arm64: Fix memblock current_limit with 64K pages and 48-bit VA

With 48-bit VA space, the 64K page configuration uses 3 levels instead
of 2 and PUD_SIZE != PMD_SIZE. Since with 64K pages we only cover
PMD_SIZE with the initial swapper_pg_dir populated in head.S, the
memblock current_limit needs to be set accordingly in map_mem() to avoid
allocating unmapped memory. The memblock current_limit is progressively
increased as more blocks are mapped.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6894ef3..0bf90d2 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -297,11 +297,15 @@ static void __init map_mem(void)
         * create_mapping requires puds, pmds and ptes to be allocated from
         * memory addressable from the initial direct kernel mapping.
         *
-        * The initial direct kernel mapping, located at swapper_pg_dir,
-        * gives us PUD_SIZE memory starting from PHYS_OFFSET (which must be
-        * aligned to 2MB as per Documentation/arm64/booting.txt).
+        * The initial direct kernel mapping, located at swapper_pg_dir, gives
+        * us PUD_SIZE (4K pages) or PMD_SIZE (64K pages) memory starting from
+        * PHYS_OFFSET (which must be aligned to 2MB as per
+        * Documentation/arm64/booting.txt).
         */
-       limit = PHYS_OFFSET + PUD_SIZE;
+       if (IS_ENABLED(CONFIG_ARM64_64K_PAGES))
+               limit = PHYS_OFFSET + PMD_SIZE;
+       else
+               limit = PHYS_OFFSET + PUD_SIZE;
        memblock_set_current_limit(limit);
 
        /* map all the memory banks */