From 1619b69edce14c4a4665fa8ff4c587dcc77202a9 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 14 Sep 2021 22:17:23 +1000 Subject: [PATCH] powerpc/boot: Fix build failure since GCC 4.9 removal Stephen reported that the build was broken since commit 6d2ef226f2f1 ("compiler_attributes.h: drop __has_attribute() support for gcc4"), with errors such as: include/linux/compiler_attributes.h:296:5: warning: "__has_attribute" is not defined, evaluates to 0 [-Wundef] 296 | #if __has_attribute(__warning__) | ^~~~~~~~~~~~~~~ make[2]: *** [arch/powerpc/boot/Makefile:225: arch/powerpc/boot/crt0.o] Error 1 But we expect __has_attribute() to always be defined now that we've stopped using GCC 4. Linus debugged it to the point of reading the GCC sources, and noticing that the problem is that __has_attribute() is not defined when preprocessing assembly files, which is what we're doing here. Our assembly files don't include, or need, compiler_attributes.h, but they are getting it unconditionally from the -include in BOOT_CFLAGS, which is then added in its entirety to BOOT_AFLAGS. That -include was added in commit 77433830ed16 ("powerpc: boot: include compiler_attributes.h") so that we'd have "fallthrough" and other attributes defined for the C files in arch/powerpc/boot. But it's not needed for assembly files. The minimal fix is to move the addition to BOOT_CFLAGS of -include compiler_attributes.h until after we've copied BOOT_CFLAGS into BOOT_AFLAGS. That avoids including compiler_attributes.h for asm files, but makes no other change to BOOT_CFLAGS or BOOT_AFLAGS. Reported-by: Stephen Rothwell Debugged-by: Linus Torvalds Signed-off-by: Michael Ellerman Tested-by: Guenter Roeck Signed-off-by: Linus Torvalds --- arch/powerpc/boot/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile index 6900d0ac2421..089ee3ea55c8 100644 --- a/arch/powerpc/boot/Makefile +++ b/arch/powerpc/boot/Makefile @@ -35,7 +35,6 @@ endif BOOTCFLAGS := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -O2 -msoft-float -mno-altivec -mno-vsx \ -pipe -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \ - -include $(srctree)/include/linux/compiler_attributes.h \ $(LINUXINCLUDE) ifdef CONFIG_PPC64_BOOT_WRAPPER @@ -70,6 +69,7 @@ ifeq ($(call cc-option-yn, -fstack-protector),y) BOOTCFLAGS += -fno-stack-protector endif +BOOTCFLAGS += -include $(srctree)/include/linux/compiler_attributes.h BOOTCFLAGS += -I$(objtree)/$(obj) -I$(srctree)/$(obj) DTC_FLAGS ?= -p 1024