linux/arch/arm64/kernel/entry-fpsimd.S
Mark Brown ad4711f962 arm64/sve: Skip flushing Z registers with 128 bit vectors
When the SVE vector length is 128 bits then there are no bits in the Z
registers which are not shared with the V registers so we can skip them
when zeroing state not shared with FPSIMD, this results in a minor
performance improvement.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210512151131.27877-4-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2021-05-26 20:04:28 +01:00

88 lines
1.7 KiB
ArmAsm

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* FP/SIMD state saving and restoring
*
* Copyright (C) 2012 ARM Ltd.
* Author: Catalin Marinas <catalin.marinas@arm.com>
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/fpsimdmacros.h>
/*
* Save the FP registers.
*
* x0 - pointer to struct fpsimd_state
*/
SYM_FUNC_START(fpsimd_save_state)
fpsimd_save x0, 8
ret
SYM_FUNC_END(fpsimd_save_state)
/*
* Load the FP registers.
*
* x0 - pointer to struct fpsimd_state
*/
SYM_FUNC_START(fpsimd_load_state)
fpsimd_restore x0, 8
ret
SYM_FUNC_END(fpsimd_load_state)
#ifdef CONFIG_ARM64_SVE
SYM_FUNC_START(sve_save_state)
sve_save 0, x1, 2
ret
SYM_FUNC_END(sve_save_state)
SYM_FUNC_START(sve_load_state)
sve_load 0, x1, x2, 3, x4
ret
SYM_FUNC_END(sve_load_state)
SYM_FUNC_START(sve_get_vl)
_sve_rdvl 0, 1
ret
SYM_FUNC_END(sve_get_vl)
SYM_FUNC_START(sve_set_vq)
sve_load_vq x0, x1, x2
ret
SYM_FUNC_END(sve_set_vq)
/*
* Load SVE state from FPSIMD state.
*
* x0 = pointer to struct fpsimd_state
* x1 = VQ - 1
*
* Each SVE vector will be loaded with the first 128-bits taken from FPSIMD
* and the rest zeroed. All the other SVE registers will be zeroed.
*/
SYM_FUNC_START(sve_load_from_fpsimd_state)
sve_load_vq x1, x2, x3
fpsimd_restore x0, 8
sve_flush_p_ffr
ret
SYM_FUNC_END(sve_load_from_fpsimd_state)
/*
* Zero all SVE registers but the first 128-bits of each vector
*
* VQ must already be configured by caller, any further updates of VQ
* will need to ensure that the register state remains valid.
*
* x0 = VQ - 1
*/
SYM_FUNC_START(sve_flush_live)
cbz x0, 1f // A VQ-1 of 0 is 128 bits so no extra Z state
sve_flush_z
1: sve_flush_p_ffr
ret
SYM_FUNC_END(sve_flush_live)
#endif /* CONFIG_ARM64_SVE */