+#ifndef PSI_HAVE_FFI_CLOSURE_ALLOC
+# if HAVE_UNISTD_H
+# include <unistd.h>
+# endif
+# if HAVE_SYS_MMAN_H
+# include <sys/mman.h>
+# ifndef MAP_ANONYMOUS
+# define MAP_ANONYMOUS MAP_ANON
+# endif
+# endif
+#endif
+
+static void *psi_ffi_closure_alloc(size_t s, void **code)
+{
+#ifdef PSI_HAVE_FFI_CLOSURE_ALLOC
+ return ffi_closure_alloc(s, code);
+#elif HAVE_MMAP
+ *code = mmap(NULL, s, PROT_EXEC|PROT_WRITE|PROT_READ,
+ MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+ if (MAP_FAILED == *code) {
+ return NULL;
+ }
+ return *code;
+#else
+ return NULL;
+#endif
+}
+
+static void psi_ffi_closure_free(void *c)
+{
+#ifdef PSI_HAVE_FFI_CLOSURE_ALLOC
+ ffi_closure_free(c);
+#elif HAVE_MMAP
+ munmap(c, sizeof(ffi_closure));
+#endif
+}
+