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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * s390 TRNG device driver
4 *
5 * Driver for the TRNG (true random number generation) command
6 * available via CPACF extension MSA 7 on the s390 arch.
7
8 * Copyright IBM Corp. 2017
9 * Author(s): Harald Freudenberger <freude@de.ibm.com>
10 */
11
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#include <asm/archrandom.h>
27
28MODULE_LICENSE("GPL v2");
29MODULE_AUTHOR("IBM Corporation");
30MODULE_DESCRIPTION("s390 CPACF TRNG device driver");
31
32
33/* trng related debug feature things */
34
35static debug_info_t *debug_info;
36
37#define DEBUG_DBG(...) debug_sprintf_event(debug_info, 6, ##__VA_ARGS__)
38#define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__)
39#define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__)
40#define DEBUG_ERR(...) debug_sprintf_event(debug_info, 3, ##__VA_ARGS__)
41
42
43/* trng helpers */
44
45static atomic64_t trng_dev_counter = ATOMIC64_INIT(0);
46static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0);
47
48
49/* file io functions */
50
51static int trng_open(struct inode *inode, struct file *file)
52{
53 return nonseekable_open(inode, file);
54}
55
56static ssize_t trng_read(struct file *file, char __user *ubuf,
57 size_t nbytes, loff_t *ppos)
58{
59 u8 buf[32];
60 u8 *p = buf;
61 unsigned int n;
62 ssize_t ret = 0;
63
64 /*
65 * use buf for requests <= sizeof(buf),
66 * otherwise allocate one page and fetch
67 * pagewise.
68 */
69
70 if (nbytes > sizeof(buf)) {
71 p = (u8 *) __get_free_page(GFP_KERNEL);
72 if (!p)
73 return -ENOMEM;
74 }
75
76 while (nbytes) {
77 if (need_resched()) {
78 if (signal_pending(current)) {
79 if (ret == 0)
80 ret = -ERESTARTSYS;
81 break;
82 }
83 schedule();
84 }
85 n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes;
86 cpacf_trng(NULL, 0, p, n);
87 atomic64_add(n, &trng_dev_counter);
88 if (copy_to_user(ubuf, p, n)) {
89 ret = -EFAULT;
90 break;
91 }
92 nbytes -= n;
93 ubuf += n;
94 ret += n;
95 }
96
97 if (p != buf)
98 free_page((unsigned long) p);
99
100 DEBUG_DBG("trng_read()=%zd\n", ret);
101 return ret;
102}
103
104
105/* sysfs */
106
107static ssize_t trng_counter_show(struct device *dev,
108 struct device_attribute *attr, char *buf)
109{
110 u64 dev_counter = atomic64_read(&trng_dev_counter);
111 u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
112 u64 arch_counter = atomic64_read(&s390_arch_random_counter);
113
114 return sysfs_emit(buf,
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}
122static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);
123
124static struct attribute *trng_dev_attrs[] = {
125 &dev_attr_byte_counter.attr,
126 NULL
127};
128
129static const struct attribute_group trng_dev_attr_group = {
130 .attrs = trng_dev_attrs
131};
132
133static const struct attribute_group *trng_dev_attr_groups[] = {
134 &trng_dev_attr_group,
135 NULL
136};
137
138static const struct file_operations trng_fops = {
139 .owner = THIS_MODULE,
140 .open = &trng_open,
141 .release = NULL,
142 .read = &trng_read,
143 .llseek = noop_llseek,
144};
145
146static struct miscdevice trng_dev = {
147 .name = "trng",
148 .minor = MISC_DYNAMIC_MINOR,
149 .mode = 0444,
150 .fops = &trng_fops,
151 .groups = trng_dev_attr_groups,
152};
153
154
155/* hwrng_register */
156
157static inline void _trng_hwrng_read(u8 *buf, size_t len)
158{
159 cpacf_trng(NULL, 0, buf, len);
160 atomic64_add(len, &trng_hwrng_counter);
161}
162
163static int trng_hwrng_data_read(struct hwrng *rng, u32 *data)
164{
165 size_t len = sizeof(*data);
166
167 _trng_hwrng_read((u8 *) data, len);
168
169 DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len);
170
171 return len;
172}
173
174static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
175{
176 size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE;
177
178 _trng_hwrng_read((u8 *) data, len);
179
180 DEBUG_DBG("trng_hwrng_read()=%zu\n", len);
181
182 return len;
183}
184
185/*
186 * hwrng register struct
187 * The trng is supposed to have 100% entropy, and thus we register with a very
188 * high quality value. If we ever have a better driver in the future, we should
189 * change this value again when we merge this driver.
190 */
191static struct hwrng trng_hwrng_dev = {
192 .name = "s390-trng",
193 .data_read = trng_hwrng_data_read,
194 .read = trng_hwrng_read,
195};
196
197
198/* init and exit */
199
200static void __init trng_debug_init(void)
201{
202 debug_info = debug_register("trng", 1, 1, 4 * sizeof(long));
203 debug_register_view(debug_info, &debug_sprintf_view);
204 debug_set_level(debug_info, 3);
205}
206
207static void trng_debug_exit(void)
208{
209 debug_unregister(debug_info);
210}
211
212static int __init trng_init(void)
213{
214 int ret;
215
216 trng_debug_init();
217
218 /* check if subfunction CPACF_PRNO_TRNG is available */
219 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) {
220 DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n");
221 ret = -ENODEV;
222 goto out_dbg;
223 }
224
225 ret = misc_register(&trng_dev);
226 if (ret) {
227 DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret);
228 goto out_dbg;
229 }
230
231 ret = hwrng_register(&trng_hwrng_dev);
232 if (ret) {
233 DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret);
234 goto out_misc;
235 }
236
237 DEBUG_DBG("trng_init successful\n");
238
239 return 0;
240
241out_misc:
242 misc_deregister(&trng_dev);
243out_dbg:
244 trng_debug_exit();
245 return ret;
246}
247
248static void __exit trng_exit(void)
249{
250 hwrng_unregister(&trng_hwrng_dev);
251 misc_deregister(&trng_dev);
252 trng_debug_exit();
253}
254
255module_cpu_feature_match(S390_CPU_FEATURE_MSA, trng_init);
256module_exit(trng_exit);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * s390 TRNG device driver
4 *
5 * Driver for the TRNG (true random number generation) command
6 * available via CPACF extension MSA 7 on the s390 arch.
7
8 * Copyright IBM Corp. 2017
9 * Author(s): Harald Freudenberger <freude@de.ibm.com>
10 */
11
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#include <asm/archrandom.h>
27
28MODULE_LICENSE("GPL v2");
29MODULE_AUTHOR("IBM Corporation");
30MODULE_DESCRIPTION("s390 CPACF TRNG device driver");
31
32
33/* trng related debug feature things */
34
35static debug_info_t *debug_info;
36
37#define DEBUG_DBG(...) debug_sprintf_event(debug_info, 6, ##__VA_ARGS__)
38#define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__)
39#define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__)
40#define DEBUG_ERR(...) debug_sprintf_event(debug_info, 3, ##__VA_ARGS__)
41
42
43/* trng helpers */
44
45static atomic64_t trng_dev_counter = ATOMIC64_INIT(0);
46static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0);
47
48
49/* file io functions */
50
51static int trng_open(struct inode *inode, struct file *file)
52{
53 return nonseekable_open(inode, file);
54}
55
56static ssize_t trng_read(struct file *file, char __user *ubuf,
57 size_t nbytes, loff_t *ppos)
58{
59 u8 buf[32];
60 u8 *p = buf;
61 unsigned int n;
62 ssize_t ret = 0;
63
64 /*
65 * use buf for requests <= sizeof(buf),
66 * otherwise allocate one page and fetch
67 * pagewise.
68 */
69
70 if (nbytes > sizeof(buf)) {
71 p = (u8 *) __get_free_page(GFP_KERNEL);
72 if (!p)
73 return -ENOMEM;
74 }
75
76 while (nbytes) {
77 if (need_resched()) {
78 if (signal_pending(current)) {
79 if (ret == 0)
80 ret = -ERESTARTSYS;
81 break;
82 }
83 schedule();
84 }
85 n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes;
86 cpacf_trng(NULL, 0, p, n);
87 atomic64_add(n, &trng_dev_counter);
88 if (copy_to_user(ubuf, p, n)) {
89 ret = -EFAULT;
90 break;
91 }
92 nbytes -= n;
93 ubuf += n;
94 ret += n;
95 }
96
97 if (p != buf)
98 free_page((unsigned long) p);
99
100 DEBUG_DBG("trng_read()=%zd\n", ret);
101 return ret;
102}
103
104
105/* sysfs */
106
107static ssize_t trng_counter_show(struct device *dev,
108 struct device_attribute *attr, char *buf)
109{
110 u64 dev_counter = atomic64_read(&trng_dev_counter);
111 u64 hwrng_counter = atomic64_read(&trng_hwrng_counter);
112 u64 arch_counter = atomic64_read(&s390_arch_random_counter);
113
114 return sysfs_emit(buf,
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}
122static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL);
123
124static struct attribute *trng_dev_attrs[] = {
125 &dev_attr_byte_counter.attr,
126 NULL
127};
128
129static const struct attribute_group trng_dev_attr_group = {
130 .attrs = trng_dev_attrs
131};
132
133static const struct attribute_group *trng_dev_attr_groups[] = {
134 &trng_dev_attr_group,
135 NULL
136};
137
138static const struct file_operations trng_fops = {
139 .owner = THIS_MODULE,
140 .open = &trng_open,
141 .release = NULL,
142 .read = &trng_read,
143 .llseek = noop_llseek,
144};
145
146static struct miscdevice trng_dev = {
147 .name = "trng",
148 .minor = MISC_DYNAMIC_MINOR,
149 .mode = 0444,
150 .fops = &trng_fops,
151 .groups = trng_dev_attr_groups,
152};
153
154
155/* hwrng_register */
156
157static inline void _trng_hwrng_read(u8 *buf, size_t len)
158{
159 cpacf_trng(NULL, 0, buf, len);
160 atomic64_add(len, &trng_hwrng_counter);
161}
162
163static int trng_hwrng_data_read(struct hwrng *rng, u32 *data)
164{
165 size_t len = sizeof(*data);
166
167 _trng_hwrng_read((u8 *) data, len);
168
169 DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len);
170
171 return len;
172}
173
174static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
175{
176 size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE;
177
178 _trng_hwrng_read((u8 *) data, len);
179
180 DEBUG_DBG("trng_hwrng_read()=%zu\n", len);
181
182 return len;
183}
184
185/*
186 * hwrng register struct
187 * The trng is supposed to have 100% entropy, and thus we register with a very
188 * high quality value. If we ever have a better driver in the future, we should
189 * change this value again when we merge this driver.
190 */
191static struct hwrng trng_hwrng_dev = {
192 .name = "s390-trng",
193 .data_read = trng_hwrng_data_read,
194 .read = trng_hwrng_read,
195};
196
197
198/* init and exit */
199
200static void __init trng_debug_init(void)
201{
202 debug_info = debug_register("trng", 1, 1, 4 * sizeof(long));
203 debug_register_view(debug_info, &debug_sprintf_view);
204 debug_set_level(debug_info, 3);
205}
206
207static void trng_debug_exit(void)
208{
209 debug_unregister(debug_info);
210}
211
212static int __init trng_init(void)
213{
214 int ret;
215
216 trng_debug_init();
217
218 /* check if subfunction CPACF_PRNO_TRNG is available */
219 if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) {
220 DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n");
221 ret = -ENODEV;
222 goto out_dbg;
223 }
224
225 ret = misc_register(&trng_dev);
226 if (ret) {
227 DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret);
228 goto out_dbg;
229 }
230
231 ret = hwrng_register(&trng_hwrng_dev);
232 if (ret) {
233 DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret);
234 goto out_misc;
235 }
236
237 DEBUG_DBG("trng_init successful\n");
238
239 return 0;
240
241out_misc:
242 misc_deregister(&trng_dev);
243out_dbg:
244 trng_debug_exit();
245 return ret;
246}
247
248static void __exit trng_exit(void)
249{
250 hwrng_unregister(&trng_hwrng_dev);
251 misc_deregister(&trng_dev);
252 trng_debug_exit();
253}
254
255module_cpu_feature_match(S390_CPU_FEATURE_MSA, trng_init);
256module_exit(trng_exit);