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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> | |
12 | #include <linux/sched.h> | |
13 | #include <linux/errno.h> | |
14 | #include <linux/ptrace.h> | |
fbd7053a VG |
15 | #include <linux/uaccess.h> |
16 | #include <linux/kdebug.h> | |
17 | #include <asm/pgalloc.h> | |
da1677b0 | 18 | #include <asm/mmu.h> |
fbd7053a VG |
19 | |
20 | static int handle_vmalloc_fault(struct mm_struct *mm, unsigned long address) | |
21 | { | |
22 | /* | |
23 | * Synchronize this task's top level page-table | |
24 | * with the 'reference' page table. | |
25 | */ | |
26 | pgd_t *pgd, *pgd_k; | |
27 | pud_t *pud, *pud_k; | |
28 | pmd_t *pmd, *pmd_k; | |
29 | ||
30 | pgd = pgd_offset_fast(mm, address); | |
31 | pgd_k = pgd_offset_k(address); | |
32 | ||
33 | if (!pgd_present(*pgd_k)) | |
34 | goto bad_area; | |
35 | ||
36 | pud = pud_offset(pgd, address); | |
37 | pud_k = pud_offset(pgd_k, address); | |
38 | if (!pud_present(*pud_k)) | |
39 | goto bad_area; | |
40 | ||
41 | pmd = pmd_offset(pud, address); | |
42 | pmd_k = pmd_offset(pud_k, address); | |
43 | if (!pmd_present(*pmd_k)) | |
44 | goto bad_area; | |
45 | ||
46 | set_pmd(pmd, *pmd_k); | |
47 | ||
48 | /* XXX: create the TLB entry here */ | |
49 | return 0; | |
50 | ||
51 | bad_area: | |
52 | return 1; | |
53 | } | |
54 | ||
38a9ff6d | 55 | void do_page_fault(struct pt_regs *regs, unsigned long address) |
fbd7053a VG |
56 | { |
57 | struct vm_area_struct *vma = NULL; | |
58 | struct task_struct *tsk = current; | |
59 | struct mm_struct *mm = tsk->mm; | |
60 | siginfo_t info; | |
61 | int fault, ret; | |
38a9ff6d | 62 | int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ |
759496ba | 63 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
fbd7053a VG |
64 | |
65 | /* | |
66 | * We fault-in kernel-space virtual memory on-demand. The | |
67 | * 'reference' page table is init_mm.pgd. | |
68 | * | |
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, | |
72 | * nothing more. | |
73 | */ | |
74 | if (address >= VMALLOC_START && address <= VMALLOC_END) { | |
75 | ret = handle_vmalloc_fault(mm, address); | |
76 | if (unlikely(ret)) | |
77 | goto bad_area_nosemaphore; | |
78 | else | |
79 | return; | |
80 | } | |
81 | ||
82 | info.si_code = SEGV_MAPERR; | |
83 | ||
84 | /* | |
85 | * If we're in an interrupt or have no user | |
86 | * context, we must not take the fault.. | |
87 | */ | |
88 | if (in_atomic() || !mm) | |
89 | goto no_context; | |
90 | ||
759496ba JW |
91 | if (user_mode(regs)) |
92 | flags |= FAULT_FLAG_USER; | |
fbd7053a VG |
93 | retry: |
94 | down_read(&mm->mmap_sem); | |
95 | vma = find_vma(mm, address); | |
96 | if (!vma) | |
97 | goto bad_area; | |
98 | if (vma->vm_start <= address) | |
99 | goto good_area; | |
100 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
101 | goto bad_area; | |
102 | if (expand_stack(vma, address)) | |
103 | goto bad_area; | |
104 | ||
105 | /* | |
106 | * Ok, we have a good vm_area for this memory access, so | |
107 | * we can handle it.. | |
108 | */ | |
109 | good_area: | |
110 | info.si_code = SEGV_ACCERR; | |
111 | ||
112 | /* Handle protection violation, execute on heap or stack */ | |
113 | ||
38a9ff6d VG |
114 | if ((regs->ecr_vec == ECR_V_PROTV) && |
115 | (regs->ecr_cause == ECR_C_PROTV_INST_FETCH)) | |
fbd7053a VG |
116 | goto bad_area; |
117 | ||
118 | if (write) { | |
119 | if (!(vma->vm_flags & VM_WRITE)) | |
120 | goto bad_area; | |
759496ba | 121 | flags |= FAULT_FLAG_WRITE; |
fbd7053a VG |
122 | } else { |
123 | if (!(vma->vm_flags & (VM_READ | VM_EXEC))) | |
124 | goto bad_area; | |
125 | } | |
126 | ||
fbd7053a VG |
127 | /* |
128 | * If for any reason at all we couldn't handle the fault, | |
129 | * make sure we exit gracefully rather than endlessly redo | |
130 | * the fault. | |
131 | */ | |
132 | fault = handle_mm_fault(mm, vma, address, flags); | |
133 | ||
134 | /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */ | |
135 | if (unlikely(fatal_signal_pending(current))) { | |
136 | if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY)) | |
137 | up_read(&mm->mmap_sem); | |
138 | if (user_mode(regs)) | |
139 | return; | |
140 | } | |
141 | ||
142 | if (likely(!(fault & VM_FAULT_ERROR))) { | |
143 | if (flags & FAULT_FLAG_ALLOW_RETRY) { | |
144 | /* To avoid updating stats twice for retry case */ | |
145 | if (fault & VM_FAULT_MAJOR) | |
146 | tsk->maj_flt++; | |
147 | else | |
148 | tsk->min_flt++; | |
149 | ||
150 | if (fault & VM_FAULT_RETRY) { | |
151 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
152 | flags |= FAULT_FLAG_TRIED; | |
153 | goto retry; | |
154 | } | |
155 | } | |
156 | ||
157 | /* Fault Handled Gracefully */ | |
158 | up_read(&mm->mmap_sem); | |
159 | return; | |
160 | } | |
161 | ||
162 | /* TBD: switch to pagefault_out_of_memory() */ | |
163 | if (fault & VM_FAULT_OOM) | |
164 | goto out_of_memory; | |
165 | else if (fault & VM_FAULT_SIGBUS) | |
166 | goto do_sigbus; | |
167 | ||
168 | /* no man's land */ | |
169 | BUG(); | |
170 | ||
171 | /* | |
172 | * Something tried to access memory that isn't in our memory map.. | |
173 | * Fix it, but check if it's kernel or user first.. | |
174 | */ | |
175 | bad_area: | |
176 | up_read(&mm->mmap_sem); | |
177 | ||
178 | bad_area_nosemaphore: | |
179 | /* User mode accesses just cause a SIGSEGV */ | |
180 | if (user_mode(regs)) { | |
181 | tsk->thread.fault_address = address; | |
fbd7053a VG |
182 | info.si_signo = SIGSEGV; |
183 | info.si_errno = 0; | |
184 | /* info.si_code has been set above */ | |
185 | info.si_addr = (void __user *)address; | |
186 | force_sig_info(SIGSEGV, &info, tsk); | |
187 | return; | |
188 | } | |
189 | ||
190 | no_context: | |
191 | /* Are we prepared to handle this kernel fault? | |
192 | * | |
193 | * (The kernel has valid exception-points in the source | |
194 | * when it acesses user-memory. When it fails in one | |
195 | * of those points, we find it in a table and do a jump | |
196 | * to some fixup code that loads an appropriate error | |
197 | * code) | |
198 | */ | |
199 | if (fixup_exception(regs)) | |
200 | return; | |
201 | ||
38a9ff6d | 202 | die("Oops", regs, address); |
fbd7053a VG |
203 | |
204 | out_of_memory: | |
fbd7053a VG |
205 | up_read(&mm->mmap_sem); |
206 | ||
609838cf JW |
207 | if (user_mode(regs)) { |
208 | pagefault_out_of_memory(); | |
209 | return; | |
210 | } | |
fbd7053a VG |
211 | |
212 | goto no_context; | |
213 | ||
214 | do_sigbus: | |
215 | up_read(&mm->mmap_sem); | |
216 | ||
217 | if (!user_mode(regs)) | |
218 | goto no_context; | |
219 | ||
220 | tsk->thread.fault_address = address; | |
fbd7053a VG |
221 | info.si_signo = SIGBUS; |
222 | info.si_errno = 0; | |
223 | info.si_code = BUS_ADRERR; | |
224 | info.si_addr = (void __user *)address; | |
225 | force_sig_info(SIGBUS, &info, tsk); | |
226 | } |