linux/arch/x86/mm/pat/memtype_interval.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Handle caching attributes in page tables (PAT)
 *
 * Authors: Venkatesh Pallipadi <[email protected]>
 *          Suresh B Siddha <[email protected]>
 *
 * Interval tree used to store the PAT memory type reservations.
 */

#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
#include <linux/interval_tree_generic.h>
#include <linux/sched.h>
#include <linux/gfp.h>
#include <linux/pgtable.h>

#include <asm/memtype.h>

#include "memtype.h"

/*
 * The memtype tree keeps track of memory type for specific
 * physical memory areas. Without proper tracking, conflicting memory
 * types in different mappings can cause CPU cache corruption.
 *
 * The tree is an interval tree (augmented rbtree) which tree is ordered
 * by the starting address. The tree can contain multiple entries for
 * different regions which overlap. All the aliases have the same
 * cache attributes of course, as enforced by the PAT logic.
 *
 * memtype_lock protects the rbtree.
 */

static inline u64 interval_start(struct memtype *entry)
{ … }

static inline u64 interval_end(struct memtype *entry)
{ … }

INTERVAL_TREE_DEFINE(…)

static struct rb_root_cached memtype_rbroot = …;

enum { … };

static struct memtype *memtype_match(u64 start, u64 end, int match_type)
{ … }

static int memtype_check_conflict(u64 start, u64 end,
				  enum page_cache_mode reqtype,
				  enum page_cache_mode *newtype)
{ … }

int memtype_check_insert(struct memtype *entry_new, enum page_cache_mode *ret_type)
{ … }

struct memtype *memtype_erase(u64 start, u64 end)
{ … }

struct memtype *memtype_lookup(u64 addr)
{ … }

/*
 * Debugging helper, copy the Nth entry of the tree into a
 * a copy for printout. This allows us to print out the tree
 * via debugfs, without holding the memtype_lock too long:
 */
#ifdef CONFIG_DEBUG_FS
int memtype_copy_nth_element(struct memtype *entry_out, loff_t pos)
{ … }
#endif