forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
265 lines
5.6 KiB
265 lines
5.6 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* s390 TRNG device driver |
|
* |
|
* Driver for the TRNG (true random number generation) command |
|
* available via CPACF extension MSA 7 on the s390 arch. |
|
|
|
* Copyright IBM Corp. 2017 |
|
* Author(s): Harald Freudenberger <[email protected]> |
|
*/ |
|
|
|
#define KMSG_COMPONENT "trng" |
|
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt |
|
|
|
#include <linux/hw_random.h> |
|
#include <linux/kernel.h> |
|
#include <linux/module.h> |
|
#include <linux/cpufeature.h> |
|
#include <linux/miscdevice.h> |
|
#include <linux/debugfs.h> |
|
#include <linux/atomic.h> |
|
#include <linux/random.h> |
|
#include <linux/sched/signal.h> |
|
#include <asm/debug.h> |
|
#include <asm/cpacf.h> |
|
|
|
MODULE_LICENSE("GPL v2"); |
|
MODULE_AUTHOR("IBM Corporation"); |
|
MODULE_DESCRIPTION("s390 CPACF TRNG device driver"); |
|
|
|
|
|
/* trng related debug feature things */ |
|
|
|
static debug_info_t *debug_info; |
|
|
|
#define DEBUG_DBG(...) debug_sprintf_event(debug_info, 6, ##__VA_ARGS__) |
|
#define DEBUG_INFO(...) debug_sprintf_event(debug_info, 5, ##__VA_ARGS__) |
|
#define DEBUG_WARN(...) debug_sprintf_event(debug_info, 4, ##__VA_ARGS__) |
|
#define DEBUG_ERR(...) debug_sprintf_event(debug_info, 3, ##__VA_ARGS__) |
|
|
|
|
|
/* trng helpers */ |
|
|
|
static atomic64_t trng_dev_counter = ATOMIC64_INIT(0); |
|
static atomic64_t trng_hwrng_counter = ATOMIC64_INIT(0); |
|
|
|
|
|
/* file io functions */ |
|
|
|
static int trng_open(struct inode *inode, struct file *file) |
|
{ |
|
return nonseekable_open(inode, file); |
|
} |
|
|
|
static ssize_t trng_read(struct file *file, char __user *ubuf, |
|
size_t nbytes, loff_t *ppos) |
|
{ |
|
u8 buf[32]; |
|
u8 *p = buf; |
|
unsigned int n; |
|
ssize_t ret = 0; |
|
|
|
/* |
|
* use buf for requests <= sizeof(buf), |
|
* otherwise allocate one page and fetch |
|
* pagewise. |
|
*/ |
|
|
|
if (nbytes > sizeof(buf)) { |
|
p = (u8 *) __get_free_page(GFP_KERNEL); |
|
if (!p) |
|
return -ENOMEM; |
|
} |
|
|
|
while (nbytes) { |
|
if (need_resched()) { |
|
if (signal_pending(current)) { |
|
if (ret == 0) |
|
ret = -ERESTARTSYS; |
|
break; |
|
} |
|
schedule(); |
|
} |
|
n = nbytes > PAGE_SIZE ? PAGE_SIZE : nbytes; |
|
cpacf_trng(NULL, 0, p, n); |
|
atomic64_add(n, &trng_dev_counter); |
|
if (copy_to_user(ubuf, p, n)) { |
|
ret = -EFAULT; |
|
break; |
|
} |
|
nbytes -= n; |
|
ubuf += n; |
|
ret += n; |
|
} |
|
|
|
if (p != buf) |
|
free_page((unsigned long) p); |
|
|
|
DEBUG_DBG("trng_read()=%zd\n", ret); |
|
return ret; |
|
} |
|
|
|
|
|
/* sysfs */ |
|
|
|
static ssize_t trng_counter_show(struct device *dev, |
|
struct device_attribute *attr, char *buf) |
|
{ |
|
u64 dev_counter = atomic64_read(&trng_dev_counter); |
|
u64 hwrng_counter = atomic64_read(&trng_hwrng_counter); |
|
#if IS_ENABLED(CONFIG_ARCH_RANDOM) |
|
u64 arch_counter = atomic64_read(&s390_arch_random_counter); |
|
|
|
return snprintf(buf, PAGE_SIZE, |
|
"trng: %llu\n" |
|
"hwrng: %llu\n" |
|
"arch: %llu\n" |
|
"total: %llu\n", |
|
dev_counter, hwrng_counter, arch_counter, |
|
dev_counter + hwrng_counter + arch_counter); |
|
#else |
|
return snprintf(buf, PAGE_SIZE, |
|
"trng: %llu\n" |
|
"hwrng: %llu\n" |
|
"total: %llu\n", |
|
dev_counter, hwrng_counter, |
|
dev_counter + hwrng_counter); |
|
#endif |
|
} |
|
static DEVICE_ATTR(byte_counter, 0444, trng_counter_show, NULL); |
|
|
|
static struct attribute *trng_dev_attrs[] = { |
|
&dev_attr_byte_counter.attr, |
|
NULL |
|
}; |
|
|
|
static const struct attribute_group trng_dev_attr_group = { |
|
.attrs = trng_dev_attrs |
|
}; |
|
|
|
static const struct attribute_group *trng_dev_attr_groups[] = { |
|
&trng_dev_attr_group, |
|
NULL |
|
}; |
|
|
|
static const struct file_operations trng_fops = { |
|
.owner = THIS_MODULE, |
|
.open = &trng_open, |
|
.release = NULL, |
|
.read = &trng_read, |
|
.llseek = noop_llseek, |
|
}; |
|
|
|
static struct miscdevice trng_dev = { |
|
.name = "trng", |
|
.minor = MISC_DYNAMIC_MINOR, |
|
.mode = 0444, |
|
.fops = &trng_fops, |
|
.groups = trng_dev_attr_groups, |
|
}; |
|
|
|
|
|
/* hwrng_register */ |
|
|
|
static inline void _trng_hwrng_read(u8 *buf, size_t len) |
|
{ |
|
cpacf_trng(NULL, 0, buf, len); |
|
atomic64_add(len, &trng_hwrng_counter); |
|
} |
|
|
|
static int trng_hwrng_data_read(struct hwrng *rng, u32 *data) |
|
{ |
|
size_t len = sizeof(*data); |
|
|
|
_trng_hwrng_read((u8 *) data, len); |
|
|
|
DEBUG_DBG("trng_hwrng_data_read()=%zu\n", len); |
|
|
|
return len; |
|
} |
|
|
|
static int trng_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) |
|
{ |
|
size_t len = max <= PAGE_SIZE ? max : PAGE_SIZE; |
|
|
|
_trng_hwrng_read((u8 *) data, len); |
|
|
|
DEBUG_DBG("trng_hwrng_read()=%zu\n", len); |
|
|
|
return len; |
|
} |
|
|
|
/* |
|
* hwrng register struct |
|
* The trng is supposed to have 100% entropy, and thus we register with a very |
|
* high quality value. If we ever have a better driver in the future, we should |
|
* change this value again when we merge this driver. |
|
*/ |
|
static struct hwrng trng_hwrng_dev = { |
|
.name = "s390-trng", |
|
.data_read = trng_hwrng_data_read, |
|
.read = trng_hwrng_read, |
|
.quality = 1024, |
|
}; |
|
|
|
|
|
/* init and exit */ |
|
|
|
static void __init trng_debug_init(void) |
|
{ |
|
debug_info = debug_register("trng", 1, 1, 4 * sizeof(long)); |
|
debug_register_view(debug_info, &debug_sprintf_view); |
|
debug_set_level(debug_info, 3); |
|
} |
|
|
|
static void trng_debug_exit(void) |
|
{ |
|
debug_unregister(debug_info); |
|
} |
|
|
|
static int __init trng_init(void) |
|
{ |
|
int ret; |
|
|
|
trng_debug_init(); |
|
|
|
/* check if subfunction CPACF_PRNO_TRNG is available */ |
|
if (!cpacf_query_func(CPACF_PRNO, CPACF_PRNO_TRNG)) { |
|
DEBUG_INFO("trng_init CPACF_PRNO_TRNG not available\n"); |
|
ret = -ENODEV; |
|
goto out_dbg; |
|
} |
|
|
|
ret = misc_register(&trng_dev); |
|
if (ret) { |
|
DEBUG_WARN("trng_init misc_register() failed rc=%d\n", ret); |
|
goto out_dbg; |
|
} |
|
|
|
ret = hwrng_register(&trng_hwrng_dev); |
|
if (ret) { |
|
DEBUG_WARN("trng_init hwrng_register() failed rc=%d\n", ret); |
|
goto out_misc; |
|
} |
|
|
|
DEBUG_DBG("trng_init successful\n"); |
|
|
|
return 0; |
|
|
|
out_misc: |
|
misc_deregister(&trng_dev); |
|
out_dbg: |
|
trng_debug_exit(); |
|
return ret; |
|
} |
|
|
|
static void __exit trng_exit(void) |
|
{ |
|
hwrng_unregister(&trng_hwrng_dev); |
|
misc_deregister(&trng_dev); |
|
trng_debug_exit(); |
|
} |
|
|
|
module_cpu_feature_match(MSA, trng_init); |
|
module_exit(trng_exit);
|
|
|