[PATCH v4 0/3] Introduce GCC plugin infrastructure

[Emese Revfy <re.emese@gmail.com>]

This patch set introduce the GCC plugin infrastructure with examples for testing
and documentation.

GCC plugins are loadable modules that provide extra features to the compiler.
They are useful for runtime instrumentation and static analysis.

The infrastructure supports all gcc versions from 4.5 to 6.0, building
out-of-tree modules and building in a separate directory. Cross-compilation
is supported too but currently only the x86 architecture enables plugins.

This infrastructure was ported from grsecurity/PaX. It is a CII project
supported by the Linux Foundation.

Emese Revfy (3):
 GCC plugin infrastructure
 Add Cyclomatic complexity plugin
 Documentations of the GCC plugin infrastructre


Changes from v3:
 * Fix some indentation related warnings
   (Suggested by checkpatch.pl)
 * Add maintainer entries
 * Don't run gcc_plugin.sh when the GCC_PLUGINS option is disabled or unsupported
   (Reported-by: Fengguang Wu <fengguang.wu@intel.com>)

   I found a kbuild bug (or feature?) related to this patch. When a config option is disabled
   then the symbol gets undefined only when you run make clean.
   The easiest way to reproduce it is with e.g., CC_STACKPROTECTOR_STRONG:

     * patch in warning here:

diff --git a/Makefile b/Makefile
index a1a7708..9e6961f 100644
--- a/Makefile
+++ b/Makefile
@@ -664,6 +664,7 @@ ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
 else
 ifdef CONFIG_CC_STACKPROTECTOR_STRONG
   stackp-flag := -fstack-protector-strong
+  $(warning AAAAAAAA)
   ifeq ($(call cc-option, $(stackp-flag)),)
     $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
 	      -fstack-protector-strong not supported by compiler)

     * enable CC_STACKPROTECTOR_STRONG in menuconfig
     * run make and it prints out the "AAAAAAAA"
     * enable CC_STACKPROTECTOR_NONE in menuconfig
     * run make and it prints out the "AAAAAAAA"
     * run make clean, run make again and it doesn't print out the "AAAAAAAA"


Changes from v2:
 * Fixed incorrectly encoded characters
 * Generate the GIMPLE, IPA, SIMPLE_IPA and RTL pass structures
   (Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>)
 * Write plugin related warning messages to stderr instead of stdout
   (Suggested-by: Kees Cook <keescook@chromium.org>)
 * Mention the installation of the gcc plugin headers (Documentation)


Changes from v1:
 * Move the gcc-plugins make target into a separate Makefile because there may
   be a lot of plugins (Suggested-by: Rasmus Villemoes)
 * Simplify the dependencies of the plugin related config option
   (Suggested-by: Kees Cook <keescook@chromium.org>)
 * Removed the unnecessary example plugin
---
 Documentation/dontdiff                   |   1 +
 Documentation/gcc-plugins.txt            |  82 ++++
 MAINTAINERS                              |   8 +
 Makefile                                 |  41 +-
 arch/Kconfig                             |  24 +
 arch/x86/Kconfig                         |   1 +
 init/Makefile                            |   3 +
 scripts/Makefile.build                   |   2 +-
 scripts/Makefile.clean                   |   3 +-
 scripts/Makefile.gcc-plugins             |  32 ++
 scripts/Makefile.host                    |  69 ++-
 scripts/gcc-plugin.sh                    |  51 ++
 scripts/link-vmlinux.sh                  |   2 +-
 scripts/package/builddeb                 |   1 +
 tools/gcc/Makefile                       |  19 +
 tools/gcc/cyc_complexity_plugin.c        |  73 +++
 tools/gcc/gcc-common.h                   | 803 +++++++++++++++++++++++++++++++
 tools/gcc/gcc-generate-gimple-pass.h     | 173 +++++++
 tools/gcc/gcc-generate-ipa-pass.h        | 287 +++++++++++
 tools/gcc/gcc-generate-rtl-pass.h        | 173 +++++++
 tools/gcc/gcc-generate-simple_ipa-pass.h | 173 +++++++
 21 files changed, 2006 insertions(+), 15 deletions(-)