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/signal.h>
13 #include <linux/errno.h>
14 #include <linux/ptrace.h>
15 #include <linux/uaccess.h>
16 #include <linux/kdebug.h>
17 #include <linux/perf_event.h>
18 #include <asm/pgalloc.h>
22 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
23 * Refer to asm/processor.h for System Memory Map
25 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
26 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
28 noinline
static int handle_kernel_vaddr_fault(unsigned long address
)
31 * Synchronize this task's top level page-table
32 * with the 'reference' page table.
38 pgd
= pgd_offset_fast(current
->active_mm
, address
);
39 pgd_k
= pgd_offset_k(address
);
41 if (!pgd_present(*pgd_k
))
44 pud
= pud_offset(pgd
, address
);
45 pud_k
= pud_offset(pgd_k
, address
);
46 if (!pud_present(*pud_k
))
49 pmd
= pmd_offset(pud
, address
);
50 pmd_k
= pmd_offset(pud_k
, address
);
51 if (!pmd_present(*pmd_k
))
56 /* XXX: create the TLB entry here */
63 void do_page_fault(unsigned long address
, struct pt_regs
*regs
)
65 struct vm_area_struct
*vma
= NULL
;
66 struct task_struct
*tsk
= current
;
67 struct mm_struct
*mm
= tsk
->mm
;
70 int write
= regs
->ecr_cause
& ECR_C_PROTV_STORE
; /* ST/EX */
71 unsigned int flags
= FAULT_FLAG_ALLOW_RETRY
| FAULT_FLAG_KILLABLE
;
76 * We fault-in kernel-space virtual memory on-demand. The
77 * 'reference' page table is init_mm.pgd.
79 * NOTE! We MUST NOT take any locks for this case. We may
80 * be in an interrupt or a critical region, and should
81 * only copy the information from the master page table,
84 if (address
>= VMALLOC_START
) {
85 ret
= handle_kernel_vaddr_fault(address
);
87 goto bad_area_nosemaphore
;
92 info
.si_code
= SEGV_MAPERR
;
95 * If we're in an interrupt or have no user
96 * context, we must not take the fault..
98 if (faulthandler_disabled() || !mm
)
102 flags
|= FAULT_FLAG_USER
;
104 down_read(&mm
->mmap_sem
);
105 vma
= find_vma(mm
, address
);
108 if (vma
->vm_start
<= address
)
110 if (!(vma
->vm_flags
& VM_GROWSDOWN
))
112 if (expand_stack(vma
, address
))
116 * Ok, we have a good vm_area for this memory access, so
120 info
.si_code
= SEGV_ACCERR
;
122 /* Handle protection violation, execute on heap or stack */
124 if ((regs
->ecr_vec
== ECR_V_PROTV
) &&
125 (regs
->ecr_cause
== ECR_C_PROTV_INST_FETCH
))
129 if (!(vma
->vm_flags
& VM_WRITE
))
131 flags
|= FAULT_FLAG_WRITE
;
133 if (!(vma
->vm_flags
& (VM_READ
| VM_EXEC
)))
138 * If for any reason at all we couldn't handle the fault,
139 * make sure we exit gracefully rather than endlessly redo
142 fault
= handle_mm_fault(vma
, address
, flags
);
144 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
145 if (unlikely(fatal_signal_pending(current
))) {
146 if ((fault
& VM_FAULT_ERROR
) && !(fault
& VM_FAULT_RETRY
))
147 up_read(&mm
->mmap_sem
);
152 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS
, 1, regs
, address
);
154 if (likely(!(fault
& VM_FAULT_ERROR
))) {
155 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
156 /* To avoid updating stats twice for retry case */
157 if (fault
& VM_FAULT_MAJOR
) {
159 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ
, 1,
163 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN
, 1,
167 if (fault
& VM_FAULT_RETRY
) {
168 flags
&= ~FAULT_FLAG_ALLOW_RETRY
;
169 flags
|= FAULT_FLAG_TRIED
;
174 /* Fault Handled Gracefully */
175 up_read(&mm
->mmap_sem
);
179 if (fault
& VM_FAULT_OOM
)
181 else if (fault
& VM_FAULT_SIGSEGV
)
183 else if (fault
& VM_FAULT_SIGBUS
)
190 * Something tried to access memory that isn't in our memory map..
191 * Fix it, but check if it's kernel or user first..
194 up_read(&mm
->mmap_sem
);
196 bad_area_nosemaphore
:
197 /* User mode accesses just cause a SIGSEGV */
198 if (user_mode(regs
)) {
199 tsk
->thread
.fault_address
= address
;
200 info
.si_signo
= SIGSEGV
;
202 /* info.si_code has been set above */
203 info
.si_addr
= (void __user
*)address
;
204 force_sig_info(SIGSEGV
, &info
, tsk
);
209 /* Are we prepared to handle this kernel fault?
211 * (The kernel has valid exception-points in the source
212 * when it accesses user-memory. When it fails in one
213 * of those points, we find it in a table and do a jump
214 * to some fixup code that loads an appropriate error
217 if (fixup_exception(regs
))
220 die("Oops", regs
, address
);
223 up_read(&mm
->mmap_sem
);
225 if (user_mode(regs
)) {
226 pagefault_out_of_memory();
233 up_read(&mm
->mmap_sem
);
235 if (!user_mode(regs
))
238 tsk
->thread
.fault_address
= address
;
239 info
.si_signo
= SIGBUS
;
241 info
.si_code
= BUS_ADRERR
;
242 info
.si_addr
= (void __user
*)address
;
243 force_sig_info(SIGBUS
, &info
, tsk
);