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samples/seccomp: do not compile when cross compiled

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samples/seccomp relies on the host setting which is not suitable for
crosscompilation and it actually fails when crosscompiling s390 and
powerpc all{yes,mod}config on x86_64 with

samples/seccomp/bpf-helper.h:135:2: error: #error __BITS_PER_LONG value unusable.
 #error __BITS_PER_LONG value unusable.
  ^
In file included from samples/seccomp/bpf-fancy.c:13:0:
samples/seccomp/bpf-fancy.c: In function ‘main’:
samples/seccomp/bpf-fancy.c:38:11: error: ‘__NR_exit’ undeclared (first use in this function)
   SYSCALL(__NR_exit, ALLOW),

and many others. I am doing these for compile testing and it's been
quite useful to catch issues. Crosscompiling sample code on the other
hand doesn't seem all that important so it seems like the easiest way to
simply disable samples/seccomp when crosscompiling.

Fixing this properly is not that easy as Kees explains:
: IIRC, one of the problems is with build ordering problems: the kernel
: headers used by the samples aren't available when cross compiling.

Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Michal Hocko 2018-02-14 10:15:12 +01:00 committed by Kees Cook
parent d057dc4e35
commit 6275ecbcd3
1 changed files with 1 additions and 9 deletions
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10
samples/seccomp/Makefile
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@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
ifndef CROSS_COMPILE
hostprogs-$(CONFIG_SAMPLE_SECCOMP) := bpf-fancy dropper bpf-direct
HOSTCFLAGS_bpf-fancy.o += -I$(objtree)/usr/include
@ -16,7 +17,6 @@ HOSTCFLAGS_bpf-direct.o += -idirafter $(objtree)/include
bpf-direct-objs := bpf-direct.o
# Try to match the kernel target.
ifndef CROSS_COMPILE
ifndef CONFIG_64BIT
# s390 has -m31 flag to build 31 bit binaries
@ -35,12 +35,4 @@ HOSTLOADLIBES_bpf-fancy += $(MFLAG)
HOSTLOADLIBES_dropper += $(MFLAG)
endif
always := $(hostprogs-m)
else
# MIPS system calls are defined based on the -mabi that is passed
# to the toolchain which may or may not be a valid option
# for the host toolchain. So disable tests if target architecture
# is MIPS but the host isn't.
ifndef CONFIG_MIPS
always := $(hostprogs-m)
endif
endif