From e3613bb8afc2a9474c9214d65c8326c5ac02135e Mon Sep 17 00:00:00 2001 From: Stefan O'Rear Date: Sun, 16 Dec 2018 13:03:36 -0500 Subject: riscv: Add pte bit to distinguish swap from invalid Previously, invalid PTEs and swap PTEs had the same binary representation, causing errors when attempting to unmap PROT_NONE mappings, including implicit unmap on exit. Typical error: swap_info_get: Bad swap file entry 40000000007a9879 BUG: Bad page map in process a.out pte:3d4c3cc0 pmd:3e521401 Cc: stable@vger.kernel.org Signed-off-by: Stefan O'Rear Reviewed-by: Christoph Hellwig Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/pgtable-bits.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/riscv/include/asm/pgtable-bits.h') diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h index 2fa2942be221..470755cb7558 100644 --- a/arch/riscv/include/asm/pgtable-bits.h +++ b/arch/riscv/include/asm/pgtable-bits.h @@ -35,6 +35,12 @@ #define _PAGE_SPECIAL _PAGE_SOFT #define _PAGE_TABLE _PAGE_PRESENT +/* + * _PAGE_PROT_NONE is set on not-present pages (and ignored by the hardware) to + * distinguish them from swapped out pages + */ +#define _PAGE_PROT_NONE _PAGE_READ + #define _PAGE_PFN_SHIFT 10 /* Set of bits to preserve across pte_modify() */ -- cgit v1.2.3