[PATCH v3 11/29] riscv mm: manufacture shadow stack pte
Alexandre Ghiti
alex at ghiti.fr
Sun May 12 09:26:51 PDT 2024
On 04/04/2024 01:34, Deepak Gupta wrote:
> This patch implements creating shadow stack pte (on riscv). Creating
> shadow stack PTE on riscv means that clearing RWX and then setting W=1.
>
> Signed-off-by: Deepak Gupta <debug at rivosinc.com>
> ---
> arch/riscv/include/asm/pgtable.h | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 4d5983bc6766..6362407f1e83 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -408,6 +408,12 @@ static inline pte_t pte_mkwrite_novma(pte_t pte)
> return __pte(pte_val(pte) | _PAGE_WRITE);
> }
>
> +static inline pte_t pte_mkwrite_shstk(pte_t pte)
> +{
> + /* shadow stack on risc-v is XWR = 010. Clear everything and only set _PAGE_WRITE */
Nit: Not sure the comment is necessary
> + return __pte((pte_val(pte) & ~(_PAGE_LEAF)) | _PAGE_WRITE);
> +}
> +
> /* static inline pte_t pte_mkexec(pte_t pte) */
>
> static inline pte_t pte_mkdirty(pte_t pte)
> @@ -693,6 +699,12 @@ static inline pmd_t pmd_mkwrite_novma(pmd_t pmd)
> return pte_pmd(pte_mkwrite_novma(pmd_pte(pmd)));
> }
>
> +static inline pmd_t pmd_mkwrite_shstk(pmd_t pte)
> +{
> + /* shadow stack on risc-v is XWR = 010. Clear everything and only set _PAGE_WRITE */
> + return __pmd((pmd_val(pte) & ~(_PAGE_LEAF)) | _PAGE_WRITE);
> +}
> +
> static inline pmd_t pmd_wrprotect(pmd_t pmd)
> {
> return pte_pmd(pte_wrprotect(pmd_pte(pmd)));
Otherwise:
Reviewed-by: Alexandre Ghiti <alexghiti at rivosinc.com>
Thanks,
Alex
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