On Mon, May 14, 2018 at 10:46:28AM +0100, Mark Rutland wrote:
> In subsequent patches, we'll want to make use of sve_user_enable() and
> sve_user_disable() outside of kernel/fpsimd.c. Let's move these to
> <asm/fpsimd.h> where we can make use of them.
>
> To avoid ifdeffery in sequences like:
>
> if (system_supports_sve() && some_condition
> sve_user_disable();
>
> ... empty stubs are provided when support for SVE is not enabled.
>
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Dave Martin <dave.martin@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> ---
> arch/arm64/include/asm/fpsimd.h | 17 ++++++++++++++++-
> arch/arm64/kernel/fpsimd.c | 11 -----------
> 2 files changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
> index aa7162ae93e3..7377d7593c06 100644
> --- a/arch/arm64/include/asm/fpsimd.h
> +++ b/arch/arm64/include/asm/fpsimd.h
> @@ -16,11 +16,13 @@
> #ifndef __ASM_FP_H
> #define __ASM_FP_H
>
> -#include <asm/ptrace.h>
> #include <asm/errno.h>
> +#include <asm/ptrace.h>
> +#include <asm/sysreg.h>
>
> #ifndef __ASSEMBLY__
>
> +#include <linux/build_bug.h>
> #include <linux/cache.h>
> #include <linux/init.h>
> #include <linux/stddef.h>
> @@ -81,6 +83,16 @@ extern int sve_set_vector_length(struct task_struct *task,
> extern int sve_set_current_vl(unsigned long arg);
> extern int sve_get_current_vl(void);
>
> +static inline void sve_user_disable(void)
> +{
> + sysreg_clear_set(cpacr_el1, CPACR_EL1_ZEN_EL0EN, 0);
> +}
> +
> +static inline void sve_user_enable(void)
> +{
> + sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN);
> +}
> +
> /*
> * Probing and setup functions.
> * Calls to these functions must be serialised with one another.
> @@ -107,6 +119,9 @@ static inline int sve_get_current_vl(void)
> return -EINVAL;
> }
>
> +static inline void sve_user_disable(void) { }
> +static inline void sve_user_enable(void) { }
> +
Alternatively, just move the full definitions outside the #ifdef
CONFIG_ARM64_SVE.
All calls to these should be shadowed by an if
(system_supports_sve()) in any case, and setting/clearing ZEN_EL0EN
in the CPACR_EL1 ought to be harmless now that the meaning of these
bits architecturally committed.
Ideally we would have a BUG_ON(!system_supports_sve()) in those
functions, but we won't won't to pay the cost in a production kernel.
> static inline void sve_init_vq_map(void) { }
> static inline void sve_update_vq_map(void) { }
> static inline int sve_verify_vq_map(void) { return 0; }
> diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
> index 088940387a4d..79a81c7d85c6 100644
> --- a/arch/arm64/kernel/fpsimd.c
> +++ b/arch/arm64/kernel/fpsimd.c
> @@ -159,7 +159,6 @@ static void sve_free(struct task_struct *task)
> __sve_free(task);
> }
>
> -
Hmmm, Ack. Check for conflicts with the KVM FPSIMD rework [1] (though
trivial).
[...]
Cheers
---Dave
[1]
[PATCH v7 10/16] arm64/sve: Switch sve_pffr() argument from task to thread
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/576601.html
[PATCH v7 11/16] arm64/sve: Move sve_pffr() to fpsimd.h and make inline
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-May/576606.html
