UBUNTU: SAUCE: kbuild: add -fcf-protection=none when using retpoline …

…flags BugLink: [Replace -fcf-protection=none patch with new version] The gcc -fcf-protection=branch option is not compatible with -mindirect-branch=thunk-extern. The latter is used when CONFIG_RETPOLINE is selected, and this will fail to build with a gcc which has -fcf-protection=branch enabled by default. Adding -fcf-protection=none when building with retpoline support to prevents such build failures. Signed-off-by: Seth Forshee <[email protected]>
pop-os · crawfxrd · Mar 16, 2022 · Jul 8, 2019 · Sep 9, 2016 · May 27, 2016
commit fdb11c11b4e2366cb57d744d6290dcea517a1561
diff --git a/Makefile b/Makefile
@@ -899,6 +899,12 @@ CC_FLAGS_LTO	:= -flto=thin -fsplit-lto-unit
 KBUILD_LDFLAGS	+= --thinlto-cache-dir=$(extmod_prefix).thinlto-cache
 else
 CC_FLAGS_LTO	:= -flto
+# ensure -fcf-protection is disabled when using retpoline as it is
+# incompatible with -mindirect-branch=thunk-extern
+ifdef CONFIG_RETPOLINE
+KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none,)
+endif
+
 endif
 CC_FLAGS_LTO	+= -fvisibility=hidden