tests/tcg/multiarch: Add munmap-pthread.c

Add a test to detect races between munmap() and creating new threads.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20221028124227.2354792-3-iii@linux.ibm.com>
[rth: add more return insns]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tests/tcg/multiarch/Makefile.target

@@ -36,6 +36,9 @@ threadcount: LDFLAGS+=-lpthread
 
 signals: LDFLAGS+=-lrt -lpthread
 
+munmap-pthread: CFLAGS+=-pthread
+munmap-pthread: LDFLAGS+=-pthread
+
 # We define the runner for test-mmap after the individual
 # architectures have defined their supported pages sizes. If no
 # additional page sizes are defined we only run the default test.

tests/tcg/multiarch/munmap-pthread.c

@@ -0,0 +1,79 @@
+/* Test that munmap() and thread creation do not race. */
+#include <assert.h>
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+static const char nop_func[] = {
+#if defined(__aarch64__)
+    0xc0, 0x03, 0x5f, 0xd6,     /* ret */
+#elif defined(__alpha__)
+    0x01, 0x80, 0xFA, 0x6B,     /* ret */
+#elif defined(__arm__)
+    0x1e, 0xff, 0x2f, 0xe1,     /* bx lr */
+#elif defined(__riscv)
+    0x67, 0x80, 0x00, 0x00,     /* ret */
+#elif defined(__s390__)
+    0x07, 0xfe,                 /* br %r14 */
+#elif defined(__i386__) || defined(__x86_64__)
+    0xc3,                       /* ret */
+#endif
+};
+
+static void *thread_mmap_munmap(void *arg)
+{
+    volatile bool *run = arg;
+    char *p;
+    int ret;
+
+    while (*run) {
+        p = mmap(NULL, getpagesize(), PROT_READ | PROT_WRITE | PROT_EXEC,
+                 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        assert(p != MAP_FAILED);
+
+        /* Create a small translation block.  */
+        memcpy(p, nop_func, sizeof(nop_func));
+        ((void(*)(void))p)();
+
+        ret = munmap(p, getpagesize());
+        assert(ret == 0);
+    }
+
+    return NULL;
+}
+
+static void *thread_dummy(void *arg)
+{
+    return NULL;
+}
+
+int main(void)
+{
+    pthread_t mmap_munmap, dummy;
+    volatile bool run = true;
+    int i, ret;
+
+    /* Without a template, nothing to test. */
+    if (sizeof(nop_func) == 0) {
+        return EXIT_SUCCESS;
+    }
+
+    ret = pthread_create(&mmap_munmap, NULL, thread_mmap_munmap, (void *)&run);
+    assert(ret == 0);
+
+    for (i = 0; i < 1000; i++) {
+        ret = pthread_create(&dummy, NULL, thread_dummy, NULL);
+        assert(ret == 0);
+        ret = pthread_join(dummy, NULL);
+        assert(ret == 0);
+    }
+
+    run = false;
+    ret = pthread_join(mmap_munmap, NULL);
+    assert(ret == 0);
+
+    return EXIT_SUCCESS;
+}