Commit f56ffb8a authored by Deepak Gupta's avatar Deepak Gupta Committed by Paul Walmsley
Browse files

riscv/mm: manufacture shadow stack ptes 



This patch implements the creation of a shadow stack pte on
riscv. Creating shadow stack PTE on riscv means clearing RWX and then
setting W=1.

Reviewed-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: default avatarZong Li <zong.li@sifive.com>
Signed-off-by: default avatarDeepak Gupta <debug@rivosinc.com>
Tested-by: Andreas Korb <andreas.korb@aisec.fraunhofer.de> # QEMU, custom CVA6
Tested-by: default avatarValentin Haudiquet <valentin.haudiquet@canonical.com>
Link: https://patch.msgid.link/20251112-v5_user_cfi_series-v23-7-b55691eacf4f@rivosinc.com


[pjw@kernel.org: cleaned up patch description]
Signed-off-by: default avatarPaul Walmsley <pjw@kernel.org>
parent 6c7559f2

arch/riscv/include/asm/pgtable.h

+10 −0
Original line number Diff line number Diff line
@@ -456,6 +456,11 @@ 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)

{

	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)
@@ -839,6 +844,11 @@ 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)

{

	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)));