[PATCH 2/3] powerpc: allow compilation on cross-endian toolchain

[Nicholas Piggin]

On Sat, 26 Nov 2016 18:30:15 +1100
Michael Ellerman <mpe at ellerman.id.au> wrote:

> Nicholas Piggin <npiggin at gmail.com> writes:
> > On Thu, 24 Nov 2016 00:02:08 +1100
> > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> > index 617dece..8828807 100644
> > --- a/arch/powerpc/Makefile
> > +++ b/arch/powerpc/Makefile
> > @@ -73,13 +73,18 @@ MULTIPLEWORD	:= -mmultiple
> >  endif
> >  
> >  cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
> > +cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
> > +cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mcall-aixdesc)  
> 
> This blew up the world:
> 
>   http://kisskb.ellerman.id.au/kisskb/head/1ba4cb3d67e181bdc9a911d7be81f64e3d7597d2/
> 
>   Successful:	24% 63/258
> 
> I suspect you need to make -mcall-aixdesc 64-bit only.

Yes, I forgot 32-bit will pick those up. 3rd time's a charm, this compiles
64 bit be/le and 32-bit now.

--

Subject: [PATCH] powerpc: allow compilation on cross-endian toolchain

GCC can compile with either endian, but the ABI version always
defaults to the default endian. Alan Modra says:

  you need both -mbig and -mabi=elfv1 to make a powerpc64le gcc
  generate powerpc64 code

The opposite is true for powerpc64 when generating -mlittle it
requires -mabi=elfv2 to generate v2 ABI. This change adds ABI
annotations together with endianness. The kernel with ELFv2 ABI
also uses -mcall-aixdesc, but boot/ does not.

Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
---
 arch/powerpc/Makefile      | 11 ++++++++++-
 arch/powerpc/boot/Makefile |  4 +++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 617dece..a60c9c6 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -72,8 +72,15 @@ GNUTARGET	:= powerpc
 MULTIPLEWORD	:= -mmultiple
 endif
 
-cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
+ifdef CONFIG_PPC64
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mcall-aixdesc)
+aflags-$(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-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mno-strict-align
 endif
@@ -113,7 +120,9 @@ ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2,$(call cc-option,-mcall-aixdesc))
 AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2)
 else
+CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcall-aixdesc)
+AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 endif
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcmodel=medium,$(call cc-option,-mminimal-toc))
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mno-pointers-to-nested-functions)
diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index eae2dc8..7c46cf3 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -28,14 +28,16 @@ BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		 -isystem $(shell $(CROSS32CC) -print-file-name=include) \
 		 -D$(compress-y)
 
+# PPC64_BOOT_WRAPPER is little-endian specific.
 ifdef CONFIG_PPC64_BOOT_WRAPPER
 BOOTCFLAGS	+= -m64
+BOOTCFLAGS	+= $(call cc-option,-mabi=elfv2)
 endif
+
 ifdef CONFIG_CPU_BIG_ENDIAN
 BOOTCFLAGS	+= -mbig-endian
 else
 BOOTCFLAGS	+= -mlittle-endian
-BOOTCFLAGS	+= $(call cc-option,-mabi=elfv2)
 endif
 
 BOOTAFLAGS	:= -D__ASSEMBLY__ $(BOOTCFLAGS) -traditional -nostdinc
-- 
2.10.2