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Date: Sun, 10 Jul 2022 19:36:58 +0200 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, Pali Rohár <pali@...nel.org>, Arnd Bergmann <arnd@...db.de>, Segher Boessenkool <segher@...nel.crashing.org> Subject: [PATCH] powerpc/32: Don't always pass -mcpu=powerpc to the compiler Since commit 4bf4f42a2feb ("powerpc/kbuild: Set default generic machine type for 32-bit compile"), when building a 32 bits kernel with a bi-arch version of GCC, or when building a book3s/32 kernel, the option -mcpu=powerpc is passed to GCC at all time, relying on it being eventually overriden by a subsequent -mcpu=xxxx. But when building the same kernel with a 32 bits only version of GCC, that is not done, relying on gcc being built with the expected default CPU. This logic has two problems. First, it is a bit fragile to rely on whether the GCC version is bi-arch or not, because today we can have bi-arch versions of GCC configured with a 32 bits default. Second, there are some versions of GCC which don't support -mcpu=powerpc, for instance for e500 SPE-only versions. So, stop relying on this approximative logic and allow the user to decide whether he/she wants to use the toolchain's default CPU or if he/she wants to set one, and allow only possible CPUs based on the selected target. Reported-by: Pali Rohár <pali@...nel.org> Cc: Arnd Bergmann <arnd@...db.de> Cc: Segher Boessenkool <segher@...nel.crashing.org> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu> --- arch/powerpc/Makefile | 26 +------------------------- arch/powerpc/platforms/Kconfig.cputype | 24 ++++++++++++++++++++---- 2 files changed, 21 insertions(+), 29 deletions(-) diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index a0cd70712061..d54e1fe03551 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -15,23 +15,6 @@ HAS_BIARCH := $(call cc-option-yn, -m32) # Set default 32 bits cross compilers for vdso and boot wrapper CROSS32_COMPILE ?= -ifeq ($(HAS_BIARCH),y) -ifeq ($(CROSS32_COMPILE),) -ifdef CONFIG_PPC32 -# These options will be overridden by any -mcpu option that the CPU -# or platform code sets later on the command line, but they are needed -# to set a sane 32-bit cpu target for the 64-bit cross compiler which -# may default to the wrong ISA. -KBUILD_CFLAGS += -mcpu=powerpc -KBUILD_AFLAGS += -mcpu=powerpc -endif -endif -endif - -ifdef CONFIG_PPC_BOOK3S_32 -KBUILD_CFLAGS += -mcpu=powerpc -endif - # If we're on a ppc/ppc64/ppc64le machine use that defconfig, otherwise just use # ppc64_defconfig because we have nothing better to go on. uname := $(shell uname -m) @@ -183,6 +166,7 @@ endif endif CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU)) +AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU)) # Altivec option not allowed with e500mc64 in GCC. ifdef CONFIG_ALTIVEC @@ -193,14 +177,6 @@ endif CFLAGS-$(CONFIG_E5500_CPU) += $(E5500_CPU) CFLAGS-$(CONFIG_E6500_CPU) += $(call cc-option,-mcpu=e6500,$(E5500_CPU)) -ifdef CONFIG_PPC32 -ifdef CONFIG_PPC_E500MC -CFLAGS-y += $(call cc-option,-mcpu=e500mc,-mcpu=powerpc) -else -CFLAGS-$(CONFIG_E500) += $(call cc-option,-mcpu=8540 -msoft-float,-mcpu=powerpc) -endif -endif - asinstr := $(call as-instr,lis 9$(comma)foo@...h,-DHAVE_AS_ATHIGH=1) KBUILD_CPPFLAGS += -I $(srctree)/arch/$(ARCH) $(asinstr) diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype index 383ed4fe6013..197653442d9f 100644 --- a/arch/powerpc/platforms/Kconfig.cputype +++ b/arch/powerpc/platforms/Kconfig.cputype @@ -117,7 +117,8 @@ endchoice choice prompt "CPU selection" - default GENERIC_CPU + default GENERIC_CPU if PPC64 + default POWERPC_CPU if PPC32 help This will create a kernel which is optimised for a particular CPU. The resulting kernel may not run on other CPUs, so use this with care. @@ -135,9 +136,13 @@ config GENERIC_CPU select ARCH_HAS_FAST_MULTIPLIER select PPC_64S_HASH_MMU -config GENERIC_CPU +config POWERPC_CPU bool "Generic 32 bits powerpc" - depends on PPC32 && !PPC_8xx + depends on PPC32 && !PPC_8xx && !E500 + +config TOOLCHAIN_DEFAULT_CPU + bool "Rely on the toolchain's implicit default CPU" + depends on PPC32 config CELL_CPU bool "Cell Broadband Engine" @@ -196,11 +201,19 @@ config G4_CPU depends on PPC_BOOK3S_32 select ALTIVEC +config 8540_CPU + bool "8540" + depends on PPC_85xx && !PPC_E500MC + +config E500MC_CPU + bool "e500mc" + depends on PPC_85xx && PPC_E500MC + endchoice config TARGET_CPU_BOOL bool - default !GENERIC_CPU + default !GENERIC_CPU && !TOOLCHAIN_DEFAULT_CPU config TARGET_CPU string @@ -215,6 +228,9 @@ config TARGET_CPU default "e300c2" if E300C2_CPU default "e300c3" if E300C3_CPU default "G4" if G4_CPU + default "8540" if 8540_CPU + default "e500mc" if E500MC_CPU + default "powerpc" if POWERPC_CPU config PPC_BOOK3S def_bool y -- 2.36.1
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