[PATCH 2/3] riscv: cpufeature: Add ISA extension parsing for Supm

[Conor Dooley]

On Fri, Jan 16, 2026 at 10:10:32AM +0800, Guodong Xu wrote:
> Supm has been ratified in the RISC-V Pointer Masking specification
> (Version 1.0, 10/2024) and is mandated in RVA23 Profiles (Version 1.0,
> 2024-10-17) for RVA23U64. Supm indicates userspace pointer masking
> support.
> 
> Remove the previous macro aliasing of Supm to Ssnpm/Smnpm in hwcap.h,
> treating Supm as a distinct RISC-V ISA extension ID.
> 
> Add ISA parsing logic for Supm, and implement a validator to ensure
> that Supm is only reported as available if Kconfig allows it and the
> underlying Ssnpm (for supervisor mode) or Smnpm (for machine mode)
> extension is present. Supm relies on Ssnpm or Smnpm to provide the
> underlying hardware implementation.
> 
> With this change, "supm" will be reported (when available) in
> /proc/cpuinfo as part of the "isa" and "hart isa" string.
> 
> Link: https://lore.kernel.org/lkml/20260101-legume-engraved-0fae8282cfbe@spud/#r [1]
> Link: https://lore.kernel.org/all/4ebbe14b-2579-4ba6-808d-d50c24641d04@sifive.com/#r [2]
> Signed-off-by: Guodong Xu <guodong at riscstar.com>

Reviewed-by: Conor Dooley <conor.dooley at microchip.com>

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