livepatch/klp-build: switch to GNU patch and recountdiff

The klp-build script is currently very strict with input patches,
requiring them to apply cleanly via `git apply --recount`.  This
prevents the use of patches with minor contextual fuzz relative to the
target kernel sources.

To allow users to reuse a patch across similar kernel streams, switch to
using GNU patch and patchutils for intermediate patch manipulation.
Update the logic for applying, reverting, and regenerating patches:

- Use 'patch -p1' for better handling of context fuzz.
- Use 'recountdiff' to update line counts after FIX_PATCH_LINES.
- Drop git_refresh() and related git-specific logic.

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://patch.msgid.link/20260310203751.1479229-5-joe.lawrence@redhat.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index 94ed3b4a91d87873d190a39a3092bd0b047905a6..564985a1588a224ab89c9bb24cea9c49377c94a6 100755 (executable)
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -95,7 +95,7 @@ restore_files() {
 
 cleanup() {
        set +o nounset
-       revert_patches "--recount"
+       revert_patches
        restore_files
        [[ "$KEEP_TMP" -eq 0 ]] && rm -rf "$TMP_DIR"
        return 0
@@ -282,7 +282,7 @@ set_module_name() {
 }
 
 # Hardcode the value printed by the localversion script to prevent patch
-# application from appending it with '+' due to a dirty git working tree.
+# application from appending it with '+' due to a dirty working tree.
 set_kernelversion() {
        local file="$SRC/scripts/setlocalversion"
        local localversion
@@ -300,8 +300,8 @@ get_patch_input_files() {
        local patch="$1"
 
        grep0 -E '^--- ' "$patch"                               \
+               | grep0 -v -e '/dev/null' -e '1969-12-31' -e '1970-01-01' \
                | gawk '{print $2}'                             \
-               | grep0 -v '^/dev/null$'                        \
                | sed 's|^[^/]*/||'                             \
                | sort -u
 }
@@ -310,8 +310,8 @@ get_patch_output_files() {
        local patch="$1"
 
        grep0 -E '^\+\+\+ ' "$patch"                            \
+               | grep0 -v -e '/dev/null' -e '1969-12-31' -e '1970-01-01' \
                | gawk '{print $2}'                             \
-               | grep0 -v '^/dev/null$'                        \
                | sed 's|^[^/]*/||'                             \
                | sort -u
 }
@@ -323,21 +323,6 @@ get_patch_files() {
                | sort -u
 }
 
-# Make sure git re-stats the changed files
-git_refresh() {
-       local patch="$1"
-       local files=()
-
-       [[ ! -e "$SRC/.git" ]] && return
-
-       get_patch_input_files "$patch" | mapfile -t files
-
-       (
-               cd "$SRC"
-               git update-index -q --refresh -- "${files[@]}"
-       )
-}
-
 check_unsupported_patches() {
        local patch
 
@@ -358,36 +343,19 @@ check_unsupported_patches() {
 
 apply_patch() {
        local patch="$1"
-       shift
-       local extra_args=("$@")
 
        [[ ! -f "$patch" ]] && die "$patch doesn't exist"
-
-       (
-               cd "$SRC"
-
-               # The sed strips the version signature from 'git format-patch',
-               # otherwise 'git apply --recount' warns.
-               sed -n '/^-- /q;p' "$patch" |
-                       git apply "${extra_args[@]}"
-       )
+       patch -d "$SRC" -p1 --dry-run --silent --no-backup-if-mismatch -r /dev/null < "$patch"
+       patch -d "$SRC" -p1 --silent --no-backup-if-mismatch -r /dev/null < "$patch"
 
        APPLIED_PATCHES+=("$patch")
 }
 
 revert_patch() {
        local patch="$1"
-       shift
-       local extra_args=("$@")
        local tmp=()
 
-       (
-               cd "$SRC"
-
-               sed -n '/^-- /q;p' "$patch" |
-                       git apply --reverse "${extra_args[@]}"
-       )
-       git_refresh "$patch"
+       patch -d "$SRC" -p1 -R --silent --no-backup-if-mismatch -r /dev/null < "$patch"
 
        for p in "${APPLIED_PATCHES[@]}"; do
                [[ "$p" == "$patch" ]] && continue
@@ -406,11 +374,10 @@ apply_patches() {
 }
 
 revert_patches() {
-       local extra_args=("$@")
        local patches=("${APPLIED_PATCHES[@]}")
 
        for (( i=${#patches[@]}-1 ; i>=0 ; i-- )) ; do
-               revert_patch "${patches[$i]}" "${extra_args[@]}"
+               revert_patch "${patches[$i]}"
        done
 
        APPLIED_PATCHES=()
@@ -434,6 +401,7 @@ do_init() {
        APPLIED_PATCHES=()
 
        [[ -x "$FIX_PATCH_LINES" ]] || die "can't find fix-patch-lines"
+       command -v recountdiff &>/dev/null || die "recountdiff not found (install patchutils)"
 
        validate_config
        set_module_name
@@ -459,12 +427,12 @@ refresh_patch() {
        ( cd "$SRC" && echo "${input_files[@]}" | xargs cp --parents --target-directory="$tmpdir/a" )
 
        # Copy patched source files to 'b'
-       apply_patch "$patch" --recount
+       apply_patch "$patch"
        ( cd "$SRC" && echo "${output_files[@]}" | xargs cp --parents --target-directory="$tmpdir/b" )
-       revert_patch "$patch" --recount
+       revert_patch "$patch"
 
        # Diff 'a' and 'b' to make a clean patch
-       ( cd "$tmpdir" && git diff --no-index --no-prefix a b > "$patch" ) || true
+       ( cd "$tmpdir" && diff -Nupr a b > "$patch" ) || true
 }
 
 # Copy the patches to a temporary directory, fix their lines so as not to
@@ -487,8 +455,7 @@ fix_patches() {
 
                cp -f "$old_patch" "$tmp_patch"
                refresh_patch "$tmp_patch"
-               "$FIX_PATCH_LINES" "$tmp_patch" > "$new_patch"
-               refresh_patch "$new_patch"
+               "$FIX_PATCH_LINES" "$tmp_patch" | recountdiff > "$new_patch"
 
                PATCHES[i]="$new_patch"