efi/libstub: Use hidden visibility for all source files

Instead of setting the visibility pragma for a small set of symbol
declarations that could result in absolute references that we cannot
support in the stub, declare hidden visibility for all code in the
EFI stub, which is more robust and future proof.

To ensure that the #pragma is taken into account before any other
includes are processed, put it in a header file of its own and
include it via the compiler command line using the -include option.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 44531a69d32b9fd1772cb131d5696decca6e08c8..56ae87401a268f95d30c58bc87d5fc8a3412b75a 100644 (file)
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -107,9 +107,6 @@ static inline void free_screen_info(struct screen_info *si)
 {
 }
 
-/* redeclare as 'hidden' so the compiler will generate relative references */
-extern struct screen_info screen_info __attribute__((__visibility__("hidden")));
-
 static inline void efifb_setup_from_dmi(struct screen_info *si, const char *opt)
 {
 }

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index f14b7636323a75fb4e1a69769a50ed63393f2fb7..fc9e9e883eb4c571732a4cdf255da232ca1897d4 100644 (file)
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -25,6 +25,7 @@ cflags-$(CONFIG_ARM)          := $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 cflags-$(CONFIG_EFI_ARMSTUB)   += -I$(srctree)/scripts/dtc/libfdt
 
 KBUILD_CFLAGS                  := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
+                                  -include $(srctree)/drivers/firmware/efi/libstub/hidden.h \
                                   -D__NO_FORTIFY \
                                   $(call cc-option,-ffreestanding) \
                                   $(call cc-option,-fno-stack-protector) \

diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c
index ad5f24a4489b4e8fe7ee124abd9b908ba56de26b..9254cd8ab2d358c627561a17ad687c2bdd850864 100644 (file)
--- a/drivers/firmware/efi/libstub/arm64-stub.c
+++ b/drivers/firmware/efi/libstub/arm64-stub.c
@@ -6,17 +6,11 @@
  * Adapted from ARM version by Mark Salter <msalter@redhat.com>
  */
 
-/*
- * 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/memory.h>
+#include <asm/sections.h>
 #include <asm/sysreg.h>
 
 #include "efistub.h"

diff --git a/drivers/firmware/efi/libstub/hidden.h b/drivers/firmware/efi/libstub/hidden.h
new file mode 100644 (file)
index 0000000..3493b04
--- /dev/null
+++ b/drivers/firmware/efi/libstub/hidden.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * To prevent the compiler from emitting GOT-indirected (and thus absolute)
+ * references to any global symbols, override their visibility as 'hidden'
+ */
+#pragma GCC visibility push(hidden)