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Commit f4159834 authored by Christophe Leroy's avatar Christophe Leroy Committed by Greg Kroah-Hartman
Browse files

powerpc/32: Don't always pass -mcpu=powerpc to the compiler 



[ Upstream commit 446cda1b21d9a6b3697fe399c6a3a00ff4a285f5 ]

Since commit 4bf4f42a ("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: default avatarPali Rohár <pali@kernel.org>
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: default avatarPali Rohár <pali@kernel.org>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarSegher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d4df724691351531bf46d685d654689e5dfa0d74.1657549153.git.christophe.leroy@csgroup.eu


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent d78d0ee7

arch/powerpc/Makefile

+1 −25
Original line number Diff line number Diff line
@@ -17,23 +17,6 @@ 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)
@@ -192,6 +175,7 @@ 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
@@ -202,14 +186,6 @@ 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@high,-DHAVE_AS_ATHIGH=1)



KBUILD_CPPFLAGS	+= -I $(srctree)/arch/$(ARCH) $(asinstr)

arch/powerpc/platforms/Kconfig.cputype

+18 −3
Original line number Diff line number Diff line
@@ -118,9 +118,9 @@ config GENERIC_CPU 
	depends on PPC64 && CPU_LITTLE_ENDIAN

	select ARCH_HAS_FAST_MULTIPLIER



config GENERIC_CPU

config POWERPC_CPU

	bool "Generic 32 bits powerpc"

	depends on PPC32 && !PPC_8xx

	depends on PPC32 && !PPC_8xx && !PPC_85xx



config CELL_CPU

	bool "Cell Broadband Engine"
@@ -174,11 +174,23 @@ config G4_CPU 
	depends on PPC_BOOK3S_32

	select ALTIVEC



config E500_CPU

	bool "e500 (8540)"

	depends on PPC_85xx && !PPC_E500MC



config E500MC_CPU

	bool "e500mc"

	depends on PPC_85xx && PPC_E500MC



config TOOLCHAIN_DEFAULT_CPU

	bool "Rely on the toolchain's implicit default CPU"

	depends on PPC32



endchoice



config TARGET_CPU_BOOL

	bool

	default !GENERIC_CPU

	default !GENERIC_CPU && !TOOLCHAIN_DEFAULT_CPU



config TARGET_CPU

	string
@@ -193,6 +205,9 @@ config TARGET_CPU 
	default "e300c2" if E300C2_CPU

	default "e300c3" if E300C3_CPU

	default "G4" if G4_CPU

	default "8540" if E500_CPU

	default "e500mc" if E500MC_CPU

	default "powerpc" if POWERPC_CPU



config PPC_BOOK3S

	def_bool y