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    Subject[PATCH 1/2] Add /sys/firmware/memmap
    Date
    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>
    ---
    drivers/firmware/Kconfig | 11 +++
    drivers/firmware/Makefile | 1 +
    drivers/firmware/memmap.c | 176 ++++++++++++++++++++++++++++++++++++++++++
    include/linux/firmware-map.h | 100 ++++++++++++++++++++++++
    4 files changed, 288 insertions(+), 0 deletions(-)
    create mode 100644 drivers/firmware/memmap.c
    create mode 100644 include/linux/firmware-map.h

    diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
    index dc2cec6..0f416fb 100644
    --- a/drivers/firmware/Kconfig
    +++ b/drivers/firmware/Kconfig
    @@ -26,6 +26,17 @@ config EDD_OFF
    kernel. Say N if you want EDD enabled by default. EDD can be dynamically set
    using the kernel parameter 'edd={on|skipmbr|off}'.

    +config FIRMWARE_MEMMAP
    + bool "Provide BIOS memory map in sysfs"
    + depends on X86_64 || X86_32
    + default y
    + help
    + Say Y if you want to provide the raw memory map in sysfs under
    + /sys/firmware/memmap/<number>/{start,end,type}.
    +
    + This is useful for debugging, and required by kexec-tools to get an
    + unfiltered view that /proc/iomem cannot provide.
    +
    config EFI_VARS
    tristate "EFI Variable Support via sysfs"
    depends on EFI
    diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
    index 4c91471..1c3c173 100644
    --- a/drivers/firmware/Makefile
    +++ b/drivers/firmware/Makefile
    @@ -10,3 +10,4 @@ obj-$(CONFIG_DCDBAS) += dcdbas.o
    obj-$(CONFIG_DMIID) += dmi-id.o
    obj-$(CONFIG_ISCSI_IBFT_FIND) += iscsi_ibft_find.o
    obj-$(CONFIG_ISCSI_IBFT) += iscsi_ibft.o
    +obj-$(CONFIG_FIRMWARE_MEMMAP) += memmap.o
    diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c
    new file mode 100644
    index 0000000..d0de284
    --- /dev/null
    +++ b/drivers/firmware/memmap.c
    @@ -0,0 +1,176 @@
    +/*
    + * 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>
    +
    +/*
    + * String representation of enum firmware_map_type from
    + * <linux/firmware-map.h>.
    + */
    +const char *type_to_string_map[] = {
    + "RAM", /* MAP_RAM */
    + "Reserved", /* MAP_RESERVED */
    + "ACPI Tables", /* MAP_ACPI */
    + "Non-volatile Storage", /* MAP_NVS */
    +};
    +
    +/*
    + * Registration functions ------------------------------------------------------
    + */
    +
    +/*
    + * Firmware memory map entries
    + */
    +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,
    + enum firmware_map_type type,
    + struct firmware_map_entry *entry)
    +{
    + BUG_ON(start > end);
    +
    + entry->start = start;
    + entry->end = end;
    + entry->type = type;
    + INIT_LIST_HEAD(&entry->list);
    +
    + list_add_tail(&entry->list, &map_entries);
    +
    + return 0;
    +}
    +
    +int firmware_map_add(resource_size_t start, resource_size_t end,
    + enum firmware_map_type 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);
    +}
    +
    +int firmware_map_add_early(resource_size_t start, resource_size_t end,
    + enum firmware_map_type 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
    + */
    +
    +struct memmap_attribute {
    + struct attribute attr;
    + ssize_t (*show)(struct firmware_map_entry *entry, char *buf);
    +};
    +
    +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)
    +{
    + const char *str = type_to_string_map[entry->type];
    + return snprintf(buf, PAGE_SIZE, "%s\n", str);
    +}
    +
    +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
    +};
    +
    +#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);
    +}
    +
    +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,
    +};
    +
    +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_init_and_add(&entry->kobj, &memmap_ktype,
    + NULL, "%d", i++);
    + }
    +
    + return 0;
    +}
    +late_initcall(memmap_init);
    +
    diff --git a/include/linux/firmware-map.h b/include/linux/firmware-map.h
    new file mode 100644
    index 0000000..64aff3d
    --- /dev/null
    +++ b/include/linux/firmware-map.h
    @@ -0,0 +1,100 @@
    +/*
    + * include/linux/firmware-map.h:
    + * 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.
    + *
    + */
    +#ifndef _LINUX_FIRMWARE_MAP_H
    +#define _LINUX_FIRMWARE_MAP_H
    +
    +#include <linux/list.h>
    +#include <linux/kobject.h>
    +
    +/*
    + * Type used for memory maps provided by firmware. That must be some kind
    + * "superset" between all architectures. Most types are the same on each
    + * architectures, but for example ACPI only exists on x86 and ia64.
    + *
    + * If you add a new type here, make sure that you add them in
    + * drivers/firmware/memmap.c as type_to_string_map, too.
    + */
    +enum firmware_map_type {
    + MAP_RAM, /* normal RAM */
    + MAP_RESERVED, /* reserved area */
    + MAP_ACPI, /* ACPI tables, only x86 and ia64 */
    + MAP_NVS /* non-volatile storage */
    +};
    +
    +/*
    + * 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.) */
    + enum firmware_map_type type; /* type of the memory range */
    + struct list_head list; /* entry for the linked list */
    + struct kobject kobj; /* kobject for each entry */
    +};
    +
    +/*
    + * If the kernel is configured without CONFIG_FIRMWARE_MEMMAP, then
    + * the firmware_map_add() operation should do nothing.
    + */
    +#ifdef CONFIG_FIRMWARE_MEMMAP
    +
    +/**
    + * Adds a firmware mapping entry. This function uses kmalloc() for memory
    + * allocation. Use firmware_map_add_early() if you want to use the bootmem
    + * allocator.
    + *
    + * @start: Start of the memory range.
    + * @end: End of the memory range (inclusive).
    + * @type: Type of the memory range.
    + *
    + * Returns 0 on success, or -ENOMEM if no memory could be allocated.
    + */
    +int firmware_map_add(resource_size_t start, resource_size_t end,
    + enum firmware_map_type type);
    +
    +/**
    + * Adds a firmware mapping entry. This function uses the bootmem allocator
    + * for memory allocation. Use firmware_map_add() if you want to use kmalloc().
    + *
    + * @start: Start of the memory range.
    + * @end: End of the memory range (inclusive).
    + * @type: Type of the memory range.
    + *
    + * Returns 0 on success, or -ENOMEM if no memory could be allocated.
    + */
    +int firmware_map_add_early(resource_size_t start, resource_size_t end,
    + enum firmware_map_type type);
    +
    +#else /* CONFIG_FIRMWARE_MEMMAP */
    +
    +static inline int firmware_map_add(resource_size_t start, resource_size_t end,
    + enum firmware_map_type type)
    +{
    + return 0;
    +}
    +
    +static inline int firmware_map_add_early(resource_size_t start,
    + resource_size_t end,
    + enum firmware_map_type type)
    +{
    + return 0;
    +}
    +
    +#endif /* CONFIG_FIRMWARE_MEMMAP */
    +
    +#endif /* _LINUX_FIRMWARE_MAP_H */
    --
    1.5.4.5


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