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" 25 #endif 26 27 #define ZONES_WIDTH ZONES_SHIFT 28 29 #ifdef CONFIG_SPARSEMEM 30 #include <asm/sparsemem.h> 31 #define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) 32 #else 33 #define SECTIONS_SHIFT 0 34 #endif 35 36 #ifndef BUILD_VDSO32_64 37 /* 38 * page->flags layout: 39 * 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. 45 * 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 | 51 */ 52 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) 53 #define SECTIONS_WIDTH SECTIONS_SHIFT 54 #else 55 #define SECTIONS_WIDTH 0 56 #endif 57 58 #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \ 59 <= BITS_PER_LONG - NR_PAGEFLAGS 60 #define NODES_WIDTH NODES_SHIFT 61 #elif defined(CONFIG_SPARSEMEM_VMEMMAP) 62 #error "Vmemmap: No space for nodes field in page flags" 63 #else 64 #define NODES_WIDTH 0 65 #endif 66 67 /* 68 * Note that this #define MUST have a value so that it can be tested with 69 * the IS_ENABLED() macro. 70 */ 71 #if NODES_SHIFT != 0 && NODES_WIDTH == 0 72 #define NODE_NOT_IN_PAGE_FLAGS 1 73 #endif 74 75 #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) 76 #define KASAN_TAG_WIDTH 8 77 #else 78 #define KASAN_TAG_WIDTH 0 79 #endif 80 81 #ifdef CONFIG_NUMA_BALANCING 82 #define LAST__PID_SHIFT 8 83 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) 84 85 #define LAST__CPU_SHIFT NR_CPUS_BITS 86 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) 87 88 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) 89 #else 90 #define LAST_CPUPID_SHIFT 0 91 #endif 92 93 #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ 94 KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS 95 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT 96 #else 97 #define LAST_CPUPID_WIDTH 0 98 #endif 99 100 #if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0 101 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS 102 #endif 103 104 #if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \ 105 KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS 106 #error "Not enough bits in page flags" 107 #endif 108 109 /* see the comment on MAX_NR_TIERS */ 110 #define LRU_REFS_WIDTH min(__LRU_REFS_WIDTH, BITS_PER_LONG - NR_PAGEFLAGS - \ 111 ZONES_WIDTH - LRU_GEN_WIDTH - SECTIONS_WIDTH - \ 112 NODES_WIDTH - KASAN_TAG_WIDTH - LAST_CPUPID_WIDTH) 113 114 #endif 115 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ 116