[RFC PATCH v2 08/18] arm64: setup: defer R/O remapping of FDT

[Ard Biesheuvel]

We will be moving the call to kaslr_init() into setup_arch() in an
upcoming patch, and this needs the FDT to be writable so the KASLR seed
can be wiped from it.

So break out the R/O remapping of the FDT from setup_machine_fdt() and
call it explicitly from setup_arch().

Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm64/kernel/setup.c |  6 +++---
 arch/arm64/mm/mmu.c       | 12 +++++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 3505789cf4bd..ebf69312eabf 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -203,9 +203,6 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
 			cpu_relax();
 	}
 
-	/* Early fixups are done, map the FDT as read-only now */
-	fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL_RO);
-
 	name = of_flat_dt_get_machine_name();
 	if (!name)
 		return;
@@ -316,6 +313,9 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
 
 	setup_machine_fdt(__fdt_pointer);
 
+	/* Early fixups are done, map the FDT as read-only now */
+	fixmap_remap_fdt(__fdt_pointer, NULL, PAGE_KERNEL_RO);
+
 	/*
 	 * Initialise the static keys early as they may be enabled by the
 	 * cpufeature code and early parameters.
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e74a6453cb14..20dd95a750bc 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1324,7 +1324,7 @@ void __set_fixmap(enum fixed_addresses idx,
 void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
 {
 	const u64 dt_virt_base = __fix_to_virt(FIX_FDT);
-	int offset;
+	int offset, dt_size;
 	void *dt_virt;
 
 	/*
@@ -1363,13 +1363,15 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
 	if (fdt_magic(dt_virt) != FDT_MAGIC)
 		return NULL;
 
-	*size = fdt_totalsize(dt_virt);
-	if (*size > MAX_FDT_SIZE)
+	dt_size = fdt_totalsize(dt_virt);
+	if (size)
+		*size = dt_size;
+	if (dt_size > MAX_FDT_SIZE)
 		return NULL;
 
-	if (offset + *size > SWAPPER_BLOCK_SIZE)
+	if (offset + dt_size > SWAPPER_BLOCK_SIZE)
 		create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base,
-			       round_up(offset + *size, SWAPPER_BLOCK_SIZE), prot);
+			       round_up(offset + dt_size, SWAPPER_BLOCK_SIZE), prot);
 
 	return dt_virt;
 }
-- 
2.30.2