4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Stefan O'Rear sorear2@gmail.com
commit e3613bb8afc2a9474c9214d65c8326c5ac02135e upstream.
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 sorear2@gmail.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Palmer Dabbelt palmer@sifive.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/riscv/include/asm/pgtable-bits.h | 6 ++++++ arch/riscv/include/asm/pgtable.h | 8 ++++---- 2 files changed, 10 insertions(+), 4 deletions(-)
--- 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() */ --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -44,7 +44,7 @@ /* Page protection bits */ #define _PAGE_BASE (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_USER)
-#define PAGE_NONE __pgprot(0) +#define PAGE_NONE __pgprot(_PAGE_PROT_NONE) #define PAGE_READ __pgprot(_PAGE_BASE | _PAGE_READ) #define PAGE_WRITE __pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_WRITE) #define PAGE_EXEC __pgprot(_PAGE_BASE | _PAGE_EXEC) @@ -98,7 +98,7 @@ extern unsigned long empty_zero_page[PAG
static inline int pmd_present(pmd_t pmd) { - return (pmd_val(pmd) & _PAGE_PRESENT); + return (pmd_val(pmd) & (_PAGE_PRESENT | _PAGE_PROT_NONE)); }
static inline int pmd_none(pmd_t pmd) @@ -178,7 +178,7 @@ static inline pte_t *pte_offset_kernel(p
static inline int pte_present(pte_t pte) { - return (pte_val(pte) & _PAGE_PRESENT); + return (pte_val(pte) & (_PAGE_PRESENT | _PAGE_PROT_NONE)); }
static inline int pte_none(pte_t pte) @@ -380,7 +380,7 @@ static inline int ptep_clear_flush_young * * Format of swap PTE: * bit 0: _PAGE_PRESENT (zero) - * bit 1: reserved for future use (zero) + * bit 1: _PAGE_PROT_NONE (zero) * bits 2 to 6: swap type * bits 7 to XLEN-1: swap offset */