Re: [RFC PATCH v2 5/7] livepatch/klp-build: add basic out-of-tree module support

[Josh Poimboeuf <jpoimboe@kernel.org>]

On Wed, Aug 26, 2026 at 03:49:58PM -0400, Joe Lawrence wrote:
> @@ -579,13 +610,20 @@ build_kernel() {
>  find_objects() {
>  	local opts=("$@")
>  
> -	# Find root-level vmlinux.o and non-root-level .ko files,
> -	# excluding klp-tmp/ and hidden directories.
> -	find "$PWD" -mindepth 1 \
> -		    \( -path "$TMP_DIR" -o -name ".*" -o -regex "$PWD/[^/][^/]*\.ko" \) -prune -o \
> -		    -type f "${opts[@]}"				\
> -		    \( -name "*.ko" -o -path "$PWD/vmlinux.o" \)	\
> -		    -printf '%P\n'
> +	if [[ -z "$OOT_DIR" ]]; then
> +		# In-tree: find root-level vmlinux.o and non-root-level .ko files,
> +		# excluding klp-tmp/ and hidden directories.
> +		find "$PWD" -mindepth 1 \
> +			    \( -path "$TMP_DIR" -o -name ".*" -o -regex "$PWD/[^/][^/]*\.ko" \) -prune -o \
> +			    -type f "${opts[@]}"				\
> +			    \( -name "*.ko" -o -path "$PWD/vmlinux.o" \)	\
> +			    -printf '%P\n'
> +	else
> +		# OOT: find .ko at any depth under the module dir
> +		find "$OOT_DIR" -path "$OOT_DIR/.git" -prune -o \
> +			-type f "${opts[@]}" \
> +			-name "*.ko" -printf '%P\n'

Can these be unified?  Something like:

	if [[ -n "$OOT_DIR ]]; then
		path="$OOT_DIR"
	else
		path="$PWD"
	fi

	find "$path" -mindepth 1 \
		    \( -path "$TMP_DIR" -o -name ".*" -o -regex "$PWD/[^/][^/]*\.ko" \) -prune -o \
		    -type f "${opts[@]}"				\
		    \( -name "*.ko" -o -path "$PWD/vmlinux.o" \)	\
		    -printf '%P\n'

That way we get consistent behavior and the two paths with $PWD would
get silently ignored for the OOT case anyway.

> @@ -717,6 +757,7 @@ diff_objects() {
>  		cmd+=("klp")
>  		cmd+=("diff")
>  		(( ${#opts[@]} > 0 )) && cmd+=("${opts[@]}")
> +		[[ -n "$OOT_DIR" ]] && cmd+=("--symvers" "$PWD/Module.symvers")

Even with OOT_DIR it still runs in the kernel build dir, which is where
objtool looks for this file anyway, so I don't think this line is
needed?

>  		cmd+=("$orig_file")
>  		cmd+=("$patched_file")
>  		cmd+=("$out_file")
> @@ -895,13 +936,16 @@ build_patch_module() {
>  process_args "$@"
>  do_init
>  
> +BUILD_TARGET="kernel"
> +[[ -n "$OOT_DIR" ]] && BUILD_TARGET="module ${OOT_DIR##*/}"
> +
>  if (( SHORT_CIRCUIT <= 2 )); then
>  	status "Validating patch(es)"
>  	validate_patches
>  fi
>  
>  if (( SHORT_CIRCUIT <= 1 )); then
> -	status "Building original kernel"
> +	status "Building original $BUILD_TARGET"

I think we can simplify this to just "Building original objects" or so...

>  	clean_kernel
>  	build_kernel "original"
>  	status "Copying original object files"
> @@ -912,7 +956,7 @@ if (( SHORT_CIRCUIT <= 2 )); then
>  	status "Fixing patch(es)"
>  	fix_patches
>  	apply_patches "--silent"
> -	status "Building patched kernel"
> +	status "Building patched $BUILD_TARGET"

... and "Building patched objects".

-- 
Josh