[PATCH] x86/x86_64: mark rodata section read-only: make some datastructures const

Mark some key kernel datastructures readonly.  This patch was previously
posted on Jun 28th but was back then not merged because nothing was enforcing
rodata anyway..  well that changed now :)

Patch by Christoph Lameter <christoph@lameter.com> and Dave Jones
<davej@redhat.com>
Signed-off-by: NArjan van de Ven <arjan@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/i386/kernel/entry.S

@@ -657,6 +657,7 @@ ENTRY(spurious_interrupt_bug)
 	pushl $do_spurious_interrupt_bug
 	jmp error_code
 
+.section .rodata,"a"
 #include "syscall_table.S"
 
 syscall_table_size=(.-sys_call_table)

arch/i386/kernel/syscall_table.S

-.data
 ENTRY(sys_call_table)
 	.long sys_restart_syscall	/* 0 - old "setup()" system call, used for restarting */
 	.long sys_exit

arch/x86_64/ia32/ia32entry.S

@@ -341,7 +341,7 @@ ENTRY(ia32_ptregs_common)
 	jmp  ia32_sysret	/* misbalances the return cache */
 	CFI_ENDPROC
 
-	.data
+	.section .rodata,"a"
 	.align 8
 	.globl ia32_sys_call_table
 ia32_sys_call_table:

arch/x86_64/kernel/syscall.c

@@ -19,7 +19,7 @@ typedef void (*sys_call_ptr_t)(void);
 
 extern void sys_ni_syscall(void);
 
-sys_call_ptr_t sys_call_table[__NR_syscall_max+1] __cacheline_aligned = { 
+const sys_call_ptr_t sys_call_table[__NR_syscall_max+1] = {
 	/* Smells like a like a compiler bug -- it doesn't work when the & below is removed. */ 
 	[0 ... __NR_syscall_max] = &sys_ni_syscall,
 #include <asm-x86_64/unistd.h>