This source file includes following definitions.
- trng_open
- trng_read
- trng_counter_show
- _trng_hwrng_read
- trng_hwrng_data_read
- trng_hwrng_read
- trng_debug_init
- trng_debug_exit
- trng_init
- trng_exit
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12 #define KMSG_COMPONENT "trng"
13 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
14
15 #include <linux/hw_random.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/cpufeature.h>
19 #include <linux/miscdevice.h>
20 #include <linux/debugfs.h>
21 #include <linux/atomic.h>
22 #include <linux/random.h>
23 #include <linux/sched/signal.h>
24 #include <asm/debug.h>
25 #include <asm/cpacf.h>
26
27 MODULE_LICENSE("GPL v2");
28 MODULE_AUTHOR("IBM Corporation");
29 MODULE_DESCRIPTION("s390 CPACF TRNG device driver");
30
31
32
33
34 static debug_info_t *debug_info;
35
36 #define DEBUG_DBG(...) debug_sprintf_event(debug_info, 6, ##__VA_ARGS__)
37 #define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__)
38 #define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__)
39 #define DEBUG_ERR(...) debug_sprintf_event(debug_info, 3, ##__VA_ARGS__)
40
41
42
43
44 static atomic64_t trng_dev_counter = ATOMIC64_INIT(0);
45 static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0);
46
47
48
49
50 static int trng_open(struct inode *inode, struct file *file)
51 {
52 return nonseekable_open(inode, file);
53 }
54
55 static ssize_t trng_read(struct file *file, char __user *ubuf,
56 size_t nbytes, loff_t *ppos)
57 {
58 u8 buf[32];
59 u8 *p = buf;
60 unsigned int n;
61 ssize_t ret = 0;
62
63
64
65
66
67
68
69 if (nbytes > sizeof(buf)) {
70 p = (u8 *) __get_free_page(GFP_KERNEL);
71 if (!p)
72 return -ENOMEM;
73 }
74
75 while (nbytes) {
76 if (need_resched()) {
77 if (signal_pending(current)) {
78 if (ret == 0)
79 ret = -ERESTARTSYS;
80 break;
81 }
82 schedule();
83 }
84 n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes;
85 cpacf_trng(NULL, 0, p, n);
86 atomic64_add(n, &trng_dev_counter);
87 if (copy_to_user(ubuf, p, n)) {
88 ret = -EFAULT;
89 break;
90 }
91 nbytes -= n;
92 ubuf += n;
93 ret += n;
94 }
95
96 if (p != buf)
97 free_page((unsigned long) p);
98
99 DEBUG_DBG("trng_read()=%zd\n", ret);
100 return ret;
101 }
102
103
104
105
106 static ssize_t trng_counter_show(struct device *dev,
107 struct device_attribute *attr, char *buf)
108 {
109 u64 dev_counter = atomic64_read(&trng_dev_counter);
110 u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
111 #if IS_ENABLED(CONFIG_ARCH_RANDOM)
112 u64 arch_counter = atomic64_read(&s390_arch_random_counter);
113
114 return snprintf(buf, PAGE_SIZE,
115 "trng: %llu\n"
116 "hwrng: %llu\n"
117 "arch: %llu\n"
118 "total: %llu\n",
119 dev_counter, hwrng_counter, arch_counter,
120 dev_counter + hwrng_counter + arch_counter);
121 #else
122 return snprintf(buf, PAGE_SIZE,
123 "trng: %llu\n"
124 "hwrng: %llu\n"
125 "total: %llu\n",
126 dev_counter, hwrng_counter,
127 dev_counter + hwrng_counter);
128 #endif
129 }
130 static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);
131
132 static struct attribute *trng_dev_attrs[] = {
133 &dev_attr_byte_counter.attr,
134 NULL
135 };
136
137 static const struct attribute_group trng_dev_attr_group = {
138 .attrs = trng_dev_attrs
139 };
140
141 static const struct attribute_group *trng_dev_attr_groups[] = {
142 &trng_dev_attr_group,
143 NULL
144 };
145
146 static const struct file_operations trng_fops = {
147 .owner = THIS_MODULE,
148 .open = &trng_open,
149 .release = NULL,
150 .read = &trng_read,
151 .llseek = noop_llseek,
152 };
153
154 static struct miscdevice trng_dev = {
155 .name = "trng",
156 .minor = MISC_DYNAMIC_MINOR,
157 .mode = 0444,
158 .fops = &trng_fops,
159 .groups = trng_dev_attr_groups,
160 };
161
162
163
164
165 static inline void _trng_hwrng_read(u8 *buf, size_t len)
166 {
167 cpacf_trng(NULL, 0, buf, len);
168 atomic64_add(len, &trng_hwrng_counter);
169 }
170
171 static int trng_hwrng_data_read(struct hwrng *rng, u32 *data)
172 {
173 size_t len = sizeof(*data);
174
175 _trng_hwrng_read((u8 *) data, len);
176
177 DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len);
178
179 return len;
180 }
181
182 static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
183 {
184 size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE;
185
186 _trng_hwrng_read((u8 *) data, len);
187
188 DEBUG_DBG("trng_hwrng_read()=%zu\n", len);
189
190 return len;
191 }
192
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196
197
198 static struct hwrng trng_hwrng_dev = {
199 .name = "s390-trng",
200 .data_read = trng_hwrng_data_read,
201 .read = trng_hwrng_read,
202 .quality = 999,
203 };
204
205
206
207
208 static void __init trng_debug_init(void)
209 {
210 debug_info = debug_register("trng", 1, 1, 4 * sizeof(long));
211 debug_register_view(debug_info, &debug_sprintf_view);
212 debug_set_level(debug_info, 3);
213 }
214
215 static void trng_debug_exit(void)
216 {
217 debug_unregister(debug_info);
218 }
219
220 static int __init trng_init(void)
221 {
222 int ret;
223
224 trng_debug_init();
225
226
227 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) {
228 DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n");
229 ret = -ENODEV;
230 goto out_dbg;
231 }
232
233 ret = misc_register(&trng_dev);
234 if (ret) {
235 DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret);
236 goto out_dbg;
237 }
238
239 ret = hwrng_register(&trng_hwrng_dev);
240 if (ret) {
241 DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret);
242 goto out_misc;
243 }
244
245 DEBUG_DBG("trng_init successful\n");
246
247 return 0;
248
249 out_misc:
250 misc_deregister(&trng_dev);
251 out_dbg:
252 trng_debug_exit();
253 return ret;
254 }
255
256 static void __exit trng_exit(void)
257 {
258 hwrng_unregister(&trng_hwrng_dev);
259 misc_deregister(&trng_dev);
260 trng_debug_exit();
261 }
262
263 module_cpu_feature_match(MSA, trng_init);
264 module_exit(trng_exit);