[PATCH v4 0/4] powerpc patches for new Kconfig language

This series of patches improves th powerpc kbuild system. The
motivation was to to be compatible with the new Kconfig scripting
language that Yamada-san has proposed here:

https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git/?h=kconfig-shell-v3

I have tested on top of that tree and powerpc now builds there.

I think patches 1-3 are improvements to the build system even before
kconfig-shell, so they could be merged ahead of it in the powerpc
tree.

Patch 4 takes advatage of a new feature of the kconfig-shell work to
improve powerpc kconfig, so that should instead be merged with the
kbuild tree with an ack from powerpc, after patches 1-3 are merged.

v4 just brings some build fixes to patch 3 (including a change from
patch 4 that belonged in patch 3), and improvemets to changelogs.

Thanks,
Nick

Nicholas Piggin (4):
  powerpc/kbuild: set default generic machine type for 32-bit compile
  powerpc/kbuild: remove CROSS32 defines from top level powerpc Makefile
  powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS
  powerpc/kbuild: move -mprofile-kernel check to Kconfig

 arch/powerpc/Kconfig                          | 16 +------
 arch/powerpc/Makefile                         | 45 ++++++++-----------
 arch/powerpc/boot/Makefile                    | 16 ++++---
 arch/powerpc/kernel/vdso32/Makefile           | 15 +++++--
 .../tools/gcc-check-mprofile-kernel.sh        | 12 +++--
 scripts/recordmcount.pl                       | 18 +++++++-
 6 files changed, 67 insertions(+), 55 deletions(-)

-- 
2.17.0

Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit
kernels, even with -m32. Debian's powerpc64le is one such case, and
that is because it is built with --with-cpu=power8.

So when cross compiling a 32-bit kernel with a 64-bit toolchain, set
-mcpu=powerpc initially, which is the generic 32-bit powerpc machine
type and scheduling model. CPU and platform code can override this
with subsequent -mcpu flags if necessary.

This is not done for 32-bit toolchains otherwise it would override
their defaults, which are presumably set appropriately for the
environment (moreso than a 64-bit cross compiler).

This fixes a lot of build failures due to incompatible assembly when
compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain.

Cc: Segher Boessenkool <redacted>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Makefile | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 95813df90801..15ca4bafad82 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile

@@ -24,9 +24,20 @@ ifeq ($(HAS_BIARCH),y)
 ifeq ($(CROSS32_COMPILE),)
 CROSS32CC	:= $(CC) -m32
 KBUILD_ARFLAGS	+= --target=elf32-powerpc
+
+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
 
+
 export CROSS32CC CROSS32AR
 
 ifeq ($(CROSS_COMPILE),)

-- 
2.17.0

Switch VDSO32 build over to use CROSS32_COMPILE directly, and have
it pass in -m32 after the standard c_flags. This allows endianness
overrides to be removed and the endian and bitness flags moved into
standard flags variables.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Makefile               | 10 ----------
 arch/powerpc/boot/Makefile          | 16 +++++++++++-----
 arch/powerpc/kernel/vdso32/Makefile | 15 +++++++++++----
 3 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 15ca4bafad82..167b26a0780c 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile

@@ -17,14 +17,8 @@ HAS_BIARCH	:= $(call cc-option-yn, -m32)
 # Set default 32 bits cross compilers for vdso and boot wrapper
 CROSS32_COMPILE ?=
 
-CROSS32CC		:= $(CROSS32_COMPILE)gcc
-CROSS32AR		:= $(CROSS32_COMPILE)ar
-
 ifeq ($(HAS_BIARCH),y)
 ifeq ($(CROSS32_COMPILE),)
-CROSS32CC	:= $(CC) -m32
-KBUILD_ARFLAGS	+= --target=elf32-powerpc
-
 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

@@ -33,13 +27,9 @@ ifdef CONFIG_PPC32
 KBUILD_CFLAGS		+= -mcpu=powerpc
 KBUILD_AFLAGS		+= -mcpu=powerpc
 endif
-
 endif
 endif
 
-
-export CROSS32CC CROSS32AR
-
 ifeq ($(CROSS_COMPILE),)
 KBUILD_DEFCONFIG := $(shell uname -m)_defconfig
 else

diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index 26d5d2a5b8e9..49767e06202c 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile

@@ -23,19 +23,23 @@ all: $(obj)/zImage
 compress-$(CONFIG_KERNEL_GZIP) := CONFIG_KERNEL_GZIP
 compress-$(CONFIG_KERNEL_XZ)   := CONFIG_KERNEL_XZ
 
+ifdef CROSS32_COMPILE
+    BOOTCC := $(CROSS32_COMPILE)gcc
+    BOOTAR := $(CROSS32_COMPILE)ar
+else
+    BOOTCC := $(CC)
+    BOOTAR := $(AR)
+endif
+
 BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		 -fno-strict-aliasing -Os -msoft-float -pipe \
 		 -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
 		 -D$(compress-y)
 
-BOOTCC := $(CC)
 ifdef CONFIG_PPC64_BOOT_WRAPPER
 BOOTCFLAGS	+= -m64
 else
 BOOTCFLAGS	+= -m32
-ifdef CROSS32_COMPILE
-    BOOTCC := $(CROSS32_COMPILE)gcc
-endif
 endif
 
 BOOTCFLAGS	+= -isystem $(shell $(BOOTCC) -print-file-name=include)

@@ -49,6 +53,8 @@ endif
 
 BOOTAFLAGS	:= -D__ASSEMBLY__ $(BOOTCFLAGS) -traditional -nostdinc
 
+BOOTARFLAGS	:= -cr$(KBUILD_ARFLAGS)
+
 ifdef CONFIG_DEBUG_INFO
 BOOTCFLAGS	+= -g
 endif

@@ -202,7 +208,7 @@ quiet_cmd_bootas = BOOTAS  $@
       cmd_bootas = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
 
 quiet_cmd_bootar = BOOTAR  $@
-      cmd_bootar = $(CROSS32AR) -cr$(KBUILD_ARFLAGS) $@.$$$$ $(filter-out FORCE,$^); mv $@.$$$$ $@
+      cmd_bootar = $(BOOTAR) $(BOOTARFLAGS) $@.$$$$ $(filter-out FORCE,$^); mv $@.$$$$ $@
 
 $(obj-libfdt): $(obj)/%.o: $(srctree)/scripts/dtc/libfdt/%.c FORCE
 	$(call if_changed_dep,bootcc)

diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index b8c434d1d459..50112d4473bb 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile

@@ -8,8 +8,15 @@ obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o \
 
 # Build rules
 
-ifeq ($(CONFIG_PPC32),y)
-CROSS32CC := $(CC)
+ifdef CROSS32_COMPILE
+    VDSOCC := $(CROSS32_COMPILE)gcc
+else
+    VDSOCC := $(CC)
+endif
+
+CC32FLAGS :=
+ifdef CONFIG_PPC64
+CC32FLAGS += -m32
 endif
 
 targets := $(obj-vdso32) vdso32.so vdso32.so.dbg

@@ -45,9 +52,9 @@ $(obj-vdso32): %.o: %.S FORCE
 
 # actual build commands
 quiet_cmd_vdso32ld = VDSO32L $@
-      cmd_vdso32ld = $(CROSS32CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^)
+      cmd_vdso32ld = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^)
 quiet_cmd_vdso32as = VDSO32A $@
-      cmd_vdso32as = $(CROSS32CC) $(a_flags) -c -o $@ $<
+      cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
 
 # install commands for the unstripped file
 quiet_cmd_vdso_install = INSTALL $@

-- 
2.17.0

The powerpc toolchain can compile combinations of 32/64 bit and
big/little endian, so it's convenient to consider, e.g.,

  `CC -m64 -mbig-endian`

To be the C compiler for the purpose of invoking it to build target
artifacts. So overriding the the CC variable to include these flags
works for this purpose.

Unfortunately that is not compatible with the way the proposed new
Kconfig macro language implementation, which gets confused by the
the $(CC) environment variable changing.

After previous patches in this series, these flags can be carefully
passed in using the usual kbuild flags variables instead.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

---
Since v3:
- Added 32/64 flags to recordmcount.pl invocation of the toolchain,
  similarly to BE/LE. This fixes problems with toolchain default
  target bitness != kernel target bitness. I kept Steven's ack
  because it's much the same powerpc specific change, okay?

- Added a similar fix for mismatched toolchain default endianness
  or bitness to the gcc-check-mprofile-kernel.sh script. This was
  pulled in from patch 4 and improved (added comment and endianness
  flags).

 arch/powerpc/Makefile                          | 16 +++++++++-------
 .../powerpc/tools/gcc-check-mprofile-kernel.sh | 12 ++++++++----
 scripts/recordmcount.pl                        | 18 +++++++++++++++++-
 3 files changed, 34 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 167b26a0780c..6faf1d6ad9dd 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile

@@ -75,13 +75,15 @@ endif
 endif
 
 ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
-override LD	+= -EL
+KBUILD_CFLAGS	+= -mlittle-endian
+LDFLAGS		+= -EL
 LDEMULATION	:= lppc
 GNUTARGET	:= powerpcle
 MULTIPLEWORD	:= -mno-multiple
 KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-save-toc-indirect)
 else
-override LD	+= -EB
+KBUILD_CFLAGS += $(call cc-option,-mbig-endian)
+LDFLAGS		+= -EB
 LDEMULATION	:= ppc
 GNUTARGET	:= powerpc
 MULTIPLEWORD	:= -mmultiple

@@ -94,19 +96,19 @@ aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mabi=elfv2
 endif
 
-cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
-cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
 ifneq ($(cc-name),clang)
   cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mno-strict-align
 endif
 
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
+cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
 aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
 
 ifeq ($(HAS_BIARCH),y)
-override AS	+= -a$(BITS)
-override LD	+= -m elf$(BITS)$(LDEMULATION)
-override CC	+= -m$(BITS)
+KBUILD_CFLAGS	+= -m$(BITS)
+KBUILD_AFLAGS	+= -m$(BITS) -Wl,-a$(BITS)
+LDFLAGS		+= -m elf$(BITS)$(LDEMULATION)
 KBUILD_ARFLAGS	+= --target=elf$(BITS)-$(GNUTARGET)
 endif
 

diff --git a/arch/powerpc/tools/gcc-check-mprofile-kernel.sh b/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
index 061f8035bdbe..a7dd0e5d9f98 100755
--- a/arch/powerpc/tools/gcc-check-mprofile-kernel.sh
+++ b/arch/powerpc/tools/gcc-check-mprofile-kernel.sh

@@ -7,17 +7,21 @@ set -o pipefail
 # To debug, uncomment the following line
 # set -x
 
+# -mprofile-kernel is only supported on 64le, so this should not be invoked
+# for other targets. Therefore we can pass in -m64 and -mlittle-endian
+# explicitly, to take care of toolchains defaulting to other targets.
+
 # Test whether the compile option -mprofile-kernel exists and generates
 # profiling code (ie. a call to _mcount()).
 echo "int func() { return 0; }" | \
-    $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
-    grep -q "_mcount"
+    $* -m64 -mlittle-endian -S -x c -O2 -p -mprofile-kernel - -o - \
+    2> /dev/null | grep -q "_mcount"
 
 # Test whether the notrace attribute correctly suppresses calls to _mcount().
 
 echo -e "#include <linux/compiler.h>\nnotrace int func() { return 0; }" | \
-    $* -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
-    grep -q "_mcount" && \
+    $* -m64 -mlittle-endian -S -x c -O2 -p -mprofile-kernel - -o - \
+    2> /dev/null | grep -q "_mcount" && \
     exit 1
 
 echo "OK"

diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 191eb949d52c..fe06e77c15eb 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl

@@ -266,13 +266,29 @@ if ($arch eq "x86_64") {
     $objcopy .= " -O elf32-sh-linux";
 
 } elsif ($arch eq "powerpc") {
+    my $ldemulation;
+
     $local_regex = "^[0-9a-fA-F]+\\s+t\\s+(\\.?\\S+)";
     # See comment in the sparc64 section for why we use '\w'.
     $function_regex = "^([0-9a-fA-F]+)\\s+<(\\.?\\w*?)>:";
     $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s\\.?_mcount\$";
 
+    if ($endian eq "big") {
+	    $cc .= " -mbig-endian ";
+	    $ld .= " -EB ";
+	    $ldemulation = "ppc"
+    } else {
+	    $cc .= " -mlittle-endian ";
+	    $ld .= " -EL ";
+	    $ldemulation = "lppc"
+    }
     if ($bits == 64) {
-	$type = ".quad";
+        $type = ".quad";
+        $cc .= " -m64 ";
+        $ld .= " -m elf64".$ldemulation." ";
+    } else {
+        $cc .= " -m32 ";
+        $ld .= " -m elf32".$ldemulation." ";
     }
 
 } elsif ($arch eq "arm") {

-- 
2.17.0

This eliminates the workaround that requires disabling
-mprofile-kernel by default in Kconfig.

[ Note: this depends on https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kconfig-shell-v3 ]

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
Since v3:
- Moved a stray hunk back to patch 3 where it belongs.

 arch/powerpc/Kconfig  | 16 +---------------
 arch/powerpc/Makefile | 14 ++------------
 2 files changed, 3 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 512fcc177c87..af527f894f9b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -460,23 +460,9 @@ config LD_HEAD_STUB_CATCH
 
 	  If unsure, say "N".
 
-config DISABLE_MPROFILE_KERNEL
-	bool "Disable use of mprofile-kernel for kernel tracing"
-	depends on PPC64 && CPU_LITTLE_ENDIAN
-	default y
-	help
-	  Selecting this options disables use of the mprofile-kernel ABI for
-	  kernel tracing. That will cause options such as live patching
-	  (CONFIG_LIVEPATCH) which depend on CONFIG_DYNAMIC_FTRACE_WITH_REGS to
-	  be disabled also.
-
-	  If you have a toolchain which supports mprofile-kernel, then you can
-	  disable this. Otherwise leave it enabled. If you're not sure, say
-	  "Y".
-
 config MPROFILE_KERNEL
 	depends on PPC64 && CPU_LITTLE_ENDIAN
-	def_bool !DISABLE_MPROFILE_KERNEL
+	def_bool $(success $(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__)
 
 config IOMMU_HELPER
 	def_bool PPC64

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 6faf1d6ad9dd..8f7a64fe7370 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile

@@ -161,18 +161,8 @@ CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=powerpc64
 endif
 
 ifdef CONFIG_MPROFILE_KERNEL
-    ifeq ($(shell $(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__),OK)
-        CC_FLAGS_FTRACE := -pg -mprofile-kernel
-        KBUILD_CPPFLAGS += -DCC_USING_MPROFILE_KERNEL
-    else
-        # If the user asked for mprofile-kernel but the toolchain doesn't
-        # support it, emit a warning and deliberately break the build later
-        # with mprofile-kernel-not-supported. We would prefer to make this an
-        # error right here, but then the user would never be able to run
-        # oldconfig to change their configuration.
-        $(warning Compiler does not support mprofile-kernel, set CONFIG_DISABLE_MPROFILE_KERNEL)
-        CC_FLAGS_FTRACE := -mprofile-kernel-not-supported
-    endif
+	CC_FLAGS_FTRACE := -pg -mprofile-kernel
+	KBUILD_CPPFLAGS += -DCC_USING_MPROFILE_KERNEL
 endif
 
 CFLAGS-$(CONFIG_CELL_CPU) += $(call cc-option,-mcpu=cell)

-- 
2.17.0

Hi Nicholas,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Nicholas-Piggin/powerpc-patches-for-new-Kconfig-language/20180517-224044
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allmodconfig
compiler: powerpc64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        make.cross ARCH=powerpc  allmodconfig
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:468: syntax error

   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:467: invalid option

   make[2]: *** [allmodconfig] Error 1
   make[1]: *** [allmodconfig] Error 2
   make: *** [sub-make] Error 2
--
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:468: syntax error

   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:467: invalid option

   make[2]: *** [oldconfig] Error 1
   make[1]: *** [oldconfig] Error 2
   make: *** [sub-make] Error 2
--
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:468: syntax error

   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'
   arch/powerpc/Kconfig:467:warning: ignoring unsupported character '$'

quoted

arch/powerpc/Kconfig:467: invalid option

   make[2]: *** [olddefconfig] Error 1
   make[2]: Target 'oldnoconfig' not remade because of errors.
   make[1]: *** [oldnoconfig] Error 2
   make: *** [sub-make] Error 2

vim +468 arch/powerpc/Kconfig

e05c0e81 Kevin Hao       2013-07-16  443  
3d72bbc4 Michael Neuling 2013-02-13  444  config PPC_TRANSACTIONAL_MEM
3d72bbc4 Michael Neuling 2013-02-13  445         bool "Transactional Memory support for POWERPC"
3d72bbc4 Michael Neuling 2013-02-13  446         depends on PPC_BOOK3S_64
3d72bbc4 Michael Neuling 2013-02-13  447         depends on SMP
7b37a123 Michael Neuling 2014-01-08  448         select ALTIVEC
7b37a123 Michael Neuling 2014-01-08  449         select VSX
3d72bbc4 Michael Neuling 2013-02-13  450         default n
3d72bbc4 Michael Neuling 2013-02-13  451         ---help---
3d72bbc4 Michael Neuling 2013-02-13  452           Support user-mode Transactional Memory on POWERPC.
3d72bbc4 Michael Neuling 2013-02-13  453  
951eedeb Nicholas Piggin 2017-05-29  454  config LD_HEAD_STUB_CATCH
951eedeb Nicholas Piggin 2017-05-29  455  	bool "Reserve 256 bytes to cope with linker stubs in HEAD text" if EXPERT
951eedeb Nicholas Piggin 2017-05-29  456  	depends on PPC64
951eedeb Nicholas Piggin 2017-05-29  457  	default n
951eedeb Nicholas Piggin 2017-05-29  458  	help
951eedeb Nicholas Piggin 2017-05-29  459  	  Very large kernels can cause linker branch stubs to be generated by
951eedeb Nicholas Piggin 2017-05-29  460  	  code in head_64.S, which moves the head text sections out of their
951eedeb Nicholas Piggin 2017-05-29  461  	  specified location. This option can work around the problem.
951eedeb Nicholas Piggin 2017-05-29  462  
951eedeb Nicholas Piggin 2017-05-29  463  	  If unsure, say "N".
951eedeb Nicholas Piggin 2017-05-29  464  
8c50b72a Torsten Duwe    2016-03-03  465  config MPROFILE_KERNEL
8c50b72a Torsten Duwe    2016-03-03  466  	depends on PPC64 && CPU_LITTLE_ENDIAN
4421b963 Nicholas Piggin 2018-05-17 @467  	def_bool $(success $(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__)
8c50b72a Torsten Duwe    2016-03-03 @468  

:::::: The code at line 468 was first introduced by commit
:::::: 8c50b72a3b4f1f7cdfdfebd233b1cbd121262e65 powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel

:::::: TO: Torsten Duwe [off-list ref]
:::::: CC: Michael Ellerman [off-list ref]

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

On Thu, 17 May 2018 00:14:58 +1000
Nicholas Piggin [off-list ref] wrote:

This eliminates the workaround that requires disabling
-mprofile-kernel by default in Kconfig.

[ Note: this depends on https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kconfig-shell-v3 ]

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

Here is an incremental patch that brings this up to v4.

https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kconfig-shell-v4

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c7cc482cb660..60b83398b498 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -462,7 +462,7 @@ config LD_HEAD_STUB_CATCH
 
 config MPROFILE_KERNEL
 	depends on PPC64 && CPU_LITTLE_ENDIAN
-	def_bool $(success $(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__)
+	def_bool $(success,$(srctree)/arch/powerpc/tools/gcc-check-mprofile-kernel.sh $(CC) -I$(srctree)/include -D__KERNEL__)
 
 config IOMMU_HELPER
 	def_bool PPC64

-- 
2.17.0

2018-05-16 23:14 GMT+09:00 Nicholas Piggin [off-list ref]:

Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit
kernels, even with -m32. Debian's powerpc64le is one such case, and
that is because it is built with --with-cpu=power8.

So when cross compiling a 32-bit kernel with a 64-bit toolchain, set
-mcpu=powerpc initially, which is the generic 32-bit powerpc machine
type and scheduling model. CPU and platform code can override this
with subsequent -mcpu flags if necessary.

This is not done for 32-bit toolchains otherwise it would override
their defaults, which are presumably set appropriately for the
environment (moreso than a 64-bit cross compiler).

This fixes a lot of build failures due to incompatible assembly when
compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain.

Cc: Segher Boessenkool <redacted>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---

Can you please remove the noise changes?

1/4 adds some blank lines, then 2/4 removes them.

This blank line will be removed by the next patch.

+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
+

This blank line will be removed by the next patch.

 endif
 endif

+

This blank line will be removed by the next patch.

 export CROSS32CC CROSS32AR

 ifeq ($(CROSS_COMPILE),)
--
2.17.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Best Regards
Masahiro Yamada

2018-05-16 23:14 GMT+09:00 Nicholas Piggin [off-list ref]:

Your fix-up patch is good,
but could you check my comments below please?

You do not need to compare the returned string with "OK" any more.


Please remove the
echo "OK"
line from the shell script.

-        CC_FLAGS_FTRACE := -pg -mprofile-kernel
-        KBUILD_CPPFLAGS += -DCC_USING_MPROFILE_KERNEL
-    else
-        # If the user asked for mprofile-kernel but the toolchain doesn't
-        # support it, emit a warning and deliberately break the build later
-        # with mprofile-kernel-not-supported. We would prefer to make this an
-        # error right here, but then the user would never be able to run
-        # oldconfig to change their configuration.
-        $(warning Compiler does not support mprofile-kernel, set CONFIG_DISABLE_MPROFILE_KERNEL)
-        CC_FLAGS_FTRACE := -mprofile-kernel-not-supported
-    endif
+       CC_FLAGS_FTRACE := -pg -mprofile-kernel
+       KBUILD_CPPFLAGS += -DCC_USING_MPROFILE_KERNEL

Now, CONFIG_MPROFILE_KERNEL is equivalent to CC_USING_MPROFILE_KERNEL.


If you replace #ifdef CC_USING_MPROFILE_KERNEL
with #ifdef CONFIG_MPROFILE_KERNEL,
you can remove CC_USING_MRPROFILE_KERNEL entirely, right?

 endif

 CFLAGS-$(CONFIG_CELL_CPU) += $(call cc-option,-mcpu=cell)
--
2.17.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Best Regards
Masahiro Yamada

On Tue, 29 May 2018 22:39:48 +0900
Masahiro Yamada [off-list ref] wrote:

2018-05-16 23:14 GMT+09:00 Nicholas Piggin [off-list ref]:

quoted

Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit
kernels, even with -m32. Debian's powerpc64le is one such case, and
that is because it is built with --with-cpu=power8.

So when cross compiling a 32-bit kernel with a 64-bit toolchain, set
-mcpu=powerpc initially, which is the generic 32-bit powerpc machine
type and scheduling model. CPU and platform code can override this
with subsequent -mcpu flags if necessary.

This is not done for 32-bit toolchains otherwise it would override
their defaults, which are presumably set appropriately for the
environment (moreso than a 64-bit cross compiler).

This fixes a lot of build failures due to incompatible assembly when
compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain.

Cc: Segher Boessenkool <redacted>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---  

Can you please remove the noise changes?

1/4 adds some blank lines, then 2/4 removes them.

Okay sure, I will change that.

Thanks,
Nick