On 12/23/15 at 07:12pm, Xunlei Pang wrote:
> Implement the protection method for the crash kernel memory
> reservation for the 64-bit x86 kdump.
>
> Signed-off-by: Xunlei Pang <xlpang at redhat.com>
> ---
> Only provided x86_64 implementation, as I've only tested on x86_64 so far.
>
> arch/x86/kernel/machine_kexec_64.c | 43 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 819ab3f..a3d289c 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -536,3 +536,46 @@ overflow:
> return -ENOEXEC;
> }
> #endif /* CONFIG_KEXEC_FILE */
> +
> +#ifdef CONFIG_KEXEC_CORE
> +static int
> +kexec_mark_range(unsigned long start, unsigned long end, bool protect)
> +{
> + struct page *page;
> + unsigned int nr_pages;
> +
> + if (!start || !end || start >= end)
> + return 0;
> +
> + page = pfn_to_page(start >> PAGE_SHIFT);
> + nr_pages = (end + 1 - start) >> PAGE_SHIFT;
The start and end may across two pages, although the range is small than
PAGE_SIZE. You can use following to calculate count of page.
nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
Thanks
Minfei
> + if (protect)
> + return set_pages_ro(page, nr_pages);
> + else
> + return set_pages_rw(page, nr_pages);
> +}
