2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
6 * Copyright (C) 1995 - 2000 by Ralf Baechle
8 #include <linux/signal.h>
9 #include <linux/sched.h>
10 #include <linux/interrupt.h>
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/string.h>
14 #include <linux/types.h>
15 #include <linux/ptrace.h>
16 #include <linux/mman.h>
18 #include <linux/smp.h>
19 #include <linux/vt_kern.h> /* For unblank_screen() */
20 #include <linux/module.h>
22 #include <asm/branch.h>
23 #include <asm/mmu_context.h>
24 #include <asm/system.h>
25 #include <asm/uaccess.h>
26 #include <asm/ptrace.h>
27 #include <asm/highmem.h> /* For VMALLOC_END */
30 * This routine handles page faults. It determines the address,
31 * and the problem, and then passes it off to one of the appropriate
34 asmlinkage
void do_page_fault(struct pt_regs
*regs
, unsigned long write
,
35 unsigned long address
)
37 struct vm_area_struct
* vma
= NULL
;
38 struct task_struct
*tsk
= current
;
39 struct mm_struct
*mm
= tsk
->mm
;
40 const int field
= sizeof(unsigned long) * 2;
44 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(),
45 current
->comm
, current
->pid
, field
, address
, write
,
46 field
, regs
->cp0_epc
);
49 info
.si_code
= SEGV_MAPERR
;
52 * We fault-in kernel-space virtual memory on-demand. The
53 * 'reference' page table is init_mm.pgd.
55 * NOTE! We MUST NOT take any locks for this case. We may
56 * be in an interrupt or a critical region, and should
57 * only copy the information from the master page table,
60 if (unlikely(address
>= VMALLOC_START
&& address
<= VMALLOC_END
))
63 if (unlikely(address
>= MODULE_START
&& address
< MODULE_END
))
68 * If we're in an interrupt or have no user
69 * context, we must not take the fault..
71 if (in_atomic() || !mm
)
72 goto bad_area_nosemaphore
;
74 down_read(&mm
->mmap_sem
);
75 vma
= find_vma(mm
, address
);
78 if (vma
->vm_start
<= address
)
80 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
82 if (expand_stack(vma
, address
))
85 * Ok, we have a good vm_area for this memory access, so
89 info
.si_code
= SEGV_ACCERR
;
92 if (!(vma
->vm_flags
& VM_WRITE
))
95 if (!(vma
->vm_flags
& (VM_READ
| VM_WRITE
| VM_EXEC
)))
101 * If for any reason at all we couldn't handle the fault,
102 * make sure we exit gracefully rather than endlessly redo
105 switch (handle_mm_fault(mm
, vma
, address
, write
)) {
112 case VM_FAULT_SIGBUS
:
120 up_read(&mm
->mmap_sem
);
124 * Something tried to access memory that isn't in our memory map..
125 * Fix it, but check if it's kernel or user first..
128 up_read(&mm
->mmap_sem
);
130 bad_area_nosemaphore
:
131 /* User mode accesses just cause a SIGSEGV */
132 if (user_mode(regs
)) {
133 tsk
->thread
.cp0_badvaddr
= address
;
134 tsk
->thread
.error_code
= write
;
136 printk("do_page_fault() #2: sending SIGSEGV to %s for "
137 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
139 write
? "write access to" : "read access from",
141 field
, (unsigned long) regs
->cp0_epc
,
142 field
, (unsigned long) regs
->regs
[31]);
144 info
.si_signo
= SIGSEGV
;
146 /* info.si_code has been set above */
147 info
.si_addr
= (void __user
*) address
;
148 force_sig_info(SIGSEGV
, &info
, tsk
);
153 /* Are we prepared to handle this kernel fault? */
154 if (fixup_exception(regs
)) {
155 current
->thread
.cp0_baduaddr
= address
;
160 * Oops. The kernel tried to access some bad page. We'll have to
161 * terminate things with extreme prejudice.
165 printk(KERN_ALERT
"CPU %d Unable to handle kernel paging request at "
166 "virtual address %0*lx, epc == %0*lx, ra == %0*lx\n",
167 raw_smp_processor_id(), field
, address
, field
, regs
->cp0_epc
,
168 field
, regs
->regs
[31]);
172 * We ran out of memory, or some other thing happened to us that made
173 * us unable to handle the page fault gracefully.
176 up_read(&mm
->mmap_sem
);
179 down_read(&mm
->mmap_sem
);
182 printk("VM: killing process %s\n", tsk
->comm
);
188 up_read(&mm
->mmap_sem
);
190 /* Kernel mode? Handle exceptions or die */
191 if (!user_mode(regs
))
195 * Send a sigbus, regardless of whether we were in kernel
199 printk("do_page_fault() #3: sending SIGBUS to %s for "
200 "invalid %s\n%0*lx (epc == %0*lx, ra == %0*lx)\n",
202 write
? "write access to" : "read access from",
204 field
, (unsigned long) regs
->cp0_epc
,
205 field
, (unsigned long) regs
->regs
[31]);
207 tsk
->thread
.cp0_badvaddr
= address
;
208 info
.si_signo
= SIGBUS
;
210 info
.si_code
= BUS_ADRERR
;
211 info
.si_addr
= (void __user
*) address
;
212 force_sig_info(SIGBUS
, &info
, tsk
);
218 * Synchronize this task's top level page-table
219 * with the 'reference' page table.
221 * Do _not_ use "tsk" here. We might be inside
222 * an interrupt in the middle of a task switch..
224 int offset
= __pgd_offset(address
);
230 pgd
= (pgd_t
*) pgd_current
[raw_smp_processor_id()] + offset
;
231 pgd_k
= init_mm
.pgd
+ offset
;
233 if (!pgd_present(*pgd_k
))
235 set_pgd(pgd
, *pgd_k
);
237 pud
= pud_offset(pgd
, address
);
238 pud_k
= pud_offset(pgd_k
, address
);
239 if (!pud_present(*pud_k
))
242 pmd
= pmd_offset(pud
, address
);
243 pmd_k
= pmd_offset(pud_k
, address
);
244 if (!pmd_present(*pmd_k
))
246 set_pmd(pmd
, *pmd_k
);
248 pte_k
= pte_offset_kernel(pmd_k
, address
);
249 if (!pte_present(*pte_k
))