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1 /* Page Fault Handling for ARC (TLB Miss / ProtV)
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
10 #include <linux/signal.h>
11 #include <linux/interrupt.h>
12 #include <linux/sched.h>
13 #include <linux/errno.h>
14 #include <linux/ptrace.h>
15 #include <linux/uaccess.h>
16 #include <linux/kdebug.h>
17 #include <asm/pgalloc.h>
19 static int handle_vmalloc_fault(struct mm_struct
*mm
, unsigned long address
)
22 * Synchronize this task's top level page-table
23 * with the 'reference' page table.
29 pgd
= pgd_offset_fast(mm
, address
);
30 pgd_k
= pgd_offset_k(address
);
32 if (!pgd_present(*pgd_k
))
35 pud
= pud_offset(pgd
, address
);
36 pud_k
= pud_offset(pgd_k
, address
);
37 if (!pud_present(*pud_k
))
40 pmd
= pmd_offset(pud
, address
);
41 pmd_k
= pmd_offset(pud_k
, address
);
42 if (!pmd_present(*pmd_k
))
47 /* XXX: create the TLB entry here */
54 void do_page_fault(struct pt_regs
*regs
, int write
, unsigned long address
,
55 unsigned long cause_code
)
57 struct vm_area_struct
*vma
= NULL
;
58 struct task_struct
*tsk
= current
;
59 struct mm_struct
*mm
= tsk
->mm
;
62 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
63 (write
? FAULT_FLAG_WRITE
: 0);
66 * We fault-in kernel-space virtual memory on-demand. The
67 * 'reference' page table is init_mm.pgd.
69 * NOTE! We MUST NOT take any locks for this case. We may
70 * be in an interrupt or a critical region, and should
71 * only copy the information from the master page table,
74 if (address
>= VMALLOC_START
&& address
<= VMALLOC_END
) {
75 ret
= handle_vmalloc_fault(mm
, address
);
77 goto bad_area_nosemaphore
;
82 info
.si_code
= SEGV_MAPERR
;
85 * If we're in an interrupt or have no user
86 * context, we must not take the fault..
88 if (in_atomic() || !mm
)
92 down_read(&mm
->mmap_sem
);
93 vma
= find_vma(mm
, address
);
96 if (vma
->vm_start
<= address
)
98 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
100 if (expand_stack(vma
, address
))
104 * Ok, we have a good vm_area for this memory access, so
108 info
.si_code
= SEGV_ACCERR
;
110 /* Handle protection violation, execute on heap or stack */
112 if (cause_code
== ((ECR_V_PROTV
<< 16) | ECR_C_PROTV_INST_FETCH
))
116 if (!(vma
->vm_flags
& VM_WRITE
))
119 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
125 * If for any reason at all we couldn't handle the fault,
126 * make sure we exit gracefully rather than endlessly redo
129 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
131 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
132 if (unlikely(fatal_signal_pending(current
))) {
133 if ((fault
& VM_FAULT_ERROR
) && !(fault
& VM_FAULT_RETRY
))
134 up_read(&mm
->mmap_sem
);
139 if (likely(!(fault
& VM_FAULT_ERROR
))) {
140 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
141 /* To avoid updating stats twice for retry case */
142 if (fault
& VM_FAULT_MAJOR
)
147 if (fault
& VM_FAULT_RETRY
) {
148 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
149 flags
|= FAULT_FLAG_TRIED
;
154 /* Fault Handled Gracefully */
155 up_read(&mm
->mmap_sem
);
159 /* TBD: switch to pagefault_out_of_memory() */
160 if (fault
& VM_FAULT_OOM
)
162 else if (fault
& VM_FAULT_SIGBUS
)
169 * Something tried to access memory that isn't in our memory map..
170 * Fix it, but check if it's kernel or user first..
173 up_read(&mm
->mmap_sem
);
175 bad_area_nosemaphore
:
176 /* User mode accesses just cause a SIGSEGV */
177 if (user_mode(regs
)) {
178 tsk
->thread
.fault_address
= address
;
179 tsk
->thread
.cause_code
= cause_code
;
180 info
.si_signo
= SIGSEGV
;
182 /* info.si_code has been set above */
183 info
.si_addr
= (void __user
*)address
;
184 force_sig_info(SIGSEGV
, &info
, tsk
);
189 /* Are we prepared to handle this kernel fault?
191 * (The kernel has valid exception-points in the source
192 * when it acesses user-memory. When it fails in one
193 * of those points, we find it in a table and do a jump
194 * to some fixup code that loads an appropriate error
197 if (fixup_exception(regs
))
200 die("Oops", regs
, address
, cause_code
);
203 if (is_global_init(tsk
)) {
207 up_read(&mm
->mmap_sem
);
210 do_group_exit(SIGKILL
); /* This will never return */
215 up_read(&mm
->mmap_sem
);
217 if (!user_mode(regs
))
220 tsk
->thread
.fault_address
= address
;
221 tsk
->thread
.cause_code
= cause_code
;
222 info
.si_signo
= SIGBUS
;
224 info
.si_code
= BUS_ADRERR
;
225 info
.si_addr
= (void __user
*)address
;
226 force_sig_info(SIGBUS
, &info
, tsk
);