| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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| 2 | #ifndef PAGE_FLAGS_LAYOUT_H |
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| 3 | #define PAGE_FLAGS_LAYOUT_H |
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| 4 | |
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| 5 | #include <linux/numa.h> |
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| 6 | #include <generated/bounds.h> |
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| 7 | |
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| 8 | /* |
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| 9 | * When a memory allocation must conform to specific limitations (such |
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| 10 | * as being suitable for DMA) the caller will pass in hints to the |
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| 11 | * allocator in the gfp_mask, in the zone modifier bits. These bits |
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| 12 | * are used to select a priority ordered list of memory zones which |
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| 13 | * match the requested limits. See gfp_zone() in include/linux/gfp.h |
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| 14 | */ |
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| 15 | #if MAX_NR_ZONES < 2 |
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| 16 | #define ZONES_SHIFT 0 |
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| 17 | #elif MAX_NR_ZONES <= 2 |
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| 18 | #define ZONES_SHIFT 1 |
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| 19 | #elif MAX_NR_ZONES <= 4 |
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| 20 | #define ZONES_SHIFT 2 |
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| 21 | #elif MAX_NR_ZONES <= 8 |
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| 22 | #define ZONES_SHIFT 3 |
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| 23 | #else |
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| 24 | #error ZONES_SHIFT "Too many zones configured" |
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| 25 | #endif |
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| 26 | |
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| 27 | #define ZONES_WIDTH ZONES_SHIFT |
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| 28 | |
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| 29 | #ifdef CONFIG_SPARSEMEM |
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| 30 | #include <asm/sparsemem.h> |
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| 31 | #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) |
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| 32 | #else |
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| 33 | #define SECTIONS_SHIFT 0 |
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| 34 | #endif |
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| 35 | |
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| 36 | #ifndef BUILD_VDSO32_64 |
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| 37 | /* |
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| 38 | * page->flags layout: |
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| 39 | * |
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| 40 | * There are five possibilities for how page->flags get laid out. The first |
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| 41 | * pair is for the normal case without sparsemem. The second pair is for |
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| 42 | * sparsemem when there is plenty of space for node and section information. |
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| 43 | * The last is when there is insufficient space in page->flags and a separate |
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| 44 | * lookup is necessary. |
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| 45 | * |
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| 46 | * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | |
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| 47 | * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS | |
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| 48 | * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | |
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| 49 | * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS | |
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| 50 | * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | |
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| 51 | */ |
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| 52 | #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) |
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| 53 | #define SECTIONS_WIDTH SECTIONS_SHIFT |
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| 54 | #else |
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| 55 | #define SECTIONS_WIDTH 0 |
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| 56 | #endif |
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| 57 | |
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| 58 | #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \ |
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| 59 | <= BITS_PER_LONG - NR_PAGEFLAGS |
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| 60 | #define NODES_WIDTH NODES_SHIFT |
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| 61 | #elif defined(CONFIG_SPARSEMEM_VMEMMAP) |
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| 62 | #error "Vmemmap: No space for nodes field in page flags" |
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| 63 | #else |
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| 64 | #define NODES_WIDTH 0 |
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| 65 | #endif |
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| 66 | |
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| 67 | /* |
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| 68 | * Note that this #define MUST have a value so that it can be tested with |
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| 69 | * the IS_ENABLED() macro. |
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| 70 | */ |
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| 71 | #if NODES_SHIFT != 0 && NODES_WIDTH == 0 |
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| 72 | #define NODE_NOT_IN_PAGE_FLAGS 1 |
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| 73 | #endif |
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| 74 | |
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| 75 | #if defined(CONFIG_KASAN_SW_TAGS) |
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| 76 | #define KASAN_TAG_WIDTH 8 |
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| 77 | #elif defined(CONFIG_KASAN_HW_TAGS) |
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| 78 | #define KASAN_TAG_WIDTH 4 |
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| 79 | #else |
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| 80 | #define KASAN_TAG_WIDTH 0 |
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| 81 | #endif |
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| 82 | |
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| 83 | #ifdef CONFIG_NUMA_BALANCING |
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| 84 | #define LAST__PID_SHIFT 8 |
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| 85 | #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) |
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| 86 | |
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| 87 | #define LAST__CPU_SHIFT NR_CPUS_BITS |
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| 88 | #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) |
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| 89 | |
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| 90 | #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) |
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| 91 | #else |
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| 92 | #define LAST_CPUPID_SHIFT 0 |
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| 93 | #endif |
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| 94 | |
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| 95 | #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ |
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| 96 | KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS |
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| 97 | #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT |
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| 98 | #else |
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| 99 | #define LAST_CPUPID_WIDTH 0 |
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| 100 | #endif |
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| 101 | |
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| 102 | #if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0 |
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| 103 | #define LAST_CPUPID_NOT_IN_PAGE_FLAGS |
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| 104 | #endif |
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| 105 | |
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| 106 | #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ |
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| 107 | KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS |
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| 108 | #error "Not enough bits in page flags" |
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| 109 | #endif |
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| 110 | |
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| 111 | /* see the comment on MAX_NR_TIERS */ |
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| 112 | #define LRU_REFS_WIDTH min(__LRU_REFS_WIDTH, BITS_PER_LONG - NR_PAGEFLAGS - \ |
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| 113 | ZONES_WIDTH - LRU_GEN_WIDTH - SECTIONS_WIDTH - \ |
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| 114 | NODES_WIDTH - KASAN_TAG_WIDTH - LAST_CPUPID_WIDTH) |
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| 115 | |
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| 116 | #define NR_NON_PAGEFLAG_BITS (SECTIONS_WIDTH + NODES_WIDTH + ZONES_WIDTH + \ |
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| 117 | LAST_CPUPID_SHIFT + KASAN_TAG_WIDTH + \ |
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| 118 | LRU_GEN_WIDTH + LRU_REFS_WIDTH) |
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| 119 | |
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| 120 | #define NR_UNUSED_PAGEFLAG_BITS (BITS_PER_LONG - \ |
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| 121 | (NR_NON_PAGEFLAG_BITS + NR_PAGEFLAGS)) |
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| 122 | |
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| 123 | #endif |
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| 124 | #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ |
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| 125 | |
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