Re: [PATCH -V1] x86: make executable for video bios area

wangyanqing
2011-11-16T03:01:20Z

On Tue, Nov 15, 2011 at 02:42:37PM +0800, wangyanqing wrote:
> 5bd5a452662bc37c54fb6828db1a3faf87e6511c make area
> between BIOS_BEGIN and BIOS_END have NX protection
> when boot machine with acpi enable(acpi will disable pcibios).
>
> This commit make my machine can't boot, system hang with black screen
> very early when I enable CONFIG_FB_UVESA, CONFIG_X86_PAE, CONFIG_ACPI.
>
> below is the maps when boot normal without acpi:
> 00000000-00001000 rw-s 00000000 00:01 822 /dev/mem
> 00009000-0000a000 r-xp 00001000 00:01 912 /sbin/v86d
> 00010000-00050000 rwxp 00000000 00:01 818 /dev/zero
> 000a0000-000c0000 rw-s 000a0000 00:01 822 /dev/mem
> 000c0000-00100000 r-xs 000c0000 00:01 822 /dev/mem <== must executable
> 08048000-0804c000 r-xp 00001000 00:01 912 /sbin/v86d
> 0804c000-0804d000 rw-p 00004000 00:01 912 /sbin/v86d
> b7875000-b7876000 r-xp 00000000 00:00 0 [vdso]
> bfe9d000-bfebe000 rw-p 00000000 00:00 0 [stack]
>
> So I prepare this patch.It works with me.
> Any comment is welcome.
>
> Thanks.
>
> Signed-off-by: Wang YanQing <Udknight@gmail.com>
> ---
> arch/x86/include/asm/e820.h | 2 ++
> arch/x86/mm/pageattr.c | 3 ++-
> 2 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/e820.h b/arch/x86/include/asm/e820.h
> index 908b969..a6fa897 100644
> --- a/arch/x86/include/asm/e820.h
> +++ b/arch/x86/include/asm/e820.h
> @@ -72,6 +72,8 @@ struct e820map {
> #define BIOS_BEGIN 0x000a0000
> #define BIOS_END 0x00100000
>
> +#define BIOS_VIDEO 0x000c0000
> +
> #define BIOS_ROM_BASE 0xffe00000
> #define BIOS_ROM_END 0xffffffff
>
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index f9e5267..12acac0 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -260,7 +260,8 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
> * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
> */
> #ifdef CONFIG_PCI_BIOS
> - if (pcibios_enabled && within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
> + if ((pcibios_enabled || within(pfn, BIOS_VIDEO >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT)) &&
> + within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
> pgprot_val(forbidden) |= _PAGE_NX;
> #endif
>
> --
> 1.7.3.4
>

This issue also imply another question.
mmap on /dev/mem haven't check whether the target area can mmap with the request privilege.
Any comments? Linus