kbuild and powerpc patches for new Kconfig language

PATCH Superseded Nicholas Piggin 4 participants 14 messages May 10, 2018

Subsystems (2)

PowerPC Kbuild

lore

Share & tools

lore

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #0 lore raw

v2 cover kbuild and powerpc patches for new Kconfig language

I came back to these patches and I think I have solved the remaining problems -- it now builds with 64-bit big and little endian (using a le toolchain), and also 32-bit big using 64le toolchain. There might be some build failures still left, but it seems to be in much better shape now.

Reviews would be welcome. I don't quite know how it should be merged, maybe via the kbuild tree after acks from powerpc maintainer. We can decide that after it gets more testing and review.

Thanks,
Nick

Nicholas Piggin (5):
powerpc/kbuild: set default generic machine type for 32-bit compile powerpc/kbuild: remove CROSS32 defines from top level powerpc Makefile
kbuild: call cc-option with the current set of KBUILD_CFLAGS 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                         | 46 +++++++------------
 arch/powerpc/boot/Makefile                    | 16 +++++--
 arch/powerpc/kernel/vdso32/Makefile           | 15 ++++--
 .../tools/gcc-check-mprofile-kernel.sh        |  4 +-
 scripts/Kbuild.include                        |  8 ++--
 scripts/recordmcount.pl                       |  8 ++++
 7 files changed, 54 insertions(+), 59 deletions(-)

Signature · 1 line

2.17.0

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #1 lore raw

PATCH v2 1/5 powerpc/kbuild: set default generic machine type for 32-bit compile

The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit powerpc machine type and scheduling model. 32-bit platforms and CPUs can override this with -mcpu= options that come later on the command line.

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

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

arch/powerpc/Makefile +8 -0

index 95813df90801..7034b1ad50e0 100644
@@ -27,6 +27,14 @@ KBUILD_ARFLAGS	+= --target=elf32-powerpc
 endif
 endif
 
+ifdef CONFIG_PPC32
+# These options will be overridden by any -mcpu option that comes
+# later on the command line, but they are needed to set a sane
+# 32-bit cpu target for the 64-bit cross compiler.
+KBUILD_CFLAGS		+= -mcpu=powerpc
+KBUILD_AFLAGS		+= -mcpu=powerpc
+endif
+
 export CROSS32CC CROSS32AR
 
 ifeq ($(CROSS_COMPILE),)

Signature · 1 line

2.17.0

Segher Boessenkool

2018-05-10 13:10 UTC #2 lore raw

Re: [PATCH v2 1/5] powerpc/kbuild: set default generic machine type for 32-bit compile

Quoted 8 lines · Nicholas Piggin

The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit powerpc machine type and scheduling model. 32-bit platforms and CPUs can override this with -mcpu= options that come later on the command line.
This fixes a lot of build failures due to incompatible assembly when compiling 32-bit kernel with 64-bit toolchain.

So what ISA is set for gas without this patch? With what GCC version? And, why is that wrong?

Segher

Quoted 7 lines

arch/powerpc/Makefile +7 -0

+ifdef CONFIG_PPC32
+# These options will be overridden by any -mcpu option that comes
+# later on the command line, but they are needed to set a sane
+# 32-bit cpu target for the 64-bit cross compiler.
+KBUILD_CFLAGS		+= -mcpu=powerpc
+KBUILD_AFLAGS		+= -mcpu=powerpc
+endif

Nicholas Piggin

author reviewer

2018-05-10 13:24 UTC #3 lore raw

Re: [PATCH v2 1/5] powerpc/kbuild: set default generic machine type for 32-bit compile

Quoted 11 lines · On Thu, 10 May 2018 08:10:03 -0500 Segher Boessenkool…

Quoted 8 lines · Nicholas Piggin
The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit powerpc machine type and scheduling model. 32-bit platforms and CPUs can override this with -mcpu= options that come later on the command line.
This fixes a lot of build failures due to incompatible assembly when compiling 32-bit kernel with 64-bit toolchain.
So what ISA is set for gas without this patch? With what GCC version?

I'm not sure, how do I find that out?

Quoted 1 line

And, why is that wrong?

Some 32-bit platforms and CPU types do not provide -mcpu, so I assume for 32-bit toolchains that must result in the "powerpc" machine. With 64-bit toolchains

arch/powerpc/mm/hash_low_32.S:353: Error: missing operand

Which is,

tlbie r4

Is that v2.06?

Thanks,
Nick

Segher Boessenkool

2018-05-10 14:29 UTC #4 lore raw

Re: [PATCH v2 1/5] powerpc/kbuild: set default generic machine type for 32-bit compile

Quoted 9 lines · Nicholas Piggin

Quoted 7 lines · On Thu, 10 May 2018 08:10:03 -0500 Segher Boessenkool…
Quoted 6 lines · Nicholas Piggin
The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit powerpc machine type and scheduling model. 32-bit platforms and CPUs can override this with -mcpu= options that come later on the command line.

Quoted 6 lines

Quoted 4 lines
Quoted 2 lines
This fixes a lot of build failures due to incompatible assembly when compiling 32-bit kernel with 64-bit toolchain.
So what ISA is set for gas without this patch? With what GCC version?
I'm not sure, how do I find that out?

gcc --version
gcc -v <rest of command>, look at the command line options passed to as make something.s, look at what .machine is set (if any).

Quoted 4 lines

Quoted 1 line
And, why is that wrong?
Some 32-bit platforms and CPU types do not provide -mcpu, so I assume for 32-bit toolchains that must result in the "powerpc" machine. With

It results in whatever is the default for that toolchain. Depends on many things.

Quoted 9 lines

64-bit toolchains
arch/powerpc/mm/hash_low_32.S:353: Error: missing operand
Which is,
tlbie r4
Is that v2.06?

The original ISA did not have the L field, 2.xx does, for any xx even I think.

Segher

Segher Boessenkool

2018-05-10 14:52 UTC #5 lore raw

Re: [PATCH v2 1/5] powerpc/kbuild: set default generic machine type for 32-bit compile

In reply to Nicholas Piggin

Quoted 5 lines · Nicholas Piggin

The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit powerpc machine type and scheduling model. 32-bit platforms and CPUs can override this with -mcpu= options that come later on the command line.

So it turns out your compiler was configured with --with-cpu=power8; it's not that GCC defaults are bad, but who built your compiler overrode the defaults.

If the problem only happens in .S files, it might be better to put .machine directives in those. But your patch should work too, yes.

Segher

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #6 lore raw

PATCH v2 2/5 powerpc/kbuild: remove CROSS32 defines from top level powerpc Makefile

In reply to Nicholas Piggin

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 <[email protected]>

---
 arch/powerpc/Makefile               | 12 ------------
 arch/powerpc/boot/Makefile          | 16 +++++++++++-----
 arch/powerpc/kernel/vdso32/Makefile | 15 +++++++++++----
 3 files changed, 22 insertions(+), 21 deletions(-)

arch/powerpc/Makefile +0 ~~-12~~

index 7034b1ad50e0..a40f59ca2afe 100644
@@ -17,16 +17,6 @@ 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
-endif
-endif
-
 ifdef CONFIG_PPC32
 # These options will be overridden by any -mcpu option that comes
 # later on the command line, but they are needed to set a sane

@@ -35,8 +25,6 @@ KBUILD_CFLAGS		+= -mcpu=powerpc
 KBUILD_AFLAGS		+= -mcpu=powerpc
 endif
 
-export CROSS32CC CROSS32AR
-
 ifeq ($(CROSS_COMPILE),)
 KBUILD_DEFCONFIG := $(shell uname -m)_defconfig
 else

arch/powerpc/boot/Makefile +11 -5

index 26d5d2a5b8e9..49767e06202c 100644
@@ -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)

arch/powerpc/kernel/vdso32/Makefile +11 -4

index b8c434d1d459..50112d4473bb 100644
@@ -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 $@

Signature · 1 line

2.17.0

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #7 lore raw

PATCH v2 3/5 kbuild: call cc-option with the current set of KBUILD_CFLAGS

In reply to Nicholas Piggin

In some cases, the options that gcc will accept depend on options it has already been given. For example -m32 / -m64 and -mbig-endian / -mlittle-endian can have this affect.

Passing in KBUILD_CFLAGS to cc-option allows an architecture to set such basic machine types at the beginning, rather than override CC itself.

Signed-off-by Nicholas Piggin <[email protected]>

---
 scripts/Kbuild.include | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

scripts/Kbuild.include +4 -4

index 9f7eb10079cc..66869bb815d2 100644
@@ -121,7 +121,7 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
 cc-option = $(call __cc-option, $(CC),\
-	$(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
+	$(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
 
 # hostcc-option
 # Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)

@@ -131,12 +131,12 @@ hostcc-option = $(call __cc-option, $(HOSTCC),\
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
+	$(CC) -Werror $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
 
 # cc-disable-warning
 # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
 cc-disable-warning = $(call try-run,\
-	$(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
+	$(CC) -Werror $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
 # cc-name
 # Expands to either gcc or clang

@@ -160,7 +160,7 @@ cc-if-fullversion = $(shell [ $(cc-fullversion) $(1) $(2) ] && echo $(3) || echo
 # cc-ldoption
 # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
 cc-ldoption = $(call try-run,\
-	$(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
+	$(CC) $(1) $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
 
 # ld-option
 # Usage: LDFLAGS += $(call ld-option, -X)

Signature · 1 line

2.17.0

Masahiro Yamada

2018-05-10 05:30 UTC #8 lore raw

Re: [PATCH v2 3/5] kbuild: call cc-option with the current set of KBUILD_CFLAGS

2018-05-10 14:16 GMT+09:00 Nicholas Piggin <[email protected]>:

Quoted 3 lines

In some cases, the options that gcc will accept depend on options it has already been given. For example -m32 / -m64 and -mbig-endian / -mlittle-endian can have this affect.

Is cc-option not working for you?

Quoted 3 lines

Passing in KBUILD_CFLAGS to cc-option allows an architecture to set such basic machine types at the beginning, rather than override CC itself.

KBUILD_CFLAGS is passed to cc-option already
because CC_OPTION_CFLAGS includes it:

CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))

This patch drops KBUILD_CPPFLAGS,
and adds KBUILD_CFLAGS twice, doesn't it?

Quoted 49 lines

Signed-off-by Nicholas Piggin <[email protected]>

---
 scripts/Kbuild.include | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

scripts/Kbuild.include +4 -5

index 9f7eb10079cc..66869bb815d2 100644
@@ -121,7 +121,7 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
 cc-option = $(call __cc-option, $(CC),\
-       $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
+       $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
 
 # hostcc-option
 # Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)

@@ -131,12 +131,12 @@ hostcc-option = $(call __cc-option, $(HOSTCC),\
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\
-       $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
+       $(CC) -Werror $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
 
 # cc-disable-warning
 # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
 cc-disable-warning = $(call try-run,\
-       $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
+       $(CC) -Werror $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
 # cc-name
 # Expands to either gcc or clang

@@ -160,7 +160,7 @@ cc-if-fullversion = $(shell [ $(cc-fullversion) $(1) $(2) ] && echo $(3) || echo
 # cc-ldoption
 # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
 cc-ldoption = $(call try-run,\
-       $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
+       $(CC) $(1) $(KBUILD_CFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
 
 # ld-option
 # Usage: LDFLAGS += $(call ld-option, -X)
--

2.17.0

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

Signature · 2 lines

Best Regards
Masahiro Yamada

Nicholas Piggin

author reviewer

2018-05-10 06:09 UTC #9 lore raw

Re: [PATCH v2 3/5] kbuild: call cc-option with the current set of KBUILD_CFLAGS

Quoted 6 lines · On Thu, 10 May 2018 14:29:49 +0900 Masahiro Yamada…

2018-05-10 14:16 GMT+09:00 Nicholas Piggin <[email protected]>:
Quoted 3 lines
In some cases, the options that gcc will accept depend on options it has already been given. For example -m32 / -m64 and -mbig-endian / -mlittle-endian can have this affect.
Is cc-option not working for you?

I thought it wasn't, but now I try again and it does work, sorry for the noise. The bug must have been something in my previous series. This series seems to work just as well after I remove this patch.

Thanks,
Nick

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #10 lore raw

PATCH v2 4/5 powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS

In reply to Nicholas Piggin

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 thse flags works for this purpose.

Unfortunately that is not compatible with the way the proposed new Kconfig macro language will work.

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

Signed-off-by Nicholas Piggin <[email protected]>

---
 arch/powerpc/Makefile   | 16 +++++++++-------
 scripts/recordmcount.pl |  8 ++++++++
 2 files changed, 17 insertions(+), 7 deletions(-)

arch/powerpc/Makefile +9 -7

index a40f59ca2afe..5f3ec8029e50 100644
@@ -70,13 +70,15 @@ 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

@@ -89,19 +91,19 @@ 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

scripts/recordmcount.pl +8 -0

index 191eb949d52c..919711dd9d6c 100755
@@ -274,6 +274,14 @@ if ($arch eq "x86_64") {
     if ($bits == 64) {
 	$type = ".quad";
     }
+    $ld .= " -EB ";
+    if ($endian eq "big") {
+	    $cc .= " -mbig-endian ";
+	    $ld .= " -EB ";
+    } else {
+	    $cc .= " -mlittle-endian ";
+	    $ld .= " -EL ";
+    }
 
 } elsif ($arch eq "arm") {
     $alignment = 2;

Signature · 1 line

2.17.0

Michael Ellerman

reviewer

2018-05-10 13:03 UTC #11 lore raw

Re: [PATCH v2 4/5] powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS

Quoted 12 lines · Nicholas Piggin

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 thse flags works for this purpose.
Unfortunately that is not compatible with the way the proposed new Kconfig macro language will work.

Quoted 7 lines

After previous patches in this series, these flags can be carefully passed in using flags instead.
Signed-off-by Nicholas Piggin <[email protected]>
---
 arch/powerpc/Makefile   | 16 +++++++++-------
 scripts/recordmcount.pl |  8 ++++++++

We should probably at least Cc Rostedt on the recordmcount.pl change.

scripts/recordmcount.pl if ($arch eq "x86_64") {

Quoted 5 lines

scripts/recordmcount.pl +0 -0

index 191eb949d52c..919711dd9d6c 100755
@@ -274,6 +274,14 @@ if ($arch eq "x86_64") {

Despite what the above says you're patching the powerpc entry AFAICS, so I guess that's pretty harmless.

scripts/recordmcount.pl if ($arch eq "x86_64") { · line 280

Quoted 7 lines

scripts/recordmcount.pl +4 -0

     if ($bits == 64) {
 	$type = ".quad";
     }
+    $ld .= " -EB ";
+    if ($endian eq "big") {
+	    $cc .= " -mbig-endian ";
+	    $ld .= " -EB ";

Don't we end up with two "-EB"s for the big endian case?

Or do I understand perl even less than I thought I did?

scripts/recordmcount.pl if ($arch eq "x86_64") { · line 287

Quoted 7 lines

scripts/recordmcount.pl +4 -0

+    } else {
+	    $cc .= " -mlittle-endian ";
+	    $ld .= " -EL ";
+    }
 
 } elsif ($arch eq "arm") {
     $alignment = 2;

cheers

Nicholas Piggin

author reviewer

2018-05-10 13:11 UTC #12 lore raw

Re: [PATCH v2 4/5] powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS

Quoted 17 lines · On Thu, 10 May 2018 23:03:08 +1000 Michael Ellerman <[email protected]> wrote:

Quoted 15 lines · Nicholas Piggin
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 thse flags works for this purpose.
Unfortunately that is not compatible with the way the proposed new Kconfig macro language will work.
After previous patches in this series, these flags can be carefully passed in using flags instead.

Quoted 6 lines

Quoted 4 lines
Signed-off-by Nicholas Piggin <[email protected]>
---
 arch/powerpc/Makefile   | 16 +++++++++-------
 scripts/recordmcount.pl |  8 ++++++++  
We should probably at least Cc Rostedt on the recordmcount.pl change.

Sure I'll send another iteration after some more time for reviews and cc him on it.

Quoted 9 lines

scripts/recordmcount.pl if ($arch eq "x86_64") {
Quoted 6 lines
scripts/recordmcount.pl +0 -0
index 191eb949d52c..919711dd9d6c 100755
@@ -274,6 +274,14 @@ if ($arch eq "x86_64") {  
Despite what the above says you're patching the powerpc entry AFAICS, so I guess that's pretty harmless.

Yeah I didn't think it was worth a separate patch.

Quoted 11 lines

scripts/recordmcount.pl if ($arch eq "x86_64") { · line 280
Quoted 8 lines
scripts/recordmcount.pl +4 -0
     if ($bits == 64) {
 	$type = ".quad";
     }
+    $ld .= " -EB ";
+    if ($endian eq "big") {
+	    $cc .= " -mbig-endian ";
+	    $ld .= " -EB ";  
Don't we end up with two "-EB"s for the big endian case?

Quoted 1 line

Or do I understand perl even less than I thought I did?

No I was testing things and that's leaked into the commit. Good eye. I think it worked for le because the next -EL will override the first -EB, but I'll take that out.

Thanks,
Nick

Nicholas Piggin

author reviewer

2018-05-10 05:17 UTC #13 lore raw

PATCH v2 5/5 powerpc/kbuild: move -mprofile-kernel check to Kconfig

In reply to Nicholas Piggin

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 <[email protected]>

---
 arch/powerpc/Kconfig                            | 16 +---------------
 arch/powerpc/Makefile                           | 14 ++------------
 arch/powerpc/tools/gcc-check-mprofile-kernel.sh |  4 ++--
 3 files changed, 5 insertions(+), 29 deletions(-)

arch/powerpc/Kconfig +1 ~~-15~~

index 512fcc177c87..af527f894f9b 100644
@@ -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

arch/powerpc/Makefile +2 ~~-12~~

index 5f3ec8029e50..9f69b1599c61 100644
@@ -156,18 +156,8 @@ 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)

arch/powerpc/tools/gcc-check-mprofile-kernel.sh +2 -2

index 061f8035bdbe..ec4486a9c4a3 100755
@@ -10,13 +10,13 @@ set -o pipefail
 # 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 | \
+    $* -m64 -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 | \
+    $* -m64 -S -x c -O2 -p -mprofile-kernel - -o - 2> /dev/null | \
     grep -q "_mcount" && \
     exit 1

Signature · 1 line

2.17.0