Commit f922c4ab authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Linus Torvalds

module: allow symbol exports to be disabled

To allow existing C code to be incorporated into the decompressor or the
UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx
declarations into nops, and #define it in places where such exports are
undesirable.  Note that this gets rid of a rather dodgy redefine of
linux/export.h's header guard.

Link: http://lkml.kernel.org/r/20180704083651.24360-3-ard.biesheuvel@linaro.orgSigned-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
Acked-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morris <james.morris@microsoft.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 271ca788
......@@ -23,11 +23,8 @@
* _ctype[] in lib/ctype.c is needed by isspace() of linux/ctype.h.
* While both lib/ctype.c and lib/cmdline.c will bring EXPORT_SYMBOL
* which is meaningless and will cause compiling error in some cases.
* So do not include linux/export.h and define EXPORT_SYMBOL(sym)
* as empty.
*/
#define _LINUX_EXPORT_H
#define EXPORT_SYMBOL(sym)
#define __DISABLE_EXPORTS
#include "misc.h"
#include "error.h"
......
......@@ -24,6 +24,7 @@ KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
-D__NO_FORTIFY \
$(call cc-option,-ffreestanding) \
$(call cc-option,-fno-stack-protector) \
-D__DISABLE_EXPORTS
GCOV_PROFILE := n
KASAN_SANITIZE := n
......
......@@ -66,7 +66,16 @@ extern struct module __this_module;
__attribute__((section("___ksymtab" sec "+" #sym), used)) \
= { (unsigned long)&sym, __kstrtab_##sym }
#if defined(__KSYM_DEPS__)
#if defined(__DISABLE_EXPORTS)
/*
* Allow symbol exports to be disabled completely so that C code may
* be reused in other execution contexts such as the UEFI stub or the
* decompressor.
*/
#define __EXPORT_SYMBOL(sym, sec)
#elif defined(__KSYM_DEPS__)
/*
* For fine grained build dependencies, we want to tell the build system
......
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