x86/mm: Fold p4d page table layer at runtime
Change page table helpers to fold p4d at runtime.
The logic is the same as in <asm-generic/pgtable-nop4d.h>.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180214182542.69302-8-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 63c2552..c8baa7f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -65,7 +65,7 @@ extern pmdval_t early_pmd_flags;
#ifndef __PAGETABLE_P4D_FOLDED
#define set_pgd(pgdp, pgd) native_set_pgd(pgdp, pgd)
-#define pgd_clear(pgd) native_pgd_clear(pgd)
+#define pgd_clear(pgd) (pgtable_l5_enabled ? native_pgd_clear(pgd) : 0)
#endif
#ifndef set_p4d
@@ -859,6 +859,8 @@ static inline unsigned long p4d_index(unsigned long address)
#if CONFIG_PGTABLE_LEVELS > 4
static inline int pgd_present(pgd_t pgd)
{
+ if (!pgtable_l5_enabled)
+ return 1;
return pgd_flags(pgd) & _PAGE_PRESENT;
}
@@ -876,6 +878,8 @@ static inline unsigned long pgd_page_vaddr(pgd_t pgd)
/* to find an entry in a page-table-directory. */
static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
{
+ if (!pgtable_l5_enabled)
+ return (p4d_t *)pgd;
return (p4d_t *)pgd_page_vaddr(*pgd) + p4d_index(address);
}
@@ -883,6 +887,9 @@ static inline int pgd_bad(pgd_t pgd)
{
unsigned long ignore_flags = _PAGE_USER;
+ if (!pgtable_l5_enabled)
+ return 0;
+
if (IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION))
ignore_flags |= _PAGE_NX;
@@ -891,6 +898,8 @@ static inline int pgd_bad(pgd_t pgd)
static inline int pgd_none(pgd_t pgd)
{
+ if (!pgtable_l5_enabled)
+ return 0;
/*
* There is no need to do a workaround for the KNL stray
* A/D bit erratum here. PGDs only point to page tables