objtool: Enable unreachable warnings for CLANG LTO

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.

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/7b12df54bceeb0761fe9fc8269ea0c00501214a9.1650300597.git.jpoimboe@redhat.com

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9717e6f6fb31498aec1075220e346c769648decf..33c1ed58152294b3cdc82a980cdffeff97110687 100644 (file)
--- 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 20f44504a644b900eafebe483c2d2a6f14dbe46f..9361a1ef02c992afce8641c4296c90b2c0e12e54 100755 (executable)
--- 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