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fbd7053a VG |
1 | /* Page Fault Handling for ARC (TLB Miss / ProtV) |
2 | * | |
3 | * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) | |
4 | * | |
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. | |
8 | */ | |
9 | ||
10 | #include <linux/signal.h> | |
11 | #include <linux/interrupt.h> | |
3f07c014 | 12 | #include <linux/sched/signal.h> |
fbd7053a VG |
13 | #include <linux/errno.h> |
14 | #include <linux/ptrace.h> | |
fbd7053a VG |
15 | #include <linux/uaccess.h> |
16 | #include <linux/kdebug.h> | |
ceed97ab | 17 | #include <linux/perf_event.h> |
50a7ca3c | 18 | #include <linux/mm_types.h> |
fbd7053a | 19 | #include <asm/pgalloc.h> |
da1677b0 | 20 | #include <asm/mmu.h> |
fbd7053a | 21 | |
336e2136 VG |
22 | /* |
23 | * kernel virtual address is required to implement vmalloc/pkmap/fixmap | |
24 | * Refer to asm/processor.h for System Memory Map | |
25 | * | |
26 | * It simply copies the PMD entry (pointer to 2nd level page table or hugepage) | |
27 | * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared | |
28 | */ | |
29 | noinline static int handle_kernel_vaddr_fault(unsigned long address) | |
fbd7053a VG |
30 | { |
31 | /* | |
32 | * Synchronize this task's top level page-table | |
33 | * with the 'reference' page table. | |
34 | */ | |
35 | pgd_t *pgd, *pgd_k; | |
36 | pud_t *pud, *pud_k; | |
37 | pmd_t *pmd, *pmd_k; | |
38 | ||
9c41f4ee | 39 | pgd = pgd_offset_fast(current->active_mm, address); |
fbd7053a VG |
40 | pgd_k = pgd_offset_k(address); |
41 | ||
42 | if (!pgd_present(*pgd_k)) | |
43 | goto bad_area; | |
44 | ||
45 | pud = pud_offset(pgd, address); | |
46 | pud_k = pud_offset(pgd_k, address); | |
47 | if (!pud_present(*pud_k)) | |
48 | goto bad_area; | |
49 | ||
50 | pmd = pmd_offset(pud, address); | |
51 | pmd_k = pmd_offset(pud_k, address); | |
52 | if (!pmd_present(*pmd_k)) | |
53 | goto bad_area; | |
54 | ||
55 | set_pmd(pmd, *pmd_k); | |
56 | ||
57 | /* XXX: create the TLB entry here */ | |
58 | return 0; | |
59 | ||
60 | bad_area: | |
61 | return 1; | |
62 | } | |
63 | ||
21a63b56 | 64 | void do_page_fault(unsigned long address, struct pt_regs *regs) |
fbd7053a VG |
65 | { |
66 | struct vm_area_struct *vma = NULL; | |
67 | struct task_struct *tsk = current; | |
68 | struct mm_struct *mm = tsk->mm; | |
a8c715b4 | 69 | int si_code = SEGV_MAPERR; |
50a7ca3c SJ |
70 | int ret; |
71 | vm_fault_t fault; | |
38a9ff6d | 72 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
759496ba | 73 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
fbd7053a VG |
74 | |
75 | /* | |
76 | * We fault-in kernel-space virtual memory on-demand. The | |
77 | * 'reference' page table is init_mm.pgd. | |
78 | * | |
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, | |
82 | * nothing more. | |
83 | */ | |
a8c715b4 | 84 | if (address >= VMALLOC_START && !user_mode(regs)) { |
336e2136 | 85 | ret = handle_kernel_vaddr_fault(address); |
fbd7053a | 86 | if (unlikely(ret)) |
a8c715b4 | 87 | goto no_context; |
fbd7053a VG |
88 | else |
89 | return; | |
90 | } | |
91 | ||
fbd7053a VG |
92 | /* |
93 | * If we're in an interrupt or have no user | |
94 | * context, we must not take the fault.. | |
95 | */ | |
70ffdb93 | 96 | if (faulthandler_disabled() || !mm) |
fbd7053a VG |
97 | goto no_context; |
98 | ||
759496ba JW |
99 | if (user_mode(regs)) |
100 | flags |= FAULT_FLAG_USER; | |
fbd7053a VG |
101 | retry: |
102 | down_read(&mm->mmap_sem); | |
103 | vma = find_vma(mm, address); | |
104 | if (!vma) | |
105 | goto bad_area; | |
106 | if (vma->vm_start <= address) | |
107 | goto good_area; | |
108 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
109 | goto bad_area; | |
110 | if (expand_stack(vma, address)) | |
111 | goto bad_area; | |
112 | ||
113 | /* | |
114 | * Ok, we have a good vm_area for this memory access, so | |
115 | * we can handle it.. | |
116 | */ | |
117 | good_area: | |
15773ae9 | 118 | si_code = SEGV_ACCERR; |
fbd7053a VG |
119 | |
120 | /* Handle protection violation, execute on heap or stack */ | |
121 | ||
38a9ff6d VG |
122 | if ((regs->ecr_vec == ECR_V_PROTV) && |
123 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) | |
fbd7053a VG |
124 | goto bad_area; |
125 | ||
126 | if (write) { | |
127 | if (!(vma->vm_flags & VM_WRITE)) | |
128 | goto bad_area; | |
759496ba | 129 | flags |= FAULT_FLAG_WRITE; |
fbd7053a VG |
130 | } else { |
131 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
132 | goto bad_area; | |
133 | } | |
134 | ||
fbd7053a VG |
135 | /* |
136 | * If for any reason at all we couldn't handle the fault, | |
137 | * make sure we exit gracefully rather than endlessly redo | |
138 | * the fault. | |
139 | */ | |
dcddffd4 | 140 | fault = handle_mm_fault(vma, address, flags); |
fbd7053a | 141 | |
d8d7d842 | 142 | if (fatal_signal_pending(current)) { |
4d447455 VG |
143 | |
144 | /* | |
145 | * if fault retry, mmap_sem already relinquished by core mm | |
146 | * so OK to return to user mode (with signal handled first) | |
147 | */ | |
148 | if (fault & VM_FAULT_RETRY) { | |
149 | if (!user_mode(regs)) | |
150 | goto no_context; | |
fbd7053a | 151 | return; |
4d447455 | 152 | } |
fbd7053a VG |
153 | } |
154 | ||
ceed97ab VG |
155 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); |
156 | ||
fbd7053a VG |
157 | if (likely(!(fault & VM_FAULT_ERROR))) { |
158 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
159 | /* To avoid updating stats twice for retry case */ | |
ceed97ab | 160 | if (fault & VM_FAULT_MAJOR) { |
fbd7053a | 161 | tsk->maj_flt++; |
ceed97ab VG |
162 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, |
163 | regs, address); | |
164 | } else { | |
fbd7053a | 165 | tsk->min_flt++; |
ceed97ab VG |
166 | perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, |
167 | regs, address); | |
168 | } | |
fbd7053a VG |
169 | |
170 | if (fault & VM_FAULT_RETRY) { | |
171 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
172 | flags |= FAULT_FLAG_TRIED; | |
173 | goto retry; | |
174 | } | |
175 | } | |
176 | ||
177 | /* Fault Handled Gracefully */ | |
178 | up_read(&mm->mmap_sem); | |
179 | return; | |
180 | } | |
181 | ||
fbd7053a VG |
182 | if (fault & VM_FAULT_OOM) |
183 | goto out_of_memory; | |
e262eb93 | 184 | else if (fault & VM_FAULT_SIGSEGV) |
33692f27 | 185 | goto bad_area; |
fbd7053a VG |
186 | else if (fault & VM_FAULT_SIGBUS) |
187 | goto do_sigbus; | |
188 | ||
189 | /* no man's land */ | |
190 | BUG(); | |
191 | ||
192 | /* | |
193 | * Something tried to access memory that isn't in our memory map.. | |
194 | * Fix it, but check if it's kernel or user first.. | |
195 | */ | |
196 | bad_area: | |
197 | up_read(&mm->mmap_sem); | |
198 | ||
fbd7053a VG |
199 | /* User mode accesses just cause a SIGSEGV */ |
200 | if (user_mode(regs)) { | |
201 | tsk->thread.fault_address = address; | |
15773ae9 | 202 | force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk); |
fbd7053a VG |
203 | return; |
204 | } | |
205 | ||
206 | no_context: | |
207 | /* Are we prepared to handle this kernel fault? | |
208 | * | |
209 | * (The kernel has valid exception-points in the source | |
ddf720f8 | 210 | * when it accesses user-memory. When it fails in one |
fbd7053a VG |
211 | * of those points, we find it in a table and do a jump |
212 | * to some fixup code that loads an appropriate error | |
213 | * code) | |
214 | */ | |
215 | if (fixup_exception(regs)) | |
216 | return; | |
217 | ||
38a9ff6d | 218 | die("Oops", regs, address); |
fbd7053a VG |
219 | |
220 | out_of_memory: | |
fbd7053a VG |
221 | up_read(&mm->mmap_sem); |
222 | ||
609838cf JW |
223 | if (user_mode(regs)) { |
224 | pagefault_out_of_memory(); | |
225 | return; | |
226 | } | |
fbd7053a VG |
227 | |
228 | goto no_context; | |
229 | ||
230 | do_sigbus: | |
231 | up_read(&mm->mmap_sem); | |
232 | ||
233 | if (!user_mode(regs)) | |
234 | goto no_context; | |
235 | ||
236 | tsk->thread.fault_address = address; | |
15773ae9 | 237 | force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk); |
fbd7053a | 238 | } |