Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "A pair of small arm64 fixes for -rc6.

  One is a fix for the recently merged uffd-wp support (which was
  triggering a spurious warning) and the other is a fix to the clearing
  of the initial idmap pgd in some configurations

  Summary:

   - Fix spurious page-table warning when clearing PTE_UFFD_WP in a live
     pte

   - Fix clearing of the idmap pgd when using large addressing modes"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Clear the initial ID map correctly before remapping
  arm64: mm: Permit PTE SW bits to change in live mappings

Author: torvalds

arch/arm64/include/asm/pgtable-hwdef.h

@@ -170,6 +170,7 @@
 #define PTE_CONT		(_AT(pteval_t, 1) << 52)	/* Contiguous range */
 #define PTE_PXN			(_AT(pteval_t, 1) << 53)	/* Privileged XN */
 #define PTE_UXN			(_AT(pteval_t, 1) << 54)	/* User XN */
+#define PTE_SWBITS_MASK		_AT(pteval_t, (BIT(63) | GENMASK(58, 55)))
 
 #define PTE_ADDR_LOW		(((_AT(pteval_t, 1) << (50 - PAGE_SHIFT)) - 1) << PAGE_SHIFT)
 #ifdef CONFIG_ARM64_PA_BITS_52

arch/arm64/kernel/pi/map_kernel.c

@@ -173,7 +173,7 @@ static void __init remap_idmap_for_lpa2(void)
 	 * Don't bother with the FDT, we no longer need it after this.
 	 */
 	memset(init_idmap_pg_dir, 0,
-	       (u64)init_idmap_pg_dir - (u64)init_idmap_pg_end);
+	       (u64)init_idmap_pg_end - (u64)init_idmap_pg_dir);
 
 	create_init_idmap(init_idmap_pg_dir, mask);
 	dsb(ishst);

arch/arm64/mm/mmu.c

@@ -124,7 +124,8 @@ bool pgattr_change_is_safe(u64 old, u64 new)
 	 * The following mapping attributes may be updated in live
 	 * kernel mappings without the need for break-before-make.
 	 */
-	pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG;
+	pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG |
+			PTE_SWBITS_MASK;
 
 	/* creating or taking down mappings is always safe */
 	if (!pte_valid(__pte(old)) || !pte_valid(__pte(new)))