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/extable.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/signal.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 clear_siginfo(&si);
129 si.si_signo = sig;
130 si.si_errno = 0;
131 si.si_code = code;
132 si.si_addr = (void __user *)addr;
133 force_sig_info(sig, &si, tsk);
134 }
135
do_bad_area(unsigned long addr,unsigned int fsr,struct pt_regs * regs)136 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
137 {
138 struct task_struct *tsk = current;
139 struct mm_struct *mm = tsk->active_mm;
140
141 /*
142 * If we are in kernel mode at this point, we
143 * have no context to handle this fault with.
144 */
145 if (user_mode(regs))
146 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
147 else
148 __do_kernel_fault(mm, addr, fsr, regs);
149 }
150
151 #define VM_FAULT_BADMAP 0x010000
152 #define VM_FAULT_BADACCESS 0x020000
153
154 /*
155 * Check that the permissions on the VMA allow for the fault which occurred.
156 * If we encountered a write fault, we must have write permission, otherwise
157 * we allow any permission.
158 */
access_error(unsigned int fsr,struct vm_area_struct * vma)159 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
160 {
161 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
162
163 if (!(fsr ^ 0x12)) /* write? */
164 mask = VM_WRITE;
165 if (fsr & FSR_LNX_PF)
166 mask = VM_EXEC;
167
168 return vma->vm_flags & mask ? false : true;
169 }
170
__do_pf(struct mm_struct * mm,unsigned long addr,unsigned int fsr,unsigned int flags,struct task_struct * tsk)171 static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
172 unsigned int fsr, unsigned int flags, struct task_struct *tsk)
173 {
174 struct vm_area_struct *vma;
175 vm_fault_t fault;
176
177 vma = find_vma(mm, addr);
178 fault = VM_FAULT_BADMAP;
179 if (unlikely(!vma))
180 goto out;
181 if (unlikely(vma->vm_start > addr))
182 goto check_stack;
183
184 /*
185 * Ok, we have a good vm_area for this
186 * memory access, so we can handle it.
187 */
188 good_area:
189 if (access_error(fsr, vma)) {
190 fault = VM_FAULT_BADACCESS;
191 goto out;
192 }
193
194 /*
195 * If for any reason at all we couldn't handle the fault, make
196 * sure we exit gracefully rather than endlessly redo the fault.
197 */
198 fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
199 return fault;
200
201 check_stack:
202 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
203 goto good_area;
204 out:
205 return fault;
206 }
207
do_pf(unsigned long addr,unsigned int fsr,struct pt_regs * regs)208 static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
209 {
210 struct task_struct *tsk;
211 struct mm_struct *mm;
212 int sig, code;
213 vm_fault_t fault;
214 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
215
216 tsk = current;
217 mm = tsk->mm;
218
219 /*
220 * If we're in an interrupt or have no user
221 * context, we must not take the fault..
222 */
223 if (faulthandler_disabled() || !mm)
224 goto no_context;
225
226 if (user_mode(regs))
227 flags |= FAULT_FLAG_USER;
228 if (!(fsr ^ 0x12))
229 flags |= FAULT_FLAG_WRITE;
230
231 /*
232 * As per x86, we may deadlock here. However, since the kernel only
233 * validly references user space from well defined areas of the code,
234 * we can bug out early if this is from code which shouldn't.
235 */
236 if (!down_read_trylock(&mm->mmap_sem)) {
237 if (!user_mode(regs)
238 && !search_exception_tables(regs->UCreg_pc))
239 goto no_context;
240 retry:
241 down_read(&mm->mmap_sem);
242 } else {
243 /*
244 * The above down_read_trylock() might have succeeded in
245 * which case, we'll have missed the might_sleep() from
246 * down_read()
247 */
248 might_sleep();
249 #ifdef CONFIG_DEBUG_VM
250 if (!user_mode(regs) &&
251 !search_exception_tables(regs->UCreg_pc))
252 goto no_context;
253 #endif
254 }
255
256 fault = __do_pf(mm, addr, fsr, flags, tsk);
257
258 /* If we need to retry but a fatal signal is pending, handle the
259 * signal first. We do not need to release the mmap_sem because
260 * it would already be released in __lock_page_or_retry in
261 * mm/filemap.c. */
262 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
263 return 0;
264
265 if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
266 if (fault & VM_FAULT_MAJOR)
267 tsk->maj_flt++;
268 else
269 tsk->min_flt++;
270 if (fault & VM_FAULT_RETRY) {
271 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
272 * of starvation. */
273 flags &= ~FAULT_FLAG_ALLOW_RETRY;
274 goto retry;
275 }
276 }
277
278 up_read(&mm->mmap_sem);
279
280 /*
281 * Handle the "normal" case first - VM_FAULT_MAJOR
282 */
283 if (likely(!(fault &
284 (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
285 return 0;
286
287 /*
288 * If we are in kernel mode at this point, we
289 * have no context to handle this fault with.
290 */
291 if (!user_mode(regs))
292 goto no_context;
293
294 if (fault & VM_FAULT_OOM) {
295 /*
296 * We ran out of memory, call the OOM killer, and return to
297 * userspace (which will retry the fault, or kill us if we
298 * got oom-killed)
299 */
300 pagefault_out_of_memory();
301 return 0;
302 }
303
304 if (fault & VM_FAULT_SIGBUS) {
305 /*
306 * We had some memory, but were unable to
307 * successfully fix up this page fault.
308 */
309 sig = SIGBUS;
310 code = BUS_ADRERR;
311 } else {
312 /*
313 * Something tried to access memory that
314 * isn't in our memory map..
315 */
316 sig = SIGSEGV;
317 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
318 }
319
320 __do_user_fault(tsk, addr, fsr, sig, code, regs);
321 return 0;
322
323 no_context:
324 __do_kernel_fault(mm, addr, fsr, regs);
325 return 0;
326 }
327
328 /*
329 * First Level Translation Fault Handler
330 *
331 * We enter here because the first level page table doesn't contain
332 * a valid entry for the address.
333 *
334 * If the address is in kernel space (>= TASK_SIZE), then we are
335 * probably faulting in the vmalloc() area.
336 *
337 * If the init_task's first level page tables contains the relevant
338 * entry, we copy the it to this task. If not, we send the process
339 * a signal, fixup the exception, or oops the kernel.
340 *
341 * NOTE! We MUST NOT take any locks for this case. We may be in an
342 * interrupt or a critical region, and should only copy the information
343 * from the master page table, nothing more.
344 */
do_ifault(unsigned long addr,unsigned int fsr,struct pt_regs * regs)345 static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
346 {
347 unsigned int index;
348 pgd_t *pgd, *pgd_k;
349 pmd_t *pmd, *pmd_k;
350
351 if (addr < TASK_SIZE)
352 return do_pf(addr, fsr, regs);
353
354 if (user_mode(regs))
355 goto bad_area;
356
357 index = pgd_index(addr);
358
359 pgd = cpu_get_pgd() + index;
360 pgd_k = init_mm.pgd + index;
361
362 if (pgd_none(*pgd_k))
363 goto bad_area;
364
365 pmd_k = pmd_offset((pud_t *) pgd_k, addr);
366 pmd = pmd_offset((pud_t *) pgd, addr);
367
368 if (pmd_none(*pmd_k))
369 goto bad_area;
370
371 set_pmd(pmd, *pmd_k);
372 flush_pmd_entry(pmd);
373 return 0;
374
375 bad_area:
376 do_bad_area(addr, fsr, regs);
377 return 0;
378 }
379
380 /*
381 * This abort handler always returns "fault".
382 */
do_bad(unsigned long addr,unsigned int fsr,struct pt_regs * regs)383 static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
384 {
385 return 1;
386 }
387
do_good(unsigned long addr,unsigned int fsr,struct pt_regs * regs)388 static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
389 {
390 unsigned int res1, res2;
391
392 printk("dabt exception but no error!\n");
393
394 __asm__ __volatile__(
395 "mff %0,f0\n"
396 "mff %1,f1\n"
397 : "=r"(res1), "=r"(res2)
398 :
399 : "memory");
400
401 printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
402 panic("shut up\n");
403 return 0;
404 }
405
406 static struct fsr_info {
407 int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
408 int sig;
409 int code;
410 const char *name;
411 } fsr_info[] = {
412 /*
413 * The following are the standard Unicore-I and UniCore-II aborts.
414 */
415 { do_good, SIGBUS, 0, "no error" },
416 { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
417 { do_bad, SIGBUS, BUS_OBJERR, "external exception" },
418 { do_bad, SIGBUS, 0, "burst operation" },
419 { do_bad, SIGBUS, 0, "unknown 00100" },
420 { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
421 { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
422 { do_bad, SIGBUS, 0, "invalid pte" },
423 { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
424 { do_bad, SIGBUS, 0, "middle page miss" },
425 { do_bad, SIGBUS, 0, "large page miss" },
426 { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
427 { do_bad, SIGBUS, 0, "unknown 01100" },
428 { do_bad, SIGBUS, 0, "unknown 01101" },
429 { do_bad, SIGBUS, 0, "unknown 01110" },
430 { do_bad, SIGBUS, 0, "unknown 01111" },
431 { do_bad, SIGBUS, 0, "addr: up 3G or IO" },
432 { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
433 { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
434 { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
435 { do_bad, SIGBUS, 0, "unknown 10100" },
436 { do_bad, SIGBUS, 0, "unknown 10101" },
437 { do_bad, SIGBUS, 0, "unknown 10110" },
438 { do_bad, SIGBUS, 0, "unknown 10111" },
439 { do_bad, SIGBUS, 0, "unknown 11000" },
440 { do_bad, SIGBUS, 0, "unknown 11001" },
441 { do_bad, SIGBUS, 0, "unknown 11010" },
442 { do_bad, SIGBUS, 0, "unknown 11011" },
443 { do_bad, SIGBUS, 0, "unknown 11100" },
444 { do_bad, SIGBUS, 0, "unknown 11101" },
445 { do_bad, SIGBUS, 0, "unknown 11110" },
446 { do_bad, SIGBUS, 0, "unknown 11111" }
447 };
448
hook_fault_code(int nr,int (* fn)(unsigned long,unsigned int,struct pt_regs *),int sig,int code,const char * name)449 void __init hook_fault_code(int nr,
450 int (*fn) (unsigned long, unsigned int, struct pt_regs *),
451 int sig, int code, const char *name)
452 {
453 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
454 BUG();
455
456 fsr_info[nr].fn = fn;
457 fsr_info[nr].sig = sig;
458 fsr_info[nr].code = code;
459 fsr_info[nr].name = name;
460 }
461
462 /*
463 * Dispatch a data abort to the relevant handler.
464 */
do_DataAbort(unsigned long addr,unsigned int fsr,struct pt_regs * regs)465 asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
466 struct pt_regs *regs)
467 {
468 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
469 struct siginfo info;
470
471 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
472 return;
473
474 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
475 inf->name, fsr, addr);
476
477 clear_siginfo(&info);
478 info.si_signo = inf->sig;
479 info.si_errno = 0;
480 info.si_code = inf->code;
481 info.si_addr = (void __user *)addr;
482 uc32_notify_die("", regs, &info, fsr, 0);
483 }
484
do_PrefetchAbort(unsigned long addr,unsigned int ifsr,struct pt_regs * regs)485 asmlinkage void do_PrefetchAbort(unsigned long addr,
486 unsigned int ifsr, struct pt_regs *regs)
487 {
488 const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
489 struct siginfo info;
490
491 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
492 return;
493
494 printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
495 inf->name, ifsr, addr);
496
497 clear_siginfo(&info);
498 info.si_signo = inf->sig;
499 info.si_errno = 0;
500 info.si_code = inf->code;
501 info.si_addr = (void __user *)addr;
502 uc32_notify_die("", regs, &info, ifsr, 0);
503 }
504