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x86/pgtable/32: Allocate 8k page-tables when PTI is enabled

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Allocate a kernel and a user page-table root when PTI is enabled. Also
allocate a full page per root for PAE because otherwise the bit to flip in
CR3 to switch between them would be non-constant, which creates a lot of
hassle.  Keep that for a later optimization.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-18-git-send-email-joro@8bytes.org
This commit is contained in:
Joerg Roedel 2018-07-18 11:40:54 +02:00 committed by Thomas Gleixner
parent 7ffcf1497c
commit e3238faf20
2 changed files with 18 additions and 7 deletions
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20
arch/x86/kernel/head_32.S
View file

@ -512,11 +512,18 @@ ENTRY(initial_code)
ENTRY(setup_once_ref)
.long setup_once
#ifdef CONFIG_PAGE_TABLE_ISOLATION
#define PGD_ALIGN (2 * PAGE_SIZE)
#define PTI_USER_PGD_FILL 1024
#else
#define PGD_ALIGN (PAGE_SIZE)
#define PTI_USER_PGD_FILL 0
#endif
/*
* BSS section
*/
__PAGE_ALIGNED_BSS
.align PAGE_SIZE
.align PGD_ALIGN
#ifdef CONFIG_X86_PAE
.globl initial_pg_pmd
initial_pg_pmd:
@ -526,14 +533,17 @@ initial_pg_pmd:
initial_page_table:
.fill 1024,4,0
#endif
.align PGD_ALIGN
initial_pg_fixmap:
.fill 1024,4,0
.globl swapper_pg_dir
.align PGD_ALIGN
swapper_pg_dir:
.fill 1024,4,0
.fill PTI_USER_PGD_FILL,4,0
.globl empty_zero_page
empty_zero_page:
.fill 4096,1,0
.globl swapper_pg_dir
swapper_pg_dir:
.fill 1024,4,0
EXPORT_SYMBOL(empty_zero_page)
/*
@ -542,7 +552,7 @@ EXPORT_SYMBOL(empty_zero_page)
#ifdef CONFIG_X86_PAE
__PAGE_ALIGNED_DATA
/* Page-aligned for the benefit of paravirt? */
.align PAGE_SIZE
.align PGD_ALIGN
ENTRY(initial_page_table)
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
# if KPMDS == 3

5
arch/x86/mm/pgtable.c
View file

@ -343,7 +343,8 @@ static inline pgd_t *_pgd_alloc(void)
* We allocate one page for pgd.
*/
if (!SHARED_KERNEL_PMD)
return (pgd_t *)__get_free_page(PGALLOC_GFP);
return (pgd_t *)__get_free_pages(PGALLOC_GFP,
PGD_ALLOCATION_ORDER);
/*
* Now PAE kernel is not running as a Xen domain. We can allocate
@ -355,7 +356,7 @@ static inline pgd_t *_pgd_alloc(void)
static inline void _pgd_free(pgd_t *pgd)
{
if (!SHARED_KERNEL_PMD)
free_page((unsigned long)pgd);
free_pages((unsigned long)pgd, PGD_ALLOCATION_ORDER);
else
kmem_cache_free(pgd_cache, pgd);
}