From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
Will Deacon <will.deacon@arm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Thomas Garnier <thgarnie@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Serge E. Hallyn" <serge@hallyn.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Russell King <linux@armlinux.org.uk>,
Paul Mackerras <paulus@samba.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Petr Mladek <pmladek@suse.com>, Ingo Molnar <mingo@redhat.com>,
James Morris <james.l.morris@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nicolas Pitre <nico@linaro.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jessica Yu <jeyu@kernel.org>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
x86@kernel.org
Subject: [PATCH v8 2/6] module: allow symbol exports to be disabled
Date: Sun, 11 Mar 2018 12:38:11 +0000 [thread overview]
Message-ID: <20180311123815.17916-3-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <20180311123815.17916-1-ard.biesheuvel@linaro.org>
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.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/x86/boot/compressed/kaslr.c | 5 +----
drivers/firmware/efi/libstub/Makefile | 3 ++-
include/linux/export.h | 11 ++++++++++-
3 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 8199a6187251..3a2a6d7049e4 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/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 --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 7b3ba40f0745..896a882c89f4 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
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 --git a/include/linux/export.h b/include/linux/export.h
index 1a1dfdb2a5c6..25005b55b079 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -72,7 +72,16 @@ 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
--
2.15.1
next prev parent reply other threads:[~2018-03-11 12:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-11 12:38 [PATCH v8 0/6] add support for relative references in special sections Ard Biesheuvel
2018-03-11 12:38 ` [PATCH v8 1/6] arch: enable relative relocations for arm64, power and x86 Ard Biesheuvel
2018-03-11 20:20 ` Linus Torvalds
2018-03-11 20:35 ` Ard Biesheuvel
2018-03-11 21:23 ` Linus Torvalds
2018-03-11 12:38 ` Ard Biesheuvel [this message]
2018-03-11 21:31 ` [PATCH v8 2/6] module: allow symbol exports to be disabled Nicolas Pitre
2018-03-11 12:38 ` [PATCH v8 3/6] module: use relative references for __ksymtab entries Ard Biesheuvel
2018-03-11 14:12 ` Ard Biesheuvel
2018-06-25 8:56 ` Martijn Coenen
2018-06-25 9:14 ` Ard Biesheuvel
2018-06-25 10:15 ` Martijn Coenen
2018-06-25 10:52 ` Ard Biesheuvel
2018-03-11 12:38 ` [PATCH v8 4/6] init: allow initcall tables to be emitted using relative references Ard Biesheuvel
2018-03-11 12:38 ` [PATCH v8 5/6] PCI: Add support for relative addressing in quirk tables Ard Biesheuvel
2018-03-11 12:38 ` [PATCH v8 6/6] kernel: tracepoints: add support for relative references Ard Biesheuvel
2018-03-11 12:44 ` [PATCH v8 0/6] add support for relative references in special sections Ard Biesheuvel
2018-03-11 19:08 ` Kees Cook
2018-03-15 16:29 ` Ard Biesheuvel
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