1 /*
2 * linux/arch/unicore32/mm/fault.c
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Copyright (C) 2001-2010 GUAN Xue-tao
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12 #include <linux/module.h>
13 #include <linux/signal.h>
14 #include <linux/mm.h>
15 #include <linux/hardirq.h>
16 #include <linux/init.h>
17 #include <linux/kprobes.h>
18 #include <linux/uaccess.h>
19 #include <linux/page-flags.h>
20 #include <linux/sched.h>
21 #include <linux/io.h>
22
23 #include <asm/pgtable.h>
24 #include <asm/tlbflush.h>
25
26 /*
27 * Fault status register encodings. We steal bit 31 for our own purposes.
28 */
29 #define FSR_LNX_PF (1 << 31)
30
fsr_fs(unsigned int fsr)31 static inline int fsr_fs(unsigned int fsr)
32 {
33 /* xyabcde will be abcde+xy */
34 return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
35 }
36
37 /*
38 * This is useful to dump out the page tables associated with
39 * 'addr' in mm 'mm'.
40 */
show_pte(struct mm_struct * mm,unsigned long addr)41 void show_pte(struct mm_struct *mm, unsigned long addr)
42 {
43 pgd_t *pgd;
44
45 if (!mm)
46 mm = &init_mm;
47
48 printk(KERN_ALERT "pgd = %p\n", mm->pgd);
49 pgd = pgd_offset(mm, addr);
50 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
51
52 do {
53 pmd_t *pmd;
54 pte_t *pte;
55
56 if (pgd_none(*pgd))
57 break;
58
59 if (pgd_bad(*pgd)) {
60 printk("(bad)");
61 break;
62 }
63
64 pmd = pmd_offset((pud_t *) pgd, addr);
65 if (PTRS_PER_PMD != 1)
66 printk(", *pmd=%08lx", pmd_val(*pmd));
67
68 if (pmd_none(*pmd))
69 break;
70
71 if (pmd_bad(*pmd)) {
72 printk("(bad)");
73 break;
74 }
75
76 /* We must not map this if we have highmem enabled */
77 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
78 break;
79
80 pte = pte_offset_map(pmd, addr);
81 printk(", *pte=%08lx", pte_val(*pte));
82 pte_unmap(pte);
83 } while (0);
84
85 printk("\n");
86 }
87
88 /*
89 * Oops. The kernel tried to access some page that wasn't present.
90 */
__do_kernel_fault(struct mm_struct * mm,unsigned long addr,unsigned int fsr,struct pt_regs * regs)91 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
92 unsigned int fsr, struct pt_regs *regs)
93 {
94 /*
95 * Are we prepared to handle this kernel fault?
96 */
97 if (fixup_exception(regs))
98 return;
99
100 /*
101 * No handler, we'll have to terminate things with extreme prejudice.
102 */
103 bust_spinlocks(1);
104 printk(KERN_ALERT
105 "Unable to handle kernel %s at virtual address %08lx\n",
106 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
107 "paging request", addr);
108
109 show_pte(mm, addr);
110 die("Oops", regs, fsr);
111 bust_spinlocks(0);
112 do_exit(SIGKILL);
113 }
114
115 /*
116 * Something tried to access memory that isn't in our memory map..
117 * User mode accesses just cause a SIGSEGV
118 */
__do_user_fault(struct task_struct * tsk,unsigned long addr,unsigned int fsr,unsigned int sig,int code,struct pt_regs * regs)119 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
120 unsigned int fsr, unsigned int sig, int code,
121 struct pt_regs *regs)
122 {
123 struct siginfo si;
124
125 tsk->thread.address = addr;
126 tsk->thread.error_code = fsr;
127 tsk->thread.trap_no = 14;
128 si.si_signo = sig;
129 si.si_errno = 0;
130 si.si_code = code;
131 si.si_addr = (void __user *)addr;
132 force_sig_info(sig, &si, tsk);
133 }
134
do_bad_area(unsigned long addr,unsigned int fsr,struct pt_regs * regs)135 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
136 {
137 struct task_struct *tsk = current;
138 struct mm_struct *mm = tsk->active_mm;
139
140 /*
141 * If we are in kernel mode at this point, we
142 * have no context to handle this fault with.
143 */
144 if (user_mode(regs))
145 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
146 else
147 __do_kernel_fault(mm, addr, fsr, regs);
148 }
149
150 #define VM_FAULT_BADMAP 0x010000
151 #define VM_FAULT_BADACCESS 0x020000
152
153 /*
154 * Check that the permissions on the VMA allow for the fault which occurred.
155 * If we encountered a write fault, we must have write permission, otherwise
156 * we allow any permission.
157 */
access_error(unsigned int fsr,struct vm_area_struct * vma)158 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
159 {
160 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
161
162 if (!(fsr ^ 0x12)) /* write? */
163 mask = VM_WRITE;
164 if (fsr & FSR_LNX_PF)
165 mask = VM_EXEC;
166
167 return vma->vm_flags & mask ? false : true;
168 }
169
__do_pf(struct mm_struct * mm,unsigned long addr,unsigned int fsr,unsigned int flags,struct task_struct * tsk)170 static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
171 unsigned int flags, struct task_struct *tsk)
172 {
173 struct vm_area_struct *vma;
174 int fault;
175
176 vma = find_vma(mm, addr);
177 fault = VM_FAULT_BADMAP;
178 if (unlikely(!vma))
179 goto out;
180 if (unlikely(vma->vm_start > addr))
181 goto check_stack;
182
183 /*
184 * Ok, we have a good vm_area for this
185 * memory access, so we can handle it.
186 */
187 good_area:
188 if (access_error(fsr, vma)) {
189 fault = VM_FAULT_BADACCESS;
190 goto out;
191 }
192
193 /*
194 * If for any reason at all we couldn't handle the fault, make
195 * sure we exit gracefully rather than endlessly redo the fault.
196 */
197 fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
198 return fault;
199
200 check_stack:
201 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
202 goto good_area;
203 out:
204 return fault;
205 }
206
do_pf(unsigned long addr,unsigned int fsr,struct pt_regs * regs)207 static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
208 {
209 struct task_struct *tsk;
210 struct mm_struct *mm;
211 int fault, sig, code;
212 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
213
214 tsk = current;
215 mm = tsk->mm;
216
217 /*
218 * If we're in an interrupt or have no user
219 * context, we must not take the fault..
220 */
221 if (faulthandler_disabled() || !mm)
222 goto no_context;
223
224 if (user_mode(regs))
225 flags |= FAULT_FLAG_USER;
226 if (!(fsr ^ 0x12))
227 flags |= FAULT_FLAG_WRITE;
228
229 /*
230 * As per x86, we may deadlock here. However, since the kernel only
231 * validly references user space from well defined areas of the code,
232 * we can bug out early if this is from code which shouldn't.
233 */
234 if (!down_read_trylock(&mm->mmap_sem)) {
235 if (!user_mode(regs)
236 && !search_exception_tables(regs->UCreg_pc))
237 goto no_context;
238 retry:
239 down_read(&mm->mmap_sem);
240 } else {
241 /*
242 * The above down_read_trylock() might have succeeded in
243 * which case, we'll have missed the might_sleep() from
244 * down_read()
245 */
246 might_sleep();
247 #ifdef CONFIG_DEBUG_VM
248 if (!user_mode(regs) &&
249 !search_exception_tables(regs->UCreg_pc))
250 goto no_context;
251 #endif
252 }
253
254 fault = __do_pf(mm, addr, fsr, flags, tsk);
255
256 /* If we need to retry but a fatal signal is pending, handle the
257 * signal first. We do not need to release the mmap_sem because
258 * it would already be released in __lock_page_or_retry in
259 * mm/filemap.c. */
260 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
261 return 0;
262
263 if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
264 if (fault & VM_FAULT_MAJOR)
265 tsk->maj_flt++;
266 else
267 tsk->min_flt++;
268 if (fault & VM_FAULT_RETRY) {
269 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
270 * of starvation. */
271 flags &= ~FAULT_FLAG_ALLOW_RETRY;
272 goto retry;
273 }
274 }
275
276 up_read(&mm->mmap_sem);
277
278 /*
279 * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
280 */
281 if (likely(!(fault &
282 (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
283 return 0;
284
285 /*
286 * If we are in kernel mode at this point, we
287 * have no context to handle this fault with.
288 */
289 if (!user_mode(regs))
290 goto no_context;
291
292 if (fault & VM_FAULT_OOM) {
293 /*
294 * We ran out of memory, call the OOM killer, and return to
295 * userspace (which will retry the fault, or kill us if we
296 * got oom-killed)
297 */
298 pagefault_out_of_memory();
299 return 0;
300 }
301
302 if (fault & VM_FAULT_SIGBUS) {
303 /*
304 * We had some memory, but were unable to
305 * successfully fix up this page fault.
306 */
307 sig = SIGBUS;
308 code = BUS_ADRERR;
309 } else {
310 /*
311 * Something tried to access memory that
312 * isn't in our memory map..
313 */
314 sig = SIGSEGV;
315 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
316 }
317
318 __do_user_fault(tsk, addr, fsr, sig, code, regs);
319 return 0;
320
321 no_context:
322 __do_kernel_fault(mm, addr, fsr, regs);
323 return 0;
324 }
325
326 /*
327 * First Level Translation Fault Handler
328 *
329 * We enter here because the first level page table doesn't contain
330 * a valid entry for the address.
331 *
332 * If the address is in kernel space (>= TASK_SIZE), then we are
333 * probably faulting in the vmalloc() area.
334 *
335 * If the init_task's first level page tables contains the relevant
336 * entry, we copy the it to this task. If not, we send the process
337 * a signal, fixup the exception, or oops the kernel.
338 *
339 * NOTE! We MUST NOT take any locks for this case. We may be in an
340 * interrupt or a critical region, and should only copy the information
341 * from the master page table, nothing more.
342 */
do_ifault(unsigned long addr,unsigned int fsr,struct pt_regs * regs)343 static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
344 {
345 unsigned int index;
346 pgd_t *pgd, *pgd_k;
347 pmd_t *pmd, *pmd_k;
348
349 if (addr < TASK_SIZE)
350 return do_pf(addr, fsr, regs);
351
352 if (user_mode(regs))
353 goto bad_area;
354
355 index = pgd_index(addr);
356
357 pgd = cpu_get_pgd() + index;
358 pgd_k = init_mm.pgd + index;
359
360 if (pgd_none(*pgd_k))
361 goto bad_area;
362
363 pmd_k = pmd_offset((pud_t *) pgd_k, addr);
364 pmd = pmd_offset((pud_t *) pgd, addr);
365
366 if (pmd_none(*pmd_k))
367 goto bad_area;
368
369 set_pmd(pmd, *pmd_k);
370 flush_pmd_entry(pmd);
371 return 0;
372
373 bad_area:
374 do_bad_area(addr, fsr, regs);
375 return 0;
376 }
377
378 /*
379 * This abort handler always returns "fault".
380 */
do_bad(unsigned long addr,unsigned int fsr,struct pt_regs * regs)381 static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
382 {
383 return 1;
384 }
385
do_good(unsigned long addr,unsigned int fsr,struct pt_regs * regs)386 static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
387 {
388 unsigned int res1, res2;
389
390 printk("dabt exception but no error!\n");
391
392 __asm__ __volatile__(
393 "mff %0,f0\n"
394 "mff %1,f1\n"
395 : "=r"(res1), "=r"(res2)
396 :
397 : "memory");
398
399 printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
400 panic("shut up\n");
401 return 0;
402 }
403
404 static struct fsr_info {
405 int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
406 int sig;
407 int code;
408 const char *name;
409 } fsr_info[] = {
410 /*
411 * The following are the standard Unicore-I and UniCore-II aborts.
412 */
413 { do_good, SIGBUS, 0, "no error" },
414 { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
415 { do_bad, SIGBUS, BUS_OBJERR, "external exception" },
416 { do_bad, SIGBUS, 0, "burst operation" },
417 { do_bad, SIGBUS, 0, "unknown 00100" },
418 { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
419 { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
420 { do_bad, SIGBUS, 0, "invalid pte" },
421 { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
422 { do_bad, SIGBUS, 0, "middle page miss" },
423 { do_bad, SIGBUS, 0, "large page miss" },
424 { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
425 { do_bad, SIGBUS, 0, "unknown 01100" },
426 { do_bad, SIGBUS, 0, "unknown 01101" },
427 { do_bad, SIGBUS, 0, "unknown 01110" },
428 { do_bad, SIGBUS, 0, "unknown 01111" },
429 { do_bad, SIGBUS, 0, "addr: up 3G or IO" },
430 { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
431 { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
432 { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
433 { do_bad, SIGBUS, 0, "unknown 10100" },
434 { do_bad, SIGBUS, 0, "unknown 10101" },
435 { do_bad, SIGBUS, 0, "unknown 10110" },
436 { do_bad, SIGBUS, 0, "unknown 10111" },
437 { do_bad, SIGBUS, 0, "unknown 11000" },
438 { do_bad, SIGBUS, 0, "unknown 11001" },
439 { do_bad, SIGBUS, 0, "unknown 11010" },
440 { do_bad, SIGBUS, 0, "unknown 11011" },
441 { do_bad, SIGBUS, 0, "unknown 11100" },
442 { do_bad, SIGBUS, 0, "unknown 11101" },
443 { do_bad, SIGBUS, 0, "unknown 11110" },
444 { do_bad, SIGBUS, 0, "unknown 11111" }
445 };
446
hook_fault_code(int nr,int (* fn)(unsigned long,unsigned int,struct pt_regs *),int sig,int code,const char * name)447 void __init hook_fault_code(int nr,
448 int (*fn) (unsigned long, unsigned int, struct pt_regs *),
449 int sig, int code, const char *name)
450 {
451 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
452 BUG();
453
454 fsr_info[nr].fn = fn;
455 fsr_info[nr].sig = sig;
456 fsr_info[nr].code = code;
457 fsr_info[nr].name = name;
458 }
459
460 /*
461 * Dispatch a data abort to the relevant handler.
462 */
do_DataAbort(unsigned long addr,unsigned int fsr,struct pt_regs * regs)463 asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
464 struct pt_regs *regs)
465 {
466 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
467 struct siginfo info;
468
469 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
470 return;
471
472 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
473 inf->name, fsr, addr);
474
475 info.si_signo = inf->sig;
476 info.si_errno = 0;
477 info.si_code = inf->code;
478 info.si_addr = (void __user *)addr;
479 uc32_notify_die("", regs, &info, fsr, 0);
480 }
481
do_PrefetchAbort(unsigned long addr,unsigned int ifsr,struct pt_regs * regs)482 asmlinkage void do_PrefetchAbort(unsigned long addr,
483 unsigned int ifsr, struct pt_regs *regs)
484 {
485 const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
486 struct siginfo info;
487
488 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
489 return;
490
491 printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
492 inf->name, ifsr, addr);
493
494 info.si_signo = inf->sig;
495 info.si_errno = 0;
496 info.si_code = inf->code;
497 info.si_addr = (void __user *)addr;
498 uc32_notify_die("", regs, &info, ifsr, 0);
499 }
500