On 03/14/14 at 04:20pm, WANG Chao wrote:
> With kASLR enabled (CONFIG_RANDOMIZED_BASE=y), kernel virtual address
> base is PAGE_OFFSET plus a randomized offset from 0 to 1G.
>
> Current kexec-tools gets kernel vaddr and size from /proc/kcore. It
> assumes kernel vaddr start/end is within the range [0,512M). If kaslr
> enabled, kernel vaddr start/end will stay at [0+offset, 512M+offset).
>
> To adapt kaslr, introduce a new macro X86_64_RANDOMIZED_BASE_MAX_OFFSET
> to address the max offset and use this macro to filter out the kernel
> text PT_LOAD from /proc/kcore.
>
> Signed-off-by: WANG Chao <chaowang at redhat.com>
> ---
> kexec/arch/i386/crashdump-x86.c | 3 ++-
> kexec/arch/i386/crashdump-x86.h | 3 +++
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> index cb19e7d..1e6d3a3 100644
> --- a/kexec/arch/i386/crashdump-x86.c
> +++ b/kexec/arch/i386/crashdump-x86.c
> @@ -156,7 +156,8 @@ static int get_kernel_vaddr_and_size(struct kexec_info *UNUSED(info),
>
> /* Look for kernel text mapping header. */
> if ((saddr >= X86_64__START_KERNEL_map) &&
> - (eaddr <= X86_64__START_KERNEL_map + X86_64_KERNEL_TEXT_SIZE)) {
> + (saddr <= X86_64__START_KERNEL_map + X86_64_RANDOMIZE_BASE_MAX_OFFSET) &&
> + (eaddr - saddr < X86_64_KERNEL_TEXT_SIZE)) {
> saddr = _ALIGN_DOWN(saddr, X86_64_KERN_VADDR_ALIGN);
> elf_info->kern_vaddr_start = saddr;
> size = eaddr - saddr;
> diff --git a/kexec/arch/i386/crashdump-x86.h b/kexec/arch/i386/crashdump-x86.h
> index e68b626..71a09f8 100644
> --- a/kexec/arch/i386/crashdump-x86.h
> +++ b/kexec/arch/i386/crashdump-x86.h
> @@ -15,6 +15,9 @@ int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline,
> #define X86_64_PAGE_OFFSET_PRE_2_6_27 0xffff810000000000ULL
> #define X86_64_PAGE_OFFSET 0xffff880000000000ULL
>
> +/* kASLR - Kernel base offset could be randomized up to 1G */
> +#define X86_64_RANDOMIZE_BASE_MAX_OFFSET 0x40000000
> +
> #define X86_64_MAXMEM 0x3fffffffffffUL
>
> /* Kernel text size */
Acked-by: Dave Young <dyoung at redhat.com>
Thanks
Dave
