objtool/klp: Group the klp tests by architecture

Which architecture a test is for is expressed by where it lives: tests are
in generic/ or in a directory named for their architecture, each carrying
its own fixtures, and the runner executes generic/ plus the one that
matches.  A test which cannot apply here is then not run at all, rather
than running in order to announce that it did not.

Layout does this better than a declaration would.  There is no x86_only(),
and no lookup letting a fixtures/<arch>/ file shadow a generic one of the
same name -- an arch-specific test simply carries its own fixtures.

Compilers cannot work the same way: CI varies CC over the same tree, so a
compiler requirement stays a declaration in the test.

What a run leaves out is reported once:

  # not run: 5 tests in x86/ (this run is arm64)

Silence would have been cheaper and wrong.  A run covering less than the
tree holds must not look like a run that covered all of it.

Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Assisted-by: Claude:claude-opus-5
Link: https://patch.msgid.link/20260916184351.2720310-4-song@kernel.org

2 files changed, 37 insertions, 0 deletions

diff --git a/tools/objtool/tests/generic/fixtures/basic.c b/tools/objtool/tests/generic/fixtures/basic.c
new file mode 100644
index 000000000000..811529e7bfb1
--- /dev/null
+++ b/tools/objtool/tests/generic/fixtures/basic.c
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/* One changed function and one unchanged function. */
+
+/* klp diff takes the object's module name from .modinfo */
+static const char __modinfo[]
+	__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
+
+int untouched(int x)
+{
+	return x * 3;
+}
+
+int changed(int x)
+{
+#ifdef PATCHED
+	return x + 2;
+#else
+	return x + 1;
+#endif
+}
diff --git a/tools/objtool/tests/generic/test-basic.sh b/tools/objtool/tests/generic/test-basic.sh
new file mode 100755
index 000000000000..562edfbc8646
--- /dev/null
+++ b/tools/objtool/tests/generic/test-basic.sh
@@ -0,0 +1,17 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Only functions whose code changed get cloned into the patch.
+
+. "$(dirname "$0")/../lib.sh"
+
+setup
+build_pair basic.c
+run_diff
+
+assert_patched     changed
+assert_not_patched untouched
+assert_section     ".init.klp_funcs"
+assert_section     ".init.klp_objects"
+
+pass "changed function cloned, unchanged function left alone"