powerpc/boot: Fix zImage TOC alignment

[ Upstream commit 97ee351b ]

Recent toolchains force the TOC to be 256 byte aligned. We need to
enforce this alignment in the zImage linker script, otherwise pointers
to our TOC variables (__toc_start) could be incorrect. If the actual
start of the TOC and __toc_start don't have the same value we crash
early in the zImage wrapper.

Cc: stable@vger.kernel.org
Suggested-by: Alan Modra <amodra@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>

arch/powerpc/boot/zImage.lds.S

@@ -68,6 +68,7 @@ SECTIONS
   }
 
 #ifdef CONFIG_PPC64_BOOT_WRAPPER
+  . = ALIGN(256);
   .got :
   {
     __toc_start = .;