2 * Meta page fault handling.
4 * Copyright (C) 2005-2012 Imagination Technologies Ltd.
7 #include <linux/mman.h>
9 #include <linux/kernel.h>
10 #include <linux/ptrace.h>
11 #include <linux/interrupt.h>
12 #include <linux/uaccess.h>
14 #include <asm/tlbflush.h>
16 #include <asm/traps.h>
18 /* Clear any pending catch buffer state. */
19 static void clear_cbuf_entry(struct pt_regs
*regs
, unsigned long addr
,
22 PTBICTXEXTCB0 cbuf
= regs
->extcb0
;
25 /* Instruction fetch faults leave no catch buffer state. */
26 case TBIXXF_SIGNUM_IGF
:
27 case TBIXXF_SIGNUM_IPF
:
30 if (cbuf
[0].CBAddr
== addr
) {
32 cbuf
[0].CBFlags
&= ~TXCATCH0_FAULT_BITS
;
34 /* And, as this is the ONLY catch entry, we
35 * need to clear the cbuf bit from the context!
37 regs
->ctx
.SaveMask
&= ~(TBICTX_CBUF_BIT
|
42 pr_err("Failed to clear cbuf entry!\n");
46 int show_unhandled_signals
= 1;
48 int do_page_fault(struct pt_regs
*regs
, unsigned long address
,
49 unsigned int write_access
, unsigned int trapno
)
51 struct task_struct
*tsk
;
53 struct vm_area_struct
*vma
, *prev_vma
;
56 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
|
57 (write_access
? FAULT_FLAG_WRITE
: 0);
61 if ((address
>= VMALLOC_START
) && (address
< VMALLOC_END
)) {
63 * Synchronize this task's top level page-table
64 * with the 'reference' page table.
66 * Do _not_ use "tsk" here. We might be inside
67 * an interrupt in the middle of a task switch..
69 int offset
= pgd_index(address
);
75 pgd
= ((pgd_t
*)mmu_get_base()) + offset
;
76 pgd_k
= swapper_pg_dir
+ offset
;
78 /* This will never happen with the folded page table. */
79 if (!pgd_present(*pgd
)) {
80 if (!pgd_present(*pgd_k
))
81 goto bad_area_nosemaphore
;
86 pud
= pud_offset(pgd
, address
);
87 pud_k
= pud_offset(pgd_k
, address
);
88 if (!pud_present(*pud_k
))
89 goto bad_area_nosemaphore
;
92 pmd
= pmd_offset(pud
, address
);
93 pmd_k
= pmd_offset(pud_k
, address
);
94 if (!pmd_present(*pmd_k
))
95 goto bad_area_nosemaphore
;
98 pte_k
= pte_offset_kernel(pmd_k
, address
);
99 if (!pte_present(*pte_k
))
100 goto bad_area_nosemaphore
;
102 /* May only be needed on Chorus2 */
109 if (in_atomic() || !mm
)
113 down_read(&mm
->mmap_sem
);
115 vma
= find_vma_prev(mm
, address
, &prev_vma
);
117 if (!vma
|| address
< vma
->vm_start
)
118 goto check_expansion
;
122 if (!(vma
->vm_flags
& VM_WRITE
))
125 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
| VM_WRITE
)))
130 * If for any reason at all we couldn't handle the fault,
131 * make sure we exit gracefully rather than endlessly redo
134 fault
= handle_mm_fault(mm
, vma
, address
, flags
);
136 if ((fault
& VM_FAULT_RETRY
) && fatal_signal_pending(current
))
139 if (unlikely(fault
& VM_FAULT_ERROR
)) {
140 if (fault
& VM_FAULT_OOM
)
142 else if (fault
& VM_FAULT_SIGBUS
)
146 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
147 if (fault
& VM_FAULT_MAJOR
)
151 if (fault
& VM_FAULT_RETRY
) {
152 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
153 flags
|= FAULT_FLAG_TRIED
;
156 * No need to up_read(&mm->mmap_sem) as we would
157 * have already released it in __lock_page_or_retry
165 up_read(&mm
->mmap_sem
);
170 if (vma
&& (expand_stack(vma
, address
) == 0))
174 up_read(&mm
->mmap_sem
);
176 bad_area_nosemaphore
:
177 if (user_mode(regs
)) {
178 info
.si_signo
= SIGSEGV
;
180 info
.si_code
= SEGV_MAPERR
;
181 info
.si_addr
= (__force
void __user
*)address
;
182 info
.si_trapno
= trapno
;
184 if (show_unhandled_signals
&& unhandled_signal(tsk
, SIGSEGV
) &&
185 printk_ratelimit()) {
186 pr_info("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
187 task_pid_nr(tsk
) > 1 ? KERN_INFO
: KERN_EMERG
,
188 tsk
->comm
, task_pid_nr(tsk
), address
,
189 regs
->ctx
.CurrPC
, regs
->ctx
.AX
[0].U0
,
190 write_access
, trapno
, trap_name(trapno
));
191 print_vma_addr(" in ", regs
->ctx
.CurrPC
);
192 print_vma_addr(" rtp in ", regs
->ctx
.DX
[4].U1
);
196 force_sig_info(SIGSEGV
, &info
, tsk
);
202 up_read(&mm
->mmap_sem
);
205 * Send a sigbus, regardless of whether we were in kernel
208 info
.si_signo
= SIGBUS
;
210 info
.si_code
= BUS_ADRERR
;
211 info
.si_addr
= (__force
void __user
*)address
;
212 info
.si_trapno
= trapno
;
213 force_sig_info(SIGBUS
, &info
, tsk
);
215 /* Kernel mode? Handle exceptions or die */
216 if (!user_mode(regs
))
222 * We ran out of memory, or some other thing happened to us that made
223 * us unable to handle the page fault gracefully.
226 up_read(&mm
->mmap_sem
);
228 do_group_exit(SIGKILL
);
231 /* Are we prepared to handle this kernel fault? */
232 if (fixup_exception(regs
)) {
233 clear_cbuf_entry(regs
, address
, trapno
);
237 die("Oops", regs
, (write_access
<< 15) | trapno
, address
);