[PATCH v4 11/17] riscv/cfi: Support locking/disabling CFI and move OS depedent code

[Bill Roberts]

On 5/26/26 1:16 AM, Jesse Huang wrote:
> +static __always_inline int
> +dl_cfi_lock_cfi (unsigned int feature)
> +{
> +  int res = 0;
> +#ifdef __riscv_landing_pad
> +  if (feature & GNU_PROPERTY_RISCV_FEATURE_1_CFI_LP_UNLABELED)
> +    res |= prctl (PR_LOCK_INDIR_BR_LP_STATUS, 0, 0, 0, 0);
> +#endif /* __riscv_landing_pad  */
> +#ifdef __riscv_shadow_stack
> +  if (feature & GNU_PROPERTY_RISCV_FEATURE_1_CFI_SS)
> +    res |= prctl (PR_LOCK_SHADOW_STACK_STATUS, 0, 0, 0, 0);

arg2 should be PR_SHADOW_STACK_ENABLE to lock this, not 0.
This would mean it's all *unlocked*.

I am going to float a patch to the kernel before this lands, so
hopefully to prevent this broken behavior from becoming
a thing.