BACKPORT: x86/retpoline: Avoid retpolines for built-in __init functions
There's no point in building init code with retpolines, since it runs before
any potentially hostile userspace does. And before the retpoline is actually
ALTERNATIVEd into place, for much of it.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: karahmed@amazon.de
Cc: peterz@infradead.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1517484441-1420-2-git-send-email-dwmw@amazon.co.uk
Conflicts:
include/linux/init.h
BUG=chromium:805584, chromium:799480, chromium:797974
TEST=Build and boot
Change-Id: If1920469137fada69addcc18a10cbbfd8ae238ad
Signed-off-by: Guenter Roeck <groeck@chromium.org>
(cherry picked from commit 66f793099a636862a71c59d4a6ba91387b155e0c)
(cherry picked from commit ca1a3fd60368a697ef6d6669ffbdf3754519c233)
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/922933
Reviewed-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/include/linux/init.h b/include/linux/init.h
index 432ff22..090d960 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -4,6 +4,13 @@
#include <linux/compiler.h>
#include <linux/types.h>
+/* Built-in __init functions needn't be compiled with retpoline */
+#if defined(RETPOLINE) && !defined(MODULE)
+#define __noretpoline __attribute__((indirect_branch("keep")))
+#else
+#define __noretpoline
+#endif
+
/* These macros are used to mark some functions or
* initialized data (doesn't apply to uninitialized data)
* as `initialization' functions. The kernel can take this
@@ -39,7 +46,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
-#define __init __section(.init.text) __cold notrace
+#define __init __section(.init.text) __cold notrace __noretpoline
#define __initdata __section(.init.data)
#define __initconst __constsection(.init.rodata)
#define __exitdata __section(.exit.data)
