path: root/drivers/base/memory.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Memory subsystem support
 *
 * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
 *            Dave Hansen <haveblue@us.ibm.com>
 *
 * This file provides the necessary infrastructure to represent
 * a SPARSEMEM-memory-model system's physical memory in /sysfs.
 * All arch-independent code that assumes MEMORY_HOTPLUG requires
 * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/topology.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/xarray.h>
#include <linux/export.h>

#include <linux/atomic.h>
#include <linux/uaccess.h>

#define MEMORY_CLASS_NAME	"memory"

static const char *const online_type_to_str[] = {
	[MMOP_OFFLINE] = "offline",
	[MMOP_ONLINE] = "online",
	[MMOP_ONLINE_KERNEL] = "online_kernel",
	[MMOP_ONLINE_MOVABLE] = "online_movable",
};

int mhp_online_type_from_str(const char *str)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(online_type_to_str); i++) {
		if (sysfs_streq(str, online_type_to_str[i]))
			return i;
	}
	return -EINVAL;
}

#define to_memory_block(dev) container_of(dev, struct memory_block, dev)

int sections_per_block;
EXPORT_SYMBOL(sections_per_block);

static int memory_subsys_online(struct device *dev);
static int memory_subsys_offline(struct device *dev);

static const struct bus_type memory_subsys = {
	.name = MEMORY_CLASS_NAME,
	.dev_name = MEMORY_CLASS_NAME,
	.online = memory_subsys_online,
	.offline = memory_subsys_offline,
};

/*
 * Memory blocks are cached in a local radix tree to avoid
 * a costly linear search for the corresponding device on
 * the subsystem bus.
 */
static DEFINE_XARRAY(memory_blocks);

/*
 * Memory groups, indexed by memory group id (mgid).
 */
static DEFINE_XARRAY_FLAGS(memory_groups, XA_FLAGS_ALLOC);
#define MEMORY_GROUP_MARK_DYNAMIC	XA_MARK_1

static BLOCKING_NOTIFIER_HEAD(memory_chain);

int register_memory_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&memory_chain, nb);
}
EXPORT_SYMBOL(register_memory_notifier);

void unregister_memory_notifier(struct notifier_block *nb)
{
	blocking_notifier_chain_unregister(&memory_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_notifier);

static void memory_block_release(struct device *dev)
{
	struct memory_block *mem = to_memory_block(dev);
	/* Verify that the altmap is freed */
	WARN_ON(mem->altmap);
	kfree(mem);
}


/* Max block size to be set by memory_block_advise_max_size */
static unsigned long memory_block_advised_size;
static bool memory_block_advised_size_queried;

/**
 * memory_block_advise_max_size() - advise memory hotplug on the max suggested
 *				    block size, usually for alignment.
 * @size: suggestion for maximum block size. must be aligned on power of 2.
 *
 * Early boot software (pre-allocator init) may advise archs on the max block
 * size. This value can only decrease after initialization, as the intent is
 * to identify the largest supported alignment for all sources.
 *
 * Use of this value is arch-defined, as is min/max block size.
 *
 * Return: 0 on success
 *	   -EINVAL if size is 0 or not pow2 aligned
 *	   -EBUSY if value has already been probed
 */
int __init