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587064b6 PA |
1 | /* |
2 | * Copyright (C) 2014 ARM Limited | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License version 2 as | |
6 | * published by the Free Software Foundation. | |
7 | */ | |
8 | ||
9 | #include <linux/init.h> | |
10 | #include <linux/list.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/sysctl.h> | |
13 | ||
14 | #include <asm/traps.h> | |
15 | ||
16 | /* | |
17 | * The runtime support for deprecated instruction support can be in one of | |
18 | * following three states - | |
19 | * | |
20 | * 0 = undef | |
21 | * 1 = emulate (software emulation) | |
22 | * 2 = hw (supported in hardware) | |
23 | */ | |
24 | enum insn_emulation_mode { | |
25 | INSN_UNDEF, | |
26 | INSN_EMULATE, | |
27 | INSN_HW, | |
28 | }; | |
29 | ||
30 | enum legacy_insn_status { | |
31 | INSN_DEPRECATED, | |
32 | INSN_OBSOLETE, | |
33 | }; | |
34 | ||
35 | struct insn_emulation_ops { | |
36 | const char *name; | |
37 | enum legacy_insn_status status; | |
38 | struct undef_hook *hooks; | |
39 | int (*set_hw_mode)(bool enable); | |
40 | }; | |
41 | ||
42 | struct insn_emulation { | |
43 | struct list_head node; | |
44 | struct insn_emulation_ops *ops; | |
45 | int current_mode; | |
46 | int min; | |
47 | int max; | |
48 | }; | |
49 | ||
50 | static LIST_HEAD(insn_emulation); | |
51 | static int nr_insn_emulated; | |
52 | static DEFINE_RAW_SPINLOCK(insn_emulation_lock); | |
53 | ||
54 | static void register_emulation_hooks(struct insn_emulation_ops *ops) | |
55 | { | |
56 | struct undef_hook *hook; | |
57 | ||
58 | BUG_ON(!ops->hooks); | |
59 | ||
60 | for (hook = ops->hooks; hook->instr_mask; hook++) | |
61 | register_undef_hook(hook); | |
62 | ||
63 | pr_notice("Registered %s emulation handler\n", ops->name); | |
64 | } | |
65 | ||
66 | static void remove_emulation_hooks(struct insn_emulation_ops *ops) | |
67 | { | |
68 | struct undef_hook *hook; | |
69 | ||
70 | BUG_ON(!ops->hooks); | |
71 | ||
72 | for (hook = ops->hooks; hook->instr_mask; hook++) | |
73 | unregister_undef_hook(hook); | |
74 | ||
75 | pr_notice("Removed %s emulation handler\n", ops->name); | |
76 | } | |
77 | ||
78 | static int update_insn_emulation_mode(struct insn_emulation *insn, | |
79 | enum insn_emulation_mode prev) | |
80 | { | |
81 | int ret = 0; | |
82 | ||
83 | switch (prev) { | |
84 | case INSN_UNDEF: /* Nothing to be done */ | |
85 | break; | |
86 | case INSN_EMULATE: | |
87 | remove_emulation_hooks(insn->ops); | |
88 | break; | |
89 | case INSN_HW: | |
90 | if (insn->ops->set_hw_mode) { | |
91 | insn->ops->set_hw_mode(false); | |
92 | pr_notice("Disabled %s support\n", insn->ops->name); | |
93 | } | |
94 | break; | |
95 | } | |
96 | ||
97 | switch (insn->current_mode) { | |
98 | case INSN_UNDEF: | |
99 | break; | |
100 | case INSN_EMULATE: | |
101 | register_emulation_hooks(insn->ops); | |
102 | break; | |
103 | case INSN_HW: | |
104 | if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(true)) | |
105 | pr_notice("Enabled %s support\n", insn->ops->name); | |
106 | else | |
107 | ret = -EINVAL; | |
108 | break; | |
109 | } | |
110 | ||
111 | return ret; | |
112 | } | |
113 | ||
114 | static void register_insn_emulation(struct insn_emulation_ops *ops) | |
115 | { | |
116 | unsigned long flags; | |
117 | struct insn_emulation *insn; | |
118 | ||
119 | insn = kzalloc(sizeof(*insn), GFP_KERNEL); | |
120 | insn->ops = ops; | |
121 | insn->min = INSN_UNDEF; | |
122 | ||
123 | switch (ops->status) { | |
124 | case INSN_DEPRECATED: | |
125 | insn->current_mode = INSN_EMULATE; | |
126 | insn->max = INSN_HW; | |
127 | break; | |
128 | case INSN_OBSOLETE: | |
129 | insn->current_mode = INSN_UNDEF; | |
130 | insn->max = INSN_EMULATE; | |
131 | break; | |
132 | } | |
133 | ||
134 | raw_spin_lock_irqsave(&insn_emulation_lock, flags); | |
135 | list_add(&insn->node, &insn_emulation); | |
136 | nr_insn_emulated++; | |
137 | raw_spin_unlock_irqrestore(&insn_emulation_lock, flags); | |
138 | ||
139 | /* Register any handlers if required */ | |
140 | update_insn_emulation_mode(insn, INSN_UNDEF); | |
141 | } | |
142 | ||
143 | static int emulation_proc_handler(struct ctl_table *table, int write, | |
144 | void __user *buffer, size_t *lenp, | |
145 | loff_t *ppos) | |
146 | { | |
147 | int ret = 0; | |
148 | struct insn_emulation *insn = (struct insn_emulation *) table->data; | |
149 | enum insn_emulation_mode prev_mode = insn->current_mode; | |
150 | ||
151 | table->data = &insn->current_mode; | |
152 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
153 | ||
154 | if (ret || !write || prev_mode == insn->current_mode) | |
155 | goto ret; | |
156 | ||
157 | ret = update_insn_emulation_mode(insn, prev_mode); | |
158 | if (!ret) { | |
159 | /* Mode change failed, revert to previous mode. */ | |
160 | insn->current_mode = prev_mode; | |
161 | update_insn_emulation_mode(insn, INSN_UNDEF); | |
162 | } | |
163 | ret: | |
164 | table->data = insn; | |
165 | return ret; | |
166 | } | |
167 | ||
168 | static struct ctl_table ctl_abi[] = { | |
169 | { | |
170 | .procname = "abi", | |
171 | .mode = 0555, | |
172 | }, | |
173 | { } | |
174 | }; | |
175 | ||
176 | static void register_insn_emulation_sysctl(struct ctl_table *table) | |
177 | { | |
178 | unsigned long flags; | |
179 | int i = 0; | |
180 | struct insn_emulation *insn; | |
181 | struct ctl_table *insns_sysctl, *sysctl; | |
182 | ||
183 | insns_sysctl = kzalloc(sizeof(*sysctl) * (nr_insn_emulated + 1), | |
184 | GFP_KERNEL); | |
185 | ||
186 | raw_spin_lock_irqsave(&insn_emulation_lock, flags); | |
187 | list_for_each_entry(insn, &insn_emulation, node) { | |
188 | sysctl = &insns_sysctl[i]; | |
189 | ||
190 | sysctl->mode = 0644; | |
191 | sysctl->maxlen = sizeof(int); | |
192 | ||
193 | sysctl->procname = insn->ops->name; | |
194 | sysctl->data = insn; | |
195 | sysctl->extra1 = &insn->min; | |
196 | sysctl->extra2 = &insn->max; | |
197 | sysctl->proc_handler = emulation_proc_handler; | |
198 | i++; | |
199 | } | |
200 | raw_spin_unlock_irqrestore(&insn_emulation_lock, flags); | |
201 | ||
202 | table->child = insns_sysctl; | |
203 | register_sysctl_table(table); | |
204 | } | |
205 | ||
206 | /* | |
207 | * Invoked as late_initcall, since not needed before init spawned. | |
208 | */ | |
209 | static int __init armv8_deprecated_init(void) | |
210 | { | |
211 | register_insn_emulation_sysctl(ctl_abi); | |
212 | ||
213 | return 0; | |
214 | } | |
215 | ||
216 | late_initcall(armv8_deprecated_init); |