linux-kernel - [PATCH v2] x86: remove LTO_REFERENCE

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Date:	Thu,  7 Jul 2016 09:01:49 -0700
From:	"Luis R. Rodriguez" <mcgrof@...nel.org>
To:	andi@...stfloor.org
Cc:	hpa@...or.com, linux-kernel@...r.kernel.org, x86@...nel.org,
	bp@...en8.de, luto@...capital.net,
	"Luis R. Rodriguez" <mcgrof@...nel.org>
Subject: [PATCH v2] x86: remove LTO_REFERENCE_INITCALL()

The setup for LTO never made it upstream, and although this has
some users, this is now really old stuff for a gcc 4.7 LTO problem.
We know that at least LTO_REFERENCE_INITCALL() work around can
be removed if LTO is not supported on v4.7 anymore.

As per Andi the DISABLE_LTO and LTO_CFLAGS are still neeeded though.

Tested-by: 0-day
Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
---
 include/linux/init.h | 20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 1e5c131d5c9a..aa662ad80d9c 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -151,23 +151,6 @@ extern bool initcall_debug;
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_LTO
-/* Work around a LTO gcc problem: when there is no reference to a variable
- * in a module it will be moved to the end of the program. This causes
- * reordering of initcalls which the kernel does not like.
- * Add a dummy reference function to avoid this. The function is
- * deleted by the linker.
- */
-#define LTO_REFERENCE_INITCALL(x) \
-	; /* yes this is needed */			\
-	static __used __exit void *reference_##x(void)	\
-	{						\
-		return &x;				\
-	}
-#else
-#define LTO_REFERENCE_INITCALL(x)
-#endif
-
 /* initcalls are now grouped by functionality into separate 
  * subsections. Ordering inside the subsections is determined
  * by link order. 
@@ -180,8 +163,7 @@ extern bool initcall_debug;
 
 #define __define_initcall(fn, id) \
 	static initcall_t __initcall_##fn##id __used \
-	__attribute__((__section__(".initcall" #id ".init"))) = fn; \
-	LTO_REFERENCE_INITCALL(__initcall_##fn##id)
+	__attribute__((__section__(".initcall" #id ".init"))) = fn;
 
 /*
  * Early initcalls run before initializing SMP.
-- 
2.8.4