Messages in this thread Patch in this message | | | From | Josh Poimboeuf <> | Subject | [PATCH 14/18] objtool: Add toolchain hacks cmdline option | Date | Wed, 13 Apr 2022 16:19:49 -0700 |
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Objtool secretly does a few awful hacks to overcome toolchain limitations. Make those hacks explicit (and optional for other arches) by associating them with a new '--hacks' cmdline option and corresponding CONFIG_HAVE_TOOLCHAIN_HACKS.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/Kconfig | 4 ++++ arch/x86/Kconfig | 1 + arch/x86/include/asm/jump_label.h | 6 +++--- lib/Kconfig.debug | 4 ++-- lib/Kconfig.kcsan | 4 ++-- scripts/Makefile.build | 1 + scripts/link-vmlinux.sh | 4 ++++ tools/objtool/builtin-check.c | 4 +++- tools/objtool/check.c | 4 ++-- tools/objtool/include/objtool/builtin.h | 1 + 10 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig index 04cdef16db24..cb5fc88cb996 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1031,6 +1031,10 @@ config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT config HAVE_OBJTOOL bool +config HAVE_TOOLCHAIN_HACKS + bool + select OBJTOOL + config HAVE_STACK_VALIDATION bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bce0c23f3550..410c4e2c7390 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -232,6 +232,7 @@ config X86 select HAVE_MOVE_PUD select HAVE_NMI select HAVE_OBJTOOL if X86_64 + select HAVE_TOOLCHAIN_HACKS if HAVE_OBJTOOL select HAVE_OPTPROBES select HAVE_PCSPKR_PLATFORM select HAVE_PERF_EVENTS diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 3ce0e67c579c..032434791bf1 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -20,7 +20,7 @@ _ASM_PTR "%c0 + %c1 - .\n\t" \ ".popsection \n\t" -#ifdef CONFIG_OBJTOOL +#ifdef CONFIG_HAVE_TOOLCHAIN_HACKS static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { @@ -34,7 +34,7 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran return true; } -#else /* !CONFIG_OBJTOOL */ +#else /* !CONFIG_HAVE_TOOLCHAIN_HACKS */ static __always_inline bool arch_static_branch(struct static_key * const key, const bool branch) { @@ -48,7 +48,7 @@ static __always_inline bool arch_static_branch(struct static_key * const key, co return true; } -#endif /* CONFIG_OBJTOOL */ +#endif /* CONFIG_HAVE_TOOLCHAIN_HACKS */ static __always_inline bool arch_static_branch_jump(struct static_key * const key, const bool branch) { diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c0e4e47f3ce3..616b93d5db6d 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_TOOLCHAIN_HACKS || \ 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_TOOLCHAIN_HACKS 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..2bdb46354d6a 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -187,8 +187,8 @@ 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 HAVE_TOOLCHAIN_HACKS || CC_IS_GCC || CLANG_VERSION >= 140000 + select OBJTOOL if HAVE_TOOLCHAIN_HACKS 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 3f20d565733c..3b53de3dec67 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -227,6 +227,7 @@ ifdef CONFIG_OBJTOOL objtool := $(objtree)/tools/objtool/objtool objtool_args = \ + $(if $(CONFIG_HAVE_TOOLCHAIN_HACKS), --hacks) \ $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \ $(if $(CONFIG_UNWINDER_ORC), --orc) \ diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index 33f14fe1ddde..480a49e47fbc 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -117,6 +117,10 @@ objtool_link() # Don't perform vmlinux validation unless explicitly requested, # but run objtool on vmlinux.o now that we have an object file. + if is_enabled CONFIG_HAVE_TOOLCHAIN_HACKS; then + objtoolopt="${objtoolopt} --hacks" + 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 c663828834e1..13e1c46f155a 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -38,6 +38,7 @@ static int parse_dumpstr(const struct option *opt, const char *str, int unset) const struct option check_options[] = { OPT_GROUP("Actions:"), + OPT_BOOLEAN('h', "hacks", &opts.hacks, "patch some toolchain bugs/limitations"), 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"), @@ -91,7 +92,8 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]) static bool opts_valid(void) { - if (opts.ibt || + if (opts.hacks || + opts.ibt || opts.mcount || opts.noinstr || opts.orc || diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 511b76aaa6de..273ba6840ed2 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1145,7 +1145,7 @@ 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.hacks && insn->sec->noinstr && sym->profiling_func) { if (reloc) { reloc->type = R_NONE; elf_write_reloc(file->elf, reloc); @@ -1593,7 +1593,7 @@ static int handle_jump_alt(struct objtool_file *file, return -1; } - if (special_alt->key_addend & 2) { + if (opts.hacks && special_alt->key_addend & 2) { struct reloc *reloc = insn_reloc(file, orig_insn); if (reloc) { diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index 6ffa6b5dc276..7bc76edb0a85 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -17,6 +17,7 @@ enum dump { struct opts { /* actions: */ enum dump dump; + bool hacks; bool ibt; bool mcount; bool noinstr; -- 2.34.1
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