[v1, 6/6] riscv: vector: adjust minimum Vector requirement to ZVE32X

[Joel Granados]

On Tue, Mar 12, 2024 at 08:36:27PM +0800, Andy Chiu wrote:
> Make has_vector take one argument. This argument represents the minimum
> Vector subextension that the following Vector actions assume.
> 
> Also, change riscv_v_first_use_handler(), and boot code that calls
> riscv_v_setup_vsize() to accept the minimum Vector sub-extension,
> ZVE32X.
> 
> Most kernel/user interfaces requires minimum of ZVE32X. Thus, programs
> compiled and run with ZVE32X should be supported by the kernel on most
> aspects. This includes context-switch, signal, ptrace, prctl, and
> hwprobe.
> 
> One exception is that ELF_HWCAP returns 'V' only if full V is supported
> on the platform. This means that the system without a full V must not
> rely on ELF_HWCAP to tell whether it is allowable to execute Vector
> without first invoking a prctl() check.
> 
> Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
> ---
>  arch/riscv/include/asm/switch_to.h     |  2 +-
>  arch/riscv/include/asm/vector.h        | 21 ++++++++++++++-------
>  arch/riscv/include/asm/xor.h           |  2 +-
>  arch/riscv/kernel/cpufeature.c         |  5 ++++-
>  arch/riscv/kernel/kernel_mode_vector.c |  4 ++--
>  arch/riscv/kernel/process.c            |  4 ++--
>  arch/riscv/kernel/signal.c             |  6 +++---
>  arch/riscv/kernel/smpboot.c            |  2 +-
>  arch/riscv/kernel/sys_hwprobe.c        |  5 +++--
>  arch/riscv/kernel/vector.c             | 15 +++++++++------
>  arch/riscv/lib/uaccess.S               |  2 +-
>  11 files changed, 41 insertions(+), 27 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/switch_to.h b/arch/riscv/include/asm/switch_to.h
> index 7efdb0584d47..df1adf196c4f 100644
> --- a/arch/riscv/include/asm/switch_to.h
> +++ b/arch/riscv/include/asm/switch_to.h
<--- snip --->
>  
>  long riscv_v_vstate_ctrl_get_current(void)
>  {
> -	if (!has_vector())
> +	if (!has_vector(ZVE32X))
>  		return -EINVAL;
>  
>  	return current->thread.vstate_ctrl & PR_RISCV_V_VSTATE_CTRL_MASK;
> @@ -246,7 +249,7 @@ long riscv_v_vstate_ctrl_set_current(unsigned long arg)
>  	bool inherit;
>  	int cur, next;
>  
> -	if (!has_vector())
> +	if (!has_vector(ZVE32X))
>  		return -EINVAL;
>  
>  	if (arg & ~PR_RISCV_V_VSTATE_CTRL_MASK)
> @@ -296,7 +299,7 @@ static struct ctl_table riscv_v_default_vstate_table[] = {
>  
>  static int __init riscv_v_sysctl_init(void)
>  {
> -	if (has_vector())
> +	if (has_vector(ZVE32X))
>  		if (!register_sysctl("abi", riscv_v_default_vstate_table))
>  			return -EINVAL;
>  	return 0;
Not really sure why I got this, it probably has to do with this line :)
I don't see any changes that can affect sysctl here.

Acked-by: Joel Granados <j.granados at samsung.com>

> diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S
> index bc22c078aba8..bbe143bb32a0 100644
> --- a/arch/riscv/lib/uaccess.S
> +++ b/arch/riscv/lib/uaccess.S
> @@ -14,7 +14,7 @@
>  
>  SYM_FUNC_START(__asm_copy_to_user)
>  #ifdef CONFIG_RISCV_ISA_V
> -	ALTERNATIVE("j fallback_scalar_usercopy", "nop", 0, RISCV_ISA_EXT_v, CONFIG_RISCV_ISA_V)
> +	ALTERNATIVE("j fallback_scalar_usercopy", "nop", 0, RISCV_ISA_EXT_ZVE32X, CONFIG_RISCV_ISA_V)
>  	REG_L	t0, riscv_v_usercopy_threshold
>  	bltu	a2, t0, fallback_scalar_usercopy
>  	tail enter_vector_usercopy
> -- 
> 2.17.1
> 

-- 

Joel Granados
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