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1/*
2 * Page fault handler for SH with an MMU.
3 *
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2012 Paul Mundt
6 *
7 * Based on linux/arch/i386/mm/fault.c:
8 * Copyright (C) 1995 Linus Torvalds
9 *
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file "COPYING" in the main directory of this archive
12 * for more details.
13 */
14#include <linux/kernel.h>
15#include <linux/mm.h>
16#include <linux/sched/signal.h>
17#include <linux/hardirq.h>
18#include <linux/kprobes.h>
19#include <linux/perf_event.h>
20#include <linux/kdebug.h>
21#include <linux/uaccess.h>
22#include <asm/io_trapped.h>
23#include <asm/mmu_context.h>
24#include <asm/tlbflush.h>
25#include <asm/traps.h>
26
27static inline int notify_page_fault(struct pt_regs *regs, int trap)
28{
29 int ret = 0;
30
31 if (kprobes_built_in() && !user_mode(regs)) {
32 preempt_disable();
33 if (kprobe_running() && kprobe_fault_handler(regs, trap))
34 ret = 1;
35 preempt_enable();
36 }
37
38 return ret;
39}
40
41static void
42force_sig_info_fault(int si_signo, int si_code, unsigned long address,
43 struct task_struct *tsk)
44{
45 force_sig_fault(si_signo, si_code, (void __user *)address, tsk);
46}
47
48/*
49 * This is useful to dump out the page tables associated with
50 * 'addr' in mm 'mm'.
51 */
52static void show_pte(struct mm_struct *mm, unsigned long addr)
53{
54 pgd_t *pgd;
55
56 if (mm) {
57 pgd = mm->pgd;
58 } else {
59 pgd = get_TTB();
60
61 if (unlikely(!pgd))
62 pgd = swapper_pg_dir;
63 }
64
65 printk(KERN_ALERT "pgd = %p\n", pgd);
66 pgd += pgd_index(addr);
67 printk(KERN_ALERT "[%08lx] *pgd=%0*Lx", addr,
68 (u32)(sizeof(*pgd) * 2), (u64)pgd_val(*pgd));
69
70 do {
71 pud_t *pud;
72 pmd_t *pmd;
73 pte_t *pte;
74
75 if (pgd_none(*pgd))
76 break;
77
78 if (pgd_bad(*pgd)) {
79 printk("(bad)");
80 break;
81 }
82
83 pud = pud_offset(pgd, addr);
84 if (PTRS_PER_PUD != 1)
85 printk(", *pud=%0*Lx", (u32)(sizeof(*pud) * 2),
86 (u64)pud_val(*pud));
87
88 if (pud_none(*pud))
89 break;
90
91 if (pud_bad(*pud)) {
92 printk("(bad)");
93 break;
94 }
95
96 pmd = pmd_offset(pud, addr);
97 if (PTRS_PER_PMD != 1)
98 printk(", *pmd=%0*Lx", (u32)(sizeof(*pmd) * 2),
99 (u64)pmd_val(*pmd));
100
101 if (pmd_none(*pmd))
102 break;
103
104 if (pmd_bad(*pmd)) {
105 printk("(bad)");
106 break;
107 }
108
109 /* We must not map this if we have highmem enabled */
110 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
111 break;
112
113 pte = pte_offset_kernel(pmd, addr);
114 printk(", *pte=%0*Lx", (u32)(sizeof(*pte) * 2),
115 (u64)pte_val(*pte));
116 } while (0);
117
118 printk("\n");
119}
120
121static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
122{
123 unsigned index = pgd_index(address);
124 pgd_t *pgd_k;
125 pud_t *pud, *pud_k;
126 pmd_t *pmd, *pmd_k;
127
128 pgd += index;
129 pgd_k = init_mm.pgd + index;
130
131 if (!pgd_present(*pgd_k))
132 return NULL;
133
134 pud = pud_offset(pgd, address);
135 pud_k = pud_offset(pgd_k, address);
136 if (!pud_present(*pud_k))
137 return NULL;
138
139 if (!pud_present(*pud))
140 set_pud(pud, *pud_k);
141
142 pmd = pmd_offset(pud, address);
143 pmd_k = pmd_offset(pud_k, address);
144 if (!pmd_present(*pmd_k))
145 return NULL;
146
147 if (!pmd_present(*pmd))
148 set_pmd(pmd, *pmd_k);
149 else {
150 /*
151 * The page tables are fully synchronised so there must
152 * be another reason for the fault. Return NULL here to
153 * signal that we have not taken care of the fault.
154 */
155 BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
156 return NULL;
157 }
158
159 return pmd_k;
160}
161
162#ifdef CONFIG_SH_STORE_QUEUES
163#define __FAULT_ADDR_LIMIT P3_ADDR_MAX
164#else
165#define __FAULT_ADDR_LIMIT VMALLOC_END
166#endif
167
168/*
169 * Handle a fault on the vmalloc or module mapping area
170 */
171static noinline int vmalloc_fault(unsigned long address)
172{
173 pgd_t *pgd_k;
174 pmd_t *pmd_k;
175 pte_t *pte_k;
176
177 /* Make sure we are in vmalloc/module/P3 area: */
178 if (!(address >= VMALLOC_START && address < __FAULT_ADDR_LIMIT))
179 return -1;
180
181 /*
182 * Synchronize this task's top level page-table
183 * with the 'reference' page table.
184 *
185 * Do _not_ use "current" here. We might be inside
186 * an interrupt in the middle of a task switch..
187 */
188 pgd_k = get_TTB();
189 pmd_k = vmalloc_sync_one(pgd_k, address);
190 if (!pmd_k)
191 return -1;
192
193 pte_k = pte_offset_kernel(pmd_k, address);
194 if (!pte_present(*pte_k))
195 return -1;
196
197 return 0;
198}
199
200static void
201show_fault_oops(struct pt_regs *regs, unsigned long address)
202{
203 if (!oops_may_print())
204 return;
205
206 printk(KERN_ALERT "BUG: unable to handle kernel ");
207 if (address < PAGE_SIZE)
208 printk(KERN_CONT "NULL pointer dereference");
209 else
210 printk(KERN_CONT "paging request");
211
212 printk(KERN_CONT " at %08lx\n", address);
213 printk(KERN_ALERT "PC:");
214 printk_address(regs->pc, 1);
215
216 show_pte(NULL, address);
217}
218
219static noinline void
220no_context(struct pt_regs *regs, unsigned long error_code,
221 unsigned long address)
222{
223 /* Are we prepared to handle this kernel fault? */
224 if (fixup_exception(regs))
225 return;
226
227 if (handle_trapped_io(regs, address))
228 return;
229
230 /*
231 * Oops. The kernel tried to access some bad page. We'll have to
232 * terminate things with extreme prejudice.
233 */
234 bust_spinlocks(1);
235
236 show_fault_oops(regs, address);
237
238 die("Oops", regs, error_code);
239 bust_spinlocks(0);
240 do_exit(SIGKILL);
241}
242
243static void
244__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
245 unsigned long address, int si_code)
246{
247 struct task_struct *tsk = current;
248
249 /* User mode accesses just cause a SIGSEGV */
250 if (user_mode(regs)) {
251 /*
252 * It's possible to have interrupts off here:
253 */
254 local_irq_enable();
255
256 force_sig_info_fault(SIGSEGV, si_code, address, tsk);
257
258 return;
259 }
260
261 no_context(regs, error_code, address);
262}
263
264static noinline void
265bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
266 unsigned long address)
267{
268 __bad_area_nosemaphore(regs, error_code, address, SEGV_MAPERR);
269}
270
271static void
272__bad_area(struct pt_regs *regs, unsigned long error_code,
273 unsigned long address, int si_code)
274{
275 struct mm_struct *mm = current->mm;
276
277 /*
278 * Something tried to access memory that isn't in our memory map..
279 * Fix it, but check if it's kernel or user first..
280 */
281 up_read(&mm->mmap_sem);
282
283 __bad_area_nosemaphore(regs, error_code, address, si_code);
284}
285
286static noinline void
287bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address)
288{
289 __bad_area(regs, error_code, address, SEGV_MAPERR);
290}
291
292static noinline void
293bad_area_access_error(struct pt_regs *regs, unsigned long error_code,
294 unsigned long address)
295{
296 __bad_area(regs, error_code, address, SEGV_ACCERR);
297}
298
299static void
300do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address)
301{
302 struct task_struct *tsk = current;
303 struct mm_struct *mm = tsk->mm;
304
305 up_read(&mm->mmap_sem);
306
307 /* Kernel mode? Handle exceptions or die: */
308 if (!user_mode(regs))
309 no_context(regs, error_code, address);
310
311 force_sig_info_fault(SIGBUS, BUS_ADRERR, address, tsk);
312}
313
314static noinline int
315mm_fault_error(struct pt_regs *regs, unsigned long error_code,
316 unsigned long address, vm_fault_t fault)
317{
318 /*
319 * Pagefault was interrupted by SIGKILL. We have no reason to
320 * continue pagefault.
321 */
322 if (fatal_signal_pending(current)) {
323 if (!(fault & VM_FAULT_RETRY))
324 up_read(&current->mm->mmap_sem);
325 if (!user_mode(regs))
326 no_context(regs, error_code, address);
327 return 1;
328 }
329
330 if (!(fault & VM_FAULT_ERROR))
331 return 0;
332
333 if (fault & VM_FAULT_OOM) {
334 /* Kernel mode? Handle exceptions or die: */
335 if (!user_mode(regs)) {
336 up_read(&current->mm->mmap_sem);
337 no_context(regs, error_code, address);
338 return 1;
339 }
340 up_read(&current->mm->mmap_sem);
341
342 /*
343 * We ran out of memory, call the OOM killer, and return the
344 * userspace (which will retry the fault, or kill us if we got
345 * oom-killed):
346 */
347 pagefault_out_of_memory();
348 } else {
349 if (fault & VM_FAULT_SIGBUS)
350 do_sigbus(regs, error_code, address);
351 else if (fault & VM_FAULT_SIGSEGV)
352 bad_area(regs, error_code, address);
353 else
354 BUG();
355 }
356
357 return 1;
358}
359
360static inline int access_error(int error_code, struct vm_area_struct *vma)
361{
362 if (error_code & FAULT_CODE_WRITE) {
363 /* write, present and write, not present: */
364 if (unlikely(!(vma->vm_flags & VM_WRITE)))
365 return 1;
366 return 0;
367 }
368
369 /* ITLB miss on NX page */
370 if (unlikely((error_code & FAULT_CODE_ITLB) &&
371 !(vma->vm_flags & VM_EXEC)))
372 return 1;
373
374 /* read, not present: */
375 if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
376 return 1;
377
378 return 0;
379}
380
381static int fault_in_kernel_space(unsigned long address)
382{
383 return address >= TASK_SIZE;
384}
385
386/*
387 * This routine handles page faults. It determines the address,
388 * and the problem, and then passes it off to one of the appropriate
389 * routines.
390 */
391asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
392 unsigned long error_code,
393 unsigned long address)
394{
395 unsigned long vec;
396 struct task_struct *tsk;
397 struct mm_struct *mm;
398 struct vm_area_struct * vma;
399 vm_fault_t fault;
400 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
401
402 tsk = current;
403 mm = tsk->mm;
404 vec = lookup_exception_vector();
405
406 /*
407 * We fault-in kernel-space virtual memory on-demand. The
408 * 'reference' page table is init_mm.pgd.
409 *
410 * NOTE! We MUST NOT take any locks for this case. We may
411 * be in an interrupt or a critical region, and should
412 * only copy the information from the master page table,
413 * nothing more.
414 */
415 if (unlikely(fault_in_kernel_space(address))) {
416 if (vmalloc_fault(address) >= 0)
417 return;
418 if (notify_page_fault(regs, vec))
419 return;
420
421 bad_area_nosemaphore(regs, error_code, address);
422 return;
423 }
424
425 if (unlikely(notify_page_fault(regs, vec)))
426 return;
427
428 /* Only enable interrupts if they were on before the fault */
429 if ((regs->sr & SR_IMASK) != SR_IMASK)
430 local_irq_enable();
431
432 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
433
434 /*
435 * If we're in an interrupt, have no user context or are running
436 * with pagefaults disabled then we must not take the fault:
437 */
438 if (unlikely(faulthandler_disabled() || !mm)) {
439 bad_area_nosemaphore(regs, error_code, address);
440 return;
441 }
442
443retry:
444 down_read(&mm->mmap_sem);
445
446 vma = find_vma(mm, address);
447 if (unlikely(!vma)) {
448 bad_area(regs, error_code, address);
449 return;
450 }
451 if (likely(vma->vm_start <= address))
452 goto good_area;
453 if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
454 bad_area(regs, error_code, address);
455 return;
456 }
457 if (unlikely(expand_stack(vma, address))) {
458 bad_area(regs, error_code, address);
459 return;
460 }
461
462 /*
463 * Ok, we have a good vm_area for this memory access, so
464 * we can handle it..
465 */
466good_area:
467 if (unlikely(access_error(error_code, vma))) {
468 bad_area_access_error(regs, error_code, address);
469 return;
470 }
471
472 set_thread_fault_code(error_code);
473
474 if (user_mode(regs))
475 flags |= FAULT_FLAG_USER;
476 if (error_code & FAULT_CODE_WRITE)
477 flags |= FAULT_FLAG_WRITE;
478
479 /*
480 * If for any reason at all we couldn't handle the fault,
481 * make sure we exit gracefully rather than endlessly redo
482 * the fault.
483 */
484 fault = handle_mm_fault(vma, address, flags);
485
486 if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
487 if (mm_fault_error(regs, error_code, address, fault))
488 return;
489
490 if (flags & FAULT_FLAG_ALLOW_RETRY) {
491 if (fault & VM_FAULT_MAJOR) {
492 tsk->maj_flt++;
493 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
494 regs, address);
495 } else {
496 tsk->min_flt++;
497 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
498 regs, address);
499 }
500 if (fault & VM_FAULT_RETRY) {
501 flags &= ~FAULT_FLAG_ALLOW_RETRY;
502 flags |= FAULT_FLAG_TRIED;
503
504 /*
505 * No need to up_read(&mm->mmap_sem) as we would
506 * have already released it in __lock_page_or_retry
507 * in mm/filemap.c.
508 */
509 goto retry;
510 }
511 }
512
513 up_read(&mm->mmap_sem);
514}
515

Warning: That file was not part of the compilation database. It may have many parsing errors.