kernel: constructor support

Call constructors (gcc-generated initcall-like functions) during kernel
start and module load.  Constructors are e.g.  used for gcov data
initialization.

Disable constructor support for usermode Linux to prevent conflicts with
host glibc.

Signed-off-by: Peter Oberparleiter <[email protected]>
Acked-by: Rusty Russell <[email protected]>
Acked-by: WANG Cong <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Li Wei <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Al Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/init/main.c b/init/main.c
index 0e7aedeaa05f..1a65fdd06318 100644
--- a/init/main.c
+++ b/init/main.c
@@ -720,6 +720,17 @@ asmlinkage void __init start_kernel(void)
 	rest_init();
 }
 
+/* Call all constructor functions linked into the kernel. */
+static void __init do_ctors(void)
+{
+#ifdef CONFIG_CONSTRUCTORS
+	ctor_fn_t *call = (ctor_fn_t *) __ctors_start;
+
+	for (; call < (ctor_fn_t *) __ctors_end; call++)
+		(*call)();
+#endif
+}
+
 int initcall_debug;
 core_param(initcall_debug, initcall_debug, bool, 0644);
 
@@ -800,6 +811,7 @@ static void __init do_basic_setup(void)
 	usermodehelper_init();
 	driver_init();
 	init_irq_proc();
+	do_ctors();
 	do_initcalls();
 }