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 <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/b326eeb9c33231b9dfbb925f194ed7ee40edcd7c.1650300597.git.jpoimboe@redhat.com
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c0e4e47..7d2bbc3 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2036,11 +2036,11 @@
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 901c3b5..47a693c 100644
--- a/lib/Kconfig.kcsan
+++ b/lib/Kconfig.kcsan
@@ -187,8 +187,9 @@
# 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.
