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 + 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" 62 #else 63 #define NODES_WIDTH 0 64 #endif 65 66 /* 67 * Note that this #define MUST have a value so that it can be tested with 68 * the IS_ENABLED() macro. 69 */ 70 #if NODES_SHIFT != 0 && NODES_WIDTH == 0 71 #define NODE_NOT_IN_PAGE_FLAGS 1 72 #endif 73 74 #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS) 75 #define KASAN_TAG_WIDTH 8 76 #else 77 #define KASAN_TAG_WIDTH 0 78 #endif 79 80 #ifdef CONFIG_NUMA_BALANCING 81 #define LAST__PID_SHIFT 8 82 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) 83 84 #define LAST__CPU_SHIFT NR_CPUS_BITS 85 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) 86 87 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) 88 #else 89 #define LAST_CPUPID_SHIFT 0 90 #endif 91 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 95 #else 96 #define LAST_CPUPID_WIDTH 0 97 #endif 98 99 #if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0 100 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS 101 #endif 102 103 #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" 106 #endif 107 108 #endif 109 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ 110