2 * Copyright (C) 2004-2006 Atmel Corporation
4 * Based on linux/arch/sh/mm/fault.c:
5 * Copyright (C) 1999 Niibe Yutaka
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
13 #include <linux/module.h>
14 #include <linux/pagemap.h>
16 #include <linux/kdebug.h>
17 #include <asm/mmu_context.h>
18 #include <asm/sysreg.h>
20 #include <asm/uaccess.h>
23 ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain
);
25 /* Hook to register for page fault notifications */
26 int register_page_fault_notifier(struct notifier_block
*nb
)
28 return atomic_notifier_chain_register(¬ify_page_fault_chain
, nb
);
31 int unregister_page_fault_notifier(struct notifier_block
*nb
)
33 return atomic_notifier_chain_unregister(¬ify_page_fault_chain
, nb
);
36 static inline int notify_page_fault(enum die_val val
, struct pt_regs
*regs
,
39 struct die_args args
= {
43 return atomic_notifier_call_chain(¬ify_page_fault_chain
, val
, &args
);
46 static inline int notify_page_fault(enum die_val val
, struct pt_regs
*regs
,
53 int exception_trace
= 1;
56 * This routine handles page faults. It determines the address and the
57 * problem, and then passes it off to one of the appropriate routines.
59 * ecr is the Exception Cause Register. Possible values are:
60 * 6: Protection fault (instruction access)
61 * 15: Protection fault (read access)
62 * 16: Protection fault (write access)
63 * 20: Page not found (instruction access)
64 * 24: Page not found (read access)
65 * 28: Page not found (write access)
67 asmlinkage
void do_page_fault(unsigned long ecr
, struct pt_regs
*regs
)
69 struct task_struct
*tsk
;
71 struct vm_area_struct
*vma
;
72 const struct exception_table_entry
*fixup
;
73 unsigned long address
;
79 if (notify_page_fault(DIE_PAGE_FAULT
, regs
,
80 ecr
, SIGSEGV
) == NOTIFY_STOP
)
83 address
= sysreg_read(TLBEAR
);
92 * If we're in an interrupt or have no user context, we must
93 * not take the fault...
95 if (in_atomic() || !mm
|| regs
->sr
& SYSREG_BIT(GM
))
100 down_read(&mm
->mmap_sem
);
102 vma
= find_vma(mm
, address
);
105 if (vma
->vm_start
<= address
)
107 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
109 if (expand_stack(vma
, address
))
113 * Ok, we have a good vm_area for this memory access, so we
121 case ECR_PROTECTION_X
:
123 if (!(vma
->vm_flags
& VM_EXEC
))
126 case ECR_PROTECTION_R
:
128 if (!(vma
->vm_flags
& (VM_READ
| VM_WRITE
| VM_EXEC
)))
131 case ECR_PROTECTION_W
:
133 if (!(vma
->vm_flags
& VM_WRITE
))
138 panic("Unhandled case %lu in do_page_fault!", ecr
);
142 * If for any reason at all we couldn't handle the fault, make
143 * sure we exit gracefully rather than endlessly redo the
147 switch (handle_mm_fault(mm
, vma
, address
, writeaccess
)) {
154 case VM_FAULT_SIGBUS
:
162 up_read(&mm
->mmap_sem
);
166 * Something tried to access memory that isn't in our memory
167 * map. Fix it, but check if it's kernel or user first...
170 up_read(&mm
->mmap_sem
);
172 if (user_mode(regs
)) {
174 printk("%s%s[%d]: segfault at %08lx pc %08lx "
175 "sp %08lx ecr %lu\n",
176 is_init(tsk
) ? KERN_EMERG
: KERN_INFO
,
177 tsk
->comm
, tsk
->pid
, address
, regs
->pc
,
179 _exception(SIGSEGV
, regs
, code
, address
);
184 /* Are we prepared to handle this kernel fault? */
185 fixup
= search_exception_tables(regs
->pc
);
187 regs
->pc
= fixup
->fixup
;
192 * Oops. The kernel tried to access some bad page. We'll have
193 * to terminate things with extreme prejudice.
195 if (address
< PAGE_SIZE
)
197 "Unable to handle kernel NULL pointer dereference");
200 "Unable to handle kernel paging request");
201 printk(" at virtual address %08lx\n", address
);
203 page
= sysreg_read(PTBR
);
204 printk(KERN_ALERT
"ptbr = %08lx", page
);
206 page
= ((unsigned long *)page
)[address
>> 22];
207 printk(" pgd = %08lx", page
);
208 if (page
& _PAGE_PRESENT
) {
210 address
&= 0x003ff000;
211 page
= ((unsigned long *)__va(page
))[address
>> PAGE_SHIFT
];
212 printk(" pte = %08lx", page
);
216 die("Kernel access of bad area", regs
, signr
);
220 * We ran out of memory, or some other thing happened to us
221 * that made us unable to handle the page fault gracefully.
224 up_read(&mm
->mmap_sem
);
225 if (is_init(current
)) {
227 down_read(&mm
->mmap_sem
);
230 printk("VM: Killing process %s\n", tsk
->comm
);
236 up_read(&mm
->mmap_sem
);
238 /* Kernel mode? Handle exceptions or die */
241 if (!user_mode(regs
))
245 printk("%s%s[%d]: bus error at %08lx pc %08lx "
246 "sp %08lx ecr %lu\n",
247 is_init(tsk
) ? KERN_EMERG
: KERN_INFO
,
248 tsk
->comm
, tsk
->pid
, address
, regs
->pc
,
251 _exception(SIGBUS
, regs
, BUS_ADRERR
, address
);
254 asmlinkage
void do_bus_error(unsigned long addr
, int write_access
,
255 struct pt_regs
*regs
)
258 "Bus error at physical address 0x%08lx (%s access)\n",
259 addr
, write_access
? "write" : "read");
260 printk(KERN_INFO
"DTLB dump:\n");
262 die("Bus Error", regs
, SIGKILL
);
266 * This functionality is currently not possible to implement because
267 * we're using segmentation to ensure a fixed mapping of the kernel
268 * virtual address space.
270 * It would be possible to implement this, but it would require us to
271 * disable segmentation at startup and load the kernel mappings into
272 * the TLB like any other pages. There will be lots of trickery to
273 * avoid recursive invocation of the TLB miss handler, though...
275 #ifdef CONFIG_DEBUG_PAGEALLOC
276 void kernel_map_pages(struct page
*page
, int numpages
, int enable
)
280 EXPORT_SYMBOL(kernel_map_pages
);
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