[RFC v5 04/21] um: host: implement os_initcalls and os_exitcalls

[Hajime Tazaki]

From: Octavian Purdila <tavi at cs.pub.ro>

This patch implements the init and exit calls for host code. It uses
the automatic __start_<section> and __stop_<section> variables that
are defined by gcc / ld when using custom sections.

Note that this patch should be merged with "um: move arch/um/os-Linux
dir to tools/um" but for now it is separate to make the review easier.

Signed-off-by: Octavian Purdila <tavi at cs.pub.ro>
---
 tools/um/uml/util.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/um/uml/util.c b/tools/um/uml/util.c
index ecf2f390fad2..4011b36fee7e 100644
--- a/tools/um/uml/util.c
+++ b/tools/um/uml/util.c
@@ -186,3 +186,29 @@ void os_warn(const char *fmt, ...)
 	vfprintf(stderr, fmt, list);
 	va_end(list);
 }
+
+extern void (*__start_os_exitcalls)(void);
+extern void (*__stop_os_exitcalls)(void);
+
+void os_exitcalls(void)
+{
+	exitcall_t *call;
+
+	call = &__stop_os_exitcalls;
+	while (--call >= &__start_os_exitcalls)
+		(*call)();
+}
+
+extern int (*__start_os_initcalls)(void);
+extern int (*__stop_os_initcalls)(void);
+
+int os_initcalls(void)
+{
+	initcall_t *call;
+
+	call = &__stop_os_initcalls;
+	while (--call >= &__start_os_initcalls)
+		(*call)();
+
+	return 0;
+}
-- 
2.21.0 (Apple Git-122.2)