selftests/seccomp: Add powerpc support

Wire up the syscall number and regs so the tests work on powerpc.

With the powerpc kernel support just merged, all tests pass on ppc64,
ppc64 (compat), ppc64le, ppc, ppc64e and ppc64e (compat).
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/seccomp/seccomp_bpf.c

@@ -14,6 +14,7 @@
 #include <linux/filter.h>
 #include <sys/prctl.h>
 #include <sys/ptrace.h>
+#include <sys/types.h>
 #include <sys/user.h>
 #include <linux/prctl.h>
 #include <linux/ptrace.h>
@@ -1205,6 +1206,10 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # define ARCH_REGS	struct user_pt_regs
 # define SYSCALL_NUM	regs[8]
 # define SYSCALL_RET	regs[0]
+#elif defined(__powerpc__)
+# define ARCH_REGS	struct pt_regs
+# define SYSCALL_NUM	gpr[0]
+# define SYSCALL_RET	gpr[3]
 #else
 # error "Do not know how to find your architecture's registers and syscalls"
 #endif
@@ -1238,7 +1243,7 @@ void change_syscall(struct __test_metadata *_metadata,
 	ret = ptrace(PTRACE_GETREGSET, tracee, NT_PRSTATUS, &iov);
 	EXPECT_EQ(0, ret);
 
-#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__)
+#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__) || defined(__powerpc__)
 	{
 		regs.SYSCALL_NUM = syscall;
 	}
@@ -1402,6 +1407,8 @@ TEST_F(TRACE_syscall, syscall_dropped)
 #  define __NR_seccomp 383
 # elif defined(__aarch64__)
 #  define __NR_seccomp 277
+# elif defined(__powerpc__)
+#  define __NR_seccomp 358
 # else
 #  warning "seccomp syscall number unknown for this architecture"
 #  define __NR_seccomp 0xffff