efi/libstub/arm64: Force 'hidden' visibility for section markers

commit 0426a4e6 upstream.

To prevent the compiler from emitting absolute references to the section
markers when running in PIC mode, override the visibility to 'hidden' for
all contents of asm/sections.h
Tested-by: Matthias Kaehlcke <mka@chromium.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170818194947.19347-4-ard.biesheuvel@linaro.orgSigned-off-by: Ingo Molnar <mingo@kernel.org>
[nc: Fix conflict due to lack of commit 42b55734 in linux-4.4.y]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/firmware/efi/libstub/arm64-stub.c

@@ -9,9 +9,17 @@
  * published by the Free Software Foundation.
  *
  */
+
+/*
+ * To prevent the compiler from emitting GOT-indirected (and thus absolute)
+ * references to the section markers, override their visibility as 'hidden'
+ */
+#pragma GCC visibility push(hidden)
+#include <asm/sections.h>
+#pragma GCC visibility pop
+
 #include <linux/efi.h>
 #include <asm/efi.h>
-#include <asm/sections.h>
 
 efi_status_t __init handle_kernel_image(efi_system_table_t *sys_table_arg,
 					unsigned long *image_addr,