v4.19.13 snapshot.
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
new file mode 100644
index 0000000..3f02d42
--- /dev/null
+++ b/arch/um/os-Linux/helper.c
@@ -0,0 +1,164 @@
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sched.h>
+#include <linux/limits.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <kern_util.h>
+#include <os.h>
+#include <um_malloc.h>
+
+struct helper_data {
+ void (*pre_exec)(void*);
+ void *pre_data;
+ char **argv;
+ int fd;
+ char *buf;
+};
+
+static int helper_child(void *arg)
+{
+ struct helper_data *data = arg;
+ char **argv = data->argv;
+ int err, ret;
+
+ if (data->pre_exec != NULL)
+ (*data->pre_exec)(data->pre_data);
+ err = execvp_noalloc(data->buf, argv[0], argv);
+
+ /* If the exec succeeds, we don't get here */
+ CATCH_EINTR(ret = write(data->fd, &err, sizeof(err)));
+
+ return 0;
+}
+
+/* Returns either the pid of the child process we run or -E* on failure. */
+int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv)
+{
+ struct helper_data data;
+ unsigned long stack, sp;
+ int pid, fds[2], ret, n;
+
+ stack = alloc_stack(0, __cant_sleep());
+ if (stack == 0)
+ return -ENOMEM;
+
+ ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
+ if (ret < 0) {
+ ret = -errno;
+ printk(UM_KERN_ERR "run_helper : pipe failed, errno = %d\n",
+ errno);
+ goto out_free;
+ }
+
+ ret = os_set_exec_close(fds[1]);
+ if (ret < 0) {
+ printk(UM_KERN_ERR "run_helper : setting FD_CLOEXEC failed, "
+ "ret = %d\n", -ret);
+ goto out_close;
+ }
+
+ sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
+ data.pre_exec = pre_exec;
+ data.pre_data = pre_data;
+ data.argv = argv;
+ data.fd = fds[1];
+ data.buf = __cant_sleep() ? uml_kmalloc(PATH_MAX, UM_GFP_ATOMIC) :
+ uml_kmalloc(PATH_MAX, UM_GFP_KERNEL);
+ pid = clone(helper_child, (void *) sp, CLONE_VM, &data);
+ if (pid < 0) {
+ ret = -errno;
+ printk(UM_KERN_ERR "run_helper : clone failed, errno = %d\n",
+ errno);
+ goto out_free2;
+ }
+
+ close(fds[1]);
+ fds[1] = -1;
+
+ /*
+ * Read the errno value from the child, if the exec failed, or get 0 if
+ * the exec succeeded because the pipe fd was set as close-on-exec.
+ */
+ n = read(fds[0], &ret, sizeof(ret));
+ if (n == 0) {
+ ret = pid;
+ } else {
+ if (n < 0) {
+ n = -errno;
+ printk(UM_KERN_ERR "run_helper : read on pipe failed, "
+ "ret = %d\n", -n);
+ ret = n;
+ }
+ CATCH_EINTR(waitpid(pid, NULL, __WALL));
+ }
+
+out_free2:
+ kfree(data.buf);
+out_close:
+ if (fds[1] != -1)
+ close(fds[1]);
+ close(fds[0]);
+out_free:
+ free_stack(stack, 0);
+ return ret;
+}
+
+int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
+ unsigned long *stack_out)
+{
+ unsigned long stack, sp;
+ int pid, status, err;
+
+ stack = alloc_stack(0, __cant_sleep());
+ if (stack == 0)
+ return -ENOMEM;
+
+ sp = stack + UM_KERN_PAGE_SIZE - sizeof(void *);
+ pid = clone(proc, (void *) sp, flags, arg);
+ if (pid < 0) {
+ err = -errno;
+ printk(UM_KERN_ERR "run_helper_thread : clone failed, "
+ "errno = %d\n", errno);
+ return err;
+ }
+ if (stack_out == NULL) {
+ CATCH_EINTR(pid = waitpid(pid, &status, __WALL));
+ if (pid < 0) {
+ err = -errno;
+ printk(UM_KERN_ERR "run_helper_thread - wait failed, "
+ "errno = %d\n", errno);
+ pid = err;
+ }
+ if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0))
+ printk(UM_KERN_ERR "run_helper_thread - thread "
+ "returned status 0x%x\n", status);
+ free_stack(stack, 0);
+ } else
+ *stack_out = stack;
+ return pid;
+}
+
+int helper_wait(int pid)
+{
+ int ret, status;
+ int wflags = __WALL;
+
+ CATCH_EINTR(ret = waitpid(pid, &status, wflags));
+ if (ret < 0) {
+ printk(UM_KERN_ERR "helper_wait : waitpid process %d failed, "
+ "errno = %d\n", pid, errno);
+ return -errno;
+ } else if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+ printk(UM_KERN_ERR "helper_wait : process %d exited with "
+ "status 0x%x\n", pid, status);
+ return -ECHILD;
+ } else
+ return 0;
+}