[PATCH] selftests/seccomp: fix build on older kernels

[Tycho Andersen <tycho@tycho.ws>]

The seccomp selftest goes to some length to build against older kernel
headers, viz. all the #ifdefs at the beginning of the file. 201766a20e30
("ptrace: add PTRACE_GET_SYSCALL_INFO request") introduces some additional
macros, but doesn't do the #ifdef dance. Let's add that dance here to
avoid:

gcc -Wl,-no-as-needed -Wall  seccomp_bpf.c -lpthread -o seccomp_bpf
In file included from seccomp_bpf.c:51:
seccomp_bpf.c: In function ‘tracer_ptrace’:
seccomp_bpf.c:1787:20: error: ‘PTRACE_EVENTMSG_SYSCALL_ENTRY’ undeclared (first use in this function); did you mean ‘PTRACE_EVENT_CLONE’?
  EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kselftest_harness.h:608:13: note: in definition of macro ‘__EXPECT’
  __typeof__(_expected) __exp = (_expected); \
             ^~~~~~~~~
seccomp_bpf.c:1787:2: note: in expansion of macro ‘EXPECT_EQ’
  EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
  ^~~~~~~~~
seccomp_bpf.c:1787:20: note: each undeclared identifier is reported only once for each function it appears in
  EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kselftest_harness.h:608:13: note: in definition of macro ‘__EXPECT’
  __typeof__(_expected) __exp = (_expected); \
             ^~~~~~~~~
seccomp_bpf.c:1787:2: note: in expansion of macro ‘EXPECT_EQ’
  EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
  ^~~~~~~~~
seccomp_bpf.c:1788:6: error: ‘PTRACE_EVENTMSG_SYSCALL_EXIT’ undeclared (first use in this function); did you mean ‘PTRACE_EVENT_EXIT’?
    : PTRACE_EVENTMSG_SYSCALL_EXIT, msg);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
../kselftest_harness.h:608:13: note: in definition of macro ‘__EXPECT’
  __typeof__(_expected) __exp = (_expected); \
             ^~~~~~~~~
seccomp_bpf.c:1787:2: note: in expansion of macro ‘EXPECT_EQ’
  EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
  ^~~~~~~~~
make: *** [Makefile:12: seccomp_bpf] Error 1

Signed-off-by: Tycho Andersen <tycho@tycho.ws>
Fixes: 201766a20e30 ("ptrace: add PTRACE_GET_SYSCALL_INFO request")
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 6ef7f16c4cf5..7f8b5c8982e3 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -199,6 +199,11 @@ struct seccomp_notif_sizes {
 };
 #endif
 
+#ifndef PTRACE_EVENTMSG_SYSCALL_ENTRY
+#define PTRACE_EVENTMSG_SYSCALL_ENTRY	1
+#define PTRACE_EVENTMSG_SYSCALL_EXIT	2
+#endif
+
 #ifndef seccomp
 int seccomp(unsigned int op, unsigned int flags, void *args)
 {
-- 
2.20.1