linux-kernel - [PATCH v2] powerpc: Pass correct CPU reference to assembler

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Date:   Fri, 16 Dec 2022 09:35:50 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Jan-Benedict Glaw <jbglaw@...-owl.de>
Subject: [PATCH v2] powerpc: Pass correct CPU reference to assembler

Jan-Benedict reported issue with building ppc64e_defconfig
with mainline GCC work:

  powerpc64-linux-gcc -Wp,-MMD,arch/powerpc/kernel/vdso/.gettimeofday-64.o.d -nostdinc -I./arch/powerpc/include -I./arch/powerpc/include/generated  -I./include -I./arch/powerpc/include/uapi -I./arch/powerpc/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h -D__KERNEL__ -I ./arch/powerpc -DHAVE_AS_ATHIGH=1 -fmacro-prefix-map=./= -D__ASSEMBLY__ -fno-PIE -m64 -Wl,-a64 -mabi=elfv1 -Wa,-me500 -Wa,-me500mc -mabi=elfv1 -mbig-endian    -Wl,-soname=linux-vdso64.so.1 -D__VDSO64__ -s -c -o arch/powerpc/kernel/vdso/gettimeofday-64.o arch/powerpc/kernel/vdso/gettimeofday.S
	arch/powerpc/kernel/vdso/gettimeofday.S: Assembler messages:
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `stdu'
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `stdu'
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `std'
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `std'
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `ld'
	arch/powerpc/kernel/vdso/gettimeofday.S:72: Error: unrecognized opcode: `ld'
	...
	make[1]: *** [arch/powerpc/kernel/vdso/Makefile:76: arch/powerpc/kernel/vdso/gettimeofday-64.o] Error 1
	make: *** [arch/powerpc/Makefile:387: vdso_prepare] Error 2

This is due to assembler being called with -me500mc which is
a 32 bits target.

The problem comes from the fact that CONFIG_PPC_E500MC is selected for
both the e500mc (32 bits) and the e5500 (64 bits), and therefore the
following makefile rule is wrong:

  cpu-as-$(CONFIG_PPC_E500MC)    += $(call as-option,-Wa$(comma)-me500mc)

Today we have CONFIG_TARGET_CPU which provides the identification of the
expected CPU, it is used for GCC. Use it as well for the assembler.

With that change (And also commit 825eada7717c ("powerpc/64: Set
default CPU in Kconfig")), it now is:

  powerpc64-linux-gcc -Wp,-MMD,arch/powerpc/kernel/vdso/.gettimeofday-64.o.d -nostdinc -I./arch/powerpc/include -I./arch/powerpc/include/generated  -I./include -I./arch/powerpc/include/uapi -I./arch/powerpc/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/compiler-version.h -include ./include/linux/kconfig.h -D__KERNEL__ -I ./arch/powerpc -DHAVE_AS_ATHIGH=1 -fmacro-prefix-map=./= -D__ASSEMBLY__ -fno-PIE -m64 -Wl,-a64 -mabi=elfv1 -mcpu=e500mc64 -Wa,-me500mc64 -mabi=elfv1 -mbig-endian    -Wl,-soname=linux-vdso64.so.1 -D__VDSO64__ -s -c -o arch/powerpc/kernel/vdso/gettimeofday-64.o arch/powerpc/kernel/vdso/gettimeofday.S

Reported-by: Jan-Benedict Glaw <jbglaw@...-owl.de>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
v2: When target cpu is powerpc, the option to be used is -mppc

Commit 825eada7717c is in powerpc/next-test branch. Make sure the SHA doesn't change when it goes into powerpc/next
---
 arch/powerpc/Makefile | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index bf5f0a998273..528452ce80b4 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -201,18 +201,20 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
 # often slow when they are implemented at all
 KBUILD_CFLAGS		+= $(call cc-option,-mno-string)
 
-cpu-as-$(CONFIG_40x)		+= -Wa,-m405
-cpu-as-$(CONFIG_44x)		+= -Wa,-m440
 cpu-as-$(CONFIG_ALTIVEC)	+= $(call as-option,-Wa$(comma)-maltivec)
-cpu-as-$(CONFIG_PPC_E500)		+= -Wa,-me500
+
+ifeq ($(CONFIG_TARGET_CPU),powerpc)
+cpu-as-$(CONFIG_TARGET_CPU_BOOL)	+= -Wa,-mppc
+else
+cpu-as-$(CONFIG_TARGET_CPU_BOOL)	+= -Wa,-m$(CONFIG_TARGET_CPU)
+endif
 
 # When using '-many -mpower4' gas will first try and find a matching power4
 # mnemonic and failing that it will allow any valid mnemonic that GAS knows
 # about. GCC will pass -many to GAS when assembling, clang does not.
 # LLVM IAS doesn't understand either flag: https://github.com/ClangBuiltLinux/linux/issues/675
 # but LLVM IAS only supports ISA >= 2.06 for Book3S 64 anyway...
-cpu-as-$(CONFIG_PPC_BOOK3S_64)	+= $(call as-option,-Wa$(comma)-mpower4) $(call as-option,-Wa$(comma)-many)
-cpu-as-$(CONFIG_PPC_E500MC)	+= $(call as-option,-Wa$(comma)-me500mc)
+cpu-as-$(CONFIG_PPC_BOOK3S_64)	+= $(call as-option,-Wa$(comma)-many)
 
 KBUILD_AFLAGS += $(cpu-as-y)
 KBUILD_CFLAGS += $(cpu-as-y)
-- 
2.38.1