selftests: add membarrier syscall test

Add a self test for the membarrier system call.
Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/Makefile

@@ -6,6 +6,7 @@ TARGETS += firmware
 TARGETS += ftrace
 TARGETS += futex
 TARGETS += kcmp
+TARGETS += membarrier
 TARGETS += memfd
 TARGETS += memory-hotplug
 TARGETS += mount

tools/testing/selftests/membarrier/.gitignore

+membarrier_test

tools/testing/selftests/membarrier/Makefile

+CFLAGS += -g -I../../../../usr/include/
+
+all:
+	$(CC) $(CFLAGS) membarrier_test.c -o membarrier_test
+
+TEST_PROGS := membarrier_test
+
+include ../lib.mk
+
+clean:
+	$(RM) membarrier_test

tools/testing/selftests/membarrier/membarrier_test.c

+#define _GNU_SOURCE
+#define __EXPORTED_HEADERS__
+
+#include <linux/membarrier.h>
+#include <asm-generic/unistd.h>
+#include <sys/syscall.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#include "../kselftest.h"
+
+static int sys_membarrier(int cmd, int flags)
+{
+	return syscall(__NR_membarrier, cmd, flags);
+}
+
+static void test_membarrier_fail(void)
+{
+	int cmd = -1, flags = 0;
+
+	if (sys_membarrier(cmd, flags) != -1) {
+		printf("membarrier: Should fail but passed\n");
+		ksft_exit_fail();
+	}
+}
+
+static void test_membarrier_success(void)
+{
+	int flags = 0;
+
+	if (sys_membarrier(MEMBARRIER_CMD_SHARED, flags) != 0) {
+		printf("membarrier: Executing MEMBARRIER failed, %s\n",
+				strerror(errno));
+		ksft_exit_fail();
+	}
+
+	printf("membarrier: MEMBARRIER_CMD_SHARED success\n");
+}
+
+static void test_membarrier(void)
+{
+	test_membarrier_fail();
+	test_membarrier_success();
+}
+
+static int test_membarrier_exists(void)
+{
+	int flags = 0;
+
+	if (sys_membarrier(MEMBARRIER_CMD_QUERY, flags))
+		return 0;
+
+	return 1;
+}
+
+int main(int argc, char **argv)
+{
+	printf("membarrier: MEMBARRIER_CMD_QUERY ");
+	if (test_membarrier_exists()) {
+		printf("syscall implemented\n");
+		test_membarrier();
+	} else {
+		printf("syscall not implemented!\n");
+		return ksft_exit_fail();
+	}
+
+	printf("membarrier: tests done!\n");
+
+	return ksft_exit_pass();
+}