Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 697 insertions, 0 deletions

diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
new file mode 100644
index 000000000..cda53d037
--- /dev/null
+++ b/drivers/firmware/dmi-sysfs.c
@@ -0,0 +1,697 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * dmi-sysfs.c
+ *
+ * This module exports the DMI tables read-only to userspace through the
+ * sysfs file system.
+ *
+ * Data is currently found below
+ *    /sys/firmware/dmi/...
+ *
+ * DMI attributes are presented in attribute files with names
+ * formatted using %d-%d, so that the first integer indicates the
+ * structure type (0-255), and the second field is the instance of that
+ * entry.
+ *
+ * Copyright 2011 Google, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kobject.h>
+#include <linux/dmi.h>
+#include <linux/capability.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/io.h>
+#include <asm/dmi.h>
+
+#define MAX_ENTRY_TYPE 255 /* Most of these aren't used, but we consider
+			      the top entry type is only 8 bits */
+
+struct dmi_sysfs_entry {
+	struct dmi_header dh;
+	struct kobject kobj;
+	int instance;
+	int position;
+	struct list_head list;
+	struct kobject *child;
+};
+
+/*
+ * Global list of dmi_sysfs_entry.  Even though this should only be
+ * manipulated at setup and teardown, the lazy nature of the kobject
+ * system means we get lazy removes.
+ */
+static LIST_HEAD(entry_list);
+static DEFINE_SPINLOCK(entry_list_lock);
+
+/* dmi_sysfs_attribute - Top level attribute. used by all entries. */
+struct dmi_sysfs_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct dmi_sysfs_entry *entry, char *buf);
+};
+
+#define DMI_SYSFS_ATTR(_entry, _name) \
+struct dmi_sysfs_attribute dmi_sysfs_attr_##_entry##_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = 0400}, \
+	.show = dmi_sysfs_##_entry##_##_name, \
+}
+
+/*
+ * dmi_sysfs_mapped_attribute - Attribute where we require the entry be
+ * mapped in.  Use in conjunction with dmi_sysfs_specialize_attr_ops.
+ */
+struct dmi_sysfs_mapped_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct dmi_sysfs_entry *entry,
+			const struct dmi_header *dh,
+			char *buf);
+};
+
+#define DMI_SYSFS_MAPPED_ATTR(_entry, _name) \
+struct dmi_sysfs_mapped_attribute dmi_sysfs_attr_##_entry##_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = 0400}, \
+	.show = dmi_sysfs_##_entry##_##_name, \
+}
+
+/*************************************************
+ * Generic DMI entry support.
+ *************************************************/
+static void dmi_entry_free(struct kobject *kobj)
+{
+	kfree(kobj);
+}
+
+static struct dmi_sysfs_entry *to_entry(struct kobject *kobj)
+{
+	return container_of(kobj, struct dmi_sysfs_entry, kobj);
+}
+
+static struct dmi_sysfs_attribute *to_attr(struct attribute *attr)
+{
+	return container_of(attr, struct dmi_sysfs_attribute, attr);
+}
+
+static ssize_t dmi_sysfs_attr_show(struct kobject *kobj,
+				   struct attribute *_attr, char *buf)
+{
+	struct dmi_sysfs_entry *entry = to_entry(kobj);
+	struct dmi_sysfs_attribute *attr = to_attr(_attr);
+
+	/* DMI stuff is only ever admin visible */
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	return attr->show(entry, buf);
+}
+
+static const struct sysfs_ops dmi_sysfs_attr_ops = {
+	.show = dmi_sysfs_attr_show,
+};
+
+typedef ssize_t (*dmi_callback)(struct dmi_sysfs_entry *,
+				const struct dmi_header *dh, void *);
+
+struct find_dmi_data {
+	struct dmi_sysfs_entry	*entry;
+	dmi_callback		callback;
+	void			*private;
+	int			instance_countdown;
+	ssize_t			ret;
+};
+
+static void find_dmi_entry_helper(const struct dmi_header *dh,
+				  void *_data)
+{
+	struct find_dmi_data *data = _data;
+	struct dmi_sysfs_entry *entry = data->entry;
+
+	/* Is this the entry we want? */
+	if (dh->type != entry->dh.type)
+		return;
+
+	if (data->instance_countdown != 0) {
+		/* try the next instance? */
+		data->instance_countdown--;
+		return;
+	}
+
+	/*
+	 * Don't ever revisit the instance.  Short circuit later
+	 * instances by letting the instance_countdown run negative
+	 */
+	data->instance_countdown--;
+
+	/* Found the entry */
+	data->ret = data->callback(entry, dh, data->private);
+}
+
+/* State for passing the read parameters through dmi_find_entry() */
+struct dmi_read_state {
+	char *buf;
+	loff_t pos;
+	size_t count;
+};
+
+static ssize_t find_dmi_entry(struct dmi_sysfs_entry *entry,
+			      dmi_callback callback, void *private)
+{
+	struct find_dmi_data data = {
+		.entry = entry,
+		.callback = callback,
+		.private = private,
+		.instance_countdown = entry->instance,
+		.ret = -EIO,  /* To signal the entry disappeared */
+	};
+	int ret;
+
+	ret = dmi_walk(find_dmi_entry_helper, &data);
+	/* This shouldn't happen, but just in case. */
+	if (ret)
+		return -EINVAL;
+	return data.ret;
+}
+
+/*
+ * Calculate and return the byte length of the dmi entry identified by
+ * dh.  This includes both the formatted portion as well as the
+ * unformatted string space, including the two trailing nul characters.
+ */
+static size_t dmi_entry_length(const struct dmi_header *dh)
+{
+	const char *p = (const char *)dh;
+
+	p += dh->length;
+
+	while (p[0] || p[1])
+		p++;
+
+	return 2 + p - (const char *)dh;
+}
+
+/*************************************************
+ * Support bits for specialized DMI entry support
+ *************************************************/
+struct dmi_entry_attr_show_data {
+	struct attribute *attr;
+	char *buf;
+};
+
+static ssize_t dmi_entry_attr_show_helper(struct dmi_sysfs_entry *entry,
+					  const struct dmi_header *dh,
+					  void *_data)
+{
+	struct dmi_entry_attr_show_data *data = _data;
+	struct dmi_sysfs_mapped_attribute *attr;
+
+	attr = container_of(data->attr,
+			    struct dmi_sysfs_mapped_attribute, attr);
+	return attr->show(entry, dh, data->buf);
+}
+
+static ssize_t dmi_entry_attr_show(struct kobject *kobj,
+				   struct attribute *attr,
+				   char *buf)
+{
+	struct dmi_entry_attr_show_data data = {
+		.attr = attr,
+		.buf  = buf,
+	};
+	/* Find the entry according to our parent and call the
+	 * normalized show method hanging off of the attribute */
+	return find_dmi_entry(to_entry(kobj->parent),
+			      dmi_entry_attr_show_helper, &data);
+}
+
+static const struct sysfs_ops dmi_sysfs_specialize_attr_ops = {
+	.show = dmi_entry_attr_show,
+};
+
+/*************************************************
+ * Specialized DMI entry support.
+ *************************************************/
+
+/*** Type 15 - System Event Table ***/
+
+#define DMI_SEL_ACCESS_METHOD_IO8	0x00
+#define DMI_SEL_ACCESS_METHOD_IO2x8	0x01
+#define DMI_SEL_ACCESS_METHOD_IO16	0x02
+#define DMI_SEL_ACCESS_METHOD_PHYS32	0x03
+#define DMI_SEL_ACCESS_METHOD_GPNV	0x04
+
+struct dmi_system_event_log {
+	struct dmi_header header;
+	u16	area_length;
+	u16	header_start_offset;
+	u16	data_start_offset;
+	u8	access_method;
+	u8	status;
+	u32	change_token;
+	union {
+		struct {
+			u16 index_addr;
+			u16 data_addr;
+		} io;
+		u32	phys_addr32;
+		u16	gpnv_handle;
+		u32	access_method_address;
+	};
+	u8	header_format;
+	u8	type_descriptors_supported_count;
+	u8	per_log_type_descriptor_length;
+	u8	supported_log_type_descriptos[];
+} __packed;
+
+#define DMI_SYSFS_SEL_FIELD(_field) \
+static ssize_t dmi_sysfs_sel_##_field(struct dmi_sysfs_entry *entry, \
+				      const struct dmi_header *dh, \
+				      char *buf) \
+{ \
+	struct dmi_system_event_log sel; \
+	if (sizeof(sel) > dmi_entry_length(dh)) \
+		return -EIO; \
+	memcpy(&sel, dh, sizeof(sel)); \
+	return sprintf(buf, "%u\n", sel._field); \
+} \
+static DMI_SYSFS_MAPPED_ATTR(sel, _field)
+
+DMI_SYSFS_SEL_FIELD(area_length);
+DMI_SYSFS_SEL_FIELD(header_start_offset);
+DMI_SYSFS_SEL_FIELD(data_start_offset);
+DMI_SYSFS_SEL_FIELD(access_method);
+DMI_SYSFS_SEL_FIELD(status);
+DMI_SYSFS_SEL_FIELD(change_token);
+DMI_SYSFS_SEL_FIELD(access_method_address);
+DMI_SYSFS_SEL_FIELD(header_format);
+DMI_SYSFS_SEL_FIELD(type_descriptors_supported_count);
+DMI_SYSFS_SEL_FIELD(per_log_type_descriptor_length);
+
+static struct attribute *dmi_sysfs_sel_attrs[] = {
+	&dmi_sysfs_attr_sel_area_length.attr,
+	&dmi_sysfs_attr_sel_header_start_offset.attr,
+	&dmi_sysfs_attr_sel_data_start_offset.attr,
+	&dmi_sysfs_attr_sel_access_method.attr,
+	&dmi_sysfs_attr_sel_status.attr,
+	&dmi_sysfs_attr_sel_change_token.attr,
+	&dmi_sysfs_attr_sel_access_method_address.attr,
+	&dmi_sysfs_attr_sel_header_format.attr,
+	&dmi_sysfs_attr_sel_type_descriptors_supported_count.attr,
+	&dmi_sysfs_attr_sel_per_log_type_descriptor_length.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(dmi_sysfs_sel);
+
+static const struct kobj_type dmi_system_event_log_ktype = {
+	.release = dmi_entry_free,
+	.sysfs_ops = &dmi_sysfs_specialize_attr_ops,
+	.default_groups = dmi_sysfs_sel_groups,
+};
+
+#ifdef CONFIG_HAS_IOPORT
+typedef u8 (*sel_io_reader)(const struct dmi_system_event_log *sel,
+			    loff_t offset);
+
+static DEFINE_MUTEX(io_port_lock);
+
+static u8 read_sel_8bit_indexed_io(const struct dmi_system_event_log *sel,
+				   loff_t offset)
+{
+	u8 ret;
+
+	mutex_lock(&io_port_lock);
+	outb((u8)offset, sel->io.index_addr);
+	ret = inb(sel->io.data_addr);
+	mutex_unlock(&io_port_lock);
+	return ret;
+}
+
+static u8 read_sel_2x8bit_indexed_io(const struct dmi_system_event_log *sel,
+				     loff_t offset)
+{
+	u8 ret;
+
+	mutex_lock(&io_port_lock);
+	outb((u8)offset, sel->io.index_addr);
+	outb((u8)(offset >> 8), sel->io.index_addr + 1);
+	ret = inb(sel->io.data_addr);
+	mutex_unlock(&io_port_lock);
+	return ret;
+}
+
+static u8 read_sel_16bit_indexed_io(const struct dmi_system_event_log *sel,
+				    loff_t offset)
+{
+	u8 ret;
+
+	mutex_lock(&io_port_lock);
+	outw((u16)offset, sel->io.index_addr);
+	ret = inb(sel->io.data_addr);
+	mutex_unlock(&io_port_lock);
+	return ret;
+}
+
+static sel_io_reader sel_io_readers[] = {
+	[DMI_SEL_ACCESS_METHOD_IO8]	= read_sel_8bit_indexed_io,
+	[DMI_SEL_ACCESS_METHOD_IO2x8]	= read_sel_2x8bit_indexed_io,
+	[DMI_SEL_ACCESS_METHOD_IO16]	= read_sel_16bit_indexed_io,
+};
+
+static ssize_t dmi_sel_raw_read_io(struct dmi_sysfs_entry *entry,
+				   const struct dmi_system_event_log *sel,
+				   char *buf, loff_t pos, size_t count)
+{
+	ssize_t wrote = 0;
+
+	sel_io_reader io_reader = sel_io_readers[sel->access_method];
+
+	while (count && pos < sel->area_length) {
+		count--;
+		*(buf++) = io_reader(sel, pos++);
+		wrote++;
+	}
+
+	return wrote;
+}
+#endif
+
+static ssize_t dmi_sel_raw_read_phys32(struct dmi_sysfs_entry *entry,
+				       const struct dmi_system_event_log *sel,
+				       char *buf, loff_t pos, size_t count)
+{
+	u8 __iomem *mapped;
+	ssize_t wrote = 0;
+
+	mapped = dmi_remap(sel->access_method_address, sel->area_length);
+	if (!mapped)
+		return -EIO;
+
+	while (count && pos < sel->area_length) {
+		count--;
+		*(buf++) = readb(mapped + pos++);
+		wrote++;
+	}
+
+	dmi_unmap(mapped);
+	return wrote;
+}
+
+static ssize_t dmi_sel_raw_read_helper(struct dmi_sysfs_entry *entry,
+				       const struct dmi_header *dh,
+				       void *_state)
+{
+	struct dmi_read_state *state = _state;
+	struct dmi_system_event_log sel;
+
+	if (sizeof(sel) > dmi_entry_length(dh))
+		return -EIO;
+
+	memcpy(&sel, dh, sizeof(sel));
+
+	switch (sel.access_method) {
+#ifdef CONFIG_HAS_IOPORT
+	case DMI_SEL_ACCESS_METHOD_IO8:
+	case DMI_SEL_ACCESS_METHOD_IO2x8:
+	case DMI_SEL_ACCESS_METHOD_IO16:
+		return dmi_sel_raw_read_io(entry, &sel, state->buf,
+					   state->pos, state->count);
+#endif
+	case DMI_SEL_ACCESS_METHOD_PHYS32:
+		return dmi_sel_raw_read_phys32(entry, &sel, state->buf,
+					       state->pos, state->count);
+	case DMI_SEL_ACCESS_METHOD_GPNV:
+		pr_info_ratelimited("dmi-sysfs: GPNV support missing.\n");
+		return -EIO;
+	default:
+		pr_info_ratelimited("dmi-sysfs: Unknown access method %02x\n",
+			sel.access_method);
+		return -EIO;
+	}
+}
+
+static ssize_t raw_event_log_read(struct file *filp, struct kobject *kobj,
+				  const struct bin_attribute *bin_attr,
+				  char *buf, loff_t pos, size_t count)
+{
+	struct dmi_sysfs_entry *entry = to_entry(kobj->parent);
+	struct dmi_read_state state = {
+		.buf = buf,
+		.pos = pos,
+		.count = count,
+	};
+
+	return find_dmi_entry(entry, dmi_sel_raw_read_helper, &state);
+}
+
+static const BIN_ATTR_ADMIN_RO(raw_event_log, 0);
+
+static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
+{
+	int ret;
+
+	entry->child = kzalloc_obj(*entry->child);
+	if (!entry->child)
+		return -ENOMEM;
+	ret = kobject_init_and_add(entry->child,
+				   &dmi_system_event_log_ktype,
+				   &entry->kobj,
+				   "system_event_log");
+	if (ret)
+		goto out_free;
+
+	ret = sysfs_create_bin_file(entry->child, &bin_attr_raw_event_log);
+	if (ret)
+		goto out_del;
+
+	return 0;
+
+out_del:
+	kobject_del(entry->child);
+out_free:
+	kfree(entry->child);
+	return ret;
+}
+
+/*************************************************
+ * Generic DMI entry support.
+ *************************************************/
+
+static ssize_t dmi_sysfs_entry_length(struct dmi_sysfs_entry *entry, char *buf)
+{
+	return sprintf(buf, "%d\n", entry->dh.length);
+}
+
+static ssize_t dmi_sysfs_entry_handle(struct dmi_sysfs_entry *entry, char *buf)
+{
+	return sprintf(buf, "%d\n", entry->dh.handle);
+}
+
+static ssize_t dmi_sysfs_entry_type(struct dmi_sysfs_entry *entry, char *buf)
+{
+	return sprintf(buf, "%d\n", entry->dh.type);
+}
+
+static ssize_t dmi_sysfs_entry_instance(struct dmi_sysfs_entry *entry,
+					char *buf)
+{
+	return sprintf(buf, "%d\n", entry->instance);
+}
+
+static ssize_t dmi_sysfs_entry_position(struct dmi_sysfs_entry *entry,
+					char *buf)
+{
+	return sprintf(buf, "%d\n", entry->position);
+}
+
+static DMI_SYSFS_ATTR(entry, length);
+static DMI_SYSFS_ATTR(entry, handle);
+static DMI_SYSFS_ATTR(entry, type);
+static DMI_SYSFS_ATTR(entry, instance);
+static DMI_SYSFS_ATTR(entry, position);
+
+static struct attribute *dmi_sysfs_entry_attrs[] = {
+	&dmi_sysfs_attr_entry_length.attr,
+	&dmi_sysfs_attr_entry_handle.attr,
+	&dmi_sysfs_attr_entry_type.attr,
+	&dmi_sysfs_attr_entry_instance.attr,
+	&dmi_sysfs_attr_entry_position.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(dmi_sysfs_entry);
+
+static ssize_t dmi_entry_raw_read_helper(struct dmi_sysfs_entry *entry,
+					 const struct dmi_header *dh,
+					 void *_state)
+{
+	struct dmi_read_state *state = _state;
+	size_t entry_length;
+
+	entry_length = dmi_entry_length(dh);
+
+	return memory_read_from_buffer(state->buf, state->count,
+				       &state->pos, dh, entry_length);
+}
+
+static ssize_t raw_read(struct file *filp,
+			struct kobject *kobj,
+			const struct bin_attribute *bin_attr,
+			char *buf, loff_t pos, size_t count)
+{
+	struct dmi_sysfs_entry *entry = to_entry(kobj);
+	struct dmi_read_state state = {
+		.buf = buf,
+		.pos = pos,
+		.count = count,
+	};
+
+	return find_dmi_entry(entry, dmi_entry_raw_read_helper, &state);
+}
+
+static const BIN_ATTR_ADMIN_RO(raw, 0);
+
+static void dmi_sysfs_entry_release(struct kobject *kobj)
+{
+	struct dmi_sysfs_entry *entry = to_entry(kobj);
+
+	spin_lock(&entry_list_lock);
+	list_del(&entry->list);
+	spin_unlock(&entry_list_lock);
+	kfree(entry);
+}
+
+static const struct kobj_type dmi_sysfs_entry_ktype = {
+	.release = dmi_sysfs_entry_release,
+	.sysfs_ops = &dmi_sysfs_attr_ops,
+	.default_groups = dmi_sysfs_entry_groups,
+};
+
+static struct kset *dmi_kset;
+
+/* Global count of all instances seen.  Only for setup */
+static int __initdata instance_counts[MAX_ENTRY_TYPE + 1];
+
+/* Global positional count of all entries seen.  Only for setup */
+static int __initdata position_count;
+
+static void __init dmi_sysfs_register_handle(const struct dmi_header *dh,
+					     void *_ret)
+{
+	struct dmi_sysfs_entry *entry;
+	int *ret = _ret;
+
+	/* If a previous entry saw an error, short circuit */
+	if (*ret)
+		return;
+
+	/* Allocate and register a new entry into the entries set */
+	entry = kzalloc_obj(*entry);
+	if (!entry) {
+		*ret = -ENOMEM;
+		return;
+	}
+
+	/* Set the key */
+	memcpy(&entry->dh, dh, sizeof(*dh));
+	entry->instance = instance_counts[dh->type]++;
+	entry->position = position_count++;
+
+	entry->kobj.kset = dmi_kset;
+	*ret = kobject_init_and_add(&entry->kobj, &dmi_sysfs_entry_ktype, NULL,
+				    "%d-%d", dh->type, entry->instance);
+
+	/* Thread on the global list for cleanup */
+	spin_lock(&entry_list_lock);
+	list_add_tail(&entry->list, &entry_list);
+	spin_unlock(&entry_list_lock);
+
+	if (*ret) {
+		kobject_put(&entry->kobj);
+		return;
+	}
+
+	/* Handle specializations by type */
+	switch (dh->type) {
+	case DMI_ENTRY_SYSTEM_EVENT_LOG:
+		*ret = dmi_system_event_log(entry);
+		break;
+	default:
+		/* No specialization */
+		break;
+	}
+	if (*ret)
+		goto out_err;
+
+	/* Create the raw binary file to access the entry */
+	*ret = sysfs_create_bin_file(&entry->kobj, &bin_attr_raw);
+	if (*ret)
+		goto out_err;
+
+	return;
+out_err:
+	kobject_put(entry->child);
+	kobject_put(&entry->kobj);
+	return;
+}
+
+static void cleanup_entry_list(void)
+{
+	struct dmi_sysfs_entry *entry, *next;
+
+	/* No locks, we are on our way out */
+	list_for_each_entry_safe(entry, next, &entry_list, list) {
+		kobject_put(entry->child);
+		kobject_put(&entry->kobj);
+	}
+}
+
+static int __init dmi_sysfs_init(void)
+{
+	int error;
+	int val;
+
+	if (!dmi_kobj) {
+		pr_debug("dmi-sysfs: dmi entry is absent.\n");
+		error = -ENODATA;
+		goto err;
+	}
+
+	dmi_kset = kset_create_and_add("entries", NULL, dmi_kobj);
+	if (!dmi_kset) {
+		error = -ENOMEM;
+		goto err;
+	}
+
+	val = 0;
+	error = dmi_walk(dmi_sysfs_register_handle, &val);
+	if (error)
+		goto err;
+	if (val) {
+		error = val;
+		goto err;
+	}
+
+	pr_debug("dmi-sysfs: loaded.\n");
+
+	return 0;
+err:
+	cleanup_entry_list();
+	kset_unregister(dmi_kset);
+	return error;
+}
+
+/* clean up everything. */
+static void __exit dmi_sysfs_exit(void)
+{
+	pr_debug("dmi-sysfs: unloading.\n");
+	cleanup_entry_list();
+	kset_unregister(dmi_kset);
+}
+
+module_init(dmi_sysfs_init);
+module_exit(dmi_sysfs_exit);
+
+MODULE_AUTHOR("Mike Waychison <mikew@google.com>");
+MODULE_DESCRIPTION("DMI sysfs support");
+MODULE_LICENSE("GPL");