diff options
Diffstat (limited to 'include/linux/page-flags-layout.h')
| -rw-r--r-- | include/linux/page-flags-layout.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h new file mode 100644 index 000000000..7d79818dc --- /dev/null +++ b/include/linux/page-flags-layout.h @@ -0,0 +1,115 @@ +/* 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 */ |