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@xxxxxxxxxxxx>
---
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 */
+ 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)));
--
2.43.2
