Re: [PATCH v4 02/10] riscv: Add ISA extension parsing for pointer masking

[Charlie Jenkins <charlie@rivosinc.com>]

On Wed, Aug 28, 2024 at 06:01:24PM -0700, Samuel Holland wrote:
> The RISC-V Pointer Masking specification defines three extensions:
> Smmpm, Smnpm, and Ssnpm. Add support for parsing each of them. The
> specific extension which provides pointer masking support to userspace
> (Supm) depends on the kernel's privilege mode, so provide a macro to
> abstract this selection.
> 
> Smmpm implies the existence of the mseccfg CSR. As it is the only user
> of this CSR so far, there is no need for an Xlinuxmseccfg extension.
> 
> Signed-off-by: Samuel Holland <samuel.holland@sifive.com>

Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>

> ---
> 
> (no changes since v3)
> 
> Changes in v3:
>  - Rebase on riscv/for-next (ISA extension list conflicts)
>  - Remove RISCV_ISA_EXT_SxPM, which was not used anywhere
> 
> Changes in v2:
>  - Provide macros for the extension affecting the kernel and userspace
> 
>  arch/riscv/include/asm/hwcap.h | 5 +++++
>  arch/riscv/kernel/cpufeature.c | 3 +++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index 5a0bd27fd11a..aff21c6fc9b6 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -92,6 +92,9 @@
>  #define RISCV_ISA_EXT_ZCF		83
>  #define RISCV_ISA_EXT_ZCMOP		84
>  #define RISCV_ISA_EXT_ZAWRS		85
> +#define RISCV_ISA_EXT_SMMPM		86
> +#define RISCV_ISA_EXT_SMNPM		87
> +#define RISCV_ISA_EXT_SSNPM		88
>  
>  #define RISCV_ISA_EXT_XLINUXENVCFG	127
>  
> @@ -100,8 +103,10 @@
>  
>  #ifdef CONFIG_RISCV_M_MODE
>  #define RISCV_ISA_EXT_SxAIA		RISCV_ISA_EXT_SMAIA
> +#define RISCV_ISA_EXT_SUPM		RISCV_ISA_EXT_SMNPM
>  #else
>  #define RISCV_ISA_EXT_SxAIA		RISCV_ISA_EXT_SSAIA
> +#define RISCV_ISA_EXT_SUPM		RISCV_ISA_EXT_SSNPM
>  #endif
>  
>  #endif /* _ASM_RISCV_HWCAP_H */
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index b3b9735cb19a..ba3dc16e14dc 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -377,9 +377,12 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
>  	__RISCV_ISA_EXT_BUNDLE(zvksg, riscv_zvksg_bundled_exts),
>  	__RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
>  	__RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> +	__RISCV_ISA_EXT_DATA(smmpm, RISCV_ISA_EXT_SMMPM),
> +	__RISCV_ISA_EXT_SUPERSET(smnpm, RISCV_ISA_EXT_SMNPM, riscv_xlinuxenvcfg_exts),
>  	__RISCV_ISA_EXT_DATA(smstateen, RISCV_ISA_EXT_SMSTATEEN),
>  	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
>  	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
> +	__RISCV_ISA_EXT_SUPERSET(ssnpm, RISCV_ISA_EXT_SSNPM, riscv_xlinuxenvcfg_exts),
>  	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
>  	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
>  	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
> -- 
> 2.45.1
> 
> 
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