |
70 | pte_unmap(pte); | |
71 | #endif | |
72 | } while(0); | |
73 | ||
74 | printk("\n"); | |
75 | } | |
76 | ||
77 | /* | |
78 | * Oops. The kernel tried to access some page that wasn't present. | |
79 | */ | |
80 | static void | |
81 | __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, | |
82 | struct pt_regs *regs) | |
83 | { | |
84 | /* | |
85 | * Are we prepared to handle this kernel fault? | |
86 | */ | |
87 | if (fixup_exception(regs)) | |
88 | return; | |
89 | ||
90 | /* | |
91 | * No handler, we'll have to terminate things with extreme prejudice. | |
92 | */ | |
93 | bust_spinlocks(1); | |
94 | printk(KERN_ALERT | |
95 | "Unable to handle kernel %s at virtual address %08lx\n", | |
96 | (addr < PAGE_SIZE) ? "NULL pointer dereference" : | |
97 | "paging request", addr); | |
98 | ||
99 | show_pte(mm, addr); | |
100 | die("Oops", regs, fsr); | |
101 | bust_spinlocks(0); | |
102 | do_exit(SIGKILL); | |
103 | } | |
104 | ||
105 | /* | |
106 | * Something tried to access memory that isn't in our memory map.. | |
107 | * User mode accesses just cause a SIGSEGV | |
108 | */ | |
109 | static void | |
110 | __do_user_fault(struct task_struct *tsk, unsigned long addr, | |
111 | unsigned int fsr, int code, struct pt_regs *regs) | |
112 | { | |
113 | struct siginfo si; | |
114 | ||
115 | #ifdef CONFIG_DEBUG_USER | |
116 | if (user_debug & UDBG_SEGV) { | |
117 | printk(KERN_DEBUG "%s: unhandled page fault at 0x%08lx, code 0x%03x\n", | |
118 | tsk->comm, addr, fsr); | |
119 | show_pte(tsk->mm, addr); | |
120 | show_regs(regs); | |
121 | } | |
122 | #endif | |
123 | ||
124 | tsk->thread.address = addr; | |
125 | tsk->thread.error_code = fsr; | |
126 | tsk->thread.trap_no = 14; | |
127 | si.si_signo = SIGSEGV; | |
128 | si.si_errno = 0; | |
129 | si.si_code = code; | |
130 | si.si_addr = (void __user *)addr; | |
131 | force_sig_info(SIGSEGV, &si, tsk); | |
132 | } | |
133 | ||
134 | void | |
135 | do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr, | |
136 | unsigned int fsr, struct pt_regs *regs) | |
137 | { | |
138 | /* | |
139 | * If we are in kernel mode at this point, we | |
140 | * have no context to handle this fault with. | |
141 | */ | |
142 | if (user_mode(regs)) | |
143 | __do_user_fault(tsk, addr, fsr, SEGV_MAPERR, regs); | |
144 | else | |
145 | __do_kernel_fault(mm, addr, fsr, regs); | |
146 | } | |
147 | ||
148 | #define VM_FAULT_BADMAP (-20) | |
149 | #define VM_FAULT_BADACCESS (-21) | |
150 | ||
151 | static int | |
152 | __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, | |
153 | struct task_struct *tsk) | |
154 | { | |
155 | struct vm_area_struct *vma; | |
156 | int fault, mask; | |
157 | ||
158 | vma = find_vma(mm, addr); | |
159 | fault = VM_FAULT_BADMAP; | |
160 | if (!vma) | |
161 | goto out; | |
162 | if (vma->vm_start > addr) | |
163 | goto check_stack; | |
164 | ||
165 | /* | |
166 | * Ok, we have a good vm_area for this | |
167 | * memory access, so we can handle it. | |
168 | */ | |
169 | good_area: | |
170 | if (fsr & (1 << 11)) /* write? */ | |
171 | mask = VM_WRITE; | |
172 | else | |
173 | mask = VM_READ|VM_EXEC; | |
174 | ||
175 | fault = VM_FAULT_BADACCESS; | |
176 | if (!(vma->vm_flags & mask)) | |
177 | goto out; | |
178 | ||
179 | /* | |
180 | * If for any reason at all we couldn't handle | |
181 | * the fault, make sure we exit gracefully rather | |
182 | * than endlessly redo the fault. | |
183 | */ | |
184 | survive: | |
185 | fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11)); | |
186 | ||
187 | /* | |
188 | * Handle the "normal" cases first - successful and sigbus | |
189 | */ | |
190 | switch (fault) { | |
191 | case VM_FAULT_MAJOR: | |
192 | tsk->maj_flt++; | |
193 | return fault; | |
194 | case VM_FAULT_MINOR: | |
195 | tsk->min_flt++; | |
196 | case VM_FAULT_SIGBUS: | |
197 | return fault; | |
198 | } | |
199 | ||
200 | if (tsk->pid != 1) | |
201 | goto out; | |
202 | ||
203 | /* | |
204 | * If we are out of memory for pid1, | |
205 | * sleep for a while and retry | |
206 | */ | |
207 | yield(); | |
208 | goto survive; | |
209 | ||
210 | check_stack: | |
211 | if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) | |
212 | goto good_area; | |
213 | out: | |
214 | return fault; | |
215 | } | |
216 | ||
217 | static int | |
218 | do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) | |
219 | { | |
220 | struct task_struct *tsk; | |
221 | struct mm_struct *mm; | |
222 | int fault; | |
223 | ||
224 | tsk = current; | |
225 | mm = tsk->mm; | |
226 | ||
227 | /* | |
228 | * If we're in an interrupt or have no user | |
229 | * context, we must not take the fault.. | |
230 | */ | |
231 | if (in_interrupt() || !mm) | |
232 | goto no_context; | |
233 | ||
234 | down_read(&mm->mmap_sem); | |
235 | fault = __do_page_fault(mm, addr, fsr, tsk); | |
236 | up_read(&mm->mmap_sem); | |
237 | ||
238 | /* | |
239 | * Handle the "normal" case first | |
240 | */ | |
241 | if (fault > 0) | |
242 | return 0; | |
243 | ||
244 | /* | |
245 | * We had some memory, but were unable to | |
246 | * successfully fix up this page fault. | |
247 | */ | |
248 | if (fault == 0) | |
249 | goto do_sigbus; | |
250 | ||
251 | /* | |
252 | * If we are in kernel mode at this point, we | |
253 | * have no context to handle this fault with. | |
254 | */ | |
255 | if (!user_mode(regs)) | |
256 | goto no_context; | |
257 | ||
258 | if (fault == VM_FAULT_OOM) { | |
259 | /* | |
260 | * We ran out of memory, or some other thing happened to | |
261 | * us that made us unable to handle the page fault gracefully. | |
262 | */ | |
263 | printk("VM: killing process %s\n", tsk->comm); | |
264 | do_exit(SIGKILL); | |
265 | } else | |
266 | __do_user_fault(tsk, addr, fsr, fault == VM_FAULT_BADACCESS ? | |
267 | SEGV_ACCERR : SEGV_MAPERR, regs); | |
268 | return 0; | |
269 | ||
270 | ||
271 | /* | |
272 | * We ran out of memory, or some other thing happened to us that made | |
273 | * us unable to handle the page fault gracefully. | |
274 | */ | |
275 | do_sigbus: | |
276 | /* | |
277 | * Send a sigbus, regardless of whether we were in kernel | |
278 | * or user mode. | |
279 | */ | |
280 | tsk->thread.address = addr; | |
281 | tsk->thread.error_code = fsr; | |
282 | tsk->thread.trap_no = 14; | |
283 | force_sig(SIGBUS, tsk); | |
284 | #ifdef CONFIG_DEBUG_USER | |
285 | if (user_debug & UDBG_BUS) { | |
286 | printk(KERN_DEBUG "%s: sigbus at 0x%08lx, pc=0x%08lx\n", | |
287 | current->comm, addr, instruction_pointer(regs)); | |
288 | } | |
289 | #endif | |
290 | ||
291 | /* Kernel mode? Handle exceptions or die */ | |
292 | if (user_mode(regs)) | |
293 | return 0; | |
294 | ||
295 | no_context: | |
296 | __do_kernel_fault(mm, addr, fsr, regs); | |
297 | return 0; | |
298 | } | |
299 | ||
300 | /* | |
301 | * First Level Translation Fault Handler | |
302 | * | |
303 | * We enter here because the first level page table doesn't contain | |
304 | * a valid entry for the address. | |
305 | * | |
306 | * If the address is in kernel space (>= TASK_SIZE), then we are | |
307 | * probably faulting in the vmalloc() area. | |
308 | * | |
309 | * If the init_task's first level page tables contains the relevant | |
310 | * entry, we copy the it to this task. If not, we send the process | |
311 | * a signal, fixup the exception, or oops the kernel. | |
312 | * | |
313 | * NOTE! We MUST NOT take any locks for this case. We may be in an | |
314 | * interrupt or a critical region, and should only copy the information | |
315 | * from the master page table, nothing more. | |
316 | */ | |
317 | static int | |
318 | do_translation_fault(unsigned long addr, unsigned int fsr, | |
319 | struct pt_regs *regs) | |
320 | { | |
321 | struct task_struct *tsk; | |
322 | unsigned int index; | |
323 | pgd_t *pgd, *pgd_k; | |
324 | pmd_t *pmd, *pmd_k; | |
325 | ||
326 | if (addr < TASK_SIZE) | |
327 | return do_page_fault(addr, fsr, regs); | |
328 | ||
329 | index = pgd_index(addr); | |
330 | ||
331 | /* | |
332 | * FIXME: CP15 C1 is write only on ARMv3 architectures. | |
333 | */ | |
334 | pgd = cpu_get_pgd() + index; | |
335 | pgd_k = init_mm.pgd + index; | |
336 | ||
337 | if (pgd_none(*pgd_k)) | |
338 | goto bad_area; | |
339 | ||
340 | if (!pgd_present(*pgd)) | |
341 | set_pgd(pgd, *pgd_k); | |
342 | ||
343 | pmd_k = pmd_offset(pgd_k, addr); | |
344 | pmd = pmd_offset(pgd, addr); | |
345 | ||
346 | if (pmd_none(*pmd_k)) | |
347 | goto bad_area; | |
348 | ||
349 | copy_pmd(pmd, pmd_k); | |
350 | return 0; | |
351 | ||
352 | bad_area: | |
353 | tsk = current; | |
354 | ||
355 | do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); | |
356 | return 0; | |
357 | } | |
358 | ||
359 | /* | |
360 | * Some section permission faults need to be handled gracefully. | |
361 | * They can happen due to a __{get,put}_user during an oops. | |
362 | */ | |
363 | static int | |
364 | do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) | |
365 | { | |
366 | struct task_struct *tsk = current; | |
367 | do_bad_area(tsk, tsk->active_mm, addr, fsr, regs); | |
368 | return 0; | |
369 | } | |
370 | ||
371 | /* | |
372 | * This abort handler always returns "fault". | |
373 | */ | |
374 | static int | |
375 | do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs) | |
376 | { | |
377 | return 1; | |
378 | } | |
379 | ||
380 | static struct fsr_info { | |
381 | int (*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs); | |
382 | int sig; | |
383 | const char *name; | |
384 | } fsr_info[] = { | |
385 | /* | |
386 | * The following are the standard ARMv3 and ARMv4 aborts. ARMv5 | |
387 | * defines these to be "precise" aborts. | |
388 | */ | |
389 | { do_bad, SIGSEGV, "vector exception" }, | |
390 | { do_bad, SIGILL, "alignment exception" }, | |
391 | { do_bad, SIGKILL, "terminal exception" }, | |
392 | { do_bad, SIGILL, "alignment exception" }, | |
393 | { do_bad, SIGBUS, "external abort on linefetch" }, | |
394 | { do_translation_fault, SIGSEGV, "section translation fault" }, | |
395 | { do_bad, SIGBUS, "external abort on linefetch" }, | |
396 | { do_page_fault, SIGSEGV, "page translation fault" }, | |
397 | { do_bad, SIGBUS, "external abort on non-linefetch" }, | |
398 | { do_bad, SIGSEGV, "section domain fault" }, | |
399 | { do_bad, SIGBUS, "external abort on non-linefetch" }, | |
400 | { do_bad, SIGSEGV, "page domain fault" }, | |
401 | { do_bad, SIGBUS, "external abort on translation" }, | |
402 | { do_sect_fault, SIGSEGV, "section permission fault" }, | |
403 | { do_bad, SIGBUS, "external abort on translation" }, | |
404 | { do_page_fault, SIGSEGV, "page permission fault" }, | |
405 | /* | |
406 | * The following are "imprecise" aborts, which are signalled by bit | |
407 | * 10 of the FSR, and may not be recoverable. These are only | |
408 | * supported if the CPU abort handler supports bit 10. | |
409 | */ | |
410 | { do_bad, SIGBUS, "unknown 16" }, | |
411 | { do_bad, SIGBUS, "unknown 17" }, | |
412 | { do_bad, SIGBUS, "unknown 18" }, | |
413 | { do_bad, SIGBUS, "unknown 19" }, | |
414 | { do_bad, SIGBUS, "lock abort" }, /* xscale */ | |
415 | { do_bad, SIGBUS, "unknown 21" }, | |
416 | { do_bad, SIGBUS, "imprecise external abort" }, /* xscale */ | |
417 | { do_bad, SIGBUS, "unknown 23" }, | |
418 | { do_bad, SIGBUS, "dcache parity error" }, /* xscale */ | |
419 | { do_bad, SIGBUS, "unknown 25" }, | |
420 | { do_bad, SIGBUS, "unknown 26" }, | |
421 | { do_bad, SIGBUS, "unknown 27" }, | |
422 | { do_bad, SIGBUS, "unknown 28" }, | |
423 | { do_bad, SIGBUS, "unknown 29" }, | |
424 | { do_bad, SIGBUS, "unknown 30" }, | |
425 | { do_bad, SIGBUS, "unknown 31" } | |
426 | }; | |
427 | ||
428 | void __init | |
429 | hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *), | |
430 | int sig, const char *name) | |
431 | { | |
432 | if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) { | |
433 | fsr_info[nr].fn = fn; | |
434 | fsr_info[nr].sig = sig; | |
435 | fsr_info[nr].name = name; | |
436 | } | |
437 | } | |
438 | ||
439 | /* | |
440 | * Dispatch a data abort to the relevant handler. | |
441 | */ | |
442 | asmlinkage void | |
443 | do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) | |
444 | { | |
445 | const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6); | |
446 | ||
447 | if (!inf->fn(addr, fsr, regs)) | |
448 | return; | |
449 | ||
450 | printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n", | |
451 | inf->name, fsr, addr); | |
452 | force_sig(inf->sig, current); | |
453 | show_pte(current->mm, addr); | |
454 | die_if_kernel("Oops", regs, 0); | |
455 | } | |
456 | ||
457 | asmlinkage void | |
458 | do_PrefetchAbort(unsigned long addr, struct pt_regs *regs) | |
459 | { | |
460 | do_translation_fault(addr, 0, regs); | |
461 | } | |
462 |