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[128.199.36.147]) by smtp.gmail.com with ESMTPSA id yz5sm26694583wjc.36.2016.02.07.13.34.39 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 07 Feb 2016 13:34:39 -0800 (PST) Date: Sun, 7 Feb 2016 22:32:57 +0100 From: Emese Revfy To: linux-kbuild@vger.kernel.org Cc: pageexec@freemail.hu, spender@grsecurity.net, kernel-hardening@lists.openwall.com, mmarek@suse.com, keescook@chromium.org Subject: [PATCH 3/3] Documentation for the GCC plugin infrastructure Message-Id: <20160207223257.28ca7020daa09c082e6b9c62@gmail.com> In-Reply-To: <20160207222721.e0087a07fa604b5dac79a109@gmail.com> References: <20160207222721.e0087a07fa604b5dac79a109@gmail.com> X-Mailer: Sylpheed 3.4.3 (GTK+ 2.24.29; x86_64-pc-linux-gnu) Mime-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This is the GCC infrastructure documentation about its operation, how to add and use a new plugin with an example. --- Documentation/example_gcc_plugin.c | 103 +++++++++++++++++++++++++++++++++++++ Documentation/gcc-plugins.txt | 76 +++++++++++++++++++++++++++ 2 files changed, 179 insertions(+) create mode 100644 Documentation/example_gcc_plugin.c create mode 100644 Documentation/gcc-plugins.txt -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/Documentation/example_gcc_plugin.c b/Documentation/example_gcc_plugin.c new file mode 100644 index 0000000..950ff78 --- /dev/null +++ b/Documentation/example_gcc_plugin.c @@ -0,0 +1,103 @@ +/* + * Copyright 2011-2016 by Emese Revfy + * Licensed under the GPL v2, or (at your option) v3 + */ + +#include "gcc-common.h" + +int plugin_is_GPL_compatible; + +static struct plugin_info example_plugin_info = { + .version = "0", + .help = "example plugin\n", +}; + +static unsigned int handle_function(void) +{ + gimple_stmt_iterator gsi; + basic_block bb; + + FOR_ALL_BB_FN(bb, cfun) { + for (gsi = gsi_start_bb(bb); !gsi_end_p(gsi); gsi_next(&gsi)) + debug_gimple_stmt(gsi_stmt(gsi)); + } + return 0; +} + +#if BUILDING_GCC_VERSION >= 4009 +namespace { +static const struct pass_data example_plugin_pass_data = { +#else +static struct gimple_opt_pass example_plugin_pass = { + .pass = { +#endif + .type = GIMPLE_PASS, + .name = "example_plugin", +#if BUILDING_GCC_VERSION >= 4008 + .optinfo_flags = OPTGROUP_NONE, +#endif +#if BUILDING_GCC_VERSION >= 5000 +#elif BUILDING_GCC_VERSION >= 4009 + .has_gate = false, + .has_execute = true, +#else + .gate = NULL, + .execute = handle_function, + .sub = NULL, + .next = NULL, + .static_pass_number = 0, +#endif + .tv_id = TV_NONE, + .properties_required = 0, + .properties_provided = 0, + .properties_destroyed = 0, + .todo_flags_start = 0, + .todo_flags_finish = TODO_dump_func +#if BUILDING_GCC_VERSION < 4009 + } +#endif +}; + +#if BUILDING_GCC_VERSION >= 4009 +class example_plugin_pass : public gimple_opt_pass { +public: + example_plugin_pass() : gimple_opt_pass(example_plugin_pass_data, g) {} +#if BUILDING_GCC_VERSION >= 5000 + virtual unsigned int execute(function *) { return handle_function(); } +#else + unsigned int execute() { return handle_function(); } +#endif +}; +} + +static opt_pass *make_example_plugin_pass(void) +{ + return new example_plugin_pass(); +} +#else +static struct opt_pass *make_example_plugin_pass(void) +{ + return &example_plugin_pass.pass; +} +#endif + +int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) +{ + const char * const plugin_name = plugin_info->base_name; + struct register_pass_info example_plugin_pass_info; + + example_plugin_pass_info.pass = make_example_plugin_pass(); + example_plugin_pass_info.reference_pass_name = "ssa"; + example_plugin_pass_info.ref_pass_instance_number = 1; + example_plugin_pass_info.pos_op = PASS_POS_INSERT_AFTER; + + if (!plugin_default_version_check(version, &gcc_version)) { + error(G_("incompatible gcc/plugin versions")); + return 1; + } + + register_callback(plugin_name, PLUGIN_INFO, NULL, &example_plugin_info); + register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &example_plugin_pass_info); + + return 0; +} diff --git a/Documentation/gcc-plugins.txt b/Documentation/gcc-plugins.txt new file mode 100644 index 0000000..e669d83 --- /dev/null +++ b/Documentation/gcc-plugins.txt @@ -0,0 +1,76 @@ +GCC plugin infrastructure +========================= + + +1. Introduction +=============== + +GCC plugins are loadable modules that provide extra features to the +compiler [1]. They are useful for runtime instrumentation and static analysis. +We can analyse, change and add further code during compilation via +callbacks [2], GIMPLE [3], IPA [4] and RTL passes [5]. + +The GCC plugin infrastructure of the kernel supports all gcc versions from +4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a +separate directory. + +Currently the GCC plugin infrastructure supports only the x86 architecture. + +This infrastructure was ported from grsecurity [6] and PaX [7]. + +-- +[1] https://gcc.gnu.org/onlinedocs/gccint/Plugins.html +[2] https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API +[3] https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html +[4] https://gcc.gnu.org/onlinedocs/gccint/IPA.html +[5] https://gcc.gnu.org/onlinedocs/gccint/RTL.html +[6] https://grsecurity.net/ +[7] https://pax.grsecurity.net/ + + +2. Files +======== + +$(src)/tools/gcc + This is the directory of the GCC plugins. + +$(src)/tools/gcc/gcc-common.h + This is a compatibility header for GCC plugins. + It should be always included instead of individual gcc headers. + +$(src)/scripts/gcc-plugin.sh + This script checks the availability of the included headers in + gcc-common.h and chooses the proper host compiler to build the plugins + (gcc-4.7 can be built by either gcc or g++). + + +3. Usage +======== + +Enable a GCC plugin based feature in the kernel config: + + CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y + +To compile only the plugin(s): + + make gcc-plugins + +or just run the kernel make and compile the whole kernel with +the cyclomatic complexity GCC plugin. + + +4. How to add a new GCC plugin +============================== + +The GCC plugins are in $(src)/tools/gcc/. You can use a file or a directory +here. It must be added to $(src)/tools/gcc/Makefile, $(src)/Makefile and +$(src)/arch/Kconfig. +See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin. + + +5. Example GCC plugin +===================== + +You can find an example plugin under $(src)/Documentation/example_gcc_plugin.c . +This plugin has a GIMPLE pass that is inserted after the ssa GCC pass. +It prints out all the GIMPLE statements in a translation unit.