GCC 3.3.x/3.4 compatiblity fix in include/linux/init.h

Hello,

GCC 3.4 miscompiles the kernel because it silently optimizes away data placed in the .init.setup section by the __setup() macro.

I've initially reported it as a 3.4 regression, but it turned out to be correct behavior:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12324

__attribute__((unused)) does only avoid the warning, but doesn't mark the data as being used.

Since GCC 3.3, __attribute__((used)) can also be applied to variables. The __attribute_used__ macro from linux/compiler.h already takes care of compiler differences for us.

In this patch, I've gone a step further and proactively fixed that in all places.

Please apply.

@@ -43,12 +43,12 @@

#define __init __attribute__ ((__section__ (".init.text")))
#define __initdata __attribute__ ((__section__ (".init.data")))
#define __exitdata __attribute__ ((__section__(".exit.data")))
-#define __exit_call __attribute__ ((unused,__section__ (".exitcall.exit")))
+#define __exit_call __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))

#ifdef MODULE
#define __exit __attribute__ ((__section__(".exit.text")))
#else
-#define __exit __attribute__ ((unused,__section__(".exit.text")))
+#define __exit __attribute_used__ __attribute__ ((__section__(".exit.text")))
#endif

/* For assembly routines */
@@ -79,7 +79,8 @@ extern initcall_t __security_initcall_st
*/

#define __define_initcall(level,fn) \
- static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".initcall" level ".init"))) = fn
+ static initcall_t __initcall_##fn __attribute_used__ \
+ __attribute__((__section__(".initcall" level ".init"))) = fn

#define core_initcall(fn) __define_initcall("1",fn)
#define postcore_initcall(fn) __define_initcall("2",fn)
@@ -91,14 +92,16 @@ extern initcall_t __security_initcall_st

#define __initcall(fn) device_initcall(fn)

-#define __exitcall(fn) \
+#define __exitcall(fn) \
static exitcall_t __exitcall_##fn __exit_call = fn

#define console_initcall(fn) \
- static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".con_initcall.init")))=fn
+ static initcall_t __initcall_##fn \
+ __attribute_used__ __attribute__((__section__(".con_initcall.init")))=fn

#define security_initcall(fn) \
- static initcall_t __initcall_##fn __attribute__ ((unused,__section__ (".security_initcall.init"))) = fn
+ static initcall_t __initcall_##fn \
+ __attribute_used__ __attribute__((__section__(".security_initcall.init"))) = fn

struct obs_kernel_param {
	const char *str;

@@ -106,10 +109,11 @@ struct obs_kernel_param {
};

/* OBSOLETE: see moduleparam.h for the right way. */
-#define __setup(str, fn) \
- static char __setup_str_##fn[] __initdata = str; \
- static struct obs_kernel_param __setup_##fn \
- __attribute__((unused,__section__ (".init.setup"))) \
+#define __setup(str, fn) \
+ static char __setup_str_##fn[] __initdata = str; \
+ static struct obs_kernel_param __setup_##fn \
+ __attribute_used__ \

+		 __attribute__((__section__(".init.setup")))	\
		= { __setup_str_##fn, fn }

#endif /* __ASSEMBLY__ */

 // Bernardo Innocenti - Develer S.r.l., R&D dept.
\X/  http://www.develer.com/

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