arm64/sve: Implement a helper to load SVE registers from FPSIMD state (9c4b4c70) · Commits · 戴 / test

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>

arch/arm64/include/asm/fpsimd.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/arm64/kernel/entry-fpsimd.S

+17 −0

Original line number	Diff line number	Diff line
		@@ -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

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