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