kernel: rpm-pkg: Restore find-debuginfo.sh approach to -debuginfo package

Commit 62089b804895 ("kbuild: rpm-pkg: Generate debuginfo package
manually") effectively reverted commit a7c699d090a1 ("kbuild: rpm-pkg:
build a debuginfo RPM") but the approach it took is not safe for older
RPM releases. Restore commit a7c699d090a1 ("kbuild: rpm-pkg: build a
debuginfo RPM") for the !CONFIG_MODULE_SIG case to allow more
environments and configurations to take advantage of the separate debug
information package process.

Cc: [e-mail]
Fixes: 62089b804895 ("kbuild: rpm-pkg: Generate debuginfo package manually")
Tested-by: Stefano Garzarella <[e-mail]>
Tested-by: Steve French <[e-mail]>
Tested-by: Juergen Gross <[e-mail]>
Acked-by: Nicolas Schier <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Nathan Chancellor <[e-mail]>

scripts/package/kernel.spec

···
 %{!?_arch: %define _arch dummy}
 %{!?make: %define make make}
 %define makeflags %{?_smp_mflags} ARCH=%{ARCH}
-%define __spec_install_post /usr/lib/rpm/brp-compress || :
-%define debug_package %{nil}
 
 Name: kernel
 Summary: The Linux Kernel
···
 %define install_mod_strip 1
 %endif
 
+%if %{with_debuginfo_rpm}
+# list of debuginfo-related options taken from distribution kernel.spec
+# files
+%undefine _include_minidebuginfo
+%undefine _find_debuginfo_dwz_opts
+%undefine _unique_build_ids
+%undefine _unique_debug_names
+%undefine _unique_debug_srcs
+%undefine _debugsource_packages
+%undefine _debuginfo_subpackages
+%global _find_debuginfo_opts -r
+%global _missing_build_ids_terminate_build 1
+%global _no_recompute_build_ids 1
+%{debug_package}
+
+# later, we make all modules executable so that find-debuginfo.sh strips
+# them up. but they don't actually need to be executable, so remove the
+# executable bit, taking care to do it _after_ find-debuginfo.sh has run
+%define __spec_install_post \
+	%{?__debug_package:%{__debug_install_post}} \
+	%{__arch_install_post} \
+	%{__os_install_post} \
+	find %{buildroot}/lib/modules/%{KERNELRELEASE} -name "*.ko" -type f \\\
+		| xargs --no-run-if-empty chmod u-x
+%else
+%define __spec_install_post /usr/lib/rpm/brp-compress || :
+%endif
+# some (but not all) versions of rpmbuild emit %%debug_package with
+# %%install. since we've already emitted it manually, that would cause
+# a package redefinition error. ensure that doesn't happen
+%define debug_package %{nil}
+
 %prep
 %setup -q -n linux
 cp %{SOURCE1} .config
···
 	echo "%exclude /lib/modules/%{KERNELRELEASE}/build"
 } > %{buildroot}/kernel.list
 
-%if %{with_debuginfo_manual}
+%if 0%{with_debuginfo_manual}%{with_debuginfo_rpm} > 0
 # copying vmlinux directly to the debug directory means it will not get
 # stripped (but its source paths will still be collected + fixed up)
 mkdir -p %{buildroot}/usr/lib/debug/lib/modules/%{KERNELRELEASE}
 cp vmlinux %{buildroot}/usr/lib/debug/lib/modules/%{KERNELRELEASE}
+%endif
 
+%if %{with_debuginfo_rpm}
+# make modules executable so that find-debuginfo.sh strips them. this
+# will be undone later in %%__spec_install_post
+find %{buildroot}/lib/modules/%{KERNELRELEASE} -name "*.ko" -type f \
+	| xargs --no-run-if-empty chmod u+x
+%endif
+
+%if %{with_debuginfo_manual}
 echo /usr/lib/debug/lib/modules/%{KERNELRELEASE}/vmlinux > %{buildroot}/debuginfo.list
-
 while read -r mod; do
 	mod="${mod%.o}.ko"
 	dbg="%{buildroot}/usr/lib/debug/lib/modules/%{KERNELRELEASE}/kernel/${mod}"
···
 
 %clean
 rm -rf %{buildroot}
+%if %{with_debuginfo_rpm}
+rm -f debugfiles.list debuglinks.list debugsourcefiles.list debugsources.list \
+	elfbins.list
+%endif
 
 %post
 if [ -x /usr/bin/kernel-install ]; then

scripts/package/mkspec

···
 echo '%define with_devel 0'
 fi
 
+# use %{debug_package} machinery to generate -debuginfo
+with_debuginfo_rpm=0
 # manually generate -debuginfo package
 with_debuginfo_manual=0
 # debuginfo package generation uses find-debuginfo.sh under the hood,
···
 				with_debuginfo_manual='%{?_without_debuginfo:0}%{?!_without_debuginfo:1}'
 			fi
 		fi
+	else
+		with_debuginfo_rpm='%{?_without_debuginfo:0}%{?!_without_debuginfo:1}'
 	fi
 fi
 echo "%define with_debuginfo_manual $with_debuginfo_manual"
+echo "%define with_debuginfo_rpm $with_debuginfo_rpm"
 
 cat<<EOF
 %define ARCH ${ARCH}