Re: [PATCH 3/7] powerpc: replace cc-option-yn uses with cc-option

[Nathan Chancellor <nathan@kernel.org>]

On 8/16/2021 5:21 PM, 'Nick Desaulniers' via Clang Built Linux wrote:
> cc-option-yn can be replaced with cc-option. ie.
> Checking for support:
> ifeq ($(call cc-option-yn,$(FLAG)),y)
> becomes:
> ifneq ($(call cc-option,$(FLAG)),)
> 
> Checking for lack of support:
> ifeq ($(call cc-option-yn,$(FLAG)),n)
> becomes:
> ifeq ($(call cc-option,$(FLAG)),)
> 
> This allows us to pursue removing cc-option-yn.
> 
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>   arch/powerpc/Makefile      | 12 ++++++------
>   arch/powerpc/boot/Makefile |  5 +----
>   2 files changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 9aaf1abbc641..85e224536cf7 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -12,12 +12,12 @@
>   # Rewritten by Cort Dougan and Paul Mackerras
>   #
>   
> -HAS_BIARCH	:= $(call cc-option-yn, -m32)
> +HAS_BIARCH	:= $(call cc-option,-m32)
>   
>   # Set default 32 bits cross compilers for vdso and boot wrapper
>   CROSS32_COMPILE ?=
>   
> -ifeq ($(HAS_BIARCH),y)
> +ifeq ($(HAS_BIARCH),-m32)
>   ifeq ($(CROSS32_COMPILE),)
>   ifdef CONFIG_PPC32
>   # These options will be overridden by any -mcpu option that the CPU
> @@ -107,7 +107,7 @@ cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
>   aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
>   aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
>   
> -ifeq ($(HAS_BIARCH),y)
> +ifeq ($(HAS_BIARCH),-m32)
>   KBUILD_CFLAGS	+= -m$(BITS)
>   KBUILD_AFLAGS	+= -m$(BITS) -Wl,-a$(BITS)
>   KBUILD_LDFLAGS	+= -m elf$(BITS)$(LDEMULATION)
> @@ -125,7 +125,9 @@ LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
>   LDFLAGS_vmlinux	:= $(LDFLAGS_vmlinux-y)
>   
>   ifdef CONFIG_PPC64
> -ifeq ($(call cc-option-yn,-mcmodel=medium),y)
> +ifeq ($(call cc-option,-mcmodel=medium),)
> +	export NO_MINIMAL_TOC := -mno-minimal-toc
> +else
>   	# -mcmodel=medium breaks modules because it uses 32bit offsets from
>   	# the TOC pointer to create pointers where possible. Pointers into the
>   	# percpu data area are created by this method.
> @@ -135,8 +137,6 @@ ifeq ($(call cc-option-yn,-mcmodel=medium),y)
>   	# kernel percpu data space (starting with 0xc...). We need a full
>   	# 64bit relocation for this to work, hence -mcmodel=large.
>   	KBUILD_CFLAGS_MODULE += -mcmodel=large
> -else
> -	export NO_MINIMAL_TOC := -mno-minimal-toc
>   endif
>   endif
>   
> diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> index 10c0fb306f15..33e1de5d1c95 100644
> --- a/arch/powerpc/boot/Makefile
> +++ b/arch/powerpc/boot/Makefile
> @@ -66,10 +66,7 @@ ifdef CONFIG_DEBUG_INFO
>   BOOTCFLAGS	+= -g
>   endif
>   
> -ifeq ($(call cc-option-yn, -fstack-protector),y)
> -BOOTCFLAGS	+= -fno-stack-protector
> -endif
> -
> +BOOTCFLAGS	+= $(call cc-option,-fstack-protector)

This was previously disabling the stack protector but now it is enabling 
it. Just remove the ifeq conditional altogether as the kernel assumes 
-fno-stack-protector is always supported after commit 893ab00439a4 
("kbuild: remove cc-option test of -fno-stack-protector").

>   BOOTCFLAGS	+= -I$(objtree)/$(obj) -I$(srctree)/$(obj)
>   
>   DTC_FLAGS	?= -p 1024
>