linuxdebug/drivers/firmware/dmi-sysfs.c

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2024-07-16 15:50:57 +02:00
// 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 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,
};
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;
}
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) {
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);
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("dmi-sysfs: GPNV support missing.\n");
return -EIO;
default:
pr_info("dmi-sysfs: Unknown access method %02x\n",
sel.access_method);
return -EIO;
}
}
static ssize_t dmi_sel_raw_read(struct file *filp, struct kobject *kobj,
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 struct bin_attribute dmi_sel_raw_attr = {
.attr = {.name = "raw_event_log", .mode = 0400},
.read = dmi_sel_raw_read,
};
static int dmi_system_event_log(struct dmi_sysfs_entry *entry)
{
int ret;
entry->child = kzalloc(sizeof(*entry->child), GFP_KERNEL);
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, &dmi_sel_raw_attr);
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 dmi_entry_raw_read(struct file *filp,
struct kobject *kobj,
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 struct bin_attribute dmi_entry_raw_attr = {
.attr = {.name = "raw", .mode = 0400},
.read = dmi_entry_raw_read,
};
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 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(sizeof(*entry), GFP_KERNEL);
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, &dmi_entry_raw_attr);
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");