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/*
* linux/arch/arm/lib/copypage-armv4mc.S
*
* Copyright (C) 1995-2005 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_pgprot __pgprot(L_PTE_PRESENT | L_PTE_YOUNG | \
L_PTE_CACHEABLE)
#define TOP_PTE(x) pte_offset_kernel(top_pmd, x)
static DEFINE_SPINLOCK(minicache_lock);
/*
* ARMv4 mini-dcache optimised copy_user_page
*
* We flush the destination cache lines just before we write the data into the
* corresponding address. Since the Dcache is read-allocate, this removes the
* Dcache aliasing issue. The writes will be forwarded to the write buffer,
* and merged as appropriate.
*
* Note: We rely on all ARMv4 processors implementing the "invalidate D line"
* instruction. If your processor does not supply this, you have to write your
* own copy_user_page that does the right thing.
*/
static void __attribute__((naked))
mc_copy_user_page(void *from, void *to)
{
asm volatile(
"stmfd sp!, {r4, lr} @ 2\n\
mov r4, %2 @ 1\n\
ldmia %0!, {r2, r3, ip, lr} @ 4\n\
1: mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
stmia %1!, {r2, r3, ip, lr} @ 4\n\
ldmia %0!, {r2, r3, ip, lr} @ 4+1\n\
stmia %1!, {r2, r3, ip, lr} @ 4\n\
ldmia %0!, {r2, r3, ip, lr} @ 4\n\
mcr p15, 0, %1, c7, c6, 1 @ 1 invalidate D line\n\
stmia %1!, {r2, r3, ip, lr} @ 4\n\
ldmia %0!, {r2, r3, ip, lr} @ 4\n\
subs r4, r4, #1 @ 1\n\
stmia %1!, {r2, r3, ip, lr} @ 4\n\
ldmneia %0!, {r2, r3, ip, lr} @ 4\n\
bne 1b @ 1\n\
ldmfd sp!, {r4, pc} @ 3"
:
: "r" (from), "r" (to), "I" (PAGE_SIZE / 64));
}
void v4_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
{
spin_lock(&minicache_lock);
set_pte(TOP_PTE(0xffff8000), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot));
flush_tlb_kernel_page(0xffff8000);
mc_copy_user_page((void *)0xffff8000, kto);
spin_unlock(&minicache_lock);
}
/*
* ARMv4 optimised clear_user_page
*/
void __attribute__((naked))
v4_mc_clear_user_page(void *kaddr, unsigned long vaddr)
{
asm volatile(
"str lr, [sp, #-4]!\n\
mov r1, %0 @ 1\n\
mov r2, #0 @ 1\n\
mov r3, #0 @ 1\n\
mov ip, #0 @ 1\n\
mov lr, #0 @ 1\n\
1: mcr p15, 0, r0, c7, c6, 1 @ 1 invalidate D line\n\
stmia r0!, {r2, r3, ip, lr} @ 4\n\
stmia r0!, {r2, r3, ip, lr} @ 4\n\
mcr p15, 0, r0, c7, c6, 1 @ 1 invalidate D line\n\
stmia r0!, {r2, r3, ip, lr} @ 4\n\
stmia r0!, {r2, r3, ip, lr} @ 4\n\
subs r1, r1, #1 @ 1\n\
bne 1b @ 1\n\
ldr pc, [sp], #4"
:
: "I" (PAGE_SIZE / 64));
}
struct cpu_user_fns v4_mc_user_fns __initdata = {
.cpu_clear_user_page = v4_mc_clear_user_page,
.cpu_copy_user_page = v4_mc_copy_user_page,
};
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