1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/arch/unicore32/mm/fault.c
4 *
5 * Code specific to PKUnity SoC and UniCore ISA
6 *
7 * Copyright (C) 2001-2010 GUAN Xue-tao
8 */
9 #include <linux/extable.h>
10 #include <linux/signal.h>
11 #include <linux/mm.h>
12 #include <linux/hardirq.h>
13 #include <linux/init.h>
14 #include <linux/kprobes.h>
15 #include <linux/uaccess.h>
16 #include <linux/page-flags.h>
17 #include <linux/sched/signal.h>
18 #include <linux/io.h>
19
20 #include <asm/pgtable.h>
21 #include <asm/tlbflush.h>
22
23 /*
24 * Fault status register encodings. We steal bit 31 for our own purposes.
25 */
26 #define FSR_LNX_PF (1 << 31)
27
fsr_fs(unsigned int fsr)28 static inline int fsr_fs(unsigned int fsr)
29 {
30 /* xyabcde will be abcde+xy */
31 return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
32 }
33
34 /*
35 * This is useful to dump out the page tables associated with
36 * 'addr' in mm 'mm'.
37 */
show_pte(struct mm_struct * mm,unsigned long addr)38 void show_pte(struct mm_struct *mm, unsigned long addr)
39 {
40 pgd_t *pgd;
41
42 if (!mm)
43 mm = &init_mm;
44
45 printk(KERN_ALERT "pgd = %p\n", mm->pgd);
46 pgd = pgd_offset(mm, addr);
47 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
48
49 do {
50 pmd_t *pmd;
51 pte_t *pte;
52
53 if (pgd_none(*pgd))
54 break;
55
56 if (pgd_bad(*pgd)) {
57 printk("(bad)");
58 break;
59 }
60
61 pmd = pmd_offset((pud_t *) pgd, addr);
62 if (PTRS_PER_PMD != 1)
63 printk(", *pmd=%08lx", pmd_val(*pmd));
64
65 if (pmd_none(*pmd))
66 break;
67
68 if (pmd_bad(*pmd)) {
69 printk("(bad)");
70 break;
71 }
72
73 /* We must not map this if we have highmem enabled */
74 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
75 break;
76
77 pte = pte_offset_map(pmd, addr);
78 printk(", *pte=%08lx", pte_val(*pte));
79 pte_unmap(pte);
80 } while (0);
81
82 printk("\n");
83 }
84
85 /*
86 * Oops. The kernel tried to access some page that wasn't present.
87 */
__do_kernel_fault(struct mm_struct * mm,unsigned long addr,unsigned int fsr,struct pt_regs * regs)88 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
89 unsigned int fsr, struct pt_regs *regs)
90 {
91 /*
92 * Are we prepared to handle this kernel fault?
93 */
94 if (fixup_exception(regs))
95 return;
96
97 /*
98 * No handler, we'll have to terminate things with extreme prejudice.
99 */
100 bust_spinlocks(1);
101 printk(KERN_ALERT
102 "Unable to handle kernel %s at virtual address %08lx\n",
103 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
104 "paging request", addr);
105
106 show_pte(mm, addr);
107 die("Oops", regs, fsr);
108 bust_spinlocks(0);
109 do_exit(SIGKILL);
110 }
111
112 /*
113 * Something tried to access memory that isn't in our memory map..
114 * User mode accesses just cause a SIGSEGV
115 */
__do_user_fault(unsigned long addr,unsigned int fsr,unsigned int sig,int code,struct pt_regs * regs)116 static void __do_user_fault(unsigned long addr, unsigned int fsr,
117 unsigned int sig, int code, struct pt_regs *regs)
118 {
119 struct task_struct *tsk = current;
120
121 tsk->thread.address = addr;
122 tsk->thread.error_code = fsr;
123 tsk->thread.trap_no = 14;
124 force_sig_fault(sig, code, (void __user *)addr);
125 }
126
do_bad_area(unsigned long addr,unsigned int fsr,struct pt_regs * regs)127 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
128 {
129 struct task_struct *tsk = current;
130 struct mm_struct *mm = tsk->active_mm;
131
132 /*
133 * If we are in kernel mode at this point, we
134 * have no context to handle this fault with.
135 */
136 if (user_mode(regs))
137 __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
138 else
139 __do_kernel_fault(mm, addr, fsr, regs);
140 }
141
142 #define VM_FAULT_BADMAP 0x010000
143 #define VM_FAULT_BADACCESS 0x020000
144
145 /*
146 * Check that the permissions on the VMA allow for the fault which occurred.
147 * If we encountered a write fault, we must have write permission, otherwise
148 * we allow any permission.
149 */
access_error(unsigned int fsr,struct vm_area_struct * vma)150 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
151 {
152 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
153
154 if (!(fsr ^ 0x12)) /* write? */
155 mask = VM_WRITE;
156 if (fsr & FSR_LNX_PF)
157 mask = VM_EXEC;
158
159 return vma->vm_flags & mask ? false : true;
160 }
161
__do_pf(struct mm_struct * mm,unsigned long addr,unsigned int fsr,unsigned int flags,struct task_struct * tsk)162 static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
163 unsigned int fsr, unsigned int flags, struct task_struct *tsk)
164 {
165 struct vm_area_struct *vma;
166 vm_fault_t fault;
167
168 vma = find_vma(mm, addr);
169 fault = VM_FAULT_BADMAP;
170 if (unlikely(!vma))
171 goto out;
172 if (unlikely(vma->vm_start > addr))
173 goto check_stack;
174
175 /*
176 * Ok, we have a good vm_area for this
177 * memory access, so we can handle it.
178 */
179 good_area:
180 if (access_error(fsr, vma)) {
181 fault = VM_FAULT_BADACCESS;
182 goto out;
183 }
184
185 /*
186 * If for any reason at all we couldn't handle the fault, make
187 * sure we exit gracefully rather than endlessly redo the fault.
188 */
189 fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
190 return fault;
191
192 check_stack:
193 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
194 goto good_area;
195 out:
196 return fault;
197 }
198
do_pf(unsigned long addr,unsigned int fsr,struct pt_regs * regs)199 static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
200 {
201 struct task_struct *tsk;
202 struct mm_struct *mm;
203 int sig, code;
204 vm_fault_t fault;
205 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
206
207 tsk = current;
208 mm = tsk->mm;
209
210 /*
211 * If we're in an interrupt or have no user
212 * context, we must not take the fault..
213 */
214 if (faulthandler_disabled() || !mm)
215 goto no_context;
216
217 if (user_mode(regs))
218 flags |= FAULT_FLAG_USER;
219 if (!(fsr ^ 0x12))
220 flags |= FAULT_FLAG_WRITE;
221
222 /*
223 * As per x86, we may deadlock here. However, since the kernel only
224 * validly references user space from well defined areas of the code,
225 * we can bug out early if this is from code which shouldn't.
226 */
227 if (!down_read_trylock(&mm->mmap_sem)) {
228 if (!user_mode(regs)
229 && !search_exception_tables(regs->UCreg_pc))
230 goto no_context;
231 retry:
232 down_read(&mm->mmap_sem);
233 } else {
234 /*
235 * The above down_read_trylock() might have succeeded in
236 * which case, we'll have missed the might_sleep() from
237 * down_read()
238 */
239 might_sleep();
240 #ifdef CONFIG_DEBUG_VM
241 if (!user_mode(regs) &&
242 !search_exception_tables(regs->UCreg_pc))
243 goto no_context;
244 #endif
245 }
246
247 fault = __do_pf(mm, addr, fsr, flags, tsk);
248
249 /* If we need to retry but a fatal signal is pending, handle the
250 * signal first. We do not need to release the mmap_sem because
251 * it would already be released in __lock_page_or_retry in
252 * mm/filemap.c. */
253 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
254 return 0;
255
256 if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
257 if (fault & VM_FAULT_MAJOR)
258 tsk->maj_flt++;
259 else
260 tsk->min_flt++;
261 if (fault & VM_FAULT_RETRY) {
262 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
263 * of starvation. */
264 flags &= ~FAULT_FLAG_ALLOW_RETRY;
265 goto retry;
266 }
267 }
268
269 up_read(&mm->mmap_sem);
270
271 /*
272 * Handle the "normal" case first - VM_FAULT_MAJOR
273 */
274 if (likely(!(fault &
275 (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
276 return 0;
277
278 /*
279 * If we are in kernel mode at this point, we
280 * have no context to handle this fault with.
281 */
282 if (!user_mode(regs))
283 goto no_context;
284
285 if (fault & VM_FAULT_OOM) {
286 /*
287 * We ran out of memory, call the OOM killer, and return to
288 * userspace (which will retry the fault, or kill us if we
289 * got oom-killed)
290 */
291 pagefault_out_of_memory();
292 return 0;
293 }
294
295 if (fault & VM_FAULT_SIGBUS) {
296 /*
297 * We had some memory, but were unable to
298 * successfully fix up this page fault.
299 */
300 sig = SIGBUS;
301 code = BUS_ADRERR;
302 } else {
303 /*
304 * Something tried to access memory that
305 * isn't in our memory map..
306 */
307 sig = SIGSEGV;
308 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
309 }
310
311 __do_user_fault(addr, fsr, sig, code, regs);
312 return 0;
313
314 no_context:
315 __do_kernel_fault(mm, addr, fsr, regs);
316 return 0;
317 }
318
319 /*
320 * First Level Translation Fault Handler
321 *
322 * We enter here because the first level page table doesn't contain
323 * a valid entry for the address.
324 *
325 * If the address is in kernel space (>= TASK_SIZE), then we are
326 * probably faulting in the vmalloc() area.
327 *
328 * If the init_task's first level page tables contains the relevant
329 * entry, we copy the it to this task. If not, we send the process
330 * a signal, fixup the exception, or oops the kernel.
331 *
332 * NOTE! We MUST NOT take any locks for this case. We may be in an
333 * interrupt or a critical region, and should only copy the information
334 * from the master page table, nothing more.
335 */
do_ifault(unsigned long addr,unsigned int fsr,struct pt_regs * regs)336 static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
337 {
338 unsigned int index;
339 pgd_t *pgd, *pgd_k;
340 pmd_t *pmd, *pmd_k;
341
342 if (addr < TASK_SIZE)
343 return do_pf(addr, fsr, regs);
344
345 if (user_mode(regs))
346 goto bad_area;
347
348 index = pgd_index(addr);
349
350 pgd = cpu_get_pgd() + index;
351 pgd_k = init_mm.pgd + index;
352
353 if (pgd_none(*pgd_k))
354 goto bad_area;
355
356 pmd_k = pmd_offset((pud_t *) pgd_k, addr);
357 pmd = pmd_offset((pud_t *) pgd, addr);
358
359 if (pmd_none(*pmd_k))
360 goto bad_area;
361
362 set_pmd(pmd, *pmd_k);
363 flush_pmd_entry(pmd);
364 return 0;
365
366 bad_area:
367 do_bad_area(addr, fsr, regs);
368 return 0;
369 }
370
371 /*
372 * This abort handler always returns "fault".
373 */
do_bad(unsigned long addr,unsigned int fsr,struct pt_regs * regs)374 static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
375 {
376 return 1;
377 }
378
do_good(unsigned long addr,unsigned int fsr,struct pt_regs * regs)379 static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
380 {
381 unsigned int res1, res2;
382
383 printk("dabt exception but no error!\n");
384
385 __asm__ __volatile__(
386 "mff %0,f0\n"
387 "mff %1,f1\n"
388 : "=r"(res1), "=r"(res2)
389 :
390 : "memory");
391
392 printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
393 panic("shut up\n");
394 return 0;
395 }
396
397 static struct fsr_info {
398 int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
399 int sig;
400 int code;
401 const char *name;
402 } fsr_info[] = {
403 /*
404 * The following are the standard Unicore-I and UniCore-II aborts.
405 */
406 { do_good, SIGBUS, 0, "no error" },
407 { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
408 { do_bad, SIGBUS, BUS_OBJERR, "external exception" },
409 { do_bad, SIGBUS, 0, "burst operation" },
410 { do_bad, SIGBUS, 0, "unknown 00100" },
411 { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
412 { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
413 { do_bad, SIGBUS, 0, "invalid pte" },
414 { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
415 { do_bad, SIGBUS, 0, "middle page miss" },
416 { do_bad, SIGBUS, 0, "large page miss" },
417 { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
418 { do_bad, SIGBUS, 0, "unknown 01100" },
419 { do_bad, SIGBUS, 0, "unknown 01101" },
420 { do_bad, SIGBUS, 0, "unknown 01110" },
421 { do_bad, SIGBUS, 0, "unknown 01111" },
422 { do_bad, SIGBUS, 0, "addr: up 3G or IO" },
423 { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
424 { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
425 { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
426 { do_bad, SIGBUS, 0, "unknown 10100" },
427 { do_bad, SIGBUS, 0, "unknown 10101" },
428 { do_bad, SIGBUS, 0, "unknown 10110" },
429 { do_bad, SIGBUS, 0, "unknown 10111" },
430 { do_bad, SIGBUS, 0, "unknown 11000" },
431 { do_bad, SIGBUS, 0, "unknown 11001" },
432 { do_bad, SIGBUS, 0, "unknown 11010" },
433 { do_bad, SIGBUS, 0, "unknown 11011" },
434 { do_bad, SIGBUS, 0, "unknown 11100" },
435 { do_bad, SIGBUS, 0, "unknown 11101" },
436 { do_bad, SIGBUS, 0, "unknown 11110" },
437 { do_bad, SIGBUS, 0, "unknown 11111" }
438 };
439
hook_fault_code(int nr,int (* fn)(unsigned long,unsigned int,struct pt_regs *),int sig,int code,const char * name)440 void __init hook_fault_code(int nr,
441 int (*fn) (unsigned long, unsigned int, struct pt_regs *),
442 int sig, int code, const char *name)
443 {
444 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
445 BUG();
446
447 fsr_info[nr].fn = fn;
448 fsr_info[nr].sig = sig;
449 fsr_info[nr].code = code;
450 fsr_info[nr].name = name;
451 }
452
453 /*
454 * Dispatch a data abort to the relevant handler.
455 */
do_DataAbort(unsigned long addr,unsigned int fsr,struct pt_regs * regs)456 asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
457 struct pt_regs *regs)
458 {
459 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
460
461 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
462 return;
463
464 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
465 inf->name, fsr, addr);
466
467 uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
468 fsr, 0);
469 }
470
do_PrefetchAbort(unsigned long addr,unsigned int ifsr,struct pt_regs * regs)471 asmlinkage void do_PrefetchAbort(unsigned long addr,
472 unsigned int ifsr, struct pt_regs *regs)
473 {
474 const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
475
476 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
477 return;
478
479 printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
480 inf->name, ifsr, addr);
481
482 uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
483 ifsr, 0);
484 }
485