[PATCH v9 1/3] arm64: map FDT as RW for early_init_dt_scan()

Hsin-Yi Wang
2019-08-22T07:16:38Z

Currently in arm64, FDT is mapped to RO before it's passed to
early_init_dt_scan(). However, there might be some codes
(eg. commit "fdt: add support for rng-seed") that need to modify FDT
during init. Map FDT to RO after early fixups are done.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
---
No change since v7.
---
arch/arm64/include/asm/mmu.h | 2 +-
arch/arm64/kernel/kaslr.c | 5 +----
arch/arm64/kernel/setup.c | 9 ++++++++-
arch/arm64/mm/mmu.c | 15 +--------------
4 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index fd6161336653..f217e3292919 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -126,7 +126,7 @@ 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, int *size, pgprot_t prot);
extern void mark_linear_text_alias_ro(void);

#define INIT_MM_CONTEXT(name) \
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 5a59f7567f9c..416f537bf614 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -62,9 +62,6 @@ static __init const u8 *kaslr_get_cmdline(void *fdt)
return default_cmdline;
}

-extern void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size,
- pgprot_t prot);
-
/*
* This routine will be executed with the kernel mapped at its default virtual
* address, and if it returns successfully, the kernel will be remapped, and
@@ -93,7 +90,7 @@ u64 __init kaslr_early_init(u64 dt_phys)
* attempt at mapping the FDT in setup_machine()
*/
early_fixmap_init();
- fdt = __fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL);
+ fdt = fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL);
if (!fdt)
return 0;

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 57ff38600828..56f664561754 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -170,9 +170,13 @@ 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);
+ int size;
+ void *dt_virt = fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL);
const char *name;

+ if (dt_virt)
+ memblock_reserve(dt_phys, size);
+
if (!dt_virt || !early_init_dt_scan(dt_virt)) {
pr_crit("\n"
"Error: invalid device tree blob at physical address %pa (virtual address 0x%p)\n"
@@ -184,6 +188,9 @@ 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;
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index e67bab4d613e..1586d7fbf26a 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -877,7 +877,7 @@ void __set_fixmap(enum fixed_addresses idx,
}
}

-void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size, pgprot_t prot)
+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;
@@ -930,19 +930,6 @@ 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 *dt_virt;
- int size;
-
- dt_virt = __fixmap_remap_fdt(dt_phys, &size, PAGE_KERNEL_RO);
- if (!dt_virt)
- return NULL;
-
- memblock_reserve(dt_phys, size);
- return dt_virt;
-}
-
int __init arch_ioremap_p4d_supported(void)
{
return 0;
--
2.20.1