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>
---
v2->v3:
1) Make kexec_mark_range() more robust.
2) In kexec_mark_crashkres(), use Macro KEXEC_CONTROL_PAGE_SIZE
instead of 2*PAGE_SIZE
arch/x86/kernel/machine_kexec_64.c | 42 ++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 819ab3f..8127dc0 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -536,3 +536,45 @@ overflow:
return -ENOEXEC;
}
#endif /* CONFIG_KEXEC_FILE */
+
+static int
+kexec_mark_range(unsigned long start, unsigned long end, bool protect)
+{
+ struct page *page;
+ unsigned int nr_pages;
+
+ /* For physical range: [start, end] */
+ if (!end || start > end)
+ return 0;
+
+ page = pfn_to_page(start >> PAGE_SHIFT);
+ nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
+ if (protect)
+ return set_pages_ro(page, nr_pages);
+ else
+ return set_pages_rw(page, nr_pages);
+}
+
+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. */
+ kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
+ control += KEXEC_CONTROL_PAGE_SIZE;
+ kexec_mark_range(control, crashk_res.end, protect);
+}
+
+void arch_kexec_protect_crashkres(void)
+{
+ kexec_mark_crashkres(true);
+}
+
+void arch_kexec_unprotect_crashkres(void)
+{
+ kexec_mark_crashkres(false);
+}
--
2.5.0
