powerpc: Move EXCEPTION_TABLE to RO_DATA segment

Since the EXCEPTION_TABLE is read-only, collapse it into RO_DATA.

Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Michael Ellerman <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Rick Edgecombe <[email protected]>
Cc: Segher Boessenkool <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: x86-ml <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

arch/powerpc/kernel/vmlinux.lds.S

@@ -7,6 +7,7 @@
 
 #define BSS_FIRST_SECTIONS *(.bss.prominit)
 #define EMITS_PT_NOTE
+#define RO_EXCEPTION_TABLE_ALIGN	0
 
 #include <asm/page.h>
 #include <asm-generic/vmlinux.lds.h>
@@ -162,7 +163,6 @@ SECTIONS
 		__stop__btb_flush_fixup = .;
 	}
 #endif
-	EXCEPTION_TABLE(0)
 
 /*
  * Init sections discarded at runtime