1 files changed, 125 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/map_populate.c b/tools/testing/selftests/mm/map_populate.c
new file mode 100644
index 000000000000..9df2636c829b
--- /dev/null
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018 Dmitry Safonov, Arista Networks
+ *
+ * MAP_POPULATE | MAP_PRIVATE should COW VMA pages.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "../kselftest.h"
+
+#include "vm_util.h"
+
+#define MMAP_SZ		4096
+
+#define BUG_ON(condition, description)						\
+	do {									\
+		if (condition)							\
+			ksft_exit_fail_msg("[FAIL]\t%s:%d\t%s:%s\n",		\
+					   __func__, __LINE__, (description),	\
+					   strerror(errno));			\
+	} while (0)
+
+#define TESTS_IN_CHILD 2
+
+static void parent_f(int sock, unsigned long *smap, int child)
+{
+	int status, ret;
+
+	ret = read(sock, &status, sizeof(int));
+	BUG_ON(ret <= 0, "read(sock)");
+
+	*smap = 0x22222BAD;
+	ret = msync(smap, MMAP_SZ, MS_SYNC);
+	BUG_ON(ret, "msync()");
+
+	ret = write(sock, &status, sizeof(int));
+	BUG_ON(ret <= 0, "write(sock)");
+
+	waitpid(child, &status, 0);
+
+	/* The ksft macros don't keep counters between processes */
+	ksft_cnt.ksft_pass = WEXITSTATUS(status);
+	ksft_cnt.ksft_fail = TESTS_IN_CHILD - WEXITSTATUS(status);
+}
+
+static int child_f(int sock, unsigned long *smap, int fd)
+{
+	int ret, buf = 0;
+
+	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_POPULATE, fd, 0);
+	BUG_ON(smap == MAP_FAILED, "mmap()");
+
+	BUG_ON(*smap != 0xdeadbabe, "MAP_PRIVATE | MAP_POPULATE changed file");
+
+	ret = write(sock, &buf, sizeof(int));
+	BUG_ON(ret <= 0, "write(sock)");
+
+	ret = read(sock, &buf, sizeof(int));
+	BUG_ON(ret <= 0, "read(sock)");
+
+	ksft_test_result(*smap != 0x22222BAD, "MAP_POPULATE COW private page\n");
+	ksft_test_result(*smap == 0xdeadbabe, "The mapping state\n");
+
+	/* The ksft macros don't keep counters between processes */
+	return ksft_cnt.ksft_pass;
+}
+
+int main(int argc, char **argv)
+{
+	int sock[2], child, ret;
+	FILE *ftmp;
+	unsigned long *smap;
+
+	ksft_print_header();
+	ksft_set_plan(TESTS_IN_CHILD);
+
+	ftmp = tmpfile();
+	BUG_ON(!ftmp, "tmpfile()");
+
+	ret = ftruncate(fileno(ftmp), MMAP_SZ);
+	if (ret < 0 && errno == ENOENT) {
+		skip_test_dodgy_fs("ftruncate()");
+	}
+	BUG_ON(ret, "ftruncate()");
+
+	smap = mmap(0, MMAP_SZ, PROT_READ | PROT_WRITE,
+			MAP_SHARED, fileno(ftmp), 0);
+	BUG_ON(smap == MAP_FAILED, "mmap()");
+
+	*smap = 0xdeadbabe;
+	/* Probably unnecessary, but let it be. */
+	ret = msync(smap, MMAP_SZ, MS_SYNC);
+	BUG_ON(ret, "msync()");
+
+	ret = socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sock);
+	BUG_ON(ret, "socketpair()");
+
+	child = fork();
+	BUG_ON(child == -1, "fork()");
+
+	if (child) {
+		ret = close(sock[0]);
+		BUG_ON(ret, "close()");
+
+		parent_f(sock[1], smap, child);
+
+		ksft_finished();
+	}
+
+	ret = close(sock[1]);
+	BUG_ON(ret, "close()");
+
+	return child_f(sock[0], smap, fileno(ftmp));
+}