1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef PAGE_FLAGS_LAYOUT_H
  3#define PAGE_FLAGS_LAYOUT_H
  4
  5#include <linux/numa.h>
  6#include <generated/bounds.h>
  7
  8/*
  9 * When a memory allocation must conform to specific limitations (such
 10 * as being suitable for DMA) the caller will pass in hints to the
 11 * allocator in the gfp_mask, in the zone modifier bits.  These bits
 12 * are used to select a priority ordered list of memory zones which
 13 * match the requested limits. See gfp_zone() in include/linux/gfp.h
 14 */
 15#if MAX_NR_ZONES < 2
 16#define ZONES_SHIFT 0
 17#elif MAX_NR_ZONES <= 2
 18#define ZONES_SHIFT 1
 19#elif MAX_NR_ZONES <= 4
 20#define ZONES_SHIFT 2
 21#elif MAX_NR_ZONES <= 8
 22#define ZONES_SHIFT 3
 23#else
 24#error ZONES_SHIFT -- too many zones configured adjust calculation
 25#endif
 26
 27#ifdef CONFIG_SPARSEMEM
 28#include <asm/sparsemem.h>
 29
 30/* SECTION_SHIFT	#bits space required to store a section # */
 31#define SECTIONS_SHIFT	(MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
 32
 33#endif /* CONFIG_SPARSEMEM */
 34
 35#ifndef BUILD_VDSO32_64
 36/*
 37 * page->flags layout:
 38 *
 39 * There are five possibilities for how page->flags get laid out.  The first
 40 * pair is for the normal case without sparsemem. The second pair is for
 41 * sparsemem when there is plenty of space for node and section information.
 42 * The last is when there is insufficient space in page->flags and a separate
 43 * lookup is necessary.
 44 *
 45 * No sparsemem or sparsemem vmemmap: |       NODE     | ZONE |             ... | FLAGS |
 46 *      " plus space for last_cpupid: |       NODE     | ZONE | LAST_CPUPID ... | FLAGS |
 47 * classic sparse with space for node:| SECTION | NODE | ZONE |             ... | FLAGS |
 48 *      " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS |
 49 * classic sparse no space for node:  | SECTION |     ZONE    | ... | FLAGS |
 50 */
 51#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 52#define SECTIONS_WIDTH		SECTIONS_SHIFT
 53#else
 54#define SECTIONS_WIDTH		0
 55#endif
 56
 57#define ZONES_WIDTH		ZONES_SHIFT
 58
 59#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
 60#define NODES_WIDTH		NODES_SHIFT
 61#else
 62#ifdef CONFIG_SPARSEMEM_VMEMMAP
 63#error "Vmemmap: No space for nodes field in page flags"
 64#endif
 65#define NODES_WIDTH		0
 66#endif
 67
 68#ifdef CONFIG_NUMA_BALANCING
 69#define LAST__PID_SHIFT 8
 70#define LAST__PID_MASK  ((1 << LAST__PID_SHIFT)-1)
 71
 72#define LAST__CPU_SHIFT NR_CPUS_BITS
 73#define LAST__CPU_MASK  ((1 << LAST__CPU_SHIFT)-1)
 74
 75#define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT)
 76#else
 77#define LAST_CPUPID_SHIFT 0
 78#endif
 79
 80#ifdef CONFIG_KASAN_SW_TAGS
 81#define KASAN_TAG_WIDTH 8
 82#else
 83#define KASAN_TAG_WIDTH 0
 84#endif
 85
 86#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT+KASAN_TAG_WIDTH \
 87	<= BITS_PER_LONG - NR_PAGEFLAGS
 88#define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
 89#else
 90#define LAST_CPUPID_WIDTH 0
 91#endif
 92
 93#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH+LAST_CPUPID_WIDTH+KASAN_TAG_WIDTH \
 94	> BITS_PER_LONG - NR_PAGEFLAGS
 95#error "Not enough bits in page flags"
 96#endif
 97
 98/*
 99 * We are going to use the flags for the page to node mapping if its in
100 * there.  This includes the case where there is no node, so it is implicit.
101 * Note that this #define MUST have a value so that it can be tested with
102 * the IS_ENABLED() macro.
103 */
104#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
105#define NODE_NOT_IN_PAGE_FLAGS 1
106#endif
107
108#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
109#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
110#endif
111
112#endif
113#endif /* _LINUX_PAGE_FLAGS_LAYOUT */