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

Kees Cook
2015-03-10T01:03:04Z

On Sat, Mar 7, 2015 at 2:07 PM, Yinghai Lu <yinghai-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 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-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

This seems good. :)

Reviewed-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

-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