2 * Page fault handler for SH with an MMU.
4 * Copyright (C) 1999 Niibe Yutaka
5 * Copyright (C) 2003 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 <asm/system.h>
19 #include <asm/mmu_context.h>
22 extern void die(const char *,struct pt_regs
*,long);
25 * This routine handles page faults. It determines the address,
26 * and the problem, and then passes it off to one of the appropriate
29 asmlinkage
void __kprobes
do_page_fault(struct pt_regs
*regs
,
30 unsigned long writeaccess
,
31 unsigned long address
)
33 struct task_struct
*tsk
;
35 struct vm_area_struct
* vma
;
44 if (kgdb_nofault
&& kgdb_bus_err_hook
)
50 si_code
= SEGV_MAPERR
;
52 if (unlikely(address
>= TASK_SIZE
)) {
54 * Synchronize this task's top level page-table
55 * with the 'reference' page table.
57 * Do _not_ use "tsk" here. We might be inside
58 * an interrupt in the middle of a task switch..
60 int offset
= pgd_index(address
);
65 pgd
= get_TTB() + offset
;
66 pgd_k
= swapper_pg_dir
+ offset
;
68 /* This will never happen with the folded page table. */
69 if (!pgd_present(*pgd
)) {
70 if (!pgd_present(*pgd_k
))
71 goto bad_area_nosemaphore
;
76 pud
= pud_offset(pgd
, address
);
77 pud_k
= pud_offset(pgd_k
, address
);
78 if (pud_present(*pud
) || !pud_present(*pud_k
))
79 goto bad_area_nosemaphore
;
82 pmd
= pmd_offset(pud
, address
);
83 pmd_k
= pmd_offset(pud_k
, address
);
84 if (pmd_present(*pmd
) || !pmd_present(*pmd_k
))
85 goto bad_area_nosemaphore
;
92 * If we're in an interrupt or have no user
93 * context, we must not take the fault..
95 if (in_atomic() || !mm
)
98 down_read(&mm
->mmap_sem
);
100 vma
= find_vma(mm
, address
);
103 if (vma
->vm_start
<= address
)
105 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
107 if (expand_stack(vma
, address
))
110 * Ok, we have a good vm_area for this memory access, so
114 si_code
= SEGV_ACCERR
;
116 if (!(vma
->vm_flags
& VM_WRITE
))
119 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)))
124 * If for any reason at all we couldn't handle the fault,
125 * make sure we exit gracefully rather than endlessly redo
129 switch (handle_mm_fault(mm
, vma
, address
, writeaccess
)) {
136 case VM_FAULT_SIGBUS
:
144 up_read(&mm
->mmap_sem
);
148 * Something tried to access memory that isn't in our memory map..
149 * Fix it, but check if it's kernel or user first..
152 up_read(&mm
->mmap_sem
);
154 bad_area_nosemaphore
:
155 if (user_mode(regs
)) {
156 info
.si_signo
= SIGSEGV
;
158 info
.si_code
= si_code
;
159 info
.si_addr
= (void *) address
;
160 force_sig_info(SIGSEGV
, &info
, tsk
);
165 /* Are we prepared to handle this kernel fault? */
166 if (fixup_exception(regs
))
170 * Oops. The kernel tried to access some bad page. We'll have to
171 * terminate things with extreme prejudice.
174 if (address
< PAGE_SIZE
)
175 printk(KERN_ALERT
"Unable to handle kernel NULL pointer dereference");
177 printk(KERN_ALERT
"Unable to handle kernel paging request");
178 printk(" at virtual address %08lx\n", address
);
179 printk(KERN_ALERT
"pc = %08lx\n", regs
->pc
);
180 page
= (unsigned long)get_TTB();
182 page
= ((unsigned long *) page
)[address
>> PGDIR_SHIFT
];
183 printk(KERN_ALERT
"*pde = %08lx\n", page
);
184 if (page
& _PAGE_PRESENT
) {
186 address
&= 0x003ff000;
187 page
= ((unsigned long *) __va(page
))[address
>> PAGE_SHIFT
];
188 printk(KERN_ALERT
"*pte = %08lx\n", page
);
191 die("Oops", regs
, writeaccess
);
195 * We ran out of memory, or some other thing happened to us that made
196 * us unable to handle the page fault gracefully.
199 up_read(&mm
->mmap_sem
);
200 if (is_init(current
)) {
202 down_read(&mm
->mmap_sem
);
205 printk("VM: killing process %s\n", tsk
->comm
);
211 up_read(&mm
->mmap_sem
);
214 * Send a sigbus, regardless of whether we were in kernel
217 info
.si_signo
= SIGBUS
;
219 info
.si_code
= BUS_ADRERR
;
220 info
.si_addr
= (void *)address
;
221 force_sig_info(SIGBUS
, &info
, tsk
);
223 /* Kernel mode? Handle exceptions or die */
224 if (!user_mode(regs
))