Add char device driver 'userpanic-dev' that exposes an interface to
userspace processes to request a system panic with customized panic
message.
Signed-off-by: Woody Lin <woodylin@xxxxxxxxxx>
---
drivers/staging/android/Kconfig | 12 +++
drivers/staging/android/Makefile | 1 +
drivers/staging/android/userpanic-dev.c | 110 ++++++++++++++++++++++++
3 files changed, 123 insertions(+)
create mode 100644 drivers/staging/android/userpanic-dev.c
diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index 70498adb1575..b1968a1ee821 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -14,6 +14,18 @@ config ASHMEM
It is, in theory, a good memory allocator for low-memory devices,
because it can discard shared memory units when under memory pressure.
+config USERPANIC_CHARDEV
+ bool "User-panic device interface"
+ help
+ Say Y here to use user-panic device for user space processes to
+ request a system panic with customized panic message.
+
+ A char device '/dev/userspace_panic' is created by this driver
+ when selecting 'Y'. User processes can request panic and attach
+ customized panic message and title by ioctl(CRASH_INFO). Later any
+ panic handler can collect the panic message to build debugging
+ reports.
+
endif # if ANDROID
endmenu
diff --git a/drivers/staging/android/Makefile b/drivers/staging/android/Makefile
index e9a55a5e6529..851efb3435ac 100644
--- a/drivers/staging/android/Makefile
+++ b/drivers/staging/android/Makefile
@@ -2,3 +2,4 @@
ccflags-y += -I$(src) # needed for trace events
obj-$(CONFIG_ASHMEM) += ashmem.o
+obj-$(CONFIG_USERPANIC_CHARDEV) += userpanic-dev.o
diff --git a/drivers/staging/android/userpanic-dev.c b/drivers/staging/android/userpanic-dev.c
new file mode 100644
index 000000000000..b9a0f0c01826
--- /dev/null
+++ b/drivers/staging/android/userpanic-dev.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* userpanic-dev.c
+ *
+ * User-panic Device Interface
+ *
+ * Copyright 2021 Google LLC
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/miscdevice.h>
+
+struct userpanic_crash_info {
+ void __user *title_uaddr;
+ void __user *msg_uaddr;
+};
+
+#define CRASH_INFO (_IOW('U', 179, struct userpanic_crash_info))
+
+static int do_userpanic(const char *title, const char *msg)
+{
+ const size_t msgbuf_sz = PAGE_SIZE;
+ char *msgbuf;
+
+ msgbuf = kmalloc(msgbuf_sz, GFP_KERNEL);
+ if (!msgbuf)
+ return -ENOMEM;
+
+ pr_emerg("User process '%.*s' %d requesting kernel panic\n",
+ sizeof(current->comm), current->comm, current->pid);
+ if (msg)
+ pr_emerg(" with message: %s\n", msg);
+
+ /* Request panic with customized panic title. */
+ snprintf(msgbuf, msgbuf_sz, "U: %s: %s", current->comm, title);
+ panic(msgbuf);
+ kfree(msgbuf);
+ return -EFAULT;
+}
+
+static long userpanic_device_ioctl(struct file *file, u_int cmd, u_long arg)
+{
+ struct userpanic_crash_info crash_info;
+ char *title;
+ char *msg = NULL;
+ int ret;
+
+ switch (cmd) {
+ case CRASH_INFO:
+ if (copy_from_user(&crash_info, (void __user *)arg, sizeof(crash_info)))
+ return -EFAULT;
+
+ if (!crash_info.title_uaddr)
+ return -EINVAL;
+
+ title = strndup_user(crash_info.title_uaddr, PAGE_SIZE);
+ if (IS_ERR(title)) {
+ pr_err("failed to strndup .title_uaddr: %d\n", PTR_ERR(title));
+ return -EINVAL;
+ }
+
+ if (crash_info.msg_uaddr) {
+ msg = strndup_user(crash_info.msg_uaddr, PAGE_SIZE);
+ if (IS_ERR(msg)) {
+ kfree(title);
+ pr_err("failed to strndup .msg_uaddr: %d\n", PTR_ERR(msg));
+ return -EINVAL;
+ }
+ }
+
+ ret = do_userpanic(title, msg);
+ kfree(msg);
+ kfree(title);
+ return ret;
+ }
+
+ return -EINVAL;
+}
+
+static const struct file_operations userpanic_device_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = userpanic_device_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+};
+
+static struct miscdevice userpanic_device = {
+ .minor = MISC_DYNAMIC_MINOR,
+ .name = "userspace_panic",
+ .fops = &userpanic_device_fops,
+};
+
+static int __init userspace_panic_dev_init(void)
+{
+ int ret;
+
+ ret = misc_register(&userpanic_device);
+ if (ret)
+ pr_err("misc_register failed for userspace_panic device\n");
+
+ return ret;
+}
+
+device_initcall(userspace_panic_dev_init);
+
+MODULE_DESCRIPTION("User-panic interface device driver");
+MODULE_AUTHOR("Woody Lin <woodylin@xxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
--
2.33.0.rc2.250.ged5fa647cd-goog
