Commit 852faf80 authored by Arnd Bergmann's avatar Arnd Bergmann
Browse files

gcc-plugins: remove SANCOV gcc plugin 



With the minimum gcc version raised to 8.1, all supported compilers
now understand the -fsanitize-coverage=trace-pc option, and there
is no longer a need for the separate compiler plugin.

Since only gcc-5 was able to use the plugin for several year now,
it was already likely unused.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 8530ea3c

lib/Kconfig.debug

+0 −6
Original line number Diff line number Diff line
@@ -2153,18 +2153,12 @@ config ARCH_HAS_KCOV 
	  build and run with CONFIG_KCOV. This typically requires

	  disabling instrumentation for some early boot code.



config CC_HAS_SANCOV_TRACE_PC

	def_bool $(cc-option,-fsanitize-coverage=trace-pc)





config KCOV

	bool "Code coverage for fuzzing"

	depends on ARCH_HAS_KCOV

	depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS

	depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \

		   GCC_VERSION >= 120000 || CC_IS_CLANG

	select DEBUG_FS

	select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC

	select OBJTOOL if HAVE_NOINSTR_HACK

	help

	  KCOV exposes kernel code coverage information in a form suitable

scripts/Makefile.gcc-plugins

+0 −2
Original line number Diff line number Diff line
@@ -38,8 +38,6 @@ KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS) 


# Some plugins are enabled outside of this Makefile, but they still need to

# be included in GCC_PLUGIN so they can get built.

gcc-plugin-external-$(CONFIG_GCC_PLUGIN_SANCOV)			\

	+= sancov_plugin.so

gcc-plugin-external-$(CONFIG_GCC_PLUGIN_RANDSTRUCT)		\

	+= randomize_layout_plugin.so

scripts/Makefile.kcov

+0 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

kcov-flags-$(CONFIG_CC_HAS_SANCOV_TRACE_PC)	+= -fsanitize-coverage=trace-pc

kcov-flags-$(CONFIG_KCOV_ENABLE_COMPARISONS)	+= -fsanitize-coverage=trace-cmp

kcov-flags-$(CONFIG_GCC_PLUGIN_SANCOV)		+= -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so



export CFLAGS_KCOV := $(kcov-flags-y)

scripts/gcc-plugins/Kconfig

+0 −10
Original line number Diff line number Diff line
@@ -19,16 +19,6 @@ menuconfig GCC_PLUGINS 


if GCC_PLUGINS



config GCC_PLUGIN_SANCOV

	bool

	# Plugin can be removed once the kernel only supports GCC 6+

	depends on !CC_HAS_SANCOV_TRACE_PC

	help

	  This plugin inserts a __sanitizer_cov_trace_pc() call at the start of

	  basic blocks. It supports all gcc versions with plugin support (from

	  gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"

	  by Dmitry Vyukov <dvyukov@google.com>.



config GCC_PLUGIN_LATENT_ENTROPY

	bool "Generate some entropy during boot and runtime"

	help

scripts/gcc-plugins/sancov_plugin.c

deleted100644 → 0
+0 −134
Original line number Diff line number Diff line 
/*

 * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>

 * Licensed under the GPL v2, or (at your option) v3

 *

 * Homepage:

 * https://github.com/ephox-gcc-plugins/sancov

 *

 * This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.

 * It supports all gcc versions with plugin support (from gcc-4.5 on).

 * It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.

 *

 * You can read about it more here:

 *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296

 *  https://lwn.net/Articles/674854/

 *  https://github.com/google/syzkaller

 *  https://lwn.net/Articles/677764/

 *

 * Usage:

 * make run

 */



#include "gcc-common.h"



__visible int plugin_is_GPL_compatible;



tree sancov_fndecl;



static struct plugin_info sancov_plugin_info = {

	.version	= PLUGIN_VERSION,

	.help		= "sancov plugin\n",

};



static unsigned int sancov_execute(void)

{

	basic_block bb;



	/* Remove this line when this plugin and kcov will be in the kernel.

	if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))

		return 0;

	*/



	FOR_EACH_BB_FN(bb, cfun) {

		const_gimple stmt;

		gcall *gcall;

		gimple_stmt_iterator gsi = gsi_after_labels(bb);



		if (gsi_end_p(gsi))

			continue;



		stmt = gsi_stmt(gsi);

		gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));

		gimple_set_location(gcall, gimple_location(stmt));

		gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);

	}

	return 0;

}



#define PASS_NAME sancov



#define NO_GATE

#define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow



#include "gcc-generate-gimple-pass.h"



static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)

{

	tree leaf_attr, nothrow_attr;

	tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);



	sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);



	DECL_ASSEMBLER_NAME(sancov_fndecl);

	TREE_PUBLIC(sancov_fndecl) = 1;

	DECL_EXTERNAL(sancov_fndecl) = 1;

	DECL_ARTIFICIAL(sancov_fndecl) = 1;

	DECL_PRESERVE_P(sancov_fndecl) = 1;

	DECL_UNINLINABLE(sancov_fndecl) = 1;

	TREE_USED(sancov_fndecl) = 1;



	nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);

	decl_attributes(&sancov_fndecl, nothrow_attr, 0);

	gcc_assert(TREE_NOTHROW(sancov_fndecl));

	leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);

	decl_attributes(&sancov_fndecl, leaf_attr, 0);

}



__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)

{

	int i;

	const char * const plugin_name = plugin_info->base_name;

	const int argc = plugin_info->argc;

	const struct plugin_argument * const argv = plugin_info->argv;

	bool enable = true;



	static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {

		{

			.base = &sancov_fndecl,

			.nelt = 1,

			.stride = sizeof(sancov_fndecl),

			.cb = &gt_ggc_mx_tree_node,

			.pchw = &gt_pch_nx_tree_node

		},

		LAST_GGC_ROOT_TAB

	};



	/* BBs can be split afterwards?? */

	PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE);



	if (!plugin_default_version_check(version, &gcc_version)) {

		error(G_("incompatible gcc/plugin versions"));

		return 1;

	}



	for (i = 0; i < argc; ++i) {

		if (!strcmp(argv[i].key, "no-sancov")) {

			enable = false;

			continue;

		}

		error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);

	}



	register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);



	if (!enable)

		return 0;



#if BUILDING_GCC_VERSION < 6000

	register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);

	register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);

	register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_pass_info);

#endif



	return 0;

}