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arm64/sve: Implement a helper to load SVE registers from FPSIMD state 

In a follow-up patch, we may save the FPSIMD rather than the full SVE
state when the state has to be zeroed on return to userspace (e.g
during a syscall).

Introduce an helper to load SVE vectors from FPSIMD state and zero the rest
of SVE registers.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20200828181155.17745-7-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Julien Grall 2020-08-28 19:11:53 +01:00 committed by Will Deacon
parent 1e530f1352
commit 9c4b4c701e
2 changed files with 19 additions and 0 deletions
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2
arch/arm64/include/asm/fpsimd.h
View File

@ -70,6 +70,8 @@ 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 void sve_load_from_fpsimd_state(struct user_fpsimd_state const *state,
unsigned long vq_minus_1);
extern unsigned int sve_get_vl(void);
struct arm64_cpu_capabilities;

17
arch/arm64/kernel/entry-fpsimd.S
View File

@ -48,6 +48,23 @@ SYM_FUNC_START(sve_get_vl)
ret
SYM_FUNC_END(sve_get_vl)
/*
* 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
_for n, 0, 15, _sve_pfalse \n
_sve_wrffr 0
ret
SYM_FUNC_END(sve_load_from_fpsimd_state)
/* Zero all SVE registers but the first 128-bits of each vector */
SYM_FUNC_START(sve_flush_live)
sve_flush