The patch titled
Subject: module: allow symbol exports to be disabled
has been added to the -mm tree. Its filename is
module-allow-symbol-exports-to-be-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/module-allow-symbol-exports-to-be-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/module-allow-symbol-exports-to-be-disabled.patch
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------------------------------------------------------
From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>
Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Reviewed-by: Will Deacon <will.deacon@xxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: James Morris <james.morris@xxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Cc: Jessica Yu <jeyu@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN arch/x86/boot/compressed/kaslr.c~module-allow-symbol-exports-to-be-disabled arch/x86/boot/compressed/kaslr.c
--- a/arch/x86/boot/compressed/kaslr.c~module-allow-symbol-exports-to-be-disabled
+++ a/arch/x86/boot/compressed/kaslr.c
@@ -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"
diff -puN drivers/firmware/efi/libstub/Makefile~module-allow-symbol-exports-to-be-disabled drivers/firmware/efi/libstub/Makefile
--- a/drivers/firmware/efi/libstub/Makefile~module-allow-symbol-exports-to-be-disabled
+++ a/drivers/firmware/efi/libstub/Makefile
@@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srct
KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
-D__NO_FORTIFY \
$(call cc-option,-ffreestanding) \
- $(call cc-option,-fno-stack-protector)
+ $(call cc-option,-fno-stack-protector) \
+ -D__DISABLE_EXPORTS
GCOV_PROFILE := n
KASAN_SANITIZE := n
diff -puN include/linux/export.h~module-allow-symbol-exports-to-be-disabled include/linux/export.h
--- a/include/linux/export.h~module-allow-symbol-exports-to-be-disabled
+++ a/include/linux/export.h
@@ -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
_
Patches currently in -mm which might be from ard.biesheuvel@xxxxxxxxxx are
arch-enable-relative-relocations-for-arm64-power-and-x86.patch
module-allow-symbol-exports-to-be-disabled.patch
module-use-relative-references-for-__ksymtab-entries.patch
init-allow-initcall-tables-to-be-emitted-using-relative-references.patch
pci-add-support-for-relative-addressing-in-quirk-tables.patch
kernel-tracepoints-add-support-for-relative-references.patch
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