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499236d9 RK |
1 | /* |
2 | * Memory fault handling for Hexagon | |
3 | * | |
e1858b2a | 4 | * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. |
499236d9 RK |
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> | |
7c0f6ba6 | 29 | #include <linux/uaccess.h> |
499236d9 | 30 | #include <linux/mm.h> |
3f07c014 | 31 | #include <linux/sched/signal.h> |
499236d9 | 32 | #include <linux/signal.h> |
1e8fb9c3 | 33 | #include <linux/extable.h> |
499236d9 RK |
34 | #include <linux/hardirq.h> |
35 | ||
36 | /* | |
37 | * Decode of hardware exception sends us to one of several | |
38 | * entry points. At each, we generate canonical arguments | |
39 | * for handling by the abstract memory management code. | |
40 | */ | |
41 | #define FLT_IFETCH -1 | |
42 | #define FLT_LOAD 0 | |
43 | #define FLT_STORE 1 | |
44 | ||
45 | ||
46 | /* | |
47 | * Canonical page fault handler | |
48 | */ | |
49 | void do_page_fault(unsigned long address, long cause, struct pt_regs *regs) | |
50 | { | |
51 | struct vm_area_struct *vma; | |
52 | struct mm_struct *mm = current->mm; | |
1a4bd979 | 53 | int si_signo; |
499236d9 | 54 | int si_code = SEGV_MAPERR; |
50a7ca3c | 55 | vm_fault_t fault; |
499236d9 | 56 | const struct exception_table_entry *fixup; |
759496ba | 57 | unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; |
499236d9 RK |
58 | |
59 | /* | |
60 | * If we're in an interrupt or have no user context, | |
61 | * then must not take the fault. | |
62 | */ | |
63 | if (unlikely(in_interrupt() || !mm)) | |
64 | goto no_context; | |
65 | ||
66 | local_irq_enable(); | |
67 | ||
759496ba JW |
68 | if (user_mode(regs)) |
69 | flags |= FAULT_FLAG_USER; | |
393a86af | 70 | retry: |
499236d9 RK |
71 | down_read(&mm->mmap_sem); |
72 | vma = find_vma(mm, address); | |
73 | if (!vma) | |
74 | goto bad_area; | |
75 | ||
76 | if (vma->vm_start <= address) | |
77 | goto good_area; | |
78 | ||
79 | if (!(vma->vm_flags & VM_GROWSDOWN)) | |
80 | goto bad_area; | |
81 | ||
82 | if (expand_stack(vma, address)) | |
83 | goto bad_area; | |
84 | ||
85 | good_area: | |
86 | /* Address space is OK. Now check access rights. */ | |
87 | si_code = SEGV_ACCERR; | |
88 | ||
89 | switch (cause) { | |
90 | case FLT_IFETCH: | |
91 | if (!(vma->vm_flags & VM_EXEC)) | |
92 | goto bad_area; | |
93 | break; | |
94 | case FLT_LOAD: | |
95 | if (!(vma->vm_flags & VM_READ)) | |
96 | goto bad_area; | |
97 | break; | |
98 | case FLT_STORE: | |
99 | if (!(vma->vm_flags & VM_WRITE)) | |
100 | goto bad_area; | |
759496ba | 101 | flags |= FAULT_FLAG_WRITE; |
499236d9 RK |
102 | break; |
103 | } | |
104 | ||
dcddffd4 | 105 | fault = handle_mm_fault(vma, address, flags); |
393a86af KC |
106 | |
107 | if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) | |
108 | return; | |
499236d9 RK |
109 | |
110 | /* The most common case -- we are done. */ | |
111 | if (likely(!(fault & VM_FAULT_ERROR))) { | |
393a86af KC |
112 | if (flags & FAULT_FLAG_ALLOW_RETRY) { |
113 | if (fault & VM_FAULT_MAJOR) | |
114 | current->maj_flt++; | |
115 | else | |
116 | current->min_flt++; | |
117 | if (fault & VM_FAULT_RETRY) { | |
118 | flags &= ~FAULT_FLAG_ALLOW_RETRY; | |
45cac65b | 119 | flags |= FAULT_FLAG_TRIED; |
393a86af KC |
120 | goto retry; |
121 | } | |
122 | } | |
499236d9 RK |
123 | |
124 | up_read(&mm->mmap_sem); | |
125 | return; | |
126 | } | |
127 | ||
128 | up_read(&mm->mmap_sem); | |
129 | ||
130 | /* Handle copyin/out exception cases */ | |
131 | if (!user_mode(regs)) | |
132 | goto no_context; | |
133 | ||
134 | if (fault & VM_FAULT_OOM) { | |
135 | pagefault_out_of_memory(); | |
136 | return; | |
137 | } | |
138 | ||
139 | /* User-mode address is in the memory map, but we are | |
140 | * unable to fix up the page fault. | |
141 | */ | |
142 | if (fault & VM_FAULT_SIGBUS) { | |
1a4bd979 EB |
143 | si_signo = SIGBUS; |
144 | si_code = BUS_ADRERR; | |
499236d9 RK |
145 | } |
146 | /* Address is not in the memory map */ | |
147 | else { | |
1a4bd979 EB |
148 | si_signo = SIGSEGV; |
149 | si_code = SEGV_ACCERR; | |
499236d9 | 150 | } |
1a4bd979 | 151 | force_sig_fault(si_signo, si_code, (void __user *)address, current); |
499236d9 RK |
152 | return; |
153 | ||
154 | bad_area: | |
155 | up_read(&mm->mmap_sem); | |
156 | ||
157 | if (user_mode(regs)) { | |
1a4bd979 | 158 | force_sig_fault(SIGSEGV, si_code, (void __user *)address, current); |
499236d9 RK |
159 | return; |
160 | } | |
161 | /* Kernel-mode fault falls through */ | |
162 | ||
163 | no_context: | |
164 | fixup = search_exception_tables(pt_elr(regs)); | |
165 | if (fixup) { | |
166 | pt_set_elr(regs, fixup->fixup); | |
167 | return; | |
168 | } | |
169 | ||
170 | /* Things are looking very, very bad now */ | |
171 | bust_spinlocks(1); | |
172 | printk(KERN_EMERG "Unable to handle kernel paging request at " | |
173 | "virtual address 0x%08lx, regs %p\n", address, regs); | |
174 | die("Bad Kernel VA", regs, SIGKILL); | |
175 | } | |
176 | ||
177 | ||
178 | void read_protection_fault(struct pt_regs *regs) | |
179 | { | |
180 | unsigned long badvadr = pt_badva(regs); | |
181 | ||
182 | do_page_fault(badvadr, FLT_LOAD, regs); | |
183 | } | |
184 | ||
185 | void write_protection_fault(struct pt_regs *regs) | |
186 | { | |
187 | unsigned long badvadr = pt_badva(regs); | |
188 | ||
189 | do_page_fault(badvadr, FLT_STORE, regs); | |
190 | } | |
191 | ||
192 | void execute_protection_fault(struct pt_regs *regs) | |
193 | { | |
194 | unsigned long badvadr = pt_badva(regs); | |
195 | ||
196 | do_page_fault(badvadr, FLT_IFETCH, regs); | |
197 | } |