2 * Page fault handler for SH with an MMU.
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 - 2012 Paul Mundt
7 * Based on linux/arch/i386/mm/fault.c:
8 * Copyright (C) 1995 Linus Torvalds
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
14 #include <linux/kernel.h>
16 #include <linux/hardirq.h>
17 #include <linux/kprobes.h>
18 #include <linux/perf_event.h>
19 #include <linux/kdebug.h>
20 #include <asm/io_trapped.h>
21 #include <asm/mmu_context.h>
22 #include <asm/tlbflush.h>
23 #include <asm/traps.h>
25 static inline int notify_page_fault(struct pt_regs
*regs
, int trap
)
29 if (kprobes_built_in() && !user_mode(regs
)) {
31 if (kprobe_running() && kprobe_fault_handler(regs
, trap
))
40 force_sig_info_fault(int si_signo
, int si_code
, unsigned long address
,
41 struct task_struct
*tsk
)
45 info
.si_signo
= si_signo
;
47 info
.si_code
= si_code
;
48 info
.si_addr
= (void __user
*)address
;
50 force_sig_info(si_signo
, &info
, tsk
);
54 * This is useful to dump out the page tables associated with
57 static void show_pte(struct mm_struct
*mm
, unsigned long addr
)
66 printk(KERN_ALERT
"pgd = %p\n", pgd
);
67 pgd
+= pgd_index(addr
);
68 printk(KERN_ALERT
"[%08lx] *pgd=%0*Lx", addr
,
69 (u32
)(sizeof(*pgd
) * 2), (u64
)pgd_val(*pgd
));
84 pud
= pud_offset(pgd
, addr
);
85 if (PTRS_PER_PUD
!= 1)
86 printk(", *pud=%0*Lx", (u32
)(sizeof(*pud
) * 2),
97 pmd
= pmd_offset(pud
, addr
);
98 if (PTRS_PER_PMD
!= 1)
99 printk(", *pmd=%0*Lx", (u32
)(sizeof(*pmd
) * 2),
110 /* We must not map this if we have highmem enabled */
111 if (PageHighMem(pfn_to_page(pmd_val(*pmd
) >> PAGE_SHIFT
)))
114 pte
= pte_offset_kernel(pmd
, addr
);
115 printk(", *pte=%0*Lx", (u32
)(sizeof(*pte
) * 2),
122 static inline pmd_t
*vmalloc_sync_one(pgd_t
*pgd
, unsigned long address
)
124 unsigned index
= pgd_index(address
);
130 pgd_k
= init_mm
.pgd
+ index
;
132 if (!pgd_present(*pgd_k
))
135 pud
= pud_offset(pgd
, address
);
136 pud_k
= pud_offset(pgd_k
, address
);
137 if (!pud_present(*pud_k
))
140 if (!pud_present(*pud
))
141 set_pud(pud
, *pud_k
);
143 pmd
= pmd_offset(pud
, address
);
144 pmd_k
= pmd_offset(pud_k
, address
);
145 if (!pmd_present(*pmd_k
))
148 if (!pmd_present(*pmd
))
149 set_pmd(pmd
, *pmd_k
);
152 * The page tables are fully synchronised so there must
153 * be another reason for the fault. Return NULL here to
154 * signal that we have not taken care of the fault.
156 BUG_ON(pmd_page(*pmd
) != pmd_page(*pmd_k
));
163 #ifdef CONFIG_SH_STORE_QUEUES
164 #define __FAULT_ADDR_LIMIT P3_ADDR_MAX
166 #define __FAULT_ADDR_LIMIT VMALLOC_END
170 * Handle a fault on the vmalloc or module mapping area
172 static noinline
int vmalloc_fault(unsigned long address
)
178 /* Make sure we are in vmalloc/module/P3 area: */
179 if (!(address
>= VMALLOC_START
&& address
< __FAULT_ADDR_LIMIT
))
183 * Synchronize this task's top level page-table
184 * with the 'reference' page table.
186 * Do _not_ use "current" here. We might be inside
187 * an interrupt in the middle of a task switch..
190 pmd_k
= vmalloc_sync_one(pgd_k
, address
);
194 pte_k
= pte_offset_kernel(pmd_k
, address
);
195 if (!pte_present(*pte_k
))
202 show_fault_oops(struct pt_regs
*regs
, unsigned long address
)
204 if (!oops_may_print())
207 printk(KERN_ALERT
"BUG: unable to handle kernel ");
208 if (address
< PAGE_SIZE
)
209 printk(KERN_CONT
"NULL pointer dereference");
211 printk(KERN_CONT
"paging request");
213 printk(KERN_CONT
" at %08lx\n", address
);
214 printk(KERN_ALERT
"PC:");
215 printk_address(regs
->pc
, 1);
217 show_pte(NULL
, address
);
221 no_context(struct pt_regs
*regs
, unsigned long error_code
,
222 unsigned long address
)
224 /* Are we prepared to handle this kernel fault? */
225 if (fixup_exception(regs
))
228 if (handle_trapped_io(regs
, address
))
232 * Oops. The kernel tried to access some bad page. We'll have to
233 * terminate things with extreme prejudice.
237 show_fault_oops(regs
, address
);
239 die("Oops", regs
, error_code
);
245 __bad_area_nosemaphore(struct pt_regs
*regs
, unsigned long error_code
,
246 unsigned long address
, int si_code
)
248 struct task_struct
*tsk
= current
;
250 /* User mode accesses just cause a SIGSEGV */
251 if (user_mode(regs
)) {
253 * It's possible to have interrupts off here:
257 force_sig_info_fault(SIGSEGV
, si_code
, address
, tsk
);
262 no_context(regs
, error_code
, address
);
266 bad_area_nosemaphore(struct pt_regs
*regs
, unsigned long error_code
,
267 unsigned long address
)
269 __bad_area_nosemaphore(regs
, error_code
, address
, SEGV_MAPERR
);
273 __bad_area(struct pt_regs
*regs
, unsigned long error_code
,
274 unsigned long address
, int si_code
)
276 struct mm_struct
*mm
= current
->mm
;
279 * Something tried to access memory that isn't in our memory map..
280 * Fix it, but check if it's kernel or user first..
282 up_read(&mm
->mmap_sem
);
284 __bad_area_nosemaphore(regs
, error_code
, address
, si_code
);
288 bad_area(struct pt_regs
*regs
, unsigned long error_code
, unsigned long address
)
290 __bad_area(regs
, error_code
, address
, SEGV_MAPERR
);
294 bad_area_access_error(struct pt_regs
*regs
, unsigned long error_code
,
295 unsigned long address
)
297 __bad_area(regs
, error_code
, address
, SEGV_ACCERR
);
300 static void out_of_memory(void)
303 * We ran out of memory, call the OOM killer, and return the userspace
304 * (which will retry the fault, or kill us if we got oom-killed):
306 up_read(¤t
->mm
->mmap_sem
);
308 pagefault_out_of_memory();
312 do_sigbus(struct pt_regs
*regs
, unsigned long error_code
, unsigned long address
)
314 struct task_struct
*tsk
= current
;
315 struct mm_struct
*mm
= tsk
->mm
;
317 up_read(&mm
->mmap_sem
);
319 /* Kernel mode? Handle exceptions or die: */
320 if (!user_mode(regs
))
321 no_context(regs
, error_code
, address
);
323 force_sig_info_fault(SIGBUS
, BUS_ADRERR
, address
, tsk
);
327 mm_fault_error(struct pt_regs
*regs
, unsigned long error_code
,
328 unsigned long address
, unsigned int fault
)
331 * Pagefault was interrupted by SIGKILL. We have no reason to
332 * continue pagefault.
334 if (fatal_signal_pending(current
)) {
335 if (!(fault
& VM_FAULT_RETRY
))
336 up_read(¤t
->mm
->mmap_sem
);
337 if (!user_mode(regs
))
338 no_context(regs
, error_code
, address
);
342 if (!(fault
& VM_FAULT_ERROR
))
345 if (fault
& VM_FAULT_OOM
) {
346 /* Kernel mode? Handle exceptions or die: */
347 if (!user_mode(regs
)) {
348 up_read(¤t
->mm
->mmap_sem
);
349 no_context(regs
, error_code
, address
);
355 if (fault
& VM_FAULT_SIGBUS
)
356 do_sigbus(regs
, error_code
, address
);
364 static inline int access_error(int error_code
, struct vm_area_struct
*vma
)
366 if (error_code
& FAULT_CODE_WRITE
) {
367 /* write, present and write, not present: */
368 if (unlikely(!(vma
->vm_flags
& VM_WRITE
)))
373 /* ITLB miss on NX page */
374 if (unlikely((error_code
& FAULT_CODE_ITLB
) &&
375 !(vma
->vm_flags
& VM_EXEC
)))
378 /* read, not present: */
379 if (unlikely(!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
))))
385 static int fault_in_kernel_space(unsigned long address
)
387 return address
>= TASK_SIZE
;
391 * This routine handles page faults. It determines the address,
392 * and the problem, and then passes it off to one of the appropriate
395 asmlinkage
void __kprobes
do_page_fault(struct pt_regs
*regs
,
396 unsigned long error_code
,
397 unsigned long address
)
400 struct task_struct
*tsk
;
401 struct mm_struct
*mm
;
402 struct vm_area_struct
* vma
;
404 int write
= error_code
& FAULT_CODE_WRITE
;
405 unsigned int flags
= (FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
406 (write
? FAULT_FLAG_WRITE
: 0));
410 vec
= lookup_exception_vector();
413 * We fault-in kernel-space virtual memory on-demand. The
414 * 'reference' page table is init_mm.pgd.
416 * NOTE! We MUST NOT take any locks for this case. We may
417 * be in an interrupt or a critical region, and should
418 * only copy the information from the master page table,
421 if (unlikely(fault_in_kernel_space(address
))) {
422 if (vmalloc_fault(address
) >= 0)
424 if (notify_page_fault(regs
, vec
))
427 bad_area_nosemaphore(regs
, error_code
, address
);
431 if (unlikely(notify_page_fault(regs
, vec
)))
434 /* Only enable interrupts if they were on before the fault */
435 if ((regs
->sr
& SR_IMASK
) != SR_IMASK
)
438 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS
, 1, regs
, address
);
441 * If we're in an interrupt, have no user context or are running
442 * in an atomic region then we must not take the fault:
444 if (unlikely(in_atomic() || !mm
)) {
445 bad_area_nosemaphore(regs
, error_code
, address
);
450 down_read(&mm
->mmap_sem
);
452 vma
= find_vma(mm
, address
);
453 if (unlikely(!vma
)) {
454 bad_area(regs
, error_code
, address
);
457 if (likely(vma
->vm_start
<= address
))
459 if (unlikely(!(vma
->vm_flags
& VM_GROWSDOWN
))) {
460 bad_area(regs
, error_code
, address
);
463 if (unlikely(expand_stack(vma
, address
))) {
464 bad_area(regs
, error_code
, address
);
469 * Ok, we have a good vm_area for this memory access, so
473 if (unlikely(access_error(error_code
, vma
))) {
474 bad_area_access_error(regs
, error_code
, address
);
478 set_thread_fault_code(error_code
);
481 * If for any reason at all we couldn't handle the fault,
482 * make sure we exit gracefully rather than endlessly redo
485 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
487 if (unlikely(fault
& (VM_FAULT_RETRY
| VM_FAULT_ERROR
)))
488 if (mm_fault_error(regs
, error_code
, address
, fault
))
491 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
492 if (fault
& VM_FAULT_MAJOR
) {
494 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1,
498 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1,
501 if (fault
& VM_FAULT_RETRY
) {
502 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
505 * No need to up_read(&mm->mmap_sem) as we would
506 * have already released it in __lock_page_or_retry
513 up_read(&mm
->mmap_sem
);