linux-next/arch/arm64/lib/clear_page.S
Kristina Martsenko ce6b5ff5f1 arm64: lib: Use MOPS for copy_page() and clear_page()
Similarly to what was done to the memcpy() routines, make copy_page()
and clear_page() also use the Armv8.8 FEAT_MOPS instructions.

Note: For copy_page() this uses the CPY* instructions instead of CPYF*
as CPYF* doesn't allow src and dst to be equal. It's not clear if
copy_page() needs to allow equal src and dst but it has worked so far
with the current implementation and there is no documentation forbidding
it.

Note, the unoptimized version of copy_page() in assembler.h is left as
it is.

Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20240930161051.3777828-6-kristina.martsenko@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2024-10-17 16:42:51 +01:00

54 lines
959 B
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/linkage.h>
#include <linux/const.h>
#include <asm/assembler.h>
#include <asm/page.h>
/*
* Clear page @dest
*
* Parameters:
* x0 - dest
*/
SYM_FUNC_START(__pi_clear_page)
#ifdef CONFIG_AS_HAS_MOPS
.arch_extension mops
alternative_if_not ARM64_HAS_MOPS
b .Lno_mops
alternative_else_nop_endif
mov x1, #PAGE_SIZE
setpn [x0]!, x1!, xzr
setmn [x0]!, x1!, xzr
seten [x0]!, x1!, xzr
ret
.Lno_mops:
#endif
mrs x1, dczid_el0
tbnz x1, #4, 2f /* Branch if DC ZVA is prohibited */
and w1, w1, #0xf
mov x2, #4
lsl x1, x2, x1
1: dc zva, x0
add x0, x0, x1
tst x0, #(PAGE_SIZE - 1)
b.ne 1b
ret
2: stnp xzr, xzr, [x0]
stnp xzr, xzr, [x0, #16]
stnp xzr, xzr, [x0, #32]
stnp xzr, xzr, [x0, #48]
add x0, x0, #64
tst x0, #(PAGE_SIZE - 1)
b.ne 2b
ret
SYM_FUNC_END(__pi_clear_page)
SYM_FUNC_ALIAS(clear_page, __pi_clear_page)
EXPORT_SYMBOL(clear_page)