2 * This module provides an interface to trigger and test firmware loading.
4 * It is designed to be used for basic evaluation of the firmware loading
5 * subsystem (for example when validating firmware verification). It lacks
6 * any extra dependencies, and will not normally be loaded by the system
7 * unless explicitly requested by name.
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/printk.h>
15 #include <linux/completion.h>
16 #include <linux/firmware.h>
17 #include <linux/device.h>
19 #include <linux/miscdevice.h>
20 #include <linux/slab.h>
21 #include <linux/uaccess.h>
23 static DEFINE_MUTEX(test_fw_mutex);
24 static const struct firmware *test_firmware;
26 static ssize_t test_fw_misc_read(struct file *f, char __user *buf,
27 size_t size, loff_t *offset)
31 mutex_lock(&test_fw_mutex);
33 rc = simple_read_from_buffer(buf, size, offset,
36 mutex_unlock(&test_fw_mutex);
40 static const struct file_operations test_fw_fops = {
42 .read = test_fw_misc_read,
45 static ssize_t trigger_request_store(struct device *dev,
46 struct device_attribute *attr,
47 const char *buf, size_t count)
52 name = kstrndup(buf, count, GFP_KERNEL);
56 pr_info("loading '%s'\n", name);
58 mutex_lock(&test_fw_mutex);
59 release_firmware(test_firmware);
61 rc = request_firmware(&test_firmware, name, dev);
63 pr_info("load of '%s' failed: %d\n", name, rc);
66 pr_info("loaded: %zu\n", test_firmware->size);
70 mutex_unlock(&test_fw_mutex);
76 static DEVICE_ATTR_WO(trigger_request);
78 static DECLARE_COMPLETION(async_fw_done);
80 static void trigger_async_request_cb(const struct firmware *fw, void *context)
83 complete(&async_fw_done);
86 static ssize_t trigger_async_request_store(struct device *dev,
87 struct device_attribute *attr,
88 const char *buf, size_t count)
93 name = kstrndup(buf, count, GFP_KERNEL);
97 pr_info("loading '%s'\n", name);
99 mutex_lock(&test_fw_mutex);
100 release_firmware(test_firmware);
101 test_firmware = NULL;
102 rc = request_firmware_nowait(THIS_MODULE, 1, name, dev, GFP_KERNEL,
103 NULL, trigger_async_request_cb);
105 pr_info("async load of '%s' failed: %d\n", name, rc);
109 /* Free 'name' ASAP, to test for race conditions */
112 wait_for_completion(&async_fw_done);
115 pr_info("loaded: %zu\n", test_firmware->size);
118 pr_err("failed to async load firmware\n");
123 mutex_unlock(&test_fw_mutex);
127 static DEVICE_ATTR_WO(trigger_async_request);
129 #define TEST_FW_DEV_ATTR(name) &dev_attr_##name.attr
131 static struct attribute *test_dev_attrs[] = {
132 TEST_FW_DEV_ATTR(trigger_request),
133 TEST_FW_DEV_ATTR(trigger_async_request),
137 ATTRIBUTE_GROUPS(test_dev);
139 static struct miscdevice test_fw_misc_device = {
140 .minor = MISC_DYNAMIC_MINOR,
141 .name = "test_firmware",
142 .fops = &test_fw_fops,
143 .groups = test_dev_groups,
146 static int __init test_firmware_init(void)
150 rc = misc_register(&test_fw_misc_device);
152 pr_err("could not register misc device: %d\n", rc);
156 pr_warn("interface ready\n");
161 module_init(test_firmware_init);
163 static void __exit test_firmware_exit(void)
165 release_firmware(test_firmware);
166 misc_deregister(&test_fw_misc_device);
167 pr_warn("removed interface\n");
170 module_exit(test_firmware_exit);
172 MODULE_AUTHOR("Kees Cook <keescook@chromium.org>");
173 MODULE_LICENSE("GPL");