[PATCH v4 2/2] efi: an sysfs interface for user to update efi firmware

Kweh, Hock Leong
2015-04-14T01:45:28Z

From: "Kweh, Hock Leong" <hock.leong.kweh@intel.com>

Introducing a kernel module to expose capsule loader interface
for user to upload capsule binaries. This module leverage the
request_firmware_direct_full_path() to obtain the binary at a
specific path input by user.

Example method to load the capsule binary:
echo -n "/path/to/capsule/binary" > /sys/devices/platform/efi_capsule_loader/capsule_loader

Cc: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Kweh, Hock Leong <hock.leong.kweh@intel.com>
---
drivers/firmware/efi/Kconfig | 12 ++
drivers/firmware/efi/Makefile | 1 +
drivers/firmware/efi/efi-capsule-loader.c | 169 +++++++++++++++++++++++++++++
3 files changed, 182 insertions(+)
create mode 100644 drivers/firmware/efi/efi-capsule-loader.c

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index f712d47..3e84ec0 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -60,6 +60,18 @@ config EFI_RUNTIME_WRAPPERS
config EFI_ARMSTUB
bool

+config EFI_CAPSULE_LOADER
+ tristate "EFI capsule loader"
+ depends on EFI
+ select FW_LOADER
+ help
+ This option exposes a loader interface for user to load EFI
+ capsule binary and update the EFI firmware through system reboot.
+ This feature does not support auto locating capsule binaries at the
+ firmware lib search path.
+
+ If unsure, say N.
+
endmenu

config UEFI_CPER
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 698846e..5ab031a 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_UEFI_CPER) += cper.o
obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o
obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o
obj-$(CONFIG_EFI_STUB) += libstub/
+obj-$(CONFIG_EFI_CAPSULE_LOADER) += efi-capsule-loader.o
diff --git a/drivers/firmware/efi/efi-capsule-loader.c b/drivers/firmware/efi/efi-capsule-loader.c
new file mode 100644
index 0000000..84b979b
--- /dev/null
+++ b/drivers/firmware/efi/efi-capsule-loader.c
@@ -0,0 +1,169 @@
+/*
+ * EFI capsule loader driver.
+ *
+ * Copyright 2015 Intel Corporation
+ *
+ * This file is part of the Linux kernel, and is made available under
+ * the terms of the GNU General Public License version 2.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/efi.h>
+#include <linux/firmware.h>
+
+#define DEV_NAME "efi_capsule_loader"
+
+static DEFINE_MUTEX(capsule_loader_lock);
+static struct platform_device *efi_capsule_pdev;
+
+/*
+ * This function will store the capsule binary and pass it to
+ * efi_capsule_update() API in capsule.c
+ */
+static int efi_capsule_store(const struct firmware *fw)
+{
+ int i;
+ int ret;
+ int count = fw->size;
+ int copy_size = (fw->size > PAGE_SIZE) ? PAGE_SIZE : fw->size;
+ int pages_needed = ALIGN(fw->size, PAGE_SIZE) >> PAGE_SHIFT;
+ struct page **pages;
+ void *page_data;
+ efi_capsule_header_t *capsule = NULL;
+
+ if (!count) {
+ pr_err("%s: Received zero binary size\n", __func__);
+ return -ENOENT;
+ }
+
+ pages = kmalloc_array(pages_needed, sizeof(void *), GFP_KERNEL);
+ if (!pages) {
+ pr_err("%s: kmalloc_array() failed\n", __func__);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < pages_needed; i++) {
+ pages[i] = alloc_page(GFP_KERNEL);
+ if (!pages[i]) {
+ pr_err("%s: alloc_page() failed\n", __func__);
+ --i;
+ ret = -ENOMEM;
+ goto failed;
+ }
+ }
+
+ for (i = 0; i < pages_needed; i++) {
+ page_data = kmap(pages[i]);
+ memcpy(page_data, fw->data + (i * PAGE_SIZE), copy_size);
+
+ if (i == 0)
+ capsule = (efi_capsule_header_t *)page_data;
+ else
+ kunmap(pages[i]);
+
+ count -= copy_size;
+ if (count < PAGE_SIZE)
+ copy_size = count;
+ }
+
+ ret = efi_capsule_update(capsule, pages);
+ if (ret) {
+ pr_err("%s: efi_capsule_update() failed\n", __func__);
+ --i;
+ goto failed;
+ }
+ kunmap(pages[0]);
+
+ /*
+ * we cannot free the pages here due to reboot need that data
+ * maintained.
+ */
+ return 0;
+
+failed:
+ while (i >= 0)
+ __free_page(pages[i--]);
+ kfree(pages);
+ return ret;
+}
+
+static ssize_t capsule_loader_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ int ret = -EBUSY;
+ const struct firmware *fw;
+
+ pr_debug("%s: Received path = %s\n", __func__, buf);
+ if (mutex_trylock(&capsule_loader_lock)) {
+ ret = request_firmware_direct_full_path(&fw, buf,
+ &efi_capsule_pdev->dev);
+ if (ret) {
+ pr_err("%s: request_firmware_direct_full_path() %s\n",
+ __func__,
+ "failed");
+ mutex_unlock(&capsule_loader_lock);
+ return ret;
+ }
+
+ ret = efi_capsule_store(fw);
+ if (ret)
+ pr_err("%s: %s, return error code = %d\n",
+ __func__,
+ "Failed to store capsule binary",
+ ret);
+ release_firmware(fw);
+ mutex_unlock(&capsule_loader_lock);
+ }
+
+ return ret ? ret : count;
+}
+static DEVICE_ATTR_WO(capsule_loader);
+
+static int __init efi_capsule_loader_init(void)
+{
+ int ret = 0;
+
+ efi_capsule_pdev = platform_device_register_simple(DEV_NAME,
+ PLATFORM_DEVID_NONE,
+ NULL, 0);
+ if (IS_ERR(efi_capsule_pdev)) {
+ pr_err("%s: platform_device_register_simple() failed\n",
+ __func__);
+ return PTR_ERR(efi_capsule_pdev);
+ }
+
+ /*
+ * create this file node for user to pass in the full path of the
+ * capsule binary
+ */
+ ret = device_create_file(&efi_capsule_pdev->dev,
+ &dev_attr_capsule_loader);
+ if (ret) {
+ pr_err("%s: device_create_file() failed\n", __func__);
+ platform_device_unregister(efi_capsule_pdev);
+ }
+
+ return ret;
+}
+module_init(efi_capsule_loader_init);
+
+/*
+ * To remove this kernel module, just perform:
+ * rmmod efi_capsule_loader.ko
+ */
+static void __exit efi_capsule_loader_exit(void)
+{
+ platform_device_unregister(efi_capsule_pdev);
+}
+module_exit(efi_capsule_loader_exit);
+
+MODULE_DESCRIPTION("EFI capsule firmware binary loader");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5