[PATCH 4.4 18/70] efi/libstub/arm64: Force hidden visibility for section markers

Greg Kroah-Hartman
2018-11-26T10:54:08Z

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit 0426a4e68f18d75515414361de9e3e1445d2644e 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.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[nc: Fix conflict due to lack of commit 42b55734030c1 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 | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/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,