[PATCH v3 7/7] selftests/livepatch: Add test for function conflict across replace_sets

[Yafang Shao <laoar.shao@gmail.com>]

Livepatches with different replace_sets must not modify the same
function. If a second livepatch attempts to modify a function that
has already been modified by a loaded livepatch with a different
replace_set, the loading will fail. if the second livepatch
shares the same replace_set, it will load successfully.

Add a test case to verify this behavior. The test result is as follows:

$ ./test-livepatch.sh
TEST: basic function patching ... ok
TEST: multiple livepatches ... ok
TEST: module function patching ... ok
TEST: module function patching (livepatch first) ... ok
TEST: function conflict: different replace_sets ... ok  <<<<
TEST: function conflict: the same replace_set ... ok    <<<<

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 .../selftests/livepatch/test-livepatch.sh     | 59 +++++++++++++++++++
 .../selftests/livepatch/test_modules/Makefile |  1 +
 .../test_modules/test_klp_atomic_replace2.c   | 55 +++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace2.c

diff --git a/tools/testing/selftests/livepatch/test-livepatch.sh b/tools/testing/selftests/livepatch/test-livepatch.sh
index 4f8fb5620c6e..9cdfc048d71c 100755
--- a/tools/testing/selftests/livepatch/test-livepatch.sh
+++ b/tools/testing/selftests/livepatch/test-livepatch.sh
@@ -6,6 +6,7 @@
 
 MOD_LIVEPATCH1=test_klp_livepatch
 MOD_REPLACE=test_klp_atomic_replace
+MOD_REPLACE2=test_klp_atomic_replace2
 MOD_TARGET=test_klp_mod_target
 MOD_TARGET_PATCH=test_klp_mod_patch
 
@@ -203,5 +204,63 @@ livepatch: '$MOD_TARGET_PATCH': unpatching complete
 % rmmod $MOD_TARGET
 $MOD_TARGET: test_klp_mod_target_exit"
 
+# - load a livepatch that modifies function A
+# - loading another livepatch with a different replace_set that modifies
+#   the same function will fail
+
+start_test "function conflict: different replace_sets"
+
+load_lp $MOD_REPLACE replace_set=0
+load_failing_mod $MOD_REPLACE2 replace_set=1
+disable_lp $MOD_REPLACE
+unload_lp $MOD_REPLACE
+
+check_result "% insmod test_modules/$MOD_REPLACE.ko replace_set=0
+livepatch: enabling patch '$MOD_REPLACE'
+livepatch: '$MOD_REPLACE': initializing patching transition
+livepatch: '$MOD_REPLACE': starting patching transition
+livepatch: '$MOD_REPLACE': completing patching transition
+livepatch: '$MOD_REPLACE': patching complete
+% insmod test_modules/$MOD_REPLACE2.ko replace_set=1
+livepatch: Livepatch patch ($MOD_REPLACE2) is not compatible with the already installed livepatches.
+insmod: ERROR: could not insert module test_modules/$MOD_REPLACE2.ko: Invalid parameters
+% echo 0 > /sys/kernel/livepatch/$MOD_REPLACE/enabled
+livepatch: '$MOD_REPLACE': initializing unpatching transition
+livepatch: '$MOD_REPLACE': starting unpatching transition
+livepatch: '$MOD_REPLACE': completing unpatching transition
+livepatch: '$MOD_REPLACE': unpatching complete
+% rmmod $MOD_REPLACE"
+
+# - load a livepatch that modifies function A
+# - loading another livepatch with the same replace_set that modifies
+#   the same function will succeed
+
+start_test "function conflict: the same replace_set"
+
+load_lp $MOD_REPLACE replace_set=0
+load_lp $MOD_REPLACE2 replace_set=0
+disable_lp $MOD_REPLACE2
+unload_lp $MOD_REPLACE2
+unload_lp $MOD_REPLACE
+
+check_result "% insmod test_modules/$MOD_REPLACE.ko replace_set=0
+livepatch: enabling patch '$MOD_REPLACE'
+livepatch: '$MOD_REPLACE': initializing patching transition
+livepatch: '$MOD_REPLACE': starting patching transition
+livepatch: '$MOD_REPLACE': completing patching transition
+livepatch: '$MOD_REPLACE': patching complete
+% insmod test_modules/$MOD_REPLACE2.ko replace_set=0
+livepatch: enabling patch '$MOD_REPLACE2'
+livepatch: '$MOD_REPLACE2': initializing patching transition
+livepatch: '$MOD_REPLACE2': starting patching transition
+livepatch: '$MOD_REPLACE2': completing patching transition
+livepatch: '$MOD_REPLACE2': patching complete
+% echo 0 > /sys/kernel/livepatch/$MOD_REPLACE2/enabled
+livepatch: '$MOD_REPLACE2': initializing unpatching transition
+livepatch: '$MOD_REPLACE2': starting unpatching transition
+livepatch: '$MOD_REPLACE2': completing unpatching transition
+livepatch: '$MOD_REPLACE2': unpatching complete
+% rmmod $MOD_REPLACE2
+% rmmod $MOD_REPLACE"
 
 exit 0
diff --git a/tools/testing/selftests/livepatch/test_modules/Makefile b/tools/testing/selftests/livepatch/test_modules/Makefile
index bdc5ae37311e..f7111d500cab 100644
--- a/tools/testing/selftests/livepatch/test_modules/Makefile
+++ b/tools/testing/selftests/livepatch/test_modules/Makefile
@@ -2,6 +2,7 @@ TESTMODS_DIR := $(realpath $(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
 KDIR ?= /lib/modules/$(shell uname -r)/build
 
 obj-m += test_klp_atomic_replace.o \
+	test_klp_atomic_replace2.o \
 	test_klp_callbacks_busy.o \
 	test_klp_callbacks_demo.o \
 	test_klp_callbacks_demo2.o \
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace2.c
new file mode 100644
index 000000000000..1dff8b6d45ab
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_atomic_replace2.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/livepatch.h>
+
+static int replace_set;
+module_param(replace_set, int, 0644);
+MODULE_PARM_DESC(replace_set, "replace_set (default=0)");
+
+#include <linux/seq_file.h>
+static int livepatch_meminfo_proc_show(struct seq_file *m, void *v)
+{
+	seq_printf(m, "%s: %s\n", THIS_MODULE->name,
+		   "this has been live patched");
+	return 0;
+}
+
+static struct klp_func funcs[] = {
+	{
+		.old_name = "meminfo_proc_show",
+		.new_func = livepatch_meminfo_proc_show,
+	}, {}
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = funcs,
+	}, {}
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+	/* set .replace_set in the init function below for demo purposes */
+};
+
+static int test_klp_atomic_replace_init(void)
+{
+	patch.replace_set = replace_set;
+	return klp_enable_patch(&patch);
+}
+
+static void test_klp_atomic_replace_exit(void)
+{
+}
+
+module_init(test_klp_atomic_replace_init);
+module_exit(test_klp_atomic_replace_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_DESCRIPTION("Livepatch test: modified function compatibility verification");
-- 
2.52.0