Re: [PATCH 09/18] arm64: fpsimd: Move sve_get_vl() and sme_get_vl() inline

[Vladimir Murzin <vladimir.murzin@arm.com>]

On 5/21/26 14:25, Mark Rutland wrote:
> The sve_get_vl() and sme_get_vl() functions are wrappers for the RDVL
> and RDSVL instructions respectively. There's no need for those to be
> out-of-line.
> 
> Replace the out-of-line assembly functions with equivalent inline
> functions.
> 
> The _sve_rdvl assembly macro is unused, and so it is removed. The
> _sme_rdsvl assembly macro is still used elsewhere, and so is kept for
> now.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Fuad Tabba <tabba@google.com>
> Cc: James Morse <james.morse@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Mark Brown <broonie@kernel.org>
> Cc: Oliver Upton <oupton@kernel.org>
> Cc: Will Deacon <will@kernel.org>
> ---
>  arch/arm64/include/asm/fpsimd.h       | 31 +++++++++++++++++++++++++--
>  arch/arm64/include/asm/fpsimdmacros.h |  6 ------
>  arch/arm64/kernel/entry-fpsimd.S      | 10 ---------
>  3 files changed, 29 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
> index 8efa3c0402a7a..36cf528e64971 100644
> --- a/arch/arm64/include/asm/fpsimd.h
> +++ b/arch/arm64/include/asm/fpsimd.h
> @@ -22,6 +22,9 @@
>  #include <linux/stddef.h>
>  #include <linux/types.h>
>  
> +#define __SVE_PREAMBLE		".arch_extension sve\n"
> +#define __SME_PREAMBLE		".arch_extension sme\n"
> +
>  /* Masks for extracting the FPSR and FPCR from the FPSCR */
>  #define VFP_FPSCR_STAT_MASK	0xf800009f
>  #define VFP_FPSCR_CTRL_MASK	0x07f79f00
> @@ -141,11 +144,23 @@ static inline void *thread_zt_state(struct thread_struct *thread)
>  	return thread->sme_state + ZA_SIG_REGS_SIZE(sme_vq);
>  }
>  
> +static inline unsigned int sve_get_vl(void)
> +{
> +	unsigned int vl;
> +
> +	asm volatile(
> +	__SVE_PREAMBLE
> +	"	rdvl %x[vl], #1\n"
> +	: [vl] "=r" (vl)
> +	);
> +
> +	return vl;
> +}
> +
>  extern void sve_save_state(void *state, u32 *pfpsr, int save_ffr);
>  extern void sve_load_state(void const *state, u32 const *pfpsr,
>  			   int restore_ffr);
>  extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1);
> -extern unsigned int sve_get_vl(void);
>  extern void sme_save_state(void *state, int zt);
>  extern void sme_load_state(void const *state, int zt);
>  
> @@ -400,8 +415,20 @@ static inline int sme_max_virtualisable_vl(void)
>  	return vec_max_virtualisable_vl(ARM64_VEC_SME);
>  }
>  
> +static inline unsigned int sme_get_vl(void)
> +{
> +	unsigned int vl;
> +
> +	asm volatile(
> +	__SME_PREAMBLE
> +	"	rdsvl %x[vl], #1\n"
> +	: [vl] "=r" (vl)
> +	);
> +
> +	return vl;
> +}
> +
>  extern void sme_alloc(struct task_struct *task, bool flush);
> -extern unsigned int sme_get_vl(void);
>  extern int sme_set_current_vl(unsigned long arg);
>  extern int sme_get_current_vl(void);
>  extern void sme_suspend_exit(void);
> diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h
> index d0bdbbf2d44ad..d75c9d4c9989b 100644
> --- a/arch/arm64/include/asm/fpsimdmacros.h
> +++ b/arch/arm64/include/asm/fpsimdmacros.h
> @@ -125,12 +125,6 @@
>  	ldr p\np, [x\nxbase, #\offset, MUL VL]
>  .endm
>  
> -/* RDVL X\nx, #\imm */
> -.macro _sve_rdvl nx, imm
> -	.arch_extension sve
> -	rdvl x\nx, #\imm
> -.endm
> -
>  /* RDFFR (unpredicated): RDFFR P\np.B */
>  .macro _sve_rdffr np
>  	.arch_extension sve
> diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S
> index 88c555745b584..7f2d31dff8c17 100644
> --- a/arch/arm64/kernel/entry-fpsimd.S
> +++ b/arch/arm64/kernel/entry-fpsimd.S
> @@ -57,11 +57,6 @@ SYM_FUNC_START(sve_load_state)
>  	ret
>  SYM_FUNC_END(sve_load_state)
>  
> -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
>   *
> @@ -84,11 +79,6 @@ SYM_FUNC_END(sve_flush_live)
>  
>  #ifdef CONFIG_ARM64_SME
>  
> -SYM_FUNC_START(sme_get_vl)
> -	_sme_rdsvl	0, 1
> -	ret
> -SYM_FUNC_END(sme_get_vl)
> -
>  /*
>   * Save the ZA and ZT state
>   *
> -- 2.30.2
> 

FWIW,

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>