[PATCH v2 12/12] selftests/livepatch: Test klp-prepare-patch with offset and fuzz

[Song Liu <song@kernel.org>]

klp-prepare-patch accepts patches which apply with an offset or fuzz,
and warns about them.  Add a test that both are accepted with a
warning, and that the combined patch has the line numbers and context of
the real source, so the #line directives refer to the right lines.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Song Liu <song@kernel.org>
---
 .../livepatch/test_klp_build/Makefile         |   3 +-
 .../test_klp_build/test-offset-and-fuzz.sh    | 120 ++++++++++++++++++
 2 files changed, 122 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/livepatch/test_klp_build/test-offset-and-fuzz.sh

diff --git a/tools/testing/selftests/livepatch/test_klp_build/Makefile b/tools/testing/selftests/livepatch/test_klp_build/Makefile
index 3650de4d6975..0daeea7a7db1 100644
--- a/tools/testing/selftests/livepatch/test_klp_build/Makefile
+++ b/tools/testing/selftests/livepatch/test_klp_build/Makefile
@@ -7,7 +7,8 @@ TEST_PROGS := \
 	test-new-and-deleted-files.sh \
 	test-line-directives.sh \
 	test-unsupported-files.sh \
-	test-patch-not-applying.sh
+	test-patch-not-applying.sh \
+	test-offset-and-fuzz.sh
 
 TEST_PROGS_EXTENDED := functions.sh
 
diff --git a/tools/testing/selftests/livepatch/test_klp_build/test-offset-and-fuzz.sh b/tools/testing/selftests/livepatch/test_klp_build/test-offset-and-fuzz.sh
new file mode 100755
index 000000000000..8e36d5aa026f
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_klp_build/test-offset-and-fuzz.sh
@@ -0,0 +1,120 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+. "$(dirname "$0")/functions.sh"
+
+# expect_warning(msg) - check that klp-prepare-patch warned, and drop the
+# warning so expect_patch() doesn't complain about it
+#	msg - the warning, without the "warning: klp-prepare-patch: " prefix
+function expect_warning() {
+	local line="warning: klp-prepare-patch: $1"
+
+	grep -qxF "$line" "$WORK_DIR/stderr" ||
+		not_ok "klp-prepare-patch didn't warn \"$1\":" "$WORK_DIR/stderr"
+
+	grep -vxF "$line" "$WORK_DIR/stderr" > "$WORK_DIR/stderr.rest"
+	mv "$WORK_DIR/stderr.rest" "$WORK_DIR/stderr"
+}
+
+setup_tree
+
+add_file drivers/foo/foo.c <<'EOT'
+int foo(int x)
+{
+	if (x < 0)
+		return -1;
+	return x;
+}
+
+int bar(void)
+{
+	return __LINE__;
+}
+
+int baz(int x)
+{
+	if (x > 100)
+		return 100;
+	return x;
+}
+EOT
+
+# - a patch made against a source with fewer lines applies at an offset, and
+#   the combined patch has the real line numbers
+
+start_test "patch with an offset"
+
+add_patch 0001-offset.patch <<'EOT'
+--- a/drivers/foo/foo.c
++++ b/drivers/foo/foo.c
+@@ -9,7 +9,7 @@
+
+ int baz(int x)
+ {
+-	if (x > 100)
+-		return 100;
++	if (x > 1000)
++		return 1000;
+ 	return x;
+ }
+EOT
+
+run_klp_prepare_patch 0001-offset.patch
+
+expect_warning "$PATCH_DIR/0001-offset.patch applied with fuzz"
+expect_patch <<'EOT'
+--- a/drivers/foo/foo.c
++++ b/drivers/foo/foo.c
+@@ -12,7 +12,8 @@ int bar(void)
+
+ int baz(int x)
+ {
+-	if (x > 100)
+-		return 100;
++	if (x > 1000)
++		return 1000;
++#line 17
+ 	return x;
+ }
+EOT
+
+# - a patch whose context differs from the source applies with fuzz, and the
+#   combined patch has the real context
+
+start_test "patch with fuzz"
+
+add_patch 0001-fuzz.patch <<'EOT'
+--- a/drivers/foo/foo.c
++++ b/drivers/foo/foo.c
+@@ -12,7 +12,7 @@
+ /* clamp x */
+ int baz(int x)
+ {
+-	if (x > 100)
+-		return 100;
++	if (x > 1000)
++		return 1000;
+ 	return x;
+ }
+EOT
+
+run_klp_prepare_patch 0001-fuzz.patch
+
+expect_warning "$PATCH_DIR/0001-fuzz.patch applied with fuzz"
+expect_patch <<'EOT'
+--- a/drivers/foo/foo.c
++++ b/drivers/foo/foo.c
+@@ -12,7 +12,8 @@ int bar(void)
+
+ int baz(int x)
+ {
+-	if (x > 100)
+-		return 100;
++	if (x > 1000)
++		return 1000;
++#line 17
+ 	return x;
+ }
+EOT
+
+exit 0
-- 
2.53.0-Meta