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[v6,24/27] x86/mm: Make the x86 GOT read-only

Message ID 20190131192533.34130-25-thgarnie@chromium.org (mailing list archive)
State New, archived
Headers show
Series x86: PIE support and option to extend KASLR randomization | expand

Commit Message

Thomas Garnier Jan. 31, 2019, 7:24 p.m. UTC 
The GOT is changed during early boot when relocations are applied. Make
it read-only directly. This table exists only for PIE binary.

Position Independent Executable (PIE) support will allow to extend the
KASLR randomization range below 0xffffffff80000000.

Signed-off-by: Thomas Garnier <thgarnie@chromium.org>
---
 include/asm-generic/vmlinux.lds.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)
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Patch

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 3d7a6a9c2370..0a038594c878 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -323,6 +323,17 @@ 
 	__end_ro_after_init = .;
 #endif
 
+#ifdef CONFIG_X86_PIE
+#define RO_GOT_X86							\
+	.got        : AT(ADDR(.got) - LOAD_OFFSET) {			\
+		__start_got = .;					\
+		*(.got);						\
+		__end_got = .;						\
+	}
+#else
+#define RO_GOT_X86
+#endif
+
 /*
  * Read only Data
  */
@@ -379,6 +390,7 @@ 
 		__end_builtin_fw = .;					\
 	}								\
 									\
+	RO_GOT_X86							\
 	TRACEDATA							\
 									\
 	/* Kernel symbol table: Normal symbols */			\