linux/drivers/firmware/memmap.c
Bernhard Walle 69ac9cd629 sysfs: add /sys/firmware/memmap
This patch adds /sys/firmware/memmap interface that represents the BIOS
(or Firmware) provided memory map. The tree looks like:

    /sys/firmware/memmap/0/start   (hex number)
                           end     (hex number)
                           type    (string)
    ...                 /1/start
                           end
                           type

With the following shell snippet one can print the memory map in the same form
the kernel prints itself when booting on x86 (the E820 map).

  --------- 8< --------------------------
    #!/bin/sh
    cd /sys/firmware/memmap
    for dir in * ; do
        start=$(cat $dir/start)
        end=$(cat $dir/end)
        type=$(cat $dir/type)
        printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type"
    done
  --------- >8 --------------------------

That patch only provides the needed interface:

 1. The sysfs interface.
 2. The structure and enumeration definition.
 3. The function firmware_map_add() and firmware_map_add_early()
    that should be called from architecture code (E820/EFI, for
    example) to add the contents to the interface.

If the kernel is compiled without CONFIG_FIRMWARE_MEMMAP, the interface does
nothing without cluttering the architecture-specific code with #ifdef's.

The purpose of the new interface is kexec: While /proc/iomem represents
the *used* memory map (e.g. modified via kernel parameters like 'memmap'
and 'mem'), the /sys/firmware/memmap tree represents the unmodified memory
map provided via the firmware. So kexec can:

 - use the original memory map for rebooting,
 - use the /proc/iomem for setting up the ELF core headers for kdump
   case that should only represent the memory of the system.

The patch has been tested on i386 and x86_64.

Signed-off-by: Bernhard Walle <bwalle@suse.de>
Acked-by: Greg KH <gregkh@suse.de>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: kexec@lists.infradead.org
Cc: yhlu.kernel@gmail.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-07-08 17:55:41 +02:00

206 lines
5.5 KiB
C

/*
* linux/drivers/firmware/memmap.c
* Copyright (C) 2008 SUSE LINUX Products GmbH
* by Bernhard Walle <bwalle@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License v2.0 as published by
* the Free Software Foundation
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/string.h>
#include <linux/firmware-map.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/bootmem.h>
/*
* Data types ------------------------------------------------------------------
*/
/*
* Firmware map entry. Because firmware memory maps are flat and not
* hierarchical, it's ok to organise them in a linked list. No parent
* information is necessary as for the resource tree.
*/
struct firmware_map_entry {
resource_size_t start; /* start of the memory range */
resource_size_t end; /* end of the memory range (incl.) */
const char *type; /* type of the memory range */
struct list_head list; /* entry for the linked list */
struct kobject kobj; /* kobject for each entry */
};
/*
* Forward declarations --------------------------------------------------------
*/
static ssize_t memmap_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf);
static ssize_t start_show(struct firmware_map_entry *entry, char *buf);
static ssize_t end_show(struct firmware_map_entry *entry, char *buf);
static ssize_t type_show(struct firmware_map_entry *entry, char *buf);
/*
* Static data -----------------------------------------------------------------
*/
struct memmap_attribute {
struct attribute attr;
ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
};
struct memmap_attribute memmap_start_attr = __ATTR_RO(start);
struct memmap_attribute memmap_end_attr = __ATTR_RO(end);
struct memmap_attribute memmap_type_attr = __ATTR_RO(type);
/*
* These are default attributes that are added for every memmap entry.
*/
static struct attribute *def_attrs[] = {
&memmap_start_attr.attr,
&memmap_end_attr.attr,
&memmap_type_attr.attr,
NULL
};
static struct sysfs_ops memmap_attr_ops = {
.show = memmap_attr_show,
};
static struct kobj_type memmap_ktype = {
.sysfs_ops = &memmap_attr_ops,
.default_attrs = def_attrs,
};
/*
* Registration functions ------------------------------------------------------
*/
/*
* Firmware memory map entries
*/
static LIST_HEAD(map_entries);
/**
* Common implementation of firmware_map_add() and firmware_map_add_early()
* which expects a pre-allocated struct firmware_map_entry.
*
* @start: Start of the memory range.
* @end: End of the memory range (inclusive).
* @type: Type of the memory range.
* @entry: Pre-allocated (either kmalloc() or bootmem allocator), uninitialised
* entry.
*/
static int firmware_map_add_entry(resource_size_t start, resource_size_t end,
const char *type,
struct firmware_map_entry *entry)
{
BUG_ON(start > end);
entry->start = start;
entry->end = end;
entry->type = type;
INIT_LIST_HEAD(&entry->list);
kobject_init(&entry->kobj, &memmap_ktype);
list_add_tail(&entry->list, &map_entries);
return 0;
}
/*
* See <linux/firmware-map.h> for documentation.
*/
int firmware_map_add(resource_size_t start, resource_size_t end,
const char *type)
{
struct firmware_map_entry *entry;
entry = kmalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC);
WARN_ON(!entry);
if (!entry)
return -ENOMEM;
return firmware_map_add_entry(start, end, type, entry);
}
/*
* See <linux/firmware-map.h> for documentation.
*/
int __init firmware_map_add_early(resource_size_t start, resource_size_t end,
const char *type)
{
struct firmware_map_entry *entry;
entry = alloc_bootmem_low(sizeof(struct firmware_map_entry));
WARN_ON(!entry);
if (!entry)
return -ENOMEM;
return firmware_map_add_entry(start, end, type, entry);
}
/*
* Sysfs functions -------------------------------------------------------------
*/
static ssize_t start_show(struct firmware_map_entry *entry, char *buf)
{
return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->start);
}
static ssize_t end_show(struct firmware_map_entry *entry, char *buf)
{
return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->end);
}
static ssize_t type_show(struct firmware_map_entry *entry, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%s\n", entry->type);
}
#define to_memmap_attr(_attr) container_of(_attr, struct memmap_attribute, attr)
#define to_memmap_entry(obj) container_of(obj, struct firmware_map_entry, kobj)
static ssize_t memmap_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
struct firmware_map_entry *entry = to_memmap_entry(kobj);
struct memmap_attribute *memmap_attr = to_memmap_attr(attr);
return memmap_attr->show(entry, buf);
}
/*
* Initialises stuff and adds the entries in the map_entries list to
* sysfs. Important is that firmware_map_add() and firmware_map_add_early()
* must be called before late_initcall.
*/
static int __init memmap_init(void)
{
int i = 0;
struct firmware_map_entry *entry;
struct kset *memmap_kset;
memmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj);
WARN_ON(!memmap_kset);
if (!memmap_kset)
return -ENOMEM;
list_for_each_entry(entry, &map_entries, list) {
entry->kobj.kset = memmap_kset;
kobject_add(&entry->kobj, NULL, "%d", i++);
}
return 0;
}
late_initcall(memmap_init);