Re: [PATCH v2] of/fdt: add dt_phys arg to early_init_dt_scan and early_init_dt_verify

Will Deacon
2024-10-28T15:41:02Z

On Wed, Oct 23, 2024 at 06:14:26PM +0100, Usama Arif wrote:
> __pa() is only intended to be used for linear map addresses and using
> it for initial_boot_params which is in fixmap for arm64 will give an
> incorrect value. Hence save the physical address when it is known at
> boot time when calling early_init_dt_scan for arm64 and use it at kexec
> time instead of converting the virtual address using __pa().
>
> Reported-by: Breno Leitao <leitao@debian.org>
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Usama Arif <usamaarif642@gmail.com>
> Fixes: ac10be5cdbfa ("arm64: Use common of_kexec_alloc_and_setup_fdt()")
> ---
> v1 -> 2:
> - pass dt_phys in early_init_dt_scan instead of creating
> anorther arch->dt function (Rob Herring)
> ---
> arch/arc/kernel/devtree.c | 2 +-
> arch/arm/kernel/devtree.c | 2 +-
> arch/arm64/kernel/setup.c | 6 +++++-
> arch/csky/kernel/setup.c | 4 ++--
> arch/loongarch/kernel/setup.c | 2 +-
> arch/microblaze/kernel/prom.c | 2 +-
> arch/mips/kernel/prom.c | 2 +-
> arch/mips/kernel/relocate.c | 2 +-
> arch/nios2/kernel/prom.c | 4 ++--
> arch/openrisc/kernel/prom.c | 2 +-
> arch/powerpc/kernel/dt_cpu_ftrs.c | 2 +-
> arch/powerpc/kernel/prom.c | 2 +-
> arch/powerpc/platforms/pseries/plpks.c | 2 +-
> arch/riscv/kernel/setup.c | 2 +-
> arch/sh/kernel/setup.c | 2 +-
> arch/um/kernel/dtb.c | 2 +-
> arch/x86/kernel/devicetree.c | 2 +-
> arch/xtensa/kernel/setup.c | 2 +-
> drivers/of/fdt.c | 14 ++++++++------
> drivers/of/kexec.c | 2 +-
> include/linux/of_fdt.h | 5 +++--
> 21 files changed, 36 insertions(+), 29 deletions(-)
>
> diff --git a/arch/arc/kernel/devtree.c b/arch/arc/kernel/devtree.c
> index 4c9e61457b2f..cc6ac7d128aa 100644
> --- a/arch/arc/kernel/devtree.c
> +++ b/arch/arc/kernel/devtree.c
> @@ -62,7 +62,7 @@ const struct machine_desc * __init setup_machine_fdt(void *dt)
> const struct machine_desc *mdesc;
> unsigned long dt_root;
>
> - if (!early_init_dt_scan(dt))
> + if (!early_init_dt_scan(dt, __pa(dt)))
> return NULL;
>
> mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
> diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
> index fdb74e64206a..3b78966e750a 100644
> --- a/arch/arm/kernel/devtree.c
> +++ b/arch/arm/kernel/devtree.c
> @@ -200,7 +200,7 @@ const struct machine_desc * __init setup_machine_fdt(void *dt_virt)
>
> mdesc_best = &__mach_desc_GENERIC_DT;
>
> - if (!dt_virt || !early_init_dt_verify(dt_virt))
> + if (!dt_virt || !early_init_dt_verify(dt_virt, __pa(dt_virt)))
> return NULL;
>
> mdesc = of_flat_dt_match_machine(mdesc_best, arch_get_next_mach);
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index b22d28ec8028..177262739c49 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -175,7 +175,11 @@ static void __init setup_machine_fdt(phys_addr_t dt_phys)
> if (dt_virt)
> memblock_reserve(dt_phys, size);
>
> - if (!dt_virt || !early_init_dt_scan(dt_virt)) {
> + /*
> + * dt_virt is a fixmap address, hence __pa(dt_virt) can't be used.
> + * Pass dt_phys directly.
> + */
> + if (!dt_virt || !early_init_dt_scan(dt_virt, dt_phys)) {

nit: It looks like early_init_dt_verify() will now return false if
!dt_virt, so we can drop the additional check here.

Will