arch/xtensa/include/asm/page.h

Source file repositories/reference/linux-study-clean/arch/xtensa/include/asm/page.h

File Facts

System
Linux kernel
Corpus path
arch/xtensa/include/asm/page.h
Extension
.h
Size
5148 bytes
Lines
178
Domain
Architecture Layer
Bucket
arch/xtensa
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _XTENSA_PAGE_H
#define _XTENSA_PAGE_H

#include <linux/const.h>

#include <asm/processor.h>
#include <asm/types.h>
#include <asm/cache.h>
#include <asm/kmem_layout.h>

#include <vdso/page.h>

#ifdef CONFIG_MMU
#define PAGE_OFFSET	XCHAL_KSEG_CACHED_VADDR
#define PHYS_OFFSET	XCHAL_KSEG_PADDR
#define MAX_LOW_PFN	(PHYS_PFN(XCHAL_KSEG_PADDR) + \
			 PHYS_PFN(XCHAL_KSEG_SIZE))
#else
#define PAGE_OFFSET	_AC(CONFIG_DEFAULT_MEM_START, UL)
#define PHYS_OFFSET	_AC(CONFIG_DEFAULT_MEM_START, UL)
#define MAX_LOW_PFN	PHYS_PFN(0xfffffffful)
#endif

/*
 * Cache aliasing:
 *
 * If the cache size for one way is greater than the page size, we have to
 * deal with cache aliasing. The cache index is wider than the page size:
 *
 * |    |cache| cache index
 * | pfn  |off|	virtual address
 * |xxxx:X|zzz|
 * |    : |   |
 * | \  / |   |
 * |trans.|   |
 * | /  \ |   |
 * |yyyy:Y|zzz|	physical address
 *
 * When the page number is translated to the physical page address, the lowest
 * bit(s) (X) that are part of the cache index are also translated (Y).
 * If this translation changes bit(s) (X), the cache index is also afected,
 * thus resulting in a different cache line than before.
 * The kernel does not provide a mechanism to ensure that the page color
 * (represented by this bit) remains the same when allocated or when pages
 * are remapped. When user pages are mapped into kernel space, the color of
 * the page might also change.
 *
 * We use the address space VMALLOC_END ... VMALLOC_END + DCACHE_WAY_SIZE * 2
 * to temporarily map a patch so we can match the color.
 */

#if DCACHE_WAY_SIZE > PAGE_SIZE
# define DCACHE_ALIAS_ORDER	(DCACHE_WAY_SHIFT - PAGE_SHIFT)
# define DCACHE_ALIAS_MASK	(PAGE_MASK & (DCACHE_WAY_SIZE - 1))
# define DCACHE_ALIAS(a)	(((a) & DCACHE_ALIAS_MASK) >> PAGE_SHIFT)
# define DCACHE_ALIAS_EQ(a,b)	((((a) ^ (b)) & DCACHE_ALIAS_MASK) == 0)
#else
# define DCACHE_ALIAS_ORDER	0
# define DCACHE_ALIAS(a)	((void)(a), 0)
#endif
#define DCACHE_N_COLORS		(1 << DCACHE_ALIAS_ORDER)

#if ICACHE_WAY_SIZE > PAGE_SIZE
# define ICACHE_ALIAS_ORDER	(ICACHE_WAY_SHIFT - PAGE_SHIFT)
# define ICACHE_ALIAS_MASK	(PAGE_MASK & (ICACHE_WAY_SIZE - 1))
# define ICACHE_ALIAS(a)	(((a) & ICACHE_ALIAS_MASK) >> PAGE_SHIFT)
# define ICACHE_ALIAS_EQ(a,b)	((((a) ^ (b)) & ICACHE_ALIAS_MASK) == 0)
#else
# define ICACHE_ALIAS_ORDER	0
#endif


#ifdef __ASSEMBLER__

#define __pgprot(x)	(x)

#else

/*
 * These are used to make use of C type-checking..
 */

typedef struct { unsigned long pte; } pte_t;		/* page table entry */
typedef struct { unsigned long pgd; } pgd_t;		/* PGD table entry */
typedef struct { unsigned long pgprot; } pgprot_t;
typedef struct page *pgtable_t;

#define pte_val(x)	((x).pte)
#define pgd_val(x)	((x).pgd)
#define pgprot_val(x)	((x).pgprot)

Annotation

Implementation Notes