On Fri, Apr 22, 2016 at 8:27 PM, Emese Revfy <re.em...@gmail.com> wrote: > The sancov gcc plugin inserts a __sanitizer_cov_trace_pc() call > at the start of basic blocks. > > This plugin is a helper plugin for the kcov feature. It supports > all gcc versions with plugin support (from gcc-4.5 on). > It is based on the gcc commit "Add fuzzing coverage support" by Dmitry Vyukov > (https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296).
+syzkaller mailing list > Signed-off-by: Emese Revfy <re.em...@gmail.com> > --- > Makefile | 10 +-- > arch/Kconfig | 9 +++ > arch/x86/purgatory/Makefile | 2 + > lib/Kconfig.debug | 2 + > scripts/Makefile.gcc-plugins | 18 +++++ > scripts/gcc-plugins/Makefile | 5 ++ > scripts/gcc-plugins/sancov_plugin.c | 144 > ++++++++++++++++++++++++++++++++++++ > 7 files changed, 181 insertions(+), 9 deletions(-) > create mode 100644 scripts/gcc-plugins/sancov_plugin.c > > diff --git a/Makefile b/Makefile > index 22f0e1b..f09f2bf 100644 > --- a/Makefile > +++ b/Makefile > @@ -365,7 +365,7 @@ LDFLAGS_MODULE = > CFLAGS_KERNEL = > AFLAGS_KERNEL = > CFLAGS_GCOV = -fprofile-arcs -ftest-coverage > -CFLAGS_KCOV = -fsanitize-coverage=trace-pc > +CFLAGS_KCOV := $(call cc-option,-fsanitize-coverage=trace-pc,) > > > # Use USERINCLUDE when you must reference the UAPI directories only. > @@ -685,14 +685,6 @@ endif > endif > KBUILD_CFLAGS += $(stackp-flag) > > -ifdef CONFIG_KCOV > - ifeq ($(call cc-option, $(CFLAGS_KCOV)),) > - $(warning Cannot use CONFIG_KCOV: \ > - -fsanitize-coverage=trace-pc is not supported by compiler) > - CFLAGS_KCOV = > - endif > -endif > - > ifeq ($(cc-name),clang) > KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,) > diff --git a/arch/Kconfig b/arch/Kconfig > index e783429..5d856c8 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -380,6 +380,15 @@ config GCC_PLUGIN_CYC_COMPLEXITY > N = the number of nodes > P = the number of connected components (exit nodes). > > +config GCC_PLUGIN_SANCOV > + bool > + depends on GCC_PLUGINS > + 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 <dvyu...@google.com>. > + > config HAVE_CC_STACKPROTECTOR > bool > help > diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile > index 12734a9..ac58c16 100644 > --- a/arch/x86/purgatory/Makefile > +++ b/arch/x86/purgatory/Makefile > @@ -8,6 +8,8 @@ PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y)) > LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z > nodefaultlib > targets += purgatory.ro > > +KCOV_INSTRUMENT := n > + > # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That > # in turn leaves some undefined symbols like __fentry__ in purgatory and not > # sure how to relocate those. Like kexec-tools, use custom flags. > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 4fff4b0..616f7ed 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -708,6 +708,8 @@ config KCOV > bool "Code coverage for fuzzing" > depends on ARCH_HAS_KCOV > select DEBUG_FS > + select GCC_PLUGINS > + select GCC_PLUGIN_SANCOV > help > KCOV exposes kernel code coverage information in a form suitable > for coverage-guided fuzzing (randomized testing). > diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins > index 282d63a..33ab13e 100644 > --- a/scripts/Makefile.gcc-plugins > +++ b/scripts/Makefile.gcc-plugins > @@ -2,8 +2,23 @@ ifdef CONFIG_GCC_PLUGINS > __PLUGINCC := $(call cc-ifversion, -ge, 0408, $(HOSTCXX), $(HOSTCC)) > PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh > "$(__PLUGINCC)" "$(HOSTCXX)" "$(CC)") > > + SANCOV_PLUGIN := -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so > + > gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += > cyc_complexity_plugin.so > > + ifdef CONFIG_GCC_PLUGIN_SANCOV > + ifeq ($(CFLAGS_KCOV),) > + # It is needed because of the gcc-plugin.sh and gcc version checks. > + gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so > + > + ifneq ($(PLUGINCC),) > + CFLAGS_KCOV := $(SANCOV_PLUGIN) > + else > + $(error Cannot use CONFIG_KCOV: -fsanitize-coverage=trace-pc is not > supported by compiler) > + endif > + endif > + endif > + > GCC_PLUGINS_CFLAGS := $(addprefix > -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) > > ifeq ($(PLUGINCC),) > @@ -15,6 +30,9 @@ ifdef CONFIG_GCC_PLUGINS > $(error error, your gcc version does not support plugins, you should > upgrade it to gcc 4.5 at least) > endif > endif > + else > + # SANCOV_PLUGIN can be only in CFLAGS_KCOV because avoid duplication. > + GCC_PLUGINS_CFLAGS := $(filter-out $(SANCOV_PLUGIN), > $(GCC_PLUGINS_CFLAGS)) > endif > > KBUILD_CFLAGS += $(GCC_PLUGINS_CFLAGS) > diff --git a/scripts/gcc-plugins/Makefile b/scripts/gcc-plugins/Makefile > index 31c72bf..79164c1 100644 > --- a/scripts/gcc-plugins/Makefile > +++ b/scripts/gcc-plugins/Makefile > @@ -14,6 +14,11 @@ export GCCPLUGINS_DIR HOSTLIBS > > $(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) := cyc_complexity_plugin.so > > +ifeq ($(CFLAGS_KCOV), > -fplugin=$(objtree)/scripts/gcc-plugins/sancov_plugin.so) > + $(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so > +endif > + > always := $($(HOSTLIBS)-y) > > cyc_complexity_plugin-objs := cyc_complexity_plugin.o > +sancov_plugin-objs := sancov_plugin.o > diff --git a/scripts/gcc-plugins/sancov_plugin.c > b/scripts/gcc-plugins/sancov_plugin.c > new file mode 100644 > index 0000000..aedd611 > --- /dev/null > +++ b/scripts/gcc-plugins/sancov_plugin.c > @@ -0,0 +1,144 @@ > +/* > + * Copyright 2011-2016 by Emese Revfy <re.em...@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 > <dvyu...@google.com>. > + * > + * You can read about it more here: > + * > https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296 > + * http://lwn.net/Articles/674854/ > + * https://github.com/google/syzkaller > + * https://lwn.net/Articles/677764/ > + * > + * Usage: > + * make run > + */ > + > +#include "gcc-common.h" > + > +int plugin_is_GPL_compatible; > + > +tree sancov_fndecl; > + > +static struct plugin_info sancov_plugin_info = { > + .version = "20160402", > + .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)); > +#if BUILDING_GCC_VERSION > 4005 > + leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL); > + decl_attributes(&sancov_fndecl, leaf_attr, 0); > +#endif > +} > + > +int plugin_init(struct plugin_name_args *plugin_info, struct > plugin_gcc_version *version) > +{ > + int i; > + struct register_pass_info sancov_plugin_pass_info; > + 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 = >_ggc_mx_tree_node, > + .pchw = >_pch_nx_tree_node > + }, > + LAST_GGC_ROOT_TAB > + }; > + > + /* BBs can be split afterwards?? */ > + sancov_plugin_pass_info.pass = > make_sancov_pass(); > +#if BUILDING_GCC_VERSION >= 4009 > + sancov_plugin_pass_info.reference_pass_name = "asan"; > +#else > + sancov_plugin_pass_info.reference_pass_name = "nrv"; > +#endif > + sancov_plugin_pass_info.ref_pass_instance_number = 0; > + sancov_plugin_pass_info.pos_op = > 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_("unkown 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 > *)>_ggc_r_gt_sancov); > + register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, > &sancov_plugin_pass_info); > +#endif > + > + return 0; > +} > -- > 2.4.1 >
