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    SubjectRe: [PATCH v6 1/3] arm64: map FDT as RW for early_init_dt_scan()
    On Wed, Jun 12, 2019 at 12:32:58PM +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 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>

    > ---
    > change log v5->v6:
    > * no change.
    > ---
    > 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 67ef25d037ea..27f6f17aae36 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);
    > 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 06941c1fe418..92bb53460401 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
    > @@ -96,7 +93,7 @@ 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 413d566405d1..6a7050319b5b 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 93ed0df4df79..5d01365a4333 100644
    > --- a/arch/arm64/mm/mmu.c
    > +++ b/arch/arm64/mm/mmu.c
    > @@ -887,7 +887,7 @@ 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;
    > @@ -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)
    > {
    > /*
    > --
    > 2.20.1
    >

    --
    Sincerely yours,
    Mike.

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