[v3,1/7] arm: use generic fixmap.h

From: Mark Salter <msalter@redhat.com>

ARM is different from other architectures in that fixmap pages are indexed
with a positive offset from FIXADDR_START.  Other architectures index with
a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
definitions, this patch redefines FIXADDR_TOP to be inclusive of the
useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
fixed page.  The newly defined FIXADDR_END is the first virtual address
past the fixed mappings.

Signed-off-by: Mark Salter <msalter@redhat.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
[kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
[kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Rob Herring <robh@kernel.org>
---
 arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
 arch/arm/include/asm/highmem.h |  1 -
 arch/arm/mm/highmem.c          | 15 ++++++++-------
 arch/arm/mm/init.c             |  2 +-
 arch/arm/mm/mmu.c              |  6 +++---
 5 files changed, 21 insertions(+), 30 deletions(-)

On Tue, Aug 12, 2014 at 11:24 AM, Kees Cook <keescook@chromium.org> wrote:
> From: Mark Salter <msalter@redhat.com>
>
> ARM is different from other architectures in that fixmap pages are indexed
> with a positive offset from FIXADDR_START.  Other architectures index with
> a negative offset from FIXADDR_TOP.  In order to use the generic fixmap.h
> definitions, this patch redefines FIXADDR_TOP to be inclusive of the
> useable range.  That is, FIXADDR_TOP is the virtual address of the topmost
> fixed page.  The newly defined FIXADDR_END is the first virtual address
> past the fixed mappings.
>
> Signed-off-by: Mark Salter <msalter@redhat.com>
> Reviewed-by: Doug Anderson <dianders@chromium.org>
> [kees: update for a05e54c103b0b8 "ARM: 8031/2: change fixmap ..."]
> [kees: fixed highmem usage, thanks to Laura Abbott and Rob Herring]
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: Laura Abbott <lauraa@codeaurora.org>
> Cc: Rob Herring <robh@kernel.org>
> ---
>  arch/arm/include/asm/fixmap.h  | 27 +++++++++------------------
>  arch/arm/include/asm/highmem.h |  1 -
>  arch/arm/mm/highmem.c          | 15 ++++++++-------
>  arch/arm/mm/init.c             |  2 +-
>  arch/arm/mm/mmu.c              |  6 +++---
>  5 files changed, 21 insertions(+), 30 deletions(-)
>
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0d0d79..a7add6f9315d 100644
> --- a/arch/arm/include/asm/fixmap.h
> +++ b/arch/arm/include/asm/fixmap.h
> @@ -2,27 +2,18 @@
>  #define _ASM_FIXMAP_H
>
>  #define FIXADDR_START          0xffc00000UL
> -#define FIXADDR_TOP            0xffe00000UL
> -#define FIXADDR_SIZE           (FIXADDR_TOP - FIXADDR_START)
> +#define FIXADDR_END            0xffe00000UL
> +#define FIXADDR_TOP            (FIXADDR_END - PAGE_SIZE)
>
> -#define FIX_KMAP_NR_PTES       (FIXADDR_SIZE >> PAGE_SHIFT)
> +#include <asm/kmap_types.h>
>
> -#define __fix_to_virt(x)       (FIXADDR_START + ((x) << PAGE_SHIFT))
> -#define __virt_to_fix(x)       (((x) - FIXADDR_START) >> PAGE_SHIFT)
> +enum fixed_addresses {
> +       FIX_KMAP_BEGIN,
> +       FIX_KMAP_END = FIX_KMAP_BEGIN + (KM_TYPE_NR * NR_CPUS) - 1,
>
> -extern void __this_fixmap_does_not_exist(void);
> +       __end_of_fixed_addresses
> +};
>
> -static inline unsigned long fix_to_virt(const unsigned int idx)
> -{
> -       if (idx >= FIX_KMAP_NR_PTES)
> -               __this_fixmap_does_not_exist();
> -       return __fix_to_virt(idx);
> -}
> -
> -static inline unsigned int virt_to_fix(const unsigned long vaddr)
> -{
> -       BUG_ON(vaddr >= FIXADDR_TOP || vaddr < FIXADDR_START);
> -       return __virt_to_fix(vaddr);
> -}
> +#include <asm-generic/fixmap.h>
>
>  #endif
> diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h
> index 535579511ed0..91b99abe7a95 100644
> --- a/arch/arm/include/asm/highmem.h
> +++ b/arch/arm/include/asm/highmem.h
> @@ -18,7 +18,6 @@
>         } while (0)
>
>  extern pte_t *pkmap_page_table;
> -extern pte_t *fixmap_page_table;
>
>  extern void *kmap_high(struct page *page);
>  extern void kunmap_high(struct page *page);
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaaca9052..f87e0b89b738 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -18,19 +18,20 @@
>  #include <asm/tlbflush.h>
>  #include "mm.h"
>
> -pte_t *fixmap_page_table;
> -
>  static inline void set_fixmap_pte(int idx, pte_t pte)
>  {
>         unsigned long vaddr = __fix_to_virt(idx);
> -       set_pte_ext(fixmap_page_table + idx, pte, 0);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       set_pte_ext(ppte, pte, 0);
>         local_flush_tlb_kernel_page(vaddr);
>  }
>
>  static inline pte_t get_fixmap_pte(unsigned long vaddr)
>  {
> -       unsigned long idx = __virt_to_fix(vaddr);
> -       return *(fixmap_page_table + idx);
> +       pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> +       return *ppte;
>  }
>
>  void *kmap(struct page *page)
> @@ -84,7 +85,7 @@ void *kmap_atomic(struct page *page)
>          * With debugging enabled, kunmap_atomic forces that entry to 0.
>          * Make sure it was indeed properly unmapped.
>          */
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Buildbot noticed that with CONFIG_DEBUG_HIGHMEM, this and the next
instance shouldn't have the leading "*" in front of the get_fixmap_pte
call. I've fixed that in my tree.

>         /*
>          * When debugging is off, kunmap_atomic leaves the previous mapping
> @@ -134,7 +135,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
>         idx = type + KM_TYPE_NR * smp_processor_id();
>         vaddr = __fix_to_virt(idx);
>  #ifdef CONFIG_DEBUG_HIGHMEM
> -       BUG_ON(!pte_none(*(fixmap_page_table + idx)));
> +       BUG_ON(!pte_none(*get_fixmap_pte(vaddr)));
>  #endif

Here too, as above.

-Kees

>         set_fixmap_pte(idx, pfn_pte(pfn, kmap_prot));
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index 659c75d808dc..ad82c05bfc3a 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -570,7 +570,7 @@ void __init mem_init(void)
>                         MLK(DTCM_OFFSET, (unsigned long) dtcm_end),
>                         MLK(ITCM_OFFSET, (unsigned long) itcm_end),
>  #endif
> -                       MLK(FIXADDR_START, FIXADDR_TOP),
> +                       MLK(FIXADDR_START, FIXADDR_END),
>                         MLM(VMALLOC_START, VMALLOC_END),
>                         MLM(PAGE_OFFSET, (unsigned long)high_memory),
>  #ifdef CONFIG_HIGHMEM
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 8348ed6b2efe..7fa0966cd15f 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1326,10 +1326,10 @@ static void __init kmap_init(void)
>  #ifdef CONFIG_HIGHMEM
>         pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
>                 PKMAP_BASE, _PAGE_KERNEL_TABLE);
> -
> -       fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START),
> -               FIXADDR_START, _PAGE_KERNEL_TABLE);
>  #endif
> +
> +       early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START,
> +                       _PAGE_KERNEL_TABLE);
>  }
>
>  static void __init map_lowmem(void)
> --
> 1.9.1
>