samples/seccomp: fix dependencies on arch macros
This change fixes the compilation error triggered here for
i386 allmodconfig in linux-next:
http://kisskb.ellerman.id.au/kisskb/buildresult/6123842/
Logic attempting to predict the host architecture has been
removed from the Makefile. Instead, the bpf-direct sample
should now compile on any architecture, but if the architecture
is not supported, it will compile a minimal main() function.
This change also ensures the samples are not compiled when
there is no seccomp filter support.
(Note, I wasn't able to reproduce the error locally, but
the existing approach was clearly flawed. This tweak
should resolve your issue and avoid other future weirdness.)
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Will Drewry <wad@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/samples/seccomp/bpf-direct.c b/samples/seccomp/bpf-direct.c
index 26f523e..151ec3f 100644
--- a/samples/seccomp/bpf-direct.c
+++ b/samples/seccomp/bpf-direct.c
@@ -8,6 +8,11 @@
* and can serve as a starting point for developing
* applications using prctl(PR_SET_SECCOMP, 2, ...).
*/
+#if defined(__i386__) || defined(__x86_64__)
+#define SUPPORTED_ARCH 1
+#endif
+
+#if defined(SUPPORTED_ARCH)
#define __USE_GNU 1
#define _GNU_SOURCE 1
@@ -43,8 +48,6 @@
#define REG_ARG3 REG_R10
#define REG_ARG4 REG_R8
#define REG_ARG5 REG_R9
-#else
-#error Unsupported platform
#endif
#ifndef PR_SET_NO_NEW_PRIVS
@@ -174,3 +177,14 @@
payload("Error message going to STDERR\n"));
return 0;
}
+#else /* SUPPORTED_ARCH */
+/*
+ * This sample is x86-only. Since kernel samples are compiled with the
+ * host toolchain, a non-x86 host will result in using only the main()
+ * below.
+ */
+int main(void)
+{
+ return 1;
+}
+#endif /* SUPPORTED_ARCH */