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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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