linux/arch/mips/include/asm/highmem.h
Ralf Baechle bb86bf28ae MIPS: Fix highmem.
Commit 351336929c (kernel.org) rsp.
b3594a089f1c17ff919f8f78505c3f20e1f6f8ce (linux-mips.org):

> From: Chris Dearman <chris@mips.com>
> Date: Wed, 19 Sep 2007 00:58:24 +0100
> Subject: [PATCH] [MIPS] Allow setting of the cache attribute at run time.
>
> Slightly tacky, but there is a precedent in the sparc archirecture code.

introduces the variable _page_cachable_default, which defaults to zero and.
is used to create the prototype PTE for __kmap_atomic in
arch/mips/mm/init.c:kmap_init before initialization in
arch/mips/mm/c-r4k.c:coherency_setup, so the default value of 0 will be
used as the CCA of kmap atomic pages which on many processors is not a
defined CCA value and may result in writes to kmap_atomic pages getting
corrupted.  Debugged by Jon Fraser (jfraser@broadcom.com).

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2009-05-14 13:50:29 +01:00

70 lines
1.9 KiB
C

/*
* highmem.h: virtual kernel memory mappings for high memory
*
* Used in CONFIG_HIGHMEM systems for memory pages which
* are not addressable by direct kernel virtual addresses.
*
* Copyright (C) 1999 Gerhard Wichert, Siemens AG
* Gerhard.Wichert@pdb.siemens.de
*
*
* Redesigned the x86 32-bit VM architecture to deal with
* up to 16 Terabyte physical memory. With current x86 CPUs
* we now support up to 64 Gigabytes physical RAM.
*
* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
*/
#ifndef _ASM_HIGHMEM_H
#define _ASM_HIGHMEM_H
#ifdef __KERNEL__
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <asm/kmap_types.h>
/* undef for production */
#define HIGHMEM_DEBUG 1
/* declarations for highmem.c */
extern unsigned long highstart_pfn, highend_pfn;
extern pte_t *pkmap_page_table;
/*
* Right now we initialize only a single pte table. It can be extended
* easily, subsequent pte tables have to be allocated in one physical
* chunk of RAM.
*/
#define LAST_PKMAP 1024
#define LAST_PKMAP_MASK (LAST_PKMAP-1)
#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
extern void * kmap_high(struct page *page);
extern void kunmap_high(struct page *page);
extern void *__kmap(struct page *page);
extern void __kunmap(struct page *page);
extern void *__kmap_atomic(struct page *page, enum km_type type);
extern void __kunmap_atomic(void *kvaddr, enum km_type type);
extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
extern struct page *__kmap_atomic_to_page(void *ptr);
#define kmap __kmap
#define kunmap __kunmap
#define kmap_atomic __kmap_atomic
#define kunmap_atomic __kunmap_atomic
#define kmap_atomic_to_page __kmap_atomic_to_page
#define flush_cache_kmaps() flush_cache_all()
extern void kmap_init(void);
#define kmap_prot PAGE_KERNEL
#endif /* __KERNEL__ */
#endif /* _ASM_HIGHMEM_H */