[PATCH] Avoid overwriting the current pgd (V4, x86_64)
kexec: Avoid overwriting the current pgd (V4, x86_64)
This patch upgrades the x86_64-specific kexec code to avoid overwriting the
current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used
to start a secondary kernel that dumps the memory of the previous kernel.
The code introduces a new set of page tables. These tables are used to provide
an executable identity mapping without overwriting the current pgd.
Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
diff --git a/include/asm-x86_64/kexec.h b/include/asm-x86_64/kexec.h
index c564bae..5fab957 100644
--- a/include/asm-x86_64/kexec.h
+++ b/include/asm-x86_64/kexec.h
@@ -1,6 +1,27 @@
#ifndef _X86_64_KEXEC_H
#define _X86_64_KEXEC_H
+#define PA_CONTROL_PAGE 0
+#define VA_CONTROL_PAGE 1
+#define PA_PGD 2
+#define VA_PGD 3
+#define PA_PUD_0 4
+#define VA_PUD_0 5
+#define PA_PMD_0 6
+#define VA_PMD_0 7
+#define PA_PTE_0 8
+#define VA_PTE_0 9
+#define PA_PUD_1 10
+#define VA_PUD_1 11
+#define PA_PMD_1 12
+#define VA_PMD_1 13
+#define PA_PTE_1 14
+#define VA_PTE_1 15
+#define PA_TABLE_PAGE 16
+#define PAGES_NR 17
+
+#ifndef __ASSEMBLY__
+
#include <linux/string.h>
#include <asm/page.h>
@@ -64,4 +85,12 @@
newregs->rip = (unsigned long)current_text_addr();
}
}
+
+NORET_TYPE void
+relocate_kernel(unsigned long indirection_page,
+ unsigned long page_list,
+ unsigned long start_address) ATTRIB_NORET;
+
+#endif /* __ASSEMBLY__ */
+
#endif /* _X86_64_KEXEC_H */