Messages in this thread | | | Date | Mon, 13 May 2019 11:58:53 +0300 | From | Mike Rapoport <> | Subject | Re: [PATCH v2 2/2] amr64: map FDT as RW for early_init_dt_scan() |
| |
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 >
-- Sincerely yours, Mike.
| |