| 1 |
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| 2 |
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| 3 | |
| 4 | * copyright.
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| 5 | *
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| 6 | * This software may be used and distributed according to the terms
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| 7 | * of the GNU General Public License, incorporated herein by reference.
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| 8 |
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| 9 | #include <linux/sched/signal.h>
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| 10 | #include <linux/module.h>
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| 11 | #include <linux/fs.h>
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| 12 | #include <linux/interrupt.h>
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| 13 | #include <linux/miscdevice.h>
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| 14 | #include <linux/hw_random.h>
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| 15 | #include <linux/delay.h>
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| 16 | #include <linux/uaccess.h>
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| 17 | #include <init.h>
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| 18 | #include <irq_kern.h>
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| 19 | #include <os.h>
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| 20 |
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| 21 | |
| 22 | * core module information
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| 23 |
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| 24 | #define RNG_MODULE_NAME "hw_random"
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| 25 |
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| 26 | |
| 27 | * time, in the module case. Presumably, the module subsystem
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| 28 | * protects against a module being loaded twice at the same time.
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| 29 |
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| 30 | static int random_fd = -1;
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| 31 | static struct hwrng hwrng;
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| 32 | static DECLARE_COMPLETION(have_data);
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| 33 |
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| 34 | static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block)
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| 35 | {
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| 36 | int ret;
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| 37 |
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| 38 | for (;;) {
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| 39 | ret = os_read_file(random_fd, buf, max);
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| 40 | if (block && ret == -EAGAIN) {
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| 41 | add_sigio_fd(random_fd);
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| 42 |
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| 43 | ret = wait_for_completion_killable(&have_data);
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| 44 |
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| 45 | ignore_sigio_fd(random_fd);
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| 46 | deactivate_fd(random_fd, RANDOM_IRQ);
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| 47 |
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| 48 | if (ret < 0)
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| 49 | break;
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| 50 | } else {
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| 51 | break;
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| 52 | }
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| 53 | }
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| 54 |
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| 55 | return ret != -EAGAIN ? ret : 0;
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| 56 | }
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| 57 |
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| 58 | static irqreturn_t random_interrupt(int irq, void *data)
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| 59 | {
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| 60 | complete(&have_data);
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| 61 |
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| 62 | return IRQ_HANDLED;
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| 63 | }
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| 64 |
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| 65 | |
| 66 | * rng_init - initialize RNG module
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| 67 |
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| 68 | static int __init rng_init (void)
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| 69 | {
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| 70 | int err;
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| 71 |
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| 72 | err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
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| 73 | if (err < 0)
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| 74 | goto out;
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| 75 |
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| 76 | random_fd = err;
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| 77 | err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
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| 78 | 0, "random", NULL);
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| 79 | if (err < 0)
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| 80 | goto err_out_cleanup_hw;
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| 81 |
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| 82 | sigio_broken();
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| 83 | hwrng.name = RNG_MODULE_NAME;
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| 84 | hwrng.read = rng_dev_read;
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| 85 |
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| 86 | err = hwrng_register(&hwrng);
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| 87 | if (err) {
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| 88 | pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err);
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| 89 | goto err_out_cleanup_hw;
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| 90 | }
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| 91 | out:
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| 92 | return err;
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| 93 |
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| 94 | err_out_cleanup_hw:
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| 95 | os_close_file(random_fd);
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| 96 | random_fd = -1;
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| 97 | goto out;
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| 98 | }
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| 99 |
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| 100 | |
| 101 | * rng_cleanup - shutdown RNG module
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| 102 |
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| 103 |
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| 104 | static void cleanup(void)
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| 105 | {
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| 106 | free_irq_by_fd(random_fd);
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| 107 | os_close_file(random_fd);
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| 108 | }
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| 109 |
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| 110 | static void __exit rng_cleanup(void)
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| 111 | {
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| 112 | hwrng_unregister(&hwrng);
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| 113 | os_close_file(random_fd);
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| 114 | }
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| 115 |
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| 116 | module_init (rng_init);
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| 117 | module_exit (rng_cleanup);
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| 118 | __uml_exitcall(cleanup);
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| 119 |
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| 120 | MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
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| 121 | MODULE_LICENSE("GPL");
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