[PATCH v4 1/3] amr64: map FDT as RW for early_init_dt_scan()

[Hsin-Yi Wang]

Currently in arm64, FDT is mapped to RO before it's passed to
early_init_dt_scan(). However, there might be some code that needs
to modify FDT during init. Map FDT to RW until unflatten DT.

Signed-off-by: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx>
---
change log v2->v4:
* v3 abandoned
* add an arg pgprot_t to fixmap_remap_fdt()
---
 arch/arm64/include/asm/mmu.h | 2 +-
 arch/arm64/kernel/setup.c    | 5 ++++-
 arch/arm64/mm/mmu.c          | 4 ++--
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 67ef25d037ea..4499cb00ece7 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -137,7 +137,7 @@ extern void init_mem_pgprot(void);
 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
 			       unsigned long virt, phys_addr_t size,
 			       pgprot_t prot, bool page_mappings_only);
-extern void *fixmap_remap_fdt(phys_addr_t dt_phys);
+extern void *fixmap_remap_fdt(phys_addr_t dt_phys, pgprot_t prot);
 extern void mark_linear_text_alias_ro(void);
 
 #define INIT_MM_CONTEXT(name)	\
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 413d566405d1..064df3de1d14 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -181,7 +181,7 @@ static void __init smp_build_mpidr_hash(void)
 
 static void __init setup_machine_fdt(phys_addr_t dt_phys)
 {
-	void *dt_virt = fixmap_remap_fdt(dt_phys);
+	void *dt_virt = fixmap_remap_fdt(dt_phys, PAGE_KERNEL);
 	const char *name;
 
 	if (!dt_virt || !early_init_dt_scan(dt_virt)) {
@@ -320,6 +320,9 @@ void __init setup_arch(char **cmdline_p)
 	/* Parse the ACPI tables for possible boot-time configuration */
 	acpi_boot_table_init();
 
+	/* remap fdt to RO */
+	fixmap_remap_fdt(__fdt_pointer, PAGE_KERNEL_RO);
+
 	if (acpi_disabled)
 		unflatten_device_tree();
 
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index a170c6369a68..29648e86f7e5 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -940,12 +940,12 @@ void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
 	return dt_virt;
 }
 
-void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
+void *__init fixmap_remap_fdt(phys_addr_t dt_phys, pgprot_t prot)
 {
 	void *dt_virt;
 	int size;
 
-	dt_virt = __fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL_RO);
+	dt_virt = __fixmap_remap_fdt(dt_phys, &size, prot);
 	if (!dt_virt)
 		return NULL;
 
-- 
2.20.1