On Fri, Jul 22, 2016 at 11:37:39AM -0300, Arnaldo Carvalho de Melo wrote:

Em Thu, Jul 21, 2016 at 10:41:18PM -0500, Josh Poimboeuf escreveu:

quoted

On Fri, Jul 22, 2016 at 09:23:02AM +1000, Stephen Rothwell wrote:

quoted

It just looks like objtool was not written with cross compilation in
mind?

quoted

I don't know yet what the specific problem is, but objtool should work
fine in a cross-compiled environment.  It needs to be compiled with the
host (powerpc) compiler, but then it needs to disassemble target (x86)
files.  It worked fine before the bitsperlong.h files were merged.

So, trying to summarize from the various messages in this thread:

In Tue, Jul 19, 2016 at 01:26:08PM +1000, Stephen Rothwell wrote:

quoted

It produces these errors (from the x86_64 allmodconfig build):

In file included from
/home/sfr/next/next/tools/arch/x86/include/uapi/asm/bitsperlong.h:10:0,
                 from /usr/include/asm-generic/int-ll64.h:11,
                 from /usr/include/powerpc64le-linux-gnu/asm/types.h:27,
                 from /home/sfr/next/next/tools/include/linux/types.h:9,
                 from /home/sfr/next/next/tools/include/linux/list.h:4,
                 from elf.h:23,
                 from elf.c:30:
/home/sfr/next/next/tools/include/asm-generic/bitsperlong.h:13:2:
error: #error Inconsistent word size. Check asm/bitsperlong.h
 #error Inconsistent word size. Check asm/bitsperlong.h
  ^

So it starts at tools/arch/x86/include/uapi/asm/bitsperlong.h, and as
you mention, this should've instead be using the host headers, i.e.:

   tools/arch/powerpc/include/uapi/asm/bitsperlong.h

Which it will if it uses HOSTARCH in tools/objtool/Makefile when setting
up the header search path, I have two csets in my perf/core branch that
fixes this, and that are equivalent to the last patch Stephen tried:

  $ git log --oneline -2
  87f7dc54366a objtool: Use tools/scripts/Makefile.arch to get ARCH and HOSTARCH
  0eec6770ab60 tools build: Add HOSTARCH Makefile variable
  $ 

Ok, so now it uses the right file, see the whole sequence at the end of this
e-mail, but it boils down to:

-----------------------------------------------------------------------------
#if defined(__powerpc64__)
# define __BITS_PER_LONG 64
#else
# define __BITS_PER_LONG 32
#endif

#ifdef __SIZEOF_LONG__
#define BITS_PER_LONG (__CHAR_BIT__ * __SIZEOF_LONG__)
#else
#define BITS_PER_LONG __WORDSIZE
#endif

#if BITS_PER_LONG != __BITS_PER_LONG
#error Inconsistent word size. Check asm/bitsperlong.h
#endif
-----------------------------------------------------------------------------

Which I think has no problems, right? The last problem reported ty Stephen now is:

In Fri, 22 Jul 2016 09:23:02 +1000, Stephen Rothwell wrote:

quoted

That gets me this errors from the x86_64 allmodconfig build:

quoted

tools/objtool/objtool-in.o: In function `decode_instructions':
tools/objtool/builtin-check.c:276: undefined reference to `arch_decode_instruction'

Should work, since ARCH should be x86 and then tools/objtool/Build will have
this:

objtool-y += arch/$(ARCH)/

Turned into:

objtool-y += arch/x86/

Which will build tools/objtool/arch/x86/decode.c, that will provide that
arch_decode_instruction() function :-\

I.e. with the two patches I mentioned, that are equivalent to the last patch I
sent to Stephen for testing, we would end up with HOSTARCH=powerpc and
ARCH=x86, no?

Thanks for spelling it out, that helped a lot.

I'm guessing Stephen is setting ARCH=x86_64 on the command-line rather
than ARCH=x86.  How about the following patch?  Stephen, can you confirm
this fixes it?  This is on top of Arnaldo's other two fixes here:

  https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git perf/core

From: Josh Poimboeuf <redacted>
Subject: [PATCH] tools build: fix objtool build with ARCH=x86_64

The objtool build fails in a cross-compiled environment on a non-x86
host with "ARCH=x86_64":

  tools/objtool/objtool-in.o: In function `decode_instructions':
  tools/objtool/builtin-check.c:276: undefined reference to `arch_decode_instruction'

We could override the ARCH environment variable and change it back to
x86, similar to what the objtool Makefile was doing before; but it's
tricky to override environment variables consistently.

Instead, take a similar approach used by the Linux top-level Makefile
and introduce a SRCARCH Makefile variable which evaluates to "x86" when
ARCH is either "x86_64" or "x86".

Reported-by: Stephen Rothwell <redacted>
Signed-off-by: Josh Poimboeuf <redacted>
---
 tools/objtool/Build         |  2 +-
 tools/objtool/Makefile      |  2 +-
 tools/scripts/Makefile.arch | 32 ++++++++++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/tools/objtool/Build b/tools/objtool/Build
index 2457916..d6cdece 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build

@@ -1,4 +1,4 @@
-objtool-y += arch/$(ARCH)/
+objtool-y += arch/$(SRCARCH)/
 objtool-y += builtin-check.o
 objtool-y += elf.o
 objtool-y += special.o

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index c9ad80a..577f2d4 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile

@@ -29,7 +29,7 @@ elfshdr := $(shell echo '\#include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | gre
 CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
 
 AWK = awk
-export srctree OUTPUT CFLAGS ARCH AWK
+export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include
 
 $(OBJTOOL_IN): fixdep FORCE

diff --git a/tools/scripts/Makefile.arch b/tools/scripts/Makefile.arch
index 887321c..ad85b92 100644
--- a/tools/scripts/Makefile.arch
+++ b/tools/scripts/Makefile.arch

@@ -5,10 +5,42 @@ HOSTARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
                                   -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
                                   -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \
                                   -e s/tile.*/tile/ )
+
 ifndef ARCH
 ARCH := $(HOSTARCH)
 endif
 
+SRCARCH := $(ARCH)
+
+# Additional ARCH settings for x86
+ifeq ($(ARCH),i386)
+        SRCARCH := x86
+endif
+ifeq ($(ARCH),x86_64)
+        SRCARCH := x86
+endif
+
+# Additional ARCH settings for sparc
+ifeq ($(ARCH),sparc32)
+       SRCARCH := sparc
+endif
+ifeq ($(ARCH),sparc64)
+       SRCARCH := sparc
+endif
+
+# Additional ARCH settings for sh
+ifeq ($(ARCH),sh64)
+       SRCARCH := sh
+endif
+
+# Additional ARCH settings for tile
+ifeq ($(ARCH),tilepro)
+       SRCARCH := tile
+endif
+ifeq ($(ARCH),tilegx)
+       SRCARCH := tile
+endif
+
 LP64 := $(shell echo __LP64__ | ${CC} ${CFLAGS} -E -x c - | tail -n 1)
 ifeq ($(LP64), 1)
   IS_64_BIT := 1