1 files changed, 116 insertions, 0 deletions
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c
new file mode 100644
index 000000000000..dd802783ea84
--- /dev/null
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_syscall.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017-2023 SUSE
+ * Authors: Libor Pechacek <lpechacek@suse.cz>
+ *          Nicolai Stange <nstange@suse.de>
+ *          Marcos Paulo de Souza <mpdesouza@suse.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/livepatch.h>
+
+#if defined(__x86_64__)
+#define FN_PREFIX __x64_
+#elif defined(__s390x__)
+#define FN_PREFIX __s390x_
+#elif defined(__aarch64__)
+#define FN_PREFIX __arm64_
+#else
+/* powerpc does not select ARCH_HAS_SYSCALL_WRAPPER */
+#define FN_PREFIX
+#endif
+
+/* Protects klp_pids */
+static DEFINE_MUTEX(kpid_mutex);
+
+static unsigned int npids, npids_pending;
+static int klp_pids[NR_CPUS];
+module_param_array(klp_pids, int, &npids_pending, 0);
+MODULE_PARM_DESC(klp_pids, "Array of pids to be transitioned to livepatched state.");
+
+static ssize_t npids_show(struct kobject *kobj, struct kobj_attribute *attr,
+			  char *buf)
+{
+	return sprintf(buf, "%u\n", npids_pending);
+}
+
+static struct kobj_attribute klp_attr = __ATTR_RO(npids);
+static struct kobject *klp_kobj;
+
+static asmlinkage long lp_sys_getpid(void)
+{
+	int i;
+
+	mutex_lock(&kpid_mutex);
+	if (npids_pending > 0) {
+		for (i = 0; i < npids; i++) {
+			if (current->pid == klp_pids[i]) {
+				klp_pids[i] = 0;
+				npids_pending--;
+				break;
+			}
+		}
+	}
+	mutex_unlock(&kpid_mutex);
+
+	return task_tgid_vnr(current);
+}
+
+static struct klp_func vmlinux_funcs[] = {
+	{
+		.old_name = __stringify(FN_PREFIX) "sys_getpid",
+		.new_func = lp_sys_getpid,
+	}, {}
+};
+
+static struct klp_object objs[] = {
+	{
+		/* name being NULL means vmlinux */
+		.funcs = vmlinux_funcs,
+	}, {}
+};
+
+static struct klp_patch patch = {
+	.mod = THIS_MODULE,
+	.objs = objs,
+};
+
+static int livepatch_init(void)
+{
+	int ret;
+
+	klp_kobj = kobject_create_and_add("test_klp_syscall", kernel_kobj);
+	if (!klp_kobj)
+		return -ENOMEM;
+
+	ret = sysfs_create_file(klp_kobj, &klp_attr.attr);
+	if (ret) {
+		kobject_put(klp_kobj);
+		return ret;
+	}
+
+	/*
+	 * Save the number pids to transition to livepatched state before the
+	 * number of pending pids is decremented.
+	 */
+	npids = npids_pending;
+
+	return klp_enable_patch(&patch);
+}
+
+static void livepatch_exit(void)
+{
+	kobject_put(klp_kobj);
+}
+
+module_init(livepatch_init);
+module_exit(livepatch_exit);
+MODULE_LICENSE("GPL");
+MODULE_INFO(livepatch, "Y");
+MODULE_AUTHOR("Libor Pechacek <lpechacek@suse.cz>");
+MODULE_AUTHOR("Nicolai Stange <nstange@suse.de>");
+MODULE_AUTHOR("Marcos Paulo de Souza <mpdesouza@suse.com>");
+MODULE_DESCRIPTION("Livepatch test: syscall transition");