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>

1 files changed, 8 insertions, 4 deletions

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 6894ef3e6234..0bf90d26e745 100644
--- 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 */