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, 175 insertions, 0 deletions

diff --git a/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h b/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h
new file mode 100644
index 000000000000..a27e2b36afaa
--- /dev/null
+++ b/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h
@@ -0,0 +1,175 @@
+/*
+ * Generator for SIMPLE_IPA pass related boilerplate code/data
+ *
+ * Supports gcc 4.5-6
+ *
+ * Usage:
+ *
+ * 1. before inclusion define PASS_NAME
+ * 2. before inclusion define NO_* for unimplemented callbacks
+ *    NO_GATE
+ *    NO_EXECUTE
+ * 3. before inclusion define PROPERTIES_* and TODO_FLAGS_* to override
+ *    the default 0 values
+ * 4. for convenience, all the above will be undefined after inclusion!
+ * 5. the only exported name is make_PASS_NAME_pass() to register with gcc
+ */
+
+#ifndef PASS_NAME
+#error at least PASS_NAME must be defined
+#else
+#define __GCC_PLUGIN_STRINGIFY(n)       #n
+#define _GCC_PLUGIN_STRINGIFY(n)        __GCC_PLUGIN_STRINGIFY(n)
+#define _GCC_PLUGIN_CONCAT2(x, y)       x ## y
+#define _GCC_PLUGIN_CONCAT3(x, y, z)    x ## y ## z
+
+#define __PASS_NAME_PASS_DATA(n)        _GCC_PLUGIN_CONCAT2(n, _pass_data)
+#define _PASS_NAME_PASS_DATA            __PASS_NAME_PASS_DATA(PASS_NAME)
+
+#define __PASS_NAME_PASS(n)             _GCC_PLUGIN_CONCAT2(n, _pass)
+#define _PASS_NAME_PASS                 __PASS_NAME_PASS(PASS_NAME)
+
+#define _PASS_NAME_NAME                 _GCC_PLUGIN_STRINGIFY(PASS_NAME)
+
+#define __MAKE_PASS_NAME_PASS(n)        _GCC_PLUGIN_CONCAT3(make_, n, _pass)
+#define _MAKE_PASS_NAME_PASS            __MAKE_PASS_NAME_PASS(PASS_NAME)
+
+#ifdef NO_GATE
+#define _GATE NULL
+#define _HAS_GATE false
+#else
+#define __GATE(n)                       _GCC_PLUGIN_CONCAT2(n, _gate)
+#define _GATE                           __GATE(PASS_NAME)
+#define _HAS_GATE true
+#endif
+
+#ifdef NO_EXECUTE
+#define _EXECUTE NULL
+#define _HAS_EXECUTE false
+#else
+#define __EXECUTE(n)                    _GCC_PLUGIN_CONCAT2(n, _execute)
+#define _EXECUTE                        __EXECUTE(PASS_NAME)
+#define _HAS_EXECUTE true
+#endif
+
+#ifndef PROPERTIES_REQUIRED
+#define PROPERTIES_REQUIRED 0
+#endif
+
+#ifndef PROPERTIES_PROVIDED
+#define PROPERTIES_PROVIDED 0
+#endif
+
+#ifndef PROPERTIES_DESTROYED
+#define PROPERTIES_DESTROYED 0
+#endif
+
+#ifndef TODO_FLAGS_START
+#define TODO_FLAGS_START 0
+#endif
+
+#ifndef TODO_FLAGS_FINISH
+#define TODO_FLAGS_FINISH 0
+#endif
+
+#if BUILDING_GCC_VERSION >= 4009
+namespace {
+static const pass_data _PASS_NAME_PASS_DATA = {
+#else
+static struct simple_ipa_opt_pass _PASS_NAME_PASS = {
+        .pass = {
+#endif
+                .type                   = SIMPLE_IPA_PASS,
+                .name                   = _PASS_NAME_NAME,
+#if BUILDING_GCC_VERSION >= 4008
+                .optinfo_flags          = OPTGROUP_NONE,
+#endif
+#if BUILDING_GCC_VERSION >= 5000
+#elif BUILDING_GCC_VERSION == 4009
+                .has_gate               = _HAS_GATE,
+                .has_execute            = _HAS_EXECUTE,
+#else
+                .gate                   = _GATE,
+                .execute                = _EXECUTE,
+                .sub                    = NULL,
+                .next                   = NULL,
+                .static_pass_number     = 0,
+#endif
+                .tv_id                  = TV_NONE,
+                .properties_required    = PROPERTIES_REQUIRED,
+                .properties_provided    = PROPERTIES_PROVIDED,
+                .properties_destroyed   = PROPERTIES_DESTROYED,
+                .todo_flags_start       = TODO_FLAGS_START,
+                .todo_flags_finish      = TODO_FLAGS_FINISH,
+#if BUILDING_GCC_VERSION < 4009
+        }
+#endif
+};
+
+#if BUILDING_GCC_VERSION >= 4009
+class _PASS_NAME_PASS : public simple_ipa_opt_pass {
+public:
+        _PASS_NAME_PASS() : simple_ipa_opt_pass(_PASS_NAME_PASS_DATA, g) {}
+
+#ifndef NO_GATE
+#if BUILDING_GCC_VERSION >= 5000
+        virtual bool gate(function *) { return _GATE(); }
+#else
+        virtual bool gate(void) { return _GATE(); }
+#endif
+#endif
+
+        virtual opt_pass *clone() { return new _PASS_NAME_PASS(); }
+
+#ifndef NO_EXECUTE
+#if BUILDING_GCC_VERSION >= 5000
+        virtual unsigned int execute(function *) { return _EXECUTE(); }
+#else
+        virtual unsigned int execute(void) { return _EXECUTE(); }
+#endif
+#endif
+};
+}
+
+opt_pass *_MAKE_PASS_NAME_PASS(void)
+{
+        return new _PASS_NAME_PASS();
+}
+#else
+struct opt_pass *_MAKE_PASS_NAME_PASS(void)
+{
+        return &_PASS_NAME_PASS.pass;
+}
+#endif
+
+/* clean up user provided defines */
+#undef PASS_NAME
+#undef NO_GATE
+#undef NO_EXECUTE
+
+#undef PROPERTIES_DESTROYED
+#undef PROPERTIES_PROVIDED
+#undef PROPERTIES_REQUIRED
+#undef TODO_FLAGS_FINISH
+#undef TODO_FLAGS_START
+
+/* clean up generated defines */
+#undef _EXECUTE
+#undef __EXECUTE
+#undef _GATE
+#undef __GATE
+#undef _GCC_PLUGIN_CONCAT2
+#undef _GCC_PLUGIN_CONCAT3
+#undef _GCC_PLUGIN_STRINGIFY
+#undef __GCC_PLUGIN_STRINGIFY
+#undef _HAS_EXECUTE
+#undef _HAS_GATE
+#undef _MAKE_PASS_NAME_PASS
+#undef __MAKE_PASS_NAME_PASS
+#undef _PASS_NAME_NAME
+#undef _PASS_NAME_PASS
+#undef __PASS_NAME_PASS
+#undef _PASS_NAME_PASS_DATA
+#undef __PASS_NAME_PASS_DATA
+
+#endif /* PASS_NAME */