Unverified Commit e3613bb8 authored by Stefan O'Rear's avatar Stefan O'Rear Committed by Palmer Dabbelt
Browse files

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: default avatarStefan O'Rear <sorear2@gmail.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent d1393711

arch/riscv/include/asm/pgtable-bits.h

+6 −0
Original line number Diff line number Diff line
@@ -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() */

arch/riscv/include/asm/pgtable.h

+4 −4
Original line number Diff line number Diff line
@@ -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[PAGE_SIZE / sizeof(unsigned long)]; 


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(pmd_t *pmd, unsigned long addr) 


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(struct vm_area_struct *vma, 
 *

 * 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

 */

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