Re: [PATCH v3 6/7] x86, boot: Split kernel_ident_mapping_init to another file

[Kees Cook]

On Sat, Mar 7, 2015 at 2:07 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> We need to include that in boot::decompress_kernel stage to set new
> ident mapping.
>
> Also add checking for __pa/__va macro definition, as we need to override them
> in boot::decompress_kernel stage.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

This seems good. :)

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

-Kees

> ---
>  arch/x86/include/asm/page.h |  5 +++
>  arch/x86/mm/ident_map.c     | 74 +++++++++++++++++++++++++++++++++++++++++++++
>  arch/x86/mm/init_64.c       | 74 +--------------------------------------------
>  3 files changed, 80 insertions(+), 73 deletions(-)
>  create mode 100644 arch/x86/mm/ident_map.c
>
> diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
> index 802dde3..cf8f619 100644
> --- a/arch/x86/include/asm/page.h
> +++ b/arch/x86/include/asm/page.h
> @@ -37,7 +37,10 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
>         alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO | movableflags, vma, vaddr)
>  #define __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
>
> +#ifndef __pa
>  #define __pa(x)                __phys_addr((unsigned long)(x))
> +#endif
> +
>  #define __pa_nodebug(x)        __phys_addr_nodebug((unsigned long)(x))
>  /* __pa_symbol should be used for C visible symbols.
>     This seems to be the official gcc blessed way to do such arithmetic. */
> @@ -51,7 +54,9 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
>  #define __pa_symbol(x) \
>         __phys_addr_symbol(__phys_reloc_hide((unsigned long)(x)))
>
> +#ifndef __va
>  #define __va(x)                        ((void *)((unsigned long)(x)+PAGE_OFFSET))
> +#endif
>
>  #define __boot_va(x)           __va(x)
>  #define __boot_pa(x)           __pa(x)
> diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
> new file mode 100644
> index 0000000..751ca92
> --- /dev/null
> +++ b/arch/x86/mm/ident_map.c
> @@ -0,0 +1,74 @@
> +
> +static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
> +                          unsigned long addr, unsigned long end)
> +{
> +       addr &= PMD_MASK;
> +       for (; addr < end; addr += PMD_SIZE) {
> +               pmd_t *pmd = pmd_page + pmd_index(addr);
> +
> +               if (!pmd_present(*pmd))
> +                       set_pmd(pmd, __pmd(addr | pmd_flag));
> +       }
> +}
> +static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
> +                         unsigned long addr, unsigned long end)
> +{
> +       unsigned long next;
> +
> +       for (; addr < end; addr = next) {
> +               pud_t *pud = pud_page + pud_index(addr);
> +               pmd_t *pmd;
> +
> +               next = (addr & PUD_MASK) + PUD_SIZE;
> +               if (next > end)
> +                       next = end;
> +
> +               if (pud_present(*pud)) {
> +                       pmd = pmd_offset(pud, 0);
> +                       ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +                       continue;
> +               }
> +               pmd = (pmd_t *)info->alloc_pgt_page(info->context);
> +               if (!pmd)
> +                       return -ENOMEM;
> +               ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +               set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
> +       }
> +
> +       return 0;
> +}
> +
> +int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
> +                             unsigned long addr, unsigned long end)
> +{
> +       unsigned long next;
> +       int result;
> +       int off = info->kernel_mapping ? pgd_index(__PAGE_OFFSET) : 0;
> +
> +       for (; addr < end; addr = next) {
> +               pgd_t *pgd = pgd_page + pgd_index(addr) + off;
> +               pud_t *pud;
> +
> +               next = (addr & PGDIR_MASK) + PGDIR_SIZE;
> +               if (next > end)
> +                       next = end;
> +
> +               if (pgd_present(*pgd)) {
> +                       pud = pud_offset(pgd, 0);
> +                       result = ident_pud_init(info, pud, addr, next);
> +                       if (result)
> +                               return result;
> +                       continue;
> +               }
> +
> +               pud = (pud_t *)info->alloc_pgt_page(info->context);
> +               if (!pud)
> +                       return -ENOMEM;
> +               result = ident_pud_init(info, pud, addr, next);
> +               if (result)
> +                       return result;
> +               set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
> +       }
> +
> +       return 0;
> +}
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index 30eb05a..c30efb6 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -56,79 +56,7 @@
>
>  #include "mm_internal.h"
>
> -static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
> -                          unsigned long addr, unsigned long end)
> -{
> -       addr &= PMD_MASK;
> -       for (; addr < end; addr += PMD_SIZE) {
> -               pmd_t *pmd = pmd_page + pmd_index(addr);
> -
> -               if (!pmd_present(*pmd))
> -                       set_pmd(pmd, __pmd(addr | pmd_flag));
> -       }
> -}
> -static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
> -                         unsigned long addr, unsigned long end)
> -{
> -       unsigned long next;
> -
> -       for (; addr < end; addr = next) {
> -               pud_t *pud = pud_page + pud_index(addr);
> -               pmd_t *pmd;
> -
> -               next = (addr & PUD_MASK) + PUD_SIZE;
> -               if (next > end)
> -                       next = end;
> -
> -               if (pud_present(*pud)) {
> -                       pmd = pmd_offset(pud, 0);
> -                       ident_pmd_init(info->pmd_flag, pmd, addr, next);
> -                       continue;
> -               }
> -               pmd = (pmd_t *)info->alloc_pgt_page(info->context);
> -               if (!pmd)
> -                       return -ENOMEM;
> -               ident_pmd_init(info->pmd_flag, pmd, addr, next);
> -               set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
> -       }
> -
> -       return 0;
> -}
> -
> -int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
> -                             unsigned long addr, unsigned long end)
> -{
> -       unsigned long next;
> -       int result;
> -       int off = info->kernel_mapping ? pgd_index(__PAGE_OFFSET) : 0;
> -
> -       for (; addr < end; addr = next) {
> -               pgd_t *pgd = pgd_page + pgd_index(addr) + off;
> -               pud_t *pud;
> -
> -               next = (addr & PGDIR_MASK) + PGDIR_SIZE;
> -               if (next > end)
> -                       next = end;
> -
> -               if (pgd_present(*pgd)) {
> -                       pud = pud_offset(pgd, 0);
> -                       result = ident_pud_init(info, pud, addr, next);
> -                       if (result)
> -                               return result;
> -                       continue;
> -               }
> -
> -               pud = (pud_t *)info->alloc_pgt_page(info->context);
> -               if (!pud)
> -                       return -ENOMEM;
> -               result = ident_pud_init(info, pud, addr, next);
> -               if (result)
> -                       return result;
> -               set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
> -       }
> -
> -       return 0;
> -}
> +#include "ident_map.c"
>
>  static int __init parse_direct_gbpages_off(char *arg)
>  {
> --
> 1.8.4.5
>



-- 
Kees Cook
Chrome OS Security
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