[PATCH 6/6] arm64/efi: remove idmap manipulations from UEFI code

[Grant Likely]

On Fri, Oct 24, 2014 at 1:39 PM, Ard Biesheuvel
<ard.biesheuvel at linaro.org> wrote:
> Now that we have moved the call to SetVirtualAddressMap() to the stub,
> UEFI has no use for the ID map, so we can drop the code that installs
> ID mappings for UEFI memory regions.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

I have to say, this series makes me happy. :-)

This method will go a long way to catching UEFI implementations that
do incorrect things after exitbootservices is called. I'm assuming
that any attempt to access a region that boot services has not
requested will get trapped by the kernel, correct?

g.

> ---
>  arch/arm64/include/asm/efi.h |  4 ++--
>  arch/arm64/include/asm/mmu.h |  2 --
>  arch/arm64/kernel/efi.c      | 26 +-------------------------
>  arch/arm64/kernel/setup.c    |  2 +-
>  arch/arm64/mm/mmu.c          | 10 ----------
>  5 files changed, 4 insertions(+), 40 deletions(-)
>
> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
> index d752e5480096..09854df5a2a1 100644
> --- a/arch/arm64/include/asm/efi.h
> +++ b/arch/arm64/include/asm/efi.h
> @@ -6,10 +6,10 @@
>
>  #ifdef CONFIG_EFI
>  extern void efi_init(void);
> -extern void efi_idmap_init(void);
> +extern void efi_virtmap_init(void);
>  #else
>  #define efi_init()
> -#define efi_idmap_init()
> +#define efi_virtmap_init()
>  #endif
>
>  void efi_load_rt_mapping(void);
> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
> index bcf166043a8b..df33cf02300a 100644
> --- a/arch/arm64/include/asm/mmu.h
> +++ b/arch/arm64/include/asm/mmu.h
> @@ -31,8 +31,6 @@ extern void paging_init(void);
>  extern void setup_mm_for_reboot(void);
>  extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
>  extern void init_mem_pgprot(void);
> -/* create an identity mapping for memory (or io if map_io is true) */
> -extern void create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io);
>  extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
>                                unsigned long virt, phys_addr_t size,
>                                int map_io, int map_xn);
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index cbff3e8eff11..02bd7e877f0b 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -53,27 +53,6 @@ static int __init is_normal_ram(efi_memory_desc_t *md)
>         return 0;
>  }
>
> -static void __init efi_setup_idmap(void)
> -{
> -       struct memblock_region *r;
> -       efi_memory_desc_t *md;
> -       u64 paddr, npages, size;
> -
> -       for_each_memblock(memory, r)
> -               create_id_mapping(r->base, r->size, 0);
> -
> -       /* map runtime io spaces */
> -       for_each_efi_memory_desc(&memmap, md) {
> -               if (!(md->attribute & EFI_MEMORY_RUNTIME) || is_normal_ram(md))
> -                       continue;
> -               paddr = md->phys_addr;
> -               npages = md->num_pages;
> -               memrange_efi_to_native(&paddr, &npages);
> -               size = npages << PAGE_SHIFT;
> -               create_id_mapping(paddr, size, 1);
> -       }
> -}
> -
>  /*
>   * Translate a EFI virtual address into a physical address: this is necessary,
>   * as some data members of the EFI system table are virtually remapped after
> @@ -251,16 +230,13 @@ static struct mm_struct efi_mm = {
>         INIT_MM_CONTEXT(efi_mm)
>  };
>
> -void __init efi_idmap_init(void)
> +void __init efi_virtmap_init(void)
>  {
>         efi_memory_desc_t *md;
>
>         if (!efi_enabled(EFI_BOOT))
>                 return;
>
> -       /* boot time idmap_pg_dir is incomplete, so fill in missing parts */
> -       efi_setup_idmap();
> -
>         for_each_efi_memory_desc(&memmap, md) {
>                 u64 paddr, npages, size;
>
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 2437196cc5d4..a6028490a28f 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -392,7 +392,7 @@ void __init setup_arch(char **cmdline_p)
>         paging_init();
>         request_standard_resources();
>
> -       efi_idmap_init();
> +       efi_virtmap_init();
>
>         unflatten_device_tree();
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index f7d17a5a1f56..19eae06aab81 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -282,16 +282,6 @@ static void __init create_mapping(phys_addr_t phys, unsigned long virt,
>                          size, 0, 0);
>  }
>
> -void __init create_id_mapping(phys_addr_t addr, phys_addr_t size, int map_io)
> -{
> -       if ((addr >> PGDIR_SHIFT) >= ARRAY_SIZE(idmap_pg_dir)) {
> -               pr_warn("BUG: not creating id mapping for %pa\n", &addr);
> -               return;
> -       }
> -       __create_mapping(&init_mm, &idmap_pg_dir[pgd_index(addr)],
> -                        addr, addr, size, map_io, 0);
> -}
> -
>  void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
>                                unsigned long virt, phys_addr_t size,
>                                int map_io, int map_xn)
> --
> 1.8.3.2
>