Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 613 insertions, 0 deletions

diff --git a/drivers/acpi/pfr_update.c b/drivers/acpi/pfr_update.c
new file mode 100644
index 000000000..9afd2c52f
--- /dev/null
+++ b/drivers/acpi/pfr_update.c
@@ -0,0 +1,613 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI Platform Firmware Runtime Update Device driver
+ *
+ * Copyright (C) 2021 Intel Corporation
+ * Author: Chen Yu <yu.c.chen@intel.com>
+ *
+ * pfr_update driver is used for Platform Firmware Runtime
+ * Update, which includes the code injection and driver update.
+ */
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/efi.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/idr.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/uio.h>
+#include <linux/uuid.h>
+
+#include <uapi/linux/pfrut.h>
+
+#define PFRU_FUNC_STANDARD_QUERY	0
+#define PFRU_FUNC_QUERY_UPDATE_CAP	1
+#define PFRU_FUNC_QUERY_BUF		2
+#define PFRU_FUNC_START		3
+
+#define PFRU_CODE_INJECT_TYPE	1
+#define PFRU_DRIVER_UPDATE_TYPE	2
+
+#define PFRU_REVID_1		1
+#define PFRU_REVID_2		2
+#define PFRU_DEFAULT_REV_ID	PFRU_REVID_1
+
+enum cap_index {
+	CAP_STATUS_IDX = 0,
+	CAP_UPDATE_IDX = 1,
+	CAP_CODE_TYPE_IDX = 2,
+	CAP_FW_VER_IDX = 3,
+	CAP_CODE_RT_VER_IDX = 4,
+	CAP_DRV_TYPE_IDX = 5,
+	CAP_DRV_RT_VER_IDX = 6,
+	CAP_DRV_SVN_IDX = 7,
+	CAP_PLAT_ID_IDX = 8,
+	CAP_OEM_ID_IDX = 9,
+	CAP_OEM_INFO_IDX = 10,
+	CAP_NR_IDX
+};
+
+enum buf_index {
+	BUF_STATUS_IDX = 0,
+	BUF_EXT_STATUS_IDX = 1,
+	BUF_ADDR_LOW_IDX = 2,
+	BUF_ADDR_HI_IDX = 3,
+	BUF_SIZE_IDX = 4,
+	BUF_NR_IDX
+};
+
+enum update_index {
+	UPDATE_STATUS_IDX = 0,
+	UPDATE_EXT_STATUS_IDX = 1,
+	UPDATE_AUTH_TIME_LOW_IDX = 2,
+	UPDATE_AUTH_TIME_HI_IDX = 3,
+	UPDATE_EXEC_TIME_LOW_IDX = 4,
+	UPDATE_EXEC_TIME_HI_IDX = 5,
+	UPDATE_NR_IDX
+};
+
+enum pfru_start_action {
+	START_STAGE = 0,
+	START_ACTIVATE = 1,
+	START_STAGE_ACTIVATE = 2,
+};
+
+struct pfru_device {
+	u32 rev_id, index;
+	struct device *parent_dev;
+	struct miscdevice miscdev;
+};
+
+static DEFINE_IDA(pfru_ida);
+
+/*
+ * Manual reference:
+ * https://uefi.org/sites/default/files/resources/Intel_MM_OS_Interface_Spec_Rev100.pdf
+ *
+ * pfru_guid is the parameter for _DSM method
+ */
+static const guid_t pfru_guid =
+	GUID_INIT(0xECF9533B, 0x4A3C, 0x4E89, 0x93, 0x9E, 0xC7, 0x71,
+		  0x12, 0x60, 0x1C, 0x6D);
+
+/* pfru_code_inj_guid is the UUID to identify code injection EFI capsule file */
+static const guid_t pfru_code_inj_guid =
+	GUID_INIT(0xB2F84B79, 0x7B6E, 0x4E45, 0x88, 0x5F, 0x3F, 0xB9,
+		  0xBB, 0x18, 0x54, 0x02);
+
+/* pfru_drv_update_guid is the UUID to identify driver update EFI capsule file */
+static const guid_t pfru_drv_update_guid =
+	GUID_INIT(0x4569DD8C, 0x75F1, 0x429A, 0xA3, 0xD6, 0x24, 0xDE,
+		  0x80, 0x97, 0xA0, 0xDF);
+
+static inline int pfru_valid_revid(u32 id)
+{
+	return id == PFRU_REVID_1 || id == PFRU_REVID_2;
+}
+
+static inline struct pfru_device *to_pfru_dev(struct file *file)
+{
+	return container_of(file->private_data, struct pfru_device, miscdev);
+}
+
+static int query_capability(struct pfru_update_cap_info *cap_hdr,
+			    struct pfru_device *pfru_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	union acpi_object *out_obj, *elem;
+	int ret = -EINVAL;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id,
+					  PFRU_FUNC_QUERY_UPDATE_CAP,
+					  NULL, ACPI_TYPE_PACKAGE);
+	if (!out_obj) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Query cap failed with no object\n");
+		return ret;
+	}
+
+	if (out_obj->package.count < CAP_NR_IDX ||
+	    out_obj->package.elements[CAP_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_UPDATE_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_CODE_TYPE_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_FW_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_CODE_RT_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_DRV_TYPE_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_DRV_RT_VER_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_DRV_SVN_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[CAP_PLAT_ID_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_OEM_ID_IDX].type != ACPI_TYPE_BUFFER ||
+	    out_obj->package.elements[CAP_OEM_INFO_IDX].type != ACPI_TYPE_BUFFER) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Query cap failed with invalid package count/type\n");
+		goto free_acpi_buffer;
+	}
+
+	elem = out_obj->package.elements;
+
+	cap_hdr->status = elem[CAP_STATUS_IDX].integer.value;
+	if (cap_hdr->status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev, "Query cap Error Status:%d\n",
+			cap_hdr->status);
+		goto free_acpi_buffer;
+	}
+
+	if (elem[CAP_CODE_TYPE_IDX].buffer.length > sizeof(cap_hdr->code_type) ||
+	    elem[CAP_DRV_TYPE_IDX].buffer.length > sizeof(cap_hdr->drv_type) ||
+	    elem[CAP_PLAT_ID_IDX].buffer.length > sizeof(cap_hdr->platform_id) ||
+	    elem[CAP_OEM_ID_IDX].buffer.length > sizeof(cap_hdr->oem_id))
+		goto free_acpi_buffer;
+
+	cap_hdr->update_cap = elem[CAP_UPDATE_IDX].integer.value;
+	memcpy(&cap_hdr->code_type,
+	       elem[CAP_CODE_TYPE_IDX].buffer.pointer,
+	       elem[CAP_CODE_TYPE_IDX].buffer.length);
+	cap_hdr->fw_version = elem[CAP_FW_VER_IDX].integer.value;
+	cap_hdr->code_rt_version = elem[CAP_CODE_RT_VER_IDX].integer.value;
+	memcpy(&cap_hdr->drv_type,
+	       elem[CAP_DRV_TYPE_IDX].buffer.pointer,
+	       elem[CAP_DRV_TYPE_IDX].buffer.length);
+	cap_hdr->drv_rt_version = elem[CAP_DRV_RT_VER_IDX].integer.value;
+	cap_hdr->drv_svn = elem[CAP_DRV_SVN_IDX].integer.value;
+	memcpy(&cap_hdr->platform_id,
+	       elem[CAP_PLAT_ID_IDX].buffer.pointer,
+	       elem[CAP_PLAT_ID_IDX].buffer.length);
+	memcpy(&cap_hdr->oem_id,
+	       elem[CAP_OEM_ID_IDX].buffer.pointer,
+	       elem[CAP_OEM_ID_IDX].buffer.length);
+	cap_hdr->oem_info_len = elem[CAP_OEM_INFO_IDX].buffer.length;
+
+	ret = 0;
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static int query_buffer(struct pfru_com_buf_info *info,
+			struct pfru_device *pfru_dev)
+{
+	acpi_handle handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	union acpi_object *out_obj;
+	int ret = -EINVAL;
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id, PFRU_FUNC_QUERY_BUF,
+					  NULL, ACPI_TYPE_PACKAGE);
+	if (!out_obj) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Query buf failed with no object\n");
+		return ret;
+	}
+
+	if (out_obj->package.count < BUF_NR_IDX ||
+	    out_obj->package.elements[BUF_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_ADDR_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_ADDR_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[BUF_SIZE_IDX].type != ACPI_TYPE_INTEGER) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Query buf failed with invalid package count/type\n");
+		goto free_acpi_buffer;
+	}
+
+	info->status = out_obj->package.elements[BUF_STATUS_IDX].integer.value;
+	info->ext_status =
+		out_obj->package.elements[BUF_EXT_STATUS_IDX].integer.value;
+	if (info->status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev,
+			"Query buf failed with Error Status:%d\n", info->status);
+		dev_dbg(pfru_dev->parent_dev,
+			"Query buf failed with Error Extended Status:%d\n", info->ext_status);
+
+		goto free_acpi_buffer;
+	}
+
+	info->addr_lo =
+		out_obj->package.elements[BUF_ADDR_LOW_IDX].integer.value;
+	info->addr_hi =
+		out_obj->package.elements[BUF_ADDR_HI_IDX].integer.value;
+	info->buf_size = out_obj->package.elements[BUF_SIZE_IDX].integer.value;
+
+	ret = 0;
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static int get_image_type(const struct efi_manage_capsule_image_header *img_hdr,
+			  struct pfru_device *pfru_dev)
+{
+	const efi_guid_t *image_type_id = &img_hdr->image_type_id;
+
+	/* check whether this is a code injection or driver update */
+	if (guid_equal(image_type_id, &pfru_code_inj_guid))
+		return PFRU_CODE_INJECT_TYPE;
+
+	if (guid_equal(image_type_id, &pfru_drv_update_guid))
+		return PFRU_DRIVER_UPDATE_TYPE;
+
+	return -EINVAL;
+}
+
+static int adjust_efi_size(const struct efi_manage_capsule_image_header *img_hdr,
+			   int size)
+{
+	/*
+	 * The (u64 hw_ins) was introduced in UEFI spec version 2,
+	 * and (u64 capsule_support) was introduced in version 3.
+	 * The size needs to be adjusted accordingly. That is to
+	 * say, version 1 should subtract the size of hw_ins+capsule_support,
+	 * and version 2 should sbstract the size of capsule_support.
+	 */
+	size += sizeof(struct efi_manage_capsule_image_header);
+	switch (img_hdr->ver) {
+	case 1:
+		return size - 2 * sizeof(u64);
+
+	case 2:
+		return size - sizeof(u64);
+
+	default:
+		/* only support version 1 and 2 */
+		return -EINVAL;
+	}
+}
+
+static bool applicable_image(const void *data, struct pfru_update_cap_info *cap,
+			     struct pfru_device *pfru_dev)
+{
+	struct pfru_payload_hdr *payload_hdr;
+	const efi_capsule_header_t *cap_hdr = data;
+	const struct efi_manage_capsule_header *m_hdr;
+	const struct efi_manage_capsule_image_header *m_img_hdr;
+	const struct efi_image_auth *auth;
+	int type, size;
+
+	/*
+	 * If the code in the capsule is older than the current
+	 * firmware code, the update will be rejected by the firmware,
+	 * so check the version of it upfront without engaging the
+	 * Management Mode update mechanism which may be costly.
+	 */
+	size = cap_hdr->headersize;
+	m_hdr = data + size;
+	/*
+	 * Current data structure size plus variable array indicated
+	 * by number of (emb_drv_cnt + payload_cnt)
+	 */
+	size += offsetof(struct efi_manage_capsule_header, offset_list) +
+		(m_hdr->emb_drv_cnt + m_hdr->payload_cnt) * sizeof(u64);
+	m_img_hdr = data + size;
+
+	type = get_image_type(m_img_hdr, pfru_dev);
+	if (type < 0) {
+		dev_dbg(pfru_dev->parent_dev, "Invalid image type\n");
+		return false;
+	}
+
+	size = adjust_efi_size(m_img_hdr, size);
+	if (size < 0) {
+		dev_dbg(pfru_dev->parent_dev, "Invalid image size\n");
+		return false;
+	}
+
+	auth = data + size;
+	size += sizeof(u64) + auth->auth_info.hdr.len;
+	payload_hdr = (struct pfru_payload_hdr *)(data + size);
+
+	/* finally compare the version */
+	if (type == PFRU_CODE_INJECT_TYPE)
+		return payload_hdr->rt_ver >= cap->code_rt_version;
+
+	return payload_hdr->svn_ver >= cap->drv_svn;
+}
+
+static void print_update_debug_info(struct pfru_updated_result *result,
+				    struct pfru_device *pfru_dev)
+{
+	dev_dbg(pfru_dev->parent_dev, "Update result:\n");
+	dev_dbg(pfru_dev->parent_dev, "Authentication Time Low:%lld\n",
+		result->low_auth_time);
+	dev_dbg(pfru_dev->parent_dev, "Authentication Time High:%lld\n",
+		result->high_auth_time);
+	dev_dbg(pfru_dev->parent_dev, "Execution Time Low:%lld\n",
+		result->low_exec_time);
+	dev_dbg(pfru_dev->parent_dev, "Execution Time High:%lld\n",
+		result->high_exec_time);
+}
+
+static int start_update(int action, struct pfru_device *pfru_dev)
+{
+	union acpi_object *out_obj, in_obj, in_buf;
+	struct pfru_updated_result update_result;
+	acpi_handle handle;
+	int ret = -EINVAL;
+
+	memset(&in_obj, 0, sizeof(in_obj));
+	memset(&in_buf, 0, sizeof(in_buf));
+	in_obj.type = ACPI_TYPE_PACKAGE;
+	in_obj.package.count = 1;
+	in_obj.package.elements = &in_buf;
+	in_buf.type = ACPI_TYPE_INTEGER;
+	in_buf.integer.value = action;
+
+	handle = ACPI_HANDLE(pfru_dev->parent_dev);
+	out_obj = acpi_evaluate_dsm_typed(handle, &pfru_guid,
+					  pfru_dev->rev_id, PFRU_FUNC_START,
+					  &in_obj, ACPI_TYPE_PACKAGE);
+	if (!out_obj) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Update failed to start with no object\n");
+		return ret;
+	}
+
+	if (out_obj->package.count < UPDATE_NR_IDX ||
+	    out_obj->package.elements[UPDATE_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXT_STATUS_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].type != ACPI_TYPE_INTEGER ||
+	    out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].type != ACPI_TYPE_INTEGER) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Update failed with invalid package count/type\n");
+		goto free_acpi_buffer;
+	}
+
+	update_result.status =
+		out_obj->package.elements[UPDATE_STATUS_IDX].integer.value;
+	update_result.ext_status =
+		out_obj->package.elements[UPDATE_EXT_STATUS_IDX].integer.value;
+
+	if (update_result.status != DSM_SUCCEED) {
+		ret = -EBUSY;
+		dev_dbg(pfru_dev->parent_dev,
+			"Update failed with Error Status:%d\n", update_result.status);
+		dev_dbg(pfru_dev->parent_dev,
+			"Update failed with Error Extended Status:%d\n",
+			update_result.ext_status);
+
+		goto free_acpi_buffer;
+	}
+
+	update_result.low_auth_time =
+		out_obj->package.elements[UPDATE_AUTH_TIME_LOW_IDX].integer.value;
+	update_result.high_auth_time =
+		out_obj->package.elements[UPDATE_AUTH_TIME_HI_IDX].integer.value;
+	update_result.low_exec_time =
+		out_obj->package.elements[UPDATE_EXEC_TIME_LOW_IDX].integer.value;
+	update_result.high_exec_time =
+		out_obj->package.elements[UPDATE_EXEC_TIME_HI_IDX].integer.value;
+
+	print_update_debug_info(&update_result, pfru_dev);
+	ret = 0;
+
+free_acpi_buffer:
+	ACPI_FREE(out_obj);
+
+	return ret;
+}
+
+static long pfru_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct pfru_update_cap_info cap_hdr;
+	struct pfru_device *pfru_dev = to_pfru_dev(file);
+	void __user *p = (void __user *)arg;
+	u32 rev;
+	int ret;
+
+	switch (cmd) {
+	case PFRU_IOC_QUERY_CAP:
+		ret = query_capability(&cap_hdr, pfru_dev);
+		if (ret)
+			return ret;
+
+		if (copy_to_user(p, &cap_hdr, sizeof(cap_hdr)))
+			return -EFAULT;
+
+		return 0;
+
+	case PFRU_IOC_SET_REV:
+		if (copy_from_user(&rev, p, sizeof(rev)))
+			return -EFAULT;
+
+		if (!pfru_valid_revid(rev))
+			return -EINVAL;
+
+		pfru_dev->rev_id = rev;
+
+		return 0;
+
+	case PFRU_IOC_STAGE:
+		return start_update(START_STAGE, pfru_dev);
+
+	case PFRU_IOC_ACTIVATE:
+		return start_update(START_ACTIVATE, pfru_dev);
+
+	case PFRU_IOC_STAGE_ACTIVATE:
+		return start_update(START_STAGE_ACTIVATE, pfru_dev);
+
+	default:
+		return -ENOTTY;
+	}
+}
+
+static ssize_t pfru_write(struct file *file, const char __user *buf,
+			  size_t len, loff_t *ppos)
+{
+	struct pfru_device *pfru_dev = to_pfru_dev(file);
+	struct pfru_update_cap_info cap;
+	struct pfru_com_buf_info buf_info;
+	phys_addr_t phy_addr;
+	struct iov_iter iter;
+	struct iovec iov;
+	char *buf_ptr;
+	int ret;
+
+	ret = query_buffer(&buf_info, pfru_dev);
+	if (ret)
+		return ret;
+
+	if (len > buf_info.buf_size) {
+		dev_dbg(pfru_dev->parent_dev, "Capsule image size too large\n");
+		return -EINVAL;
+	}
+
+	iov.iov_base = (void __user *)buf;
+	iov.iov_len = len;
+	iov_iter_init(&iter, ITER_SOURCE, &iov, 1, len);
+
+	/* map the communication buffer */
+	phy_addr = (phys_addr_t)((buf_info.addr_hi << 32) | buf_info.addr_lo);
+	buf_ptr = memremap(phy_addr, buf_info.buf_size, MEMREMAP_WB);
+	if (!buf_ptr) {
+		dev_dbg(pfru_dev->parent_dev, "Failed to remap the buffer\n");
+		return -ENOMEM;
+	}
+
+	if (!copy_from_iter_full(buf_ptr, len, &iter)) {
+		dev_dbg(pfru_dev->parent_dev,
+			"Failed to copy the data from the user space buffer\n");
+		ret = -EINVAL;
+		goto unmap;
+	}
+
+	/* check if the capsule header has a valid version number */
+	ret = query_capability(&cap, pfru_dev);
+	if (ret)
+		goto unmap;
+
+	if (!applicable_image(buf_ptr, &cap, pfru_dev))
+		ret = -EINVAL;
+
+unmap:
+	memunmap(buf_ptr);
+
+	return ret ?: len;
+}
+
+static const struct file_operations acpi_pfru_fops = {
+	.owner		= THIS_MODULE,
+	.write		= pfru_write,
+	.unlocked_ioctl = pfru_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static void acpi_pfru_remove(struct platform_device *pdev)
+{
+	struct pfru_device *pfru_dev = platform_get_drvdata(pdev);
+
+	misc_deregister(&pfru_dev->miscdev);
+}
+
+static void pfru_put_idx(void *data)
+{
+	struct pfru_device *pfru_dev = data;
+
+	ida_free(&pfru_ida, pfru_dev->index);
+}
+
+static int acpi_pfru_probe(struct platform_device *pdev)
+{
+	struct pfru_device *pfru_dev;
+	acpi_handle handle;
+	int ret;
+
+	handle = ACPI_HANDLE(&pdev->dev);
+	if (!handle)
+		return -ENODEV;
+
+	if (!acpi_has_method(handle, "_DSM")) {
+		dev_dbg(&pdev->dev, "Missing _DSM\n");
+		return -ENODEV;
+	}
+
+	pfru_dev = devm_kzalloc(&pdev->dev, sizeof(*pfru_dev), GFP_KERNEL);
+	if (!pfru_dev)
+		return -ENOMEM;
+
+	ret = ida_alloc(&pfru_ida, GFP_KERNEL);
+	if (ret < 0)
+		return ret;
+
+	pfru_dev->index = ret;
+	ret = devm_add_action_or_reset(&pdev->dev, pfru_put_idx, pfru_dev);
+	if (ret)
+		return ret;
+
+	pfru_dev->rev_id = PFRU_DEFAULT_REV_ID;
+	pfru_dev->parent_dev = &pdev->dev;
+
+	pfru_dev->miscdev.minor = MISC_DYNAMIC_MINOR;
+	pfru_dev->miscdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+						"pfru%d", pfru_dev->index);
+	if (!pfru_dev->miscdev.name)
+		return -ENOMEM;
+
+	pfru_dev->miscdev.nodename = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+						    "acpi_pfr_update%d", pfru_dev->index);
+	if (!pfru_dev->miscdev.nodename)
+		return -ENOMEM;
+
+	pfru_dev->miscdev.fops = &acpi_pfru_fops;
+	pfru_dev->miscdev.parent = &pdev->dev;
+
+	ret = misc_register(&pfru_dev->miscdev);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, pfru_dev);
+
+	return 0;
+}
+
+static const struct acpi_device_id acpi_pfru_ids[] = {
+	{"INTC1080"},
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, acpi_pfru_ids);
+
+static struct platform_driver acpi_pfru_driver = {
+	.driver = {
+		.name = "pfr_update",
+		.acpi_match_table = acpi_pfru_ids,
+	},
+	.probe = acpi_pfru_probe,
+	.remove = acpi_pfru_remove,
+};
+module_platform_driver(acpi_pfru_driver);
+
+MODULE_DESCRIPTION("Platform Firmware Runtime Update device driver");
+MODULE_LICENSE("GPL v2");