From 22102f4559beaabcea614b29ee090c6a214f002f Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 18 Apr 2022 09:50:40 -0700 Subject: [PATCH] objtool: Make noinstr hacks optional Objtool has some hacks in place to workaround toolchain limitations which otherwise would break no-instrumentation rules. Make the hacks explicit (and optional for other arches) by turning it into a cmdline option and kernel config option. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com --- arch/Kconfig | 3 +++ arch/x86/Kconfig | 1 + lib/Kconfig.debug | 4 ++-- lib/Kconfig.kcsan | 5 +++-- scripts/Makefile.build | 1 + scripts/link-vmlinux.sh | 4 ++++ tools/objtool/builtin-check.c | 8 +++++++- tools/objtool/check.c | 2 +- tools/objtool/include/objtool/builtin.h | 1 + 9 files changed, 23 insertions(+), 6 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 9dce6d6e3bc3..6ba6e34db0ea 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1035,6 +1035,9 @@ config HAVE_OBJTOOL config HAVE_JUMP_LABEL_HACK bool +config HAVE_NOINSTR_HACK + bool + config HAVE_STACK_VALIDATION bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 26d012f1eeb8..06e7cdd76691 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -231,6 +231,7 @@ config X86 select HAVE_MOD_ARCH_SPECIFIC select HAVE_MOVE_PMD select HAVE_MOVE_PUD + select HAVE_NOINSTR_HACK if HAVE_OBJTOOL select HAVE_NMI select HAVE_OBJTOOL if X86_64 select HAVE_OPTPROBES diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c0e4e47f3ce3..7d2bbc3e558e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2036,11 +2036,11 @@ 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_OBJTOOL || \ + depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ GCC_VERSION >= 120000 || CLANG_VERSION >= 130000 select DEBUG_FS select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC - select OBJTOOL if HAVE_OBJTOOL + select OBJTOOL if HAVE_NOINSTR_HACK help KCOV exposes kernel code coverage information in a form suitable for coverage-guided fuzzing (randomized testing). diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan index 901c3b509aca..47a693c45864 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -187,8 +187,9 @@ config KCSAN_WEAK_MEMORY # We can either let objtool nop __tsan_func_{entry,exit}() and builtin # atomics instrumentation in .noinstr.text, or use a compiler that can # implement __no_kcsan to really remove all instrumentation. - depends on HAVE_OBJTOOL || CC_IS_GCC || CLANG_VERSION >= 140000 - select OBJTOOL if HAVE_OBJTOOL + depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \ + CC_IS_GCC || CLANG_VERSION >= 140000 + select OBJTOOL if HAVE_NOINSTR_HACK help Enable support for modeling a subset of weak memory, which allows detecting a subset of data races due to missing memory barriers. diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f1d2c2e4f15b..6c206a1bab97 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -228,6 +228,7 @@ objtool := $(objtree)/tools/objtool/objtool objtool_args = \ $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \ + $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \ $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \ $(if $(CONFIG_UNWINDER_ORC), --orc) \ diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index fa1f16840e76..90c9c4c05d95 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -121,6 +121,10 @@ objtool_link() objtoolopt="${objtoolopt} --hacks=jump_label" fi + if is_enabled CONFIG_HAVE_NOINSTR_HACK; then + objtoolopt="${objtoolopt} --hacks=noinstr" + fi + if is_enabled CONFIG_X86_KERNEL_IBT; then objtoolopt="${objtoolopt} --ibt" fi diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index b2c626d9e2bf..1803a63147e4 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -47,12 +47,17 @@ static int parse_hacks(const struct option *opt, const char *str, int unset) found = true; } + if (!str || strstr(str, "noinstr")) { + opts.hack_noinstr = true; + found = true; + } + return found ? 0 : -1; } const struct option check_options[] = { OPT_GROUP("Actions:"), - OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label", "patch toolchain bugs/limitations", parse_hacks), + OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr", "patch toolchain bugs/limitations", parse_hacks), OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"), OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"), OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"), @@ -108,6 +113,7 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]) static bool opts_valid(void) { if (opts.hack_jump_label || + opts.hack_noinstr || opts.ibt || opts.mcount || opts.noinstr || diff --git a/tools/objtool/check.c b/tools/objtool/check.c index d157978c58b3..30b24dce48b5 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1144,7 +1144,7 @@ static void annotate_call_site(struct objtool_file *file, * attribute so they need a little help, NOP out any such calls from * noinstr text. */ - if (insn->sec->noinstr && sym->profiling_func) { + if (opts.hack_noinstr && insn->sec->noinstr && sym->profiling_func) { if (reloc) { reloc->type = R_NONE; elf_write_reloc(file->elf, reloc); diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index c6acf05ec859..f3a1a754b5c4 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -13,6 +13,7 @@ struct opts { /* actions: */ bool dump_orc; bool hack_jump_label; + bool hack_noinstr; bool ibt; bool mcount; bool noinstr;