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1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef PAGE_FLAGS_LAYOUT_H
3 #define PAGE_FLAGS_LAYOUT_H
5 #include <linux/numa.h>
6 #include <generated/bounds.h>
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
17 #elif MAX_NR_ZONES <= 2
19 #elif MAX_NR_ZONES <= 4
21 #elif MAX_NR_ZONES <= 8
24 #error ZONES_SHIFT "Too many zones configured"
27 #define ZONES_WIDTH ZONES_SHIFT
29 #ifdef CONFIG_SPARSEMEM
30 #include <asm/sparsemem.h>
31 #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
33 #define SECTIONS_SHIFT 0
36 #ifndef BUILD_VDSO32_64
40 * There are five possibilities for how page->flags get laid out. The first
41 * pair is for the normal case without sparsemem. The second pair is for
42 * sparsemem when there is plenty of space for node and section information.
43 * The last is when there is insufficient space in page->flags and a separate
44 * lookup is necessary.
46 * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS |
47 * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS |
48 * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS |
49 * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS |
50 * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS |
52 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
53 #define SECTIONS_WIDTH SECTIONS_SHIFT
55 #define SECTIONS_WIDTH 0
58 #if ZONES_WIDTH + SECTIONS_WIDTH + NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
59 #define NODES_WIDTH NODES_SHIFT
60 #elif defined(CONFIG_SPARSEMEM_VMEMMAP)
61 #error "Vmemmap: No space for nodes field in page flags"
67 * Note that this #define MUST have a value so that it can be tested with
68 * the IS_ENABLED() macro.
70 #if NODES_SHIFT != 0 && NODES_WIDTH == 0
71 #define NODE_NOT_IN_PAGE_FLAGS 1
74 #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
75 #define KASAN_TAG_WIDTH 8
77 #define KASAN_TAG_WIDTH 0
80 #ifdef CONFIG_NUMA_BALANCING
81 #define LAST__PID_SHIFT 8
82 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1)
84 #define LAST__CPU_SHIFT NR_CPUS_BITS
85 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1)
87 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT)
89 #define LAST_CPUPID_SHIFT 0
92 #if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT \
93 <= BITS_PER_LONG - NR_PAGEFLAGS
94 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
96 #define LAST_CPUPID_WIDTH 0
99 #if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0
100 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS
103 #if ZONES_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH \
104 > BITS_PER_LONG - NR_PAGEFLAGS
105 #error "Not enough bits in page flags"
109 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */