GCC plugin infrastructure

This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too.
Currently the x86, arm, arm64 and uml architectures enable plugins.

The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
there. The plugins compile with these options:
 * -fno-rtti: gcc is compiled with this option so the plugins must use it too
 * -fno-exceptions: this is inherited from gcc too
 * -fasynchronous-unwind-tables: this is inherited from gcc too
 * -ggdb: it is useful for debugging a plugin (better backtrace on internal
    errors)
 * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
 * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
    variable, plugin-version.h)

The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
scripts/gcc-plugins/gcc-common.h.

The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.

The gcc-generate-*-pass.h headers automatically generate the registration
structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.

Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.

Based on work created by the PaX Team.

Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 7304d2e37a98..94a19add522d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4979,6 +4979,15 @@ L:	linux-scsi@vger.kernel.org
 S:      Odd Fixes (e.g., new signatures)
 F:      drivers/scsi/fdomain.*
 
+GCC PLUGINS
+M:      Kees Cook <keescook@chromium.org>
+R:      Emese Revfy <re.emese@gmail.com>
+L:      kernel-hardening@lists.openwall.com
+S:      Maintained
+F:      scripts/gcc-plugins/
+F:      scripts/gcc-plugin.sh
+F:      Documentation/gcc-plugins.txt
+
 GCOV BASED KERNEL PROFILING
 M:      Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 S:      Maintained