@@ -8,6 +8,7 @@
#ifndef __ASM_KERNEL_PGTABLE_H
#define __ASM_KERNEL_PGTABLE_H
+#include <asm/boot.h>
#include <asm/pgtable-hwdef.h>
#include <asm/sparsemem.h>
@@ -88,10 +89,11 @@
/* the initial ID map may need two extra pages if it needs to be extended */
#if VA_BITS < 48
-#define INIT_IDMAP_DIR_SIZE (INIT_DIR_SIZE + (2 * PAGE_SIZE))
+#define INIT_IDMAP_DIR_SIZE ((INIT_IDMAP_DIR_PAGES + 2) * PAGE_SIZE)
#else
-#define INIT_IDMAP_DIR_SIZE INIT_DIR_SIZE
+#define INIT_IDMAP_DIR_SIZE (INIT_IDMAP_DIR_PAGES * PAGE_SIZE)
#endif
+#define INIT_IDMAP_DIR_PAGES EARLY_PAGES(KIMAGE_VADDR, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE)
/* Initial memory map size */
#if ARM64_KERNEL_USES_PMD_MAPS
@@ -82,6 +82,7 @@
* primary lowlevel boot path:
*
* Register Scope Purpose
+ * x19 create_idmap() .. __ start_kernel() ID map VA of the DT blob
* x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0
* x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset
* x28 clear_page_tables() callee preserved temp register
@@ -346,7 +347,7 @@ SYM_FUNC_START_LOCAL(create_idmap)
#endif
adrp x0, init_idmap_pg_dir
adrp x3, _text
- adrp x6, _end
+ adrp x6, _end + MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
mov x7, SWAPPER_RX_MMUFLAGS
map_memory x0, x1, x3, x6, x7, x3, IDMAP_PGD_ORDER, x10, x11, x12, x13, x14, EXTRA_SHIFT
@@ -360,6 +361,17 @@ SYM_FUNC_START_LOCAL(create_idmap)
mov x6, #SWAPPER_BLOCK_SHIFT
bl remap_region
+ /* Remap the FDT read-only after the kernel image */
+ adrp x1, _text
+ adrp x19, _end + SWAPPER_BLOCK_SIZE
+ bic x2, x19, #SWAPPER_BLOCK_SIZE - 1
+ bfi x19, x21, #0, #SWAPPER_BLOCK_SHIFT // remapped FDT address
+ add x3, x2, #MAX_FDT_SIZE + SWAPPER_BLOCK_SIZE
+ bic x4, x21, #SWAPPER_BLOCK_SIZE - 1
+ mov x5, SWAPPER_RX_MMUFLAGS
+ mov x6, #SWAPPER_BLOCK_SHIFT
+ bl remap_region
+
/*
* Since the page tables have been populated with non-cacheable
* accesses (MMU disabled), invalidate those tables again to
We need to access the DT very early to get at the command line and the KASLR seed, which currently means we rely on some hacks to call into the kernel before really calling into the kernel, which is undesirable. So instead, let's create a mapping for the FDT in the initial ID map, which is feasible now that it has been extended to cover more than a single page or block, and can be updated in place to remap other output addresses. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/include/asm/kernel-pgtable.h | 6 ++++-- arch/arm64/kernel/head.S | 14 +++++++++++++- 2 files changed, 17 insertions(+), 3 deletions(-)