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

Mike Rapoport
2019-05-25T09:31:19Z

On Thu, May 23, 2019 at 05:04:18PM -0700, Stephen Boyd wrote:
> Quoting Hsin-Yi Wang (2019-05-19 09:04:44)
> > 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;
> >
>
> Sorry, I'm still confused why we want to call memblock_reserve() again.
> Why not avoid it?

> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
> index 67ef25d037ea..d0d9de9da5c1 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, int *size, pgprot_t prot);

I'd drop '__' prefix from __fixmap_remap_fdt is it's the only function to
remain.
Otherwise makes perfect sense.

> 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 b09b6f75f759..0701c2cf1534 100644
> --- a/arch/arm64/kernel/kaslr.c
> +++ b/arch/arm64/kernel/kaslr.c
> @@ -65,9 +65,6 @@ 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
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 413d566405d1..3e97354566ff 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -181,9 +181,13 @@ 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"
> @@ -195,6 +199,9 @@ 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 a170c6369a68..ddf6086cd9dd 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -940,19 +940,6 @@ 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_pud_supported(void)
> {
> /* only 4k granule supports level 1 block mappings */
>

--
Sincerely yours,
Mike.