fork: Use clone if arch does not have the fork syscall

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/sysdeps/linux/common/fork.c

@@ -9,14 +9,34 @@
 
 #include <sys/syscall.h>
 
-#if defined __NR_fork && defined __ARCH_USE_MMU__
+#if defined __ARCH_USE_MMU__
 # include <unistd.h>
-# include <cancel.h>
+extern __typeof(fork) __libc_fork;
+# if defined __NR_fork
+#  include <cancel.h>
+#  define __NR___libc_fork __NR_fork
 _syscall0(pid_t, fork)
+
+# elif defined __NR_clone  && !defined __NR_fork
+#  include <sys/types.h>
+#  include <signal.h>
+#  include <stddef.h>
+pid_t fork(void)
+{
+	pid_t pid = INLINE_SYSCALL(clone, 4, SIGCHLD, NULL, NULL, NULL);
+
+	if (pid < 0)
+		return -1;
+
+	return pid;
+}
+
+# endif
 # ifdef __UCLIBC_HAS_THREADS__
 strong_alias(fork,__libc_fork)
 libc_hidden_weak(fork)
 # else
 libc_hidden_def(fork)
 # endif
+
 #endif

libc/sysdeps/linux/common/stubs.c

@@ -128,7 +128,7 @@ make_stub(fgetxattr)
 make_stub(flistxattr)
 #endif
 
-#ifndef __NR_fork
+#if !defined __NR_fork && !defined __NR_clone
 make_stub(fork)
 #endif