| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20251130-next-15nov_expose_sysfs-v20-2-18c80f8248dd@oss.qualcomm.com>
Date: Sun, 30 Nov 2025 23:51:24 +0530
From: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
To: Sebastian Reichel <sre@...nel.org>,
Bartosz Golaszewski <bgolasze@...cinc.com>,
Bjorn Andersson <andersson@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
linux-pm@...r.kernel.org, Bartosz Golaszewski <brgl@...ev.pl>,
Shivendra Pratap <shivendra.pratap@....qualcomm.com>
Subject: [PATCH v20 2/2] power: reset: reboot-mode: Expose sysfs for
registered reboot_modes
Currently, there is no standardized mechanism for userspace to discover
which reboot-modes are supported on a given platform. This limitation
forces tools and scripts to rely on hardcoded assumptions about the
supported reboot-modes.
Create a class 'reboot-mode' and a device under it to expose a sysfs
interface to show the available reboot mode arguments to userspace. Use
the driver_name field of the struct reboot_mode_driver to create the
device. For device-based drivers, configure the device driver name as
driver_name.
This results in the creation of:
/sys/class/reboot-mode/<driver>/reboot_modes
This read-only sysfs file will exposes the list of supported reboot
modes arguments provided by the driver, enabling userspace to query the
list of arguments.
Signed-off-by: Shivendra Pratap <shivendra.pratap@....qualcomm.com>
---
drivers/power/reset/reboot-mode.c | 76 +++++++++++++++++++++++++++++++++++++--
include/linux/reboot-mode.h | 6 ++++
2 files changed, 80 insertions(+), 2 deletions(-)
diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
index fba53f638da04655e756b5f8b7d2d666d1379535..ae03f2d96a84477f1e9f281bf3110911d7044a70 100644
--- a/drivers/power/reset/reboot-mode.c
+++ b/drivers/power/reset/reboot-mode.c
@@ -3,6 +3,8 @@
* Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
*/
+#define pr_fmt(fmt) "reboot-mode: " fmt
+
#include <linux/device.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -19,6 +21,56 @@ struct mode_info {
struct list_head list;
};
+static ssize_t reboot_modes_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct reboot_mode_driver *reboot;
+ struct mode_info *info;
+ ssize_t size = 0;
+
+ reboot = container_of(dev, struct reboot_mode_driver, reboot_mode_device);
+ if (!reboot)
+ return -ENODATA;
+ scoped_guard(mutex, &reboot->reboot_mode_mutex) {
+ list_for_each_entry(info, &reboot->head, list)
+ size += sysfs_emit_at(buf, size, "%s ", info->mode);
+ }
+
+ if (!size)
+ return -ENODATA;
+
+ return size + sysfs_emit_at(buf, size - 1, "\n");
+}
+static DEVICE_ATTR_RO(reboot_modes);
+
+static struct attribute *reboot_mode_attrs[] = {
+ &dev_attr_reboot_modes.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(reboot_mode);
+
+static const struct class reboot_mode_class = {
+ .name = "reboot-mode",
+ .dev_groups = reboot_mode_groups,
+};
+
+static void reboot_mode_device_release(struct device *dev)
+{
+ /* place holder to avoid warning on device_unregister. nothing to free */
+}
+
+static void reboot_mode_register_device(struct reboot_mode_driver *reboot)
+{
+ int ret;
+
+ reboot->reboot_mode_device.class = &reboot_mode_class;
+ reboot->reboot_mode_device.release = reboot_mode_device_release;
+ dev_set_name(&reboot->reboot_mode_device, reboot->driver_name);
+ /* Check return value to avoid compiler warning */
+ ret = device_register(&reboot->reboot_mode_device);
+ if (ret)
+ pr_debug("device_register failed for %s : %d\n", reboot->driver_name, ret);
+}
+
static unsigned int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
const char *cmd)
{
@@ -76,6 +128,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
size_t len = strlen(PREFIX);
int ret;
+ mutex_init(&reboot->reboot_mode_mutex);
INIT_LIST_HEAD(&reboot->head);
for_each_property_of_node(np, prop) {
@@ -112,6 +165,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
reboot->reboot_notifier.notifier_call = reboot_mode_notify;
register_reboot_notifier(&reboot->reboot_notifier);
+ reboot_mode_register_device(reboot);
return 0;
@@ -132,9 +186,13 @@ int reboot_mode_unregister(struct reboot_mode_driver *reboot)
struct mode_info *info;
unregister_reboot_notifier(&reboot->reboot_notifier);
+ if (device_is_registered(&reboot->reboot_mode_device))
+ device_unregister(&reboot->reboot_mode_device);
- list_for_each_entry(info, &reboot->head, list)
- kfree_const(info->mode);
+ scoped_guard(mutex, &reboot->reboot_mode_mutex) {
+ list_for_each_entry(info, &reboot->head, list)
+ kfree_const(info->mode);
+ }
return 0;
}
@@ -162,6 +220,7 @@ int devm_reboot_mode_register(struct device *dev,
if (!dr)
return -ENOMEM;
+ reboot->driver_name = reboot->dev->driver->name;
rc = reboot_mode_register(reboot);
if (rc) {
devres_free(dr);
@@ -199,6 +258,19 @@ void devm_reboot_mode_unregister(struct device *dev,
}
EXPORT_SYMBOL_GPL(devm_reboot_mode_unregister);
+static int __init reboot_mode_init(void)
+{
+ return class_register(&reboot_mode_class);
+}
+
+static void __exit reboot_mode_exit(void)
+{
+ class_unregister(&reboot_mode_class);
+}
+
+subsys_initcall(reboot_mode_init);
+module_exit(reboot_mode_exit);
+
MODULE_AUTHOR("Andy Yan <andy.yan@...k-chips.com>");
MODULE_DESCRIPTION("System reboot mode core library");
MODULE_LICENSE("GPL v2");
diff --git a/include/linux/reboot-mode.h b/include/linux/reboot-mode.h
index 4a2abb38d1d612ec0fdf05eb18c98b210f631b7f..76900c1b78003559a7b7812bad34206bb3ba5f75 100644
--- a/include/linux/reboot-mode.h
+++ b/include/linux/reboot-mode.h
@@ -2,9 +2,15 @@
#ifndef __REBOOT_MODE_H__
#define __REBOOT_MODE_H__
+#include <linux/mutex.h>
+
struct reboot_mode_driver {
struct device *dev;
struct list_head head;
+ const char *driver_name;
+ struct device reboot_mode_device;
+ /* protects reboot_mode list */
+ struct mutex reboot_mode_mutex;
int (*write)(struct reboot_mode_driver *reboot, unsigned int magic);
struct notifier_block reboot_notifier;
};
--
2.34.1
Powered by blists - more mailing lists