Commit c56aa9a6 authored by Sam Edwards's avatar Sam Edwards Committed by Will Deacon
Browse files

arm64: mm: Make map_fdt() return mapped pointer 



Currently map_fdt() accepts a physical address and relies on the caller
to keep using the same value after mapping, since the implementation
happens to install an identity mapping. This obscures the fact that the
usable pointer is defined by the mapping, not by the input value. Since
the mapping determines pointer validity, it is more natural to produce
the pointer at mapping time.

Change map_fdt() to return a void * pointing to the mapped FDT. This
clarifies the data flow, removes the implicit identity assumption, and
prepares for making map_fdt() accept a phys_addr_t in a follow-up
change.

Signed-off-by: default avatarSam Edwards <CFSworks@gmail.com>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 030b3ffb

arch/arm64/kernel/pi/map_kernel.c

+7 −6
Original line number Diff line number Diff line
@@ -191,7 +191,7 @@ static void __init remap_idmap_for_lpa2(void) 
	memset(init_pg_dir, 0, (char *)init_pg_end - (char *)init_pg_dir);

}



static void __init map_fdt(u64 fdt)

static void *__init map_fdt(u64 fdt)

{

	static u8 ptes[INIT_IDMAP_FDT_SIZE] __initdata __aligned(PAGE_SIZE);

	u64 efdt = fdt + MAX_FDT_SIZE;
@@ -205,6 +205,8 @@ static void __init map_fdt(u64 fdt) 
		  fdt, PAGE_KERNEL, IDMAP_ROOT_LEVEL,

		  (pte_t *)init_idmap_pg_dir, false, 0);

	dsb(ishst);



	return (void *)fdt;

}



/*
@@ -238,15 +240,14 @@ asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt) 
	int root_level = 4 - CONFIG_PGTABLE_LEVELS;

	int va_bits = VA_BITS;

	int chosen;



	map_fdt((u64)fdt);

	void *fdt_mapped = map_fdt((u64)fdt);



	/* Clear BSS and the initial page tables */

	memset(__bss_start, 0, (char *)init_pg_end - (char *)__bss_start);



	/* Parse the command line for CPU feature overrides */

	chosen = fdt_path_offset(fdt, chosen_str);

	init_feature_override(boot_status, fdt, chosen);

	chosen = fdt_path_offset(fdt_mapped, chosen_str);

	init_feature_override(boot_status, fdt_mapped, chosen);



	if (IS_ENABLED(CONFIG_ARM64_64K_PAGES) && !cpu_has_lva()) {

		va_bits = VA_BITS_MIN;
@@ -266,7 +267,7 @@ asmlinkage void __init early_map_kernel(u64 boot_status, void *fdt) 
	 * fill in the high bits from the seed.

	 */

	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {

		u64 kaslr_seed = kaslr_early_init(fdt, chosen);

		u64 kaslr_seed = kaslr_early_init(fdt_mapped, chosen);



		if (kaslr_seed && kaslr_requires_kpti())

			arm64_use_ng_mappings = ng_mappings_allowed();