page-flags-layout.h (3287B)
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 */