mirror of https://gitee.com/openkylin/linux.git
74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
/*
|
|
* linux/arch/arm/mm/minicache.c
|
|
*
|
|
* Copyright (C) 2001 Russell King
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This handles the mini data cache, as found on SA11x0 and XScale
|
|
* processors. When we copy a user page page, we map it in such a way
|
|
* that accesses to this page will not touch the main data cache, but
|
|
* will be cached in the mini data cache. This prevents us thrashing
|
|
* the main data cache on page faults.
|
|
*/
|
|
#include <linux/init.h>
|
|
#include <linux/mm.h>
|
|
|
|
#include <asm/page.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
/*
|
|
* 0xffff8000 to 0xffffffff is reserved for any ARM architecture
|
|
* specific hacks for copying pages efficiently.
|
|
*/
|
|
#define minicache_address (0xffff8000)
|
|
#define minicache_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
|
|
L_PTE_CACHEABLE)
|
|
|
|
static pte_t *minicache_pte;
|
|
|
|
/*
|
|
* Note that this is intended to be called only from the copy_user_page
|
|
* asm code; anything else will require special locking to prevent the
|
|
* mini-cache space being re-used. (Note: probably preempt unsafe).
|
|
*
|
|
* We rely on the fact that the minicache is 2K, and we'll be pushing
|
|
* 4K of data through it, so we don't actually have to specifically
|
|
* flush the minicache when we change the mapping.
|
|
*
|
|
* Note also: assert(PAGE_OFFSET <= virt < high_memory).
|
|
* Unsafe: preempt, kmap.
|
|
*/
|
|
unsigned long map_page_minicache(unsigned long virt)
|
|
{
|
|
set_pte(minicache_pte, pfn_pte(__pa(virt) >> PAGE_SHIFT, minicache_pgprot));
|
|
flush_tlb_kernel_page(minicache_address);
|
|
|
|
return minicache_address;
|
|
}
|
|
|
|
static int __init minicache_init(void)
|
|
{
|
|
pgd_t *pgd;
|
|
pmd_t *pmd;
|
|
|
|
spin_lock(&init_mm.page_table_lock);
|
|
|
|
pgd = pgd_offset_k(minicache_address);
|
|
pmd = pmd_alloc(&init_mm, pgd, minicache_address);
|
|
if (!pmd)
|
|
BUG();
|
|
minicache_pte = pte_alloc_kernel(&init_mm, pmd, minicache_address);
|
|
if (!minicache_pte)
|
|
BUG();
|
|
|
|
spin_unlock(&init_mm.page_table_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
core_initcall(minicache_init);
|