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-rw-r--r--tools/testing/selftests/mm/map_populate.c113
1 files changed, 113 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..6b8aeaa0bf7a
--- /dev/null
+++ b/tools/testing/selftests/mm/map_populate.c
@@ -0,0 +1,113 @@
+// 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>
+
+#ifndef MMAP_SZ
+#define MMAP_SZ 4096
+#endif
+
+#define BUG_ON(condition, description) \
+ do { \
+ if (condition) { \
+ fprintf(stderr, "[FAIL]\t%s:%d\t%s:%s\n", __func__, \
+ __LINE__, (description), strerror(errno)); \
+ exit(1); \
+ } \
+ } while (0)
+
+static int 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);
+ BUG_ON(!WIFEXITED(status), "child in unexpected state");
+
+ return 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)");
+
+ BUG_ON(*smap == 0x22222BAD, "MAP_POPULATE didn't COW private page");
+ BUG_ON(*smap != 0xdeadbabe, "mapping was corrupted");
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ int sock[2], child, ret;
+ FILE *ftmp;
+ unsigned long *smap;
+
+ ftmp = tmpfile();
+ BUG_ON(ftmp == 0, "tmpfile()");
+
+ ret = ftruncate(fileno(ftmp), MMAP_SZ);
+ 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()");
+
+ return parent_f(sock[1], smap, child);
+ }
+
+ ret = close(sock[1]);
+ BUG_ON(ret, "close()");
+
+ return child_f(sock[0], smap, fileno(ftmp));
+}