Re: [PATCH 1/8] arm: use generic fixmap.h

Leif Lindholm
2014-08-07T17:38:39Z

On Thu, Aug 07, 2014 at 08:01:46AM -0700, Kees Cook 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>
> [update for "ARM: 8031/2: change fixmap mapping region to support 32 CPUs"]
> [flipped highmem order, thanks to Laura Abbott]
> Signed-off-by: Kees Cook <keescook@chromium.org>
> Cc: Laura Abbott <lauraa@codeaurora.org>
> ---
> arch/arm/include/asm/fixmap.h | 27 +++++++++------------------
> arch/arm/mm/highmem.c | 8 ++++++--
> arch/arm/mm/init.c | 2 +-
> 3 files changed, 16 insertions(+), 21 deletions(-)
>
> diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h
> index 74124b0d0d79..190142d174ee 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 FIXADDR_SIZE (FIXADDR_END - FIXADDR_START)
>
> #define FIX_KMAP_NR_PTES (FIXADDR_SIZE >> PAGE_SHIFT)
>
> -#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_NR_PTES - 1,
> + __end_of_fixed_addresses
> +};
>
> -extern void __this_fixmap_does_not_exist(void);
> -
> -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/mm/highmem.c b/arch/arm/mm/highmem.c
> index 45aeaaca9052..a1241ee8425e 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -23,14 +23,18 @@ 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);

idx is now "unused variable".

> - return *(fixmap_page_table + idx);
> + pte_t *ppte = pte_offset_kernel(pmd_off_k(FIXADDR_START), vaddr);
> +
> + return *ppte;
> }
>
> void *kmap(struct page *page)
> 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
> --
> 1.9.1

Apart from that, verified with early_ioremap/UEFI patches on TC2.

Tested-by: Leif Lindholm <leif.lindholm@linaro.org>