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. Once GCC knows the target CPU, it adds
the correct CPU option to assembler, no need to add it explicitly.

With that change (And also commit 45f7091 ("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 -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 <[email protected]>
Signed-off-by: Christophe Leroy <[email protected]>
Acked-by: Pali Rohár <[email protected]>
[mpe: Retain -Wa,-mpower4 -Wa,-many for Book3S 64 builds for now]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/758ad54128fa9dd2fdedc4c511592111cbded900.1671475543.git.christophe.leroy@csgroup.eu

Author: chleroy

arch/powerpc/Makefile

@@ -201,18 +201,14 @@ 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
 
 # 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)
 
 KBUILD_AFLAGS += $(cpu-as-y)
 KBUILD_CFLAGS += $(cpu-as-y)