linux-kernel - [PATCH v1 1/5] powerpc/64: Set default CPU in Kconfig

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Date:   Mon, 19 Dec 2022 19:45:56 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>, jbglaw@...-owl.de
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Pali Rohár <pali@...nel.org>
Subject: [PATCH v1 1/5] powerpc/64: Set default CPU in Kconfig

Since 0069f3d14e7a ("powerpc/64e: Tie PPC_BOOK3E_64 to PPC_E500MC"), the
only possible BOOK3E/64 are E500, so no need of a default CPU over the
E5500.

When the user selects book3e, they must have an e500 compatible
compiler, and it won't work anymore with the default -mcpu=power64, see
commit d6b551b8f90c ("powerpc/64e: Fix build failure with GCC 12
(unrecognized opcode: `wrteei')").

For book3s/64, replace GENERIC_CPU by POWERPC64_CPU to match the PPC32
POWERPC_CPU, and set a default mpcu value in Kconfig directly.

When a user selects a particular CPU, they must ensure the compiler has
the requested capability. Therefore, remove hidden fallback, instead
offer user the possibility to say they want to use the toolchain
default.

It also fixes the non existing E5500_CPU which is a leftover of
commit d6b551b8f90c ("powerpc/64e: Fix build failure with GCC 12
(unrecognized opcode: `wrteei')")

Fixes: d6b551b8f90c ("powerpc/64e: Fix build failure with GCC 12 (unrecognized opcode: `wrteei')")
Reported-by: Pali Rohár <pali@...nel.org>
Tested-by: Pali Rohár <pali@...nel.org>
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/Makefile                  | 22 +++++-----------------
 arch/powerpc/platforms/Kconfig.cputype | 12 +++++++-----
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index dc4cbf0a5ca9..bf5f0a998273 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -146,19 +146,6 @@ CFLAGS-$(CONFIG_PPC32)	+= $(call cc-option, $(MULTIPLEWORD))
 
 CFLAGS-$(CONFIG_PPC32)	+= $(call cc-option,-mno-readonly-in-sdata)
 
-ifdef CONFIG_PPC_BOOK3S_64
-ifdef CONFIG_CPU_LITTLE_ENDIAN
-CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power8
-else
-CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=power4
-endif
-CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power10,	\
-				  $(call cc-option,-mtune=power9,	\
-				  $(call cc-option,-mtune=power8)))
-else ifdef CONFIG_PPC_BOOK3E_64
-CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=powerpc64
-endif
-
 ifdef CONFIG_FUNCTION_TRACER
 CC_FLAGS_FTRACE := -pg
 ifdef CONFIG_MPROFILE_KERNEL
@@ -166,11 +153,12 @@ CC_FLAGS_FTRACE += -mprofile-kernel
 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))
+CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
+AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += -mcpu=$(CONFIG_TARGET_CPU)
 
-CFLAGS-$(CONFIG_E5500_CPU) += $(call cc-option,-mcpu=e500mc64,-mcpu=powerpc64)
-CFLAGS-$(CONFIG_E6500_CPU) += $(call cc-option,-mcpu=e6500,$(E5500_CPU))
+CFLAGS-$(CONFIG_POWERPC64_CPU) += $(call cc-option,-mtune=power10,	\
+				  $(call cc-option,-mtune=power9,	\
+				  $(call cc-option,-mtune=power8)))
 
 asinstr := $(call as-instr,lis 9$(comma)foo@...h,-DHAVE_AS_ATHIGH=1)
 
diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
index 9563336e3348..31cea2eeb59e 100644
--- a/arch/powerpc/platforms/Kconfig.cputype
+++ b/arch/powerpc/platforms/Kconfig.cputype
@@ -118,19 +118,18 @@ endchoice
 
 choice
 	prompt "CPU selection"
-	default GENERIC_CPU
 	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.
 
 	  If unsure, select Generic.
 
-config GENERIC_CPU
+config POWERPC64_CPU
 	bool "Generic (POWER5 and PowerPC 970 and above)"
 	depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
 	select PPC_64S_HASH_MMU
 
-config GENERIC_CPU
+config POWERPC64_CPU
 	bool "Generic (POWER8 and above)"
 	depends on PPC_BOOK3S_64 && CPU_LITTLE_ENDIAN
 	select ARCH_HAS_FAST_MULTIPLIER
@@ -233,13 +232,12 @@ config E500MC_CPU
 
 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 && !TOOLCHAIN_DEFAULT_CPU
+	default !TOOLCHAIN_DEFAULT_CPU
 
 config TARGET_CPU
 	string
@@ -251,6 +249,10 @@ config TARGET_CPU
 	default "power8" if POWER8_CPU
 	default "power9" if POWER9_CPU
 	default "power10" if POWER10_CPU
+	default "e500mc64" if E5500_CPU
+	default "e6500" if E6500_CPU
+	default "power4" if POWERPC64_CPU && !CPU_LITTLE_ENDIAN
+	default "power8" if POWERPC64_CPU && CPU_LITTLE_ENDIAN
 	default "405" if 405_CPU
 	default "440" if 440_CPU
 	default "464" if 464_CPU
-- 
2.38.1