Ccing Vivek
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
The file is only compiled when CONFIG_KEXEC_CORE=y so #ifdef is not necessary
> +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;
> + if (protect)
> + return set_pages_ro(page, nr_pages);
> + else
> + return set_pages_rw(page, nr_pages);
May use set_memory_ro/rw to avoid converting to *page?
> +}
> +
> +static void kexec_mark_crashkres(bool protect)
> +{
> + unsigned long control;
> +
> + kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
> +
> + /* Don't touch the control code page used in crash_kexec().*/
> + control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
> + /* Control code page is located in the 2nd page. */
> + control = control + PAGE_SIZE;
> + kexec_mark_range(crashk_res.start, control - 1, protect);
> + kexec_mark_range(control + PAGE_SIZE, crashk_res.end, protect);
X86 kexec will copy the page while kexecing, could you check if we can move
that copying to earliyer while kexec loading, maybe machine_kexec_prepare so
that we can make a arch-independent implementation.
> +}
> +
> +void arch_kexec_protect_crashkres(void)
> +{
> + kexec_mark_crashkres(true);
> +}
> +
> +void arch_kexec_unprotect_crashkres(void)
> +{
> + kexec_mark_crashkres(false);
> +}
> +#endif
> --
> 2.5.0
>
>
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