/*
* linux/arch/arm/lib/copypage-xscale.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 COPYPAGE_MINICACHE 0xffff8000
#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);
/*
* XScale 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.
*/
static void __attribute__((naked))
mc_copy_user_page(void *from, void *to)
{
/*
* Strangely enough, best performance is achieved
* when prefetching destination as well. (NP)
*/
asm volatile(
"stmfd sp!, {r4, r5, lr} \n\
mov lr, %2 \n\
pld [r0, #0] \n\
pld [r0, #32] \n\
pld [r1, #0] \n\
pld [r1, #32] \n\
1: pld [r0, #64] \n\
pld [r0, #96] \n\
pld [r1, #64] \n\
pld [r1, #96] \n\
2: ldrd r2, [r0], #8 \n\
ldrd r4, [r0], #8 \n\
mov ip, r1 \n\
strd r2, [r1], #8 \n\
ldrd r2, [r0], #8 \n\
strd r4, [r1], #8 \n\
ldrd r4, [r0], #8 \n\
strd r2, [r1], #8 \n\
strd r4, [r1], #8 \n\
mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
ldrd r2, [r0], #8 \n\
mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
ldrd r4, [r0], #8 \n\
mov ip, r1 \n\
strd r2, [r1], #8 \n\
ldrd r2, [r0], #8 \n\
strd r4, [r1], #8 \n\
ldrd r4, [r0], #8 \n\
strd r2, [r1], #8 \n\
strd r4, [r1], #8 \n\
mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
subs lr, lr, #1 \n\
mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
bgt 1b \n\
beq 2b \n\
ldmfd sp!, {r4, r5, pc} "
:
: "r" (from), "r" (to), "I" (PAGE_SIZE / 64 - 1));
}
void xscale_mc_copy_user_page(void *kto, const void *kfrom, unsigned long vaddr)
{
spin_lock(&minicache_lock);
set_pte(TOP_PTE(COPYPAGE_MINICACHE), pfn_pte(__pa(kfrom) >> PAGE_SHIFT, minicache_pgprot));
flush_tlb_kernel_page(COPYPAGE_MINICACHE);
mc_copy_user_page((void *)COPYPAGE_MINICACHE, kto);
spin_unlock(&minicache_lock);
}
/*
* XScale optimised clear_user_page
*/
void __attribute__((naked))
xscale_mc_clear_user_page(void *kaddr, unsigned long vaddr)
{
asm volatile(
"mov r1, %0 \n\
mov r2, #0 \n\
mov r3, #0 \n\
1: mov ip, r0 \n\
strd r2, [r0], #8 \n\
strd r2, [r0], #8 \n\
strd r2, [r0], #8 \n\
strd r2, [r0], #8 \n\
mcr p15, 0, ip, c7, c10, 1 @ clean D line\n\
subs r1, r1, #1 \n\
mcr p15, 0, ip, c7, c6, 1 @ invalidate D line\n\
bne 1b \n\
mov pc, lr"
:
: "I" (PAGE_SIZE / 32));
}
struct cpu_user_fns xscale_mc_user_fns __initdata = {
.cpu_clear_user_page = xscale_mc_clear_user_page,
.cpu_copy_user_page = xscale_mc_copy_user_page,
};
