Commit 1e530f13 authored by Julien Grall's avatar Julien Grall Committed by Will Deacon
Browse files

arm64/sve: Implement a helper to flush SVE registers 



Introduce a new helper that will zero all SVE registers but the first
128-bits of each vector. This will be used by subsequent patches to
avoid costly store/maipulate/reload sequences in places like do_sve_acc().

Signed-off-by: default avatarJulien Grall <julien.grall@arm.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Reviewed-by: default avatarDave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20200828181155.17745-6-broonie@kernel.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 6d40f05f

arch/arm64/include/asm/fpsimd.h

+1 −0
Original line number Diff line number Diff line
@@ -69,6 +69,7 @@ static inline void *sve_pffr(struct thread_struct *thread) 
extern void sve_save_state(void *state, u32 *pfpsr);

extern void sve_load_state(void const *state, u32 const *pfpsr,

			   unsigned long vq_minus_1);

extern void sve_flush_live(void);

extern unsigned int sve_get_vl(void);



struct arm64_cpu_capabilities;

arch/arm64/include/asm/fpsimdmacros.h

+19 −0
Original line number Diff line number Diff line
@@ -164,6 +164,13 @@ 
		| ((\np) << 5)

.endm



/* PFALSE P\np.B */

.macro _sve_pfalse np

	_sve_check_preg \np

	.inst	0x2518e400			\

		| (\np)

.endm



.macro __for from:req, to:req

	.if (\from) == (\to)

		_for__body %\from
@@ -198,6 +205,18 @@ 
921:

.endm



/* Preserve the first 128-bits of Znz and zero the rest. */

.macro _sve_flush_z nz

	_sve_check_zreg \nz

	mov	v\nz\().16b, v\nz\().16b

.endm



.macro sve_flush

 _for n, 0, 31, _sve_flush_z	\n

 _for n, 0, 15, _sve_pfalse	\n

		_sve_wrffr	0

.endm



.macro sve_save nxbase, xpfpsr, nxtmp

 _for n, 0, 31,	_sve_str_v	\n, \nxbase, \n - 34

 _for n, 0, 15,	_sve_str_p	\n, \nxbase, \n - 16

arch/arm64/kernel/entry-fpsimd.S

+8 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ SYM_FUNC_START(fpsimd_load_state) 
SYM_FUNC_END(fpsimd_load_state)



#ifdef CONFIG_ARM64_SVE



SYM_FUNC_START(sve_save_state)

	sve_save 0, x1, 2

	ret
@@ -46,4 +47,11 @@ SYM_FUNC_START(sve_get_vl) 
	_sve_rdvl	0, 1

	ret

SYM_FUNC_END(sve_get_vl)



/* Zero all SVE registers but the first 128-bits of each vector */

SYM_FUNC_START(sve_flush_live)

	sve_flush

	ret

SYM_FUNC_END(sve_flush_live)



#endif /* CONFIG_ARM64_SVE */

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