kernel: add objtool to shared workdir when CONFIG_UNWINDER_ORC is set

Based on: https://patchwork.openembedded.org/patch/148047/

When x86_64 enables CONFIG_UNWINDER_ORC [ORC (Oops Rewind Capability)
unwinder for unwinding kernel stack traces], objtool is required to
generate the required information.

If we don't copy objtool to the shared workdir, out-of-tree modules
cannot generate object files.

For instance, meta-skeleton/hello-mod fails with:
    | make[3]: *** No rule to make target 'tools/objtool/objtool', needed by ...

(From OE-Core rev: 7d4fdd3b95c949277f77df90bb2e8120b8d167ae)

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
index a5b1df1b0d..9da9818962 100644
--- a/meta/classes/kernel.bbclass
+++ b/meta/classes/kernel.bbclass
@@ -487,6 +487,15 @@ do_shared_workdir () {
                 mkdir -p $kerneldir/arch/${ARCH}/include/generated/
                 cp -fR arch/${ARCH}/include/generated/* $kerneldir/arch/${ARCH}/include/generated/
         fi
+
+        if (grep -q -i -e '^CONFIG_UNWINDER_ORC=y$' $kerneldir/.config); then
+                # With CONFIG_UNWINDER_ORC (the default in 4.14), objtool is required for
+                # out-of-tree modules to be able to generate object files.
+                if [ -x tools/objtool/objtool ]; then
+                        mkdir -p ${kerneldir}/tools/objtool
+                        cp tools/objtool/objtool ${kerneldir}/tools/objtool/
+                fi
+        fi
 }
 
 # We don't need to stage anything, not the modules/firmware since those would clash with linux-firmware