Linux kernel mirror (for testing)
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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 */
102#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
103#define NODE_NOT_IN_PAGE_FLAGS
104#endif
105
106#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
107#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
108#endif
109
110#endif
111#endif /* _LINUX_PAGE_FLAGS_LAYOUT */