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