On Mon, May 13, 2019 at 08:38:19AM +0800, Hsin-Yi Wang wrote:
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@chromium.org
arch/arm64/kernel/setup.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c index 413d566405d1..08b22c1e72a9 100644 --- a/arch/arm64/kernel/setup.c +++ b/arch/arm64/kernel/setup.c @@ -179,9 +179,13 @@ static void __init smp_build_mpidr_hash(void) pr_warn("Large number of MPIDR hash buckets detected\n"); } +extern void *__init __fixmap_remap_fdt(phys_addr_t dt_phys, int *size,
pgprot_t prot);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;
This makes the fdt mapped without the call to meblock_reserve(fdt) which makes the fdt memory available for memblock allocations.
Chances that is will be actually allocated are small, but you know, things happen.
IMHO, instead of calling directly __fixmap_remap_fdt() it would be better to add pgprot parameter to fixmap_remap_fdt(). Then here and in kaslr.c it can be called with PAGE_KERNEL and below with PAGE_KERNEL_RO.
There is no problem to call memblock_reserve() for the same area twice, it's essentially a NOP.
if (!dt_virt || !early_init_dt_scan(dt_virt)) { @@ -320,6 +324,9 @@ 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);
- if (acpi_disabled) unflatten_device_tree();
2.20.1