[PATCH 14/15] samples/seccomp: be less stupid about cross compiling

[Arnd Bergmann]

The seccomp filters are currently built for the build
host, not for the machine that they are going to run
on, but they are also built for with the -m32 flag
if the kernel is built for a 32 bit machine, both
of which seems rather odd.

It broke allyesconfig on my machine, which is x86-64, but
building for 32 bit ARM, with this error message:

In file included from /usr/include/stdio.h:28:0,
                 from samples/seccomp/bpf-fancy.c:15:
/usr/include/features.h:324:26: fatal error: bits/predefs.h: No such file or directory

because there are no 32 bit libc headers installed on
this machine. We should really be building all the
samples for the target machine rather than the build
host, but since the infrastructure for that appears
to be missing right now, let's be a little bit smarter
and not pass the '-m32' flag to the HOSTCC when cross-
compiling.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Cc: Heiko Carstens <heiko.carstens at de.ibm.com>
Cc: Kees Cook <keescook at chromium.org>
Cc: James Morris <james.l.morris at oracle.com>
---
 samples/seccomp/Makefile |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/samples/seccomp/Makefile b/samples/seccomp/Makefile
index bbbd276..7203e66 100644
--- a/samples/seccomp/Makefile
+++ b/samples/seccomp/Makefile
@@ -19,6 +19,7 @@ bpf-direct-objs := bpf-direct.o
 
 # Try to match the kernel target.
 ifndef CONFIG_64BIT
+ifndef CROSS_COMPILE
 
 # s390 has -m31 flag to build 31 bit binaries
 ifndef CONFIG_S390
@@ -35,6 +36,7 @@ HOSTLOADLIBES_bpf-direct += $(MFLAG)
 HOSTLOADLIBES_bpf-fancy += $(MFLAG)
 HOSTLOADLIBES_dropper += $(MFLAG)
 endif
+endif
 
 # Tell kbuild to always build the programs
 always := $(hostprogs-y)
-- 
1.7.10.4