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 */ 114