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Commit b99b87f7 authored by Peter Oberparleiter's avatar Peter Oberparleiter Committed by Linus Torvalds
Browse files

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: default avatarPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarWANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e24aca67

include/asm-generic/sections.h

+3 −0
Original line number Diff line number Diff line
@@ -14,6 +14,9 @@ extern char __kprobes_text_start[], __kprobes_text_end[]; 
extern char __initdata_begin[], __initdata_end[];

extern char __start_rodata[], __end_rodata[];



/* Start and end of .ctors section - used for constructor calls. */

extern char __ctors_start[], __ctors_end[];



/* function descriptor handling (if any).  Override

 * in asm/sections.h */

#ifndef dereference_function_descriptor

include/asm-generic/vmlinux.lds.h

+9 −0
Original line number Diff line number Diff line
@@ -440,12 +440,21 @@ 
		INIT_TASK						\

	}



#ifdef CONFIG_CONSTRUCTORS

#define KERNEL_CTORS()	VMLINUX_SYMBOL(__ctors_start) = .; \

			*(.ctors)			   \

			VMLINUX_SYMBOL(__ctors_end) = .;

#else

#define KERNEL_CTORS()

#endif



/* init and exit section handling */

#define INIT_DATA							\

	*(.init.data)							\

	DEV_DISCARD(init.data)						\

	CPU_DISCARD(init.data)						\

	MEM_DISCARD(init.data)						\

	KERNEL_CTORS()							\

	*(.init.rodata)							\

	DEV_DISCARD(init.rodata)					\

	CPU_DISCARD(init.rodata)					\

include/linux/init.h

+3 −0
Original line number Diff line number Diff line
@@ -134,6 +134,9 @@ typedef void (*exitcall_t)(void); 
extern initcall_t __con_initcall_start[], __con_initcall_end[];

extern initcall_t __security_initcall_start[], __security_initcall_end[];



/* Used for contructor calls. */

typedef void (*ctor_fn_t)(void);



/* Defined in init/main.c */

extern int do_one_initcall(initcall_t fn);

extern char __initdata boot_command_line[];

include/linux/module.h

+6 −0
Original line number Diff line number Diff line
@@ -363,6 +363,12 @@ struct module 
	local_t ref;

#endif

#endif



#ifdef CONFIG_CONSTRUCTORS

	/* Constructor functions. */

	ctor_fn_t *ctors;

	unsigned int num_ctors;

#endif

};

#ifndef MODULE_ARCH_INIT

#define MODULE_ARCH_INIT {}

init/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -16,6 +16,11 @@ config DEFCONFIG_LIST 
	default "$ARCH_DEFCONFIG"

	default "arch/$ARCH/defconfig"



config CONSTRUCTORS

	bool

	depends on !UML

	default y



menu "General setup"



config EXPERIMENTAL