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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 adjust calculation
#endif
#ifdef CONFIG_SPARSEMEM
#include <asm/sparsemem.h>
/* SECTION_SHIFT #bits space required to store a section # */
#define SECTIONS_SHIFT (MAX_PHYSMEM_BITS - SECTION_SIZE_BITS)
#endif /* CONFIG_SPARSEMEM */
/*
* 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
#define ZONES_WIDTH ZONES_SHIFT
#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
#define NODES_WIDTH NODES_SHIFT
#else
#ifdef CONFIG_SPARSEMEM_VMEMMAP
#error "Vmemmap: No space for nodes field in page flags"
#endif
#define NODES_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 SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
#define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
#else
#define LAST_CPUPID_WIDTH 0
#endif
#ifdef CONFIG_KASAN_SW_TAGS
#define KASAN_TAG_WIDTH 8
#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH+LAST_CPUPID_WIDTH+KASAN_TAG_WIDTH \
> BITS_PER_LONG - NR_PAGEFLAGS
#error "KASAN: not enough bits in page flags for tag"
#endif
#else
#define KASAN_TAG_WIDTH 0
#endif
/*
* We are going to use the flags for the page to node mapping if its in
* there. This includes the case where there is no node, so it is implicit.
*/
#if !(NODES_WIDTH > 0 || NODES_SHIFT == 0)
#define NODE_NOT_IN_PAGE_FLAGS
#endif
#if defined(CONFIG_NUMA_BALANCING) && LAST_CPUPID_WIDTH == 0
#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
#endif
#endif /* _LINUX_PAGE_FLAGS_LAYOUT */
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