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Commit 400d3c8b authored by Hugh Dickins's avatar Hugh Dickins Committed by Greg Kroah-Hartman
Browse files

kaiser: allocate pgd with order 0 when pti=off 



The 4.9.77 version of "x86/pti/efi: broken conversion from efi to kernel
page table" looked nicer than the 4.4.112 version, but was suboptimal on
machines booted with "pti=off" (or on AMD machines): it allocated pgd
with an order 1 page whatever the setting of kaiser_enabled.

Fix that by moving the definition of PGD_ALLOCATION_ORDER from
asm/pgalloc.h to asm/pgtable.h, which already defines kaiser_enabled.

Fixes: 1b92c48a ("x86/pti/efi: broken conversion from efi to kernel page table")
Reviewed-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Cc: Steven Sistare <steven.sistare@oracle.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ae1fc8de

arch/x86/include/asm/pgalloc.h

+0 −11
Original line number Diff line number Diff line
@@ -27,17 +27,6 @@ static inline void paravirt_release_pud(unsigned long pfn) {} 
 */

extern gfp_t __userpte_alloc_gfp;



#ifdef CONFIG_PAGE_TABLE_ISOLATION

/*

 * Instead of one PGD, we acquire two PGDs.  Being order-1, it is

 * both 8k in size and 8k-aligned.  That lets us just flip bit 12

 * in a pointer to swap between the two 4k halves.

 */

#define PGD_ALLOCATION_ORDER 1

#else

#define PGD_ALLOCATION_ORDER 0

#endif



/*

 * Allocate and free page tables.

 */

arch/x86/include/asm/pgtable.h

+6 −0
Original line number Diff line number Diff line
@@ -20,9 +20,15 @@ 


#ifdef CONFIG_PAGE_TABLE_ISOLATION

extern int kaiser_enabled;

/*

 * Instead of one PGD, we acquire two PGDs.  Being order-1, it is

 * both 8k in size and 8k-aligned.  That lets us just flip bit 12

 * in a pointer to swap between the two 4k halves.

 */

#else

#define kaiser_enabled 0

#endif

#define PGD_ALLOCATION_ORDER kaiser_enabled



void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);

void ptdump_walk_pgd_level_checkwx(void);