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 /* 36 * page->flags layout: 37 * 38 * There are five possibilities for how page->flags get laid out. The first 39 * pair is for the normal case without sparsemem. The second pair is for 40 * sparsemem when there is plenty of space for node and section information. 41 * The last is when there is insufficient space in page->flags and a separate 42 * lookup is necessary. 43 * 44 * No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS | 45 * " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS | 46 * classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS | 47 * " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS | 48 * classic sparse no space for node: | SECTION | ZONE | ... | FLAGS | 49 */ 50 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP) 51 #define SECTIONS_WIDTH SECTIONS_SHIFT 52 #else 53 #define SECTIONS_WIDTH 0 54 #endif 55 56 #define ZONES_WIDTH ZONES_SHIFT 57 58 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS 59 #define NODES_WIDTH NODES_SHIFT 60 #else 61 #ifdef CONFIG_SPARSEMEM_VMEMMAP 62 #error "Vmemmap: No space for nodes field in page flags" 63 #endif 64 #define NODES_WIDTH 0 65 #endif 66 67 #ifdef CONFIG_NUMA_BALANCING 68 #define LAST__PID_SHIFT 8 69 #define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1) 70 71 #define LAST__CPU_SHIFT NR_CPUS_BITS 72 #define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1) 73 74 #define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT) 75 #else 76 #define LAST_CPUPID_SHIFT 0 77 #endif 78 79 #if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS 80 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT 81 #else 82 #define LAST_CPUPID_WIDTH 0 83 #endif 84 85 /* 86 * We are going to use the flags for the page to node mapping if its in 87 * there. This includes the case where there is no node, so it is implicit. 88 */ 89 #if !(NODES_WIDTH > 0 || NODES_SHIFT == 0) 90 #define NODE_NOT_IN_PAGE_FLAGS 91 #endif 92 93 #if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0 94 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS 95 #endif 96 97 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */ 98