[PATCH 01/18] objtool: Enable unreachable warnings for CLANG LTO

From: Josh Poimboeuf
Date: Wed Apr 13 2022 - 19:20:21 EST


With IBT support in, objtool is now fully capable of following vmlinux
code flow in LTO mode. Start reporting unreachable warnings for Clang
LTO as well.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
scripts/Makefile.build | 2 +-
scripts/link-vmlinux.sh | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9717e6f6fb31..33c1ed581522 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -231,7 +231,7 @@ objtool_args = \
$(if $(part-of-module), --module) \
$(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \
$(if $(CONFIG_FRAME_POINTER),, --no-fp) \
- $(if $(CONFIG_GCOV_KERNEL)$(CONFIG_LTO_CLANG), --no-unreachable)\
+ $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
$(if $(CONFIG_X86_SMAP), --uaccess) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 20f44504a644..9361a1ef02c9 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -140,7 +140,7 @@ objtool_link()
if ! is_enabled CONFIG_FRAME_POINTER; then
objtoolopt="${objtoolopt} --no-fp"
fi
- if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then
+ if is_enabled CONFIG_GCOV_KERNEL; then
objtoolopt="${objtoolopt} --no-unreachable"
fi
if is_enabled CONFIG_RETPOLINE; then
--
2.34.1