linux-kernel - [tip: x86/urgent] objtool: Enable unreachable warnings for CLANG LTO

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Date:   Tue, 19 Apr 2022 20:08:40 -0000
From:   "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] objtool: Enable unreachable warnings for CLANG LTO

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     4a5de9b76fcb3f477f73d5a63f6e27709e8af81f
Gitweb:        https://git.kernel.org/tip/4a5de9b76fcb3f477f73d5a63f6e27709e8af81f
Author:        Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate:    Mon, 18 Apr 2022 09:50:20 -07:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 19 Apr 2022 21:58:48 +02:00

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@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/7b12df54bceeb0761fe9fc8269ea0c00501214a9.1650300597.git.jpoimboe@redhat.com
---
 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 9717e6f..33c1ed5 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 $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount)		\
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 20f4450..9361a1e 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -140,7 +140,7 @@ objtool_link()
 		if ! is_enabled CONFIG_FRAME_POINTER; then
 			objtoolopt="${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