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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef PAGE_FLAGS_LAYOUT_H
#define PAGE_FLAGS_LAYOUT_H
#include <linux/numa.h>
#include <generated/bounds.h>
/*
* When a memory allocation must conform to specific limitations (such
* as being suitable for DMA) the caller will pass in hints to the
* allocator in the gfp_mask, in the zone modifier bits. These bits
* are used to select a priority ordered list of memory zones which
* match the requested limits. See gfp_zone() in include/linux/gfp.h
*/
#if MAX_NR_ZONES < 2
#define ZONES_SHIFT 0
#elif MAX_NR_ZONES <= 2
#define ZONES_SHIFT 1
#elif MAX_NR_ZONES <= 4
#define ZONES_SHIFT 2
#elif MAX_NR_ZONES <= 8
#define ZONES_SHIFT 3
#else
#error ZONES_SHIFT "Too many zones configured"
#endif
#define ZONES_WIDTH ZONES_SHIFT
#ifdef CONFIG_SPARSEMEM
#include <asm/sparsemem.h>
#define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
#else
#define SECTIONS_SHIFT 0
#endif
#ifndef BUILD_VDSO32_64
/*
* page->flags layout:
*
* There are five possibilities for how page->flags get laid out. The first
* pair is for the normal case without sparsemem. The second pair is for
* sparsemem when there is plenty of space for node and section information.
* The last is when there is insufficient space in page->flags and a separate
* lookup is necessary.
*
* No sparsemem or sparsemem vmemmap: | NODE | ZONE | ... | FLAGS |
* " plus space for last_cpupid: | NODE | ZONE | LAST_CPUPID ... | FLAGS |
* classic sparse with space for node:| SECTION | NODE | ZONE | ... | FLAGS |
* " plus space for last_cpupid: | SECTION | NODE | ZONE | LAST_CPUPID ... | FLAGS |
* classic sparse no space for node: | SECTION | ZONE | ... | FLAGS |
*/
#if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
#define SECTIONS_WIDTH SECTIONS_SHIFT
#else
#define SECTIONS_WIDTH 0
#endif
#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_SHIFT \
<= BITS_PER_LONG - NR_PAGEFLAGS
#define NODES_WIDTH NODES_SHIFT
#elif defined(CONFIG_SPARSEMEM_VMEMMAP)
#error "Vmemmap: No space for nodes field in page flags"
#else
#define NODES_WIDTH 0
#endif
/*
* Note that this #define MUST have a value so that it can be tested with
* the IS_ENABLED() macro.
*/
#if NODES_SHIFT != 0 && NODES_WIDTH == 0
#define NODE_NOT_IN_PAGE_FLAGS 1
#endif
#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
#define KASAN_TAG_WIDTH 8
#else
#define KASAN_TAG_WIDTH 0
#endif
#ifdef CONFIG_NUMA_BALANCING
#define LAST__PID_SHIFT 8
#define LAST__PID_MASK ((1 << LAST__PID_SHIFT)-1)
#define LAST__CPU_SHIFT NR_CPUS_BITS
#define LAST__CPU_MASK ((1 << LAST__CPU_SHIFT)-1)
#define LAST_CPUPID_SHIFT (LAST__PID_SHIFT+LAST__CPU_SHIFT)
#else
#define LAST_CPUPID_SHIFT 0
#endif
#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
KASAN_TAG_WIDTH + LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
#define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
#else
#define LAST_CPUPID_WIDTH 0
#endif
#if LAST_CPUPID_SHIFT != 0 && LAST_CPUPID_WIDTH == 0
#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
#endif
#if ZONES_WIDTH + LRU_GEN_WIDTH + SECTIONS_WIDTH + NODES_WIDTH + \
KASAN_TAG_WIDTH + LAST_CPUPID_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
#error "Not enough bits in page flags"
#endif
/* see the comment on MAX_NR_TIERS */
#define LRU_REFS_WIDTH min(__LRU_REFS_WIDTH, BITS_PER_LONG - NR_PAGEFLAGS - \
ZONES_WIDTH - LRU_GEN_WIDTH - SECTIONS_WIDTH - \
NODES_WIDTH - KASAN_TAG_WIDTH - LAST_CPUPID_WIDTH)
#endif
#endif /* _LINUX_PAGE_FLAGS_LAYOUT */
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