Commit 22102f45 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Peter Zijlstra
Browse files

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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com
parent 4ab7674f

arch/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -1035,6 +1035,9 @@ config HAVE_OBJTOOL 
config HAVE_JUMP_LABEL_HACK

	bool



config HAVE_NOINSTR_HACK

	bool



config HAVE_STACK_VALIDATION

	bool

	help

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

lib/Kconfig.debug

+2 −2
Original line number Diff line number Diff line
@@ -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).

lib/Kconfig.kcsan

+3 −2
Original line number Diff line number Diff line
@@ -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.

scripts/Makefile.build

+1 −0
Original line number Diff line number Diff line
@@ -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)				\