[PATCH] x86/x86_64: mark rodata section read only: generic infrastructure

Generic prep-work for marking the .rodata section readonly:
* Align the rodata section at 4Kb boundary
* call the mark_rodata_ro() function when available

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 9 insertions, 0 deletions

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 094d4917c1a9..35de20cf8fac 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -10,6 +10,8 @@
 #define ALIGN_FUNCTION()  . = ALIGN(8)
 
 #define RODATA                                                          \
+        . = ALIGN(4096);                                                \
+        __start_rodata = .;                                             \
         .rodata           : AT(ADDR(.rodata) - LOAD_OFFSET) {           \
                 *(.rodata) *(.rodata.*)                                 \
                 *(__vermagic)           /* Kernel version magic */      \
@@ -74,6 +76,8 @@
         __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \
                 *(__ksymtab_strings)                                    \
         }                                                               \
+        __end_rodata = .;                                               \
+        . = ALIGN(4096);                                                \
                                                                         \
         /* Built-in module parameters. */                               \
         __param : AT(ADDR(__param) - LOAD_OFFSET) {                     \
diff --git a/init/main.c b/init/main.c
index 54aaf561cf66..2ed3638deec7 100644
--- a/init/main.c
+++ b/init/main.c
@@ -52,6 +52,7 @@
 #include <asm/bugs.h>
 #include <asm/setup.h>
 #include <asm/sections.h>
+#include <asm/cacheflush.h>
 
 /*
  * This is one of the first .c files built. Error out early
@@ -99,6 +100,9 @@ extern void acpi_early_init(void);
 #else
 static inline void acpi_early_init(void) { }
 #endif
+#ifndef CONFIG_DEBUG_RODATA
+static inline void mark_rodata_ro(void) { }
+#endif
 
 #ifdef CONFIG_TC
 extern void tc_init(void);
@@ -708,6 +712,7 @@ static int init(void * unused)
          */
         free_initmem();
         unlock_kernel();
+        mark_rodata_ro();
         system_state = SYSTEM_RUNNING;
         numa_default_policy();