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499236d9 RK |
1 | /* |
2 | * Memory fault handling for Hexagon | |
3 | * | |
4 | * Copyright (c) 2010-2011 Code Aurora Forum. All rights reserved. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 and | |
8 | * only version 2 as published by the Free Software Foundation. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
18 | * 02110-1301, USA. | |
19 | */ | |
20 | ||
21 | /* | |
22 | * Page fault handling for the Hexagon Virtual Machine. | |
23 | * Can also be called by a native port emulating the HVM | |
24 | * execptions. | |
25 | */ | |
26 | ||
27 | #include <asm/pgtable.h> | |
28 | #include <asm/traps.h> | |
29 | #include <asm/uaccess.h> | |
30 | #include <linux/mm.h> | |
31 | #include <linux/signal.h> | |
32 | #include <linux/module.h> | |
33 | #include <linux/hardirq.h> | |
34 | ||
35 | /* | |
36 | * Decode of hardware exception sends us to one of several | |
37 | * entry points. At each, we generate canonical arguments | |
38 | * for handling by the abstract memory management code. | |
39 | */ | |
40 | #define FLT_IFETCH -1 | |
41 | #define FLT_LOAD 0 | |
42 | #define FLT_STORE 1 | |
43 | ||
44 | ||
45 | /* | |
46 | * Canonical page fault handler | |
47 | */ | |
48 | void do_page_fault(unsigned long address, long cause, struct pt_regs *regs) | |
49 | { | |
50 | struct vm_area_struct *vma; | |
51 | struct mm_struct *mm = current->mm; | |
52 | siginfo_t info; | |
53 | int si_code = SEGV_MAPERR; | |
54 | int fault; | |
55 | const struct exception_table_entry *fixup; | |
56 | ||
57 | /* | |
58 | * If we're in an interrupt or have no user context, | |
59 | * then must not take the fault. | |
60 | */ | |
61 | if (unlikely(in_interrupt() || !mm)) | |
62 | goto no_context; | |
63 | ||
64 | local_irq_enable(); | |
65 | ||
66 | down_read(&mm->mmap_sem); | |
67 | vma = find_vma(mm, address); | |
68 | if (!vma) | |
69 | goto bad_area; | |
70 | ||
71 | if (vma->vm_start <= address) | |
72 | goto good_area; | |
73 | ||
74 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
75 | goto bad_area; | |
76 | ||
77 | if (expand_stack(vma, address)) | |
78 | goto bad_area; | |
79 | ||
80 | good_area: | |
81 | /* Address space is OK. Now check access rights. */ | |
82 | si_code = SEGV_ACCERR; | |
83 | ||
84 | switch (cause) { | |
85 | case FLT_IFETCH: | |
86 | if (!(vma->vm_flags & VM_EXEC)) | |
87 | goto bad_area; | |
88 | break; | |
89 | case FLT_LOAD: | |
90 | if (!(vma->vm_flags & VM_READ)) | |
91 | goto bad_area; | |
92 | break; | |
93 | case FLT_STORE: | |
94 | if (!(vma->vm_flags & VM_WRITE)) | |
95 | goto bad_area; | |
96 | break; | |
97 | } | |
98 | ||
99 | fault = handle_mm_fault(mm, vma, address, (cause > 0)); | |
100 | ||
101 | /* The most common case -- we are done. */ | |
102 | if (likely(!(fault & VM_FAULT_ERROR))) { | |
103 | if (fault & VM_FAULT_MAJOR) | |
104 | current->maj_flt++; | |
105 | else | |
106 | current->min_flt++; | |
107 | ||
108 | up_read(&mm->mmap_sem); | |
109 | return; | |
110 | } | |
111 | ||
112 | up_read(&mm->mmap_sem); | |
113 | ||
114 | /* Handle copyin/out exception cases */ | |
115 | if (!user_mode(regs)) | |
116 | goto no_context; | |
117 | ||
118 | if (fault & VM_FAULT_OOM) { | |
119 | pagefault_out_of_memory(); | |
120 | return; | |
121 | } | |
122 | ||
123 | /* User-mode address is in the memory map, but we are | |
124 | * unable to fix up the page fault. | |
125 | */ | |
126 | if (fault & VM_FAULT_SIGBUS) { | |
127 | info.si_signo = SIGBUS; | |
128 | info.si_code = BUS_ADRERR; | |
129 | } | |
130 | /* Address is not in the memory map */ | |
131 | else { | |
132 | info.si_signo = SIGSEGV; | |
133 | info.si_code = SEGV_ACCERR; | |
134 | } | |
135 | info.si_errno = 0; | |
136 | info.si_addr = (void __user *)address; | |
137 | force_sig_info(info.si_code, &info, current); | |
138 | return; | |
139 | ||
140 | bad_area: | |
141 | up_read(&mm->mmap_sem); | |
142 | ||
143 | if (user_mode(regs)) { | |
144 | info.si_signo = SIGSEGV; | |
145 | info.si_errno = 0; | |
146 | info.si_code = si_code; | |
147 | info.si_addr = (void *)address; | |
148 | force_sig_info(SIGSEGV, &info, current); | |
149 | return; | |
150 | } | |
151 | /* Kernel-mode fault falls through */ | |
152 | ||
153 | no_context: | |
154 | fixup = search_exception_tables(pt_elr(regs)); | |
155 | if (fixup) { | |
156 | pt_set_elr(regs, fixup->fixup); | |
157 | return; | |
158 | } | |
159 | ||
160 | /* Things are looking very, very bad now */ | |
161 | bust_spinlocks(1); | |
162 | printk(KERN_EMERG "Unable to handle kernel paging request at " | |
163 | "virtual address 0x%08lx, regs %p\n", address, regs); | |
164 | die("Bad Kernel VA", regs, SIGKILL); | |
165 | } | |
166 | ||
167 | ||
168 | void read_protection_fault(struct pt_regs *regs) | |
169 | { | |
170 | unsigned long badvadr = pt_badva(regs); | |
171 | ||
172 | do_page_fault(badvadr, FLT_LOAD, regs); | |
173 | } | |
174 | ||
175 | void write_protection_fault(struct pt_regs *regs) | |
176 | { | |
177 | unsigned long badvadr = pt_badva(regs); | |
178 | ||
179 | do_page_fault(badvadr, FLT_STORE, regs); | |
180 | } | |
181 | ||
182 | void execute_protection_fault(struct pt_regs *regs) | |
183 | { | |
184 | unsigned long badvadr = pt_badva(regs); | |
185 | ||
186 | do_page_fault(badvadr, FLT_IFETCH, regs); | |
187 | } |