[PATCH] unwinder: move .eh_frame to RODATA

The .eh_frame section contents is never written to, so it can as well
benefit from CONFIG_DEBUG_RODATA.

Diff-ed against firstfloor tree.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/kernel/vmlinux.lds.S

@@ -102,15 +102,6 @@ SECTIONS
 	_edata = .;		/* End of data section */
   }
 
-#ifdef CONFIG_STACK_UNWIND
-  . = ALIGN(4);
-  .eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {
-	__start_unwind = .;
-  	*(.eh_frame)
-	__end_unwind = .;
-  }
-#endif
-
   . = ALIGN(THREAD_SIZE);	/* init_task */
   .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) {
 	*(.data.init_task)

arch/x86_64/kernel/vmlinux.lds.S

@@ -51,15 +51,6 @@ SECTIONS
 
   RODATA
 
-#ifdef CONFIG_STACK_UNWIND
-  . = ALIGN(8);
-  .eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {
-	__start_unwind = .;
-  	*(.eh_frame)
-	__end_unwind = .;
-  }
-#endif
-
   . = ALIGN(PAGE_SIZE);        /* Align data segment to page size boundary */
 				/* Data */
   .data : AT(ADDR(.data) - LOAD_OFFSET) {

include/asm-generic/vmlinux.lds.h

@@ -119,8 +119,7 @@
 		*(__ksymtab_strings)					\
 	}								\
 									\
-	/* Unwind data binary search table */				\
-	EH_FRAME_HDR							\
+	EH_FRAME							\
 									\
 	/* Built-in module parameters. */				\
 	__param : AT(ADDR(__param) - LOAD_OFFSET) {			\
@@ -162,15 +161,23 @@
 		VMLINUX_SYMBOL(__kprobes_text_end) = .;
 
 #ifdef CONFIG_STACK_UNWIND
-		/* Unwind data binary search table */
-#define EH_FRAME_HDR							\
+#define EH_FRAME							\
+		/* Unwind data binary search table */			\
+		. = ALIGN(8);						\
         	.eh_frame_hdr : AT(ADDR(.eh_frame_hdr) - LOAD_OFFSET) {	\
 			VMLINUX_SYMBOL(__start_unwind_hdr) = .;		\
 			*(.eh_frame_hdr)				\
 			VMLINUX_SYMBOL(__end_unwind_hdr) = .;		\
+		}							\
+		/* Unwind data */					\
+		. = ALIGN(8);						\
+		.eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {		\
+			VMLINUX_SYMBOL(__start_unwind) = .;		\
+		  	*(.eh_frame)					\
+			VMLINUX_SYMBOL(__end_unwind) = .;		\
 		}
 #else
-#define EH_FRAME_HDR
+#define EH_FRAME
 #endif
 
 		/* DWARF debug sections.

kernel/unwind.c

@@ -19,7 +19,7 @@
 #include <asm/uaccess.h>
 #include <asm/unaligned.h>
 
-extern char __start_unwind[], __end_unwind[];
+extern const char __start_unwind[], __end_unwind[];
 extern const u8 __start_unwind_hdr[], __end_unwind_hdr[];
 
 #define MAX_STACK_DEPTH 8