1 files changed, 102 insertions, 0 deletions
diff --git a/arch/s390/kernel/runtime_instr.c b/arch/s390/kernel/runtime_instr.c
new file mode 100644
index 000000000..1788a5454
--- /dev/null
+++ b/arch/s390/kernel/runtime_instr.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corp. 2012
+ * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/syscalls.h>
+#include <linux/signal.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/kernel_stat.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/runtime_instr.h>
+#include <asm/cpu_mf.h>
+#include <asm/irq.h>
+
+#include "entry.h"
+
+/* empty control block to disable RI by loading it */
+struct runtime_instr_cb runtime_instr_empty_cb;
+
+void runtime_instr_release(struct task_struct *tsk)
+{
+	kfree(tsk->thread.ri_cb);
+}
+
+static void disable_runtime_instr(void)
+{
+	struct task_struct *task = current;
+	struct pt_regs *regs;
+
+	if (!task->thread.ri_cb)
+		return;
+	regs = task_pt_regs(task);
+	preempt_disable();
+	load_runtime_instr_cb(&runtime_instr_empty_cb);
+	kfree(task->thread.ri_cb);
+	task->thread.ri_cb = NULL;
+	preempt_enable();
+
+	/*
+	 * Make sure the RI bit is deleted from the PSW. If the user did not
+	 * switch off RI before the system call the process will get a
+	 * specification exception otherwise.
+	 */
+	regs->psw.mask &= ~PSW_MASK_RI;
+}
+
+static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
+{
+	cb->rla = 0xfff;
+	cb->s = 1;
+	cb->k = 1;
+	cb->ps = 1;
+	cb->pc = 1;
+	cb->key = PAGE_DEFAULT_KEY >> 4;
+	cb->v = 1;
+}
+
+/*
+ * The signum argument is unused. In older kernels it was used to
+ * specify a real-time signal. For backwards compatibility user space
+ * should pass a valid real-time signal number (the signum argument
+ * was checked in older kernels).
+ */
+SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
+{
+	struct runtime_instr_cb *cb;
+
+	if (!test_facility(64))
+		return -EOPNOTSUPP;
+
+	if (command == S390_RUNTIME_INSTR_STOP) {
+		disable_runtime_instr();
+		return 0;
+	}
+
+	if (command != S390_RUNTIME_INSTR_START)
+		return -EINVAL;
+
+	if (!current->thread.ri_cb) {
+		cb = kzalloc(sizeof(*cb), GFP_KERNEL);
+		if (!cb)
+			return -ENOMEM;
+	} else {
+		cb = current->thread.ri_cb;
+		memset(cb, 0, sizeof(*cb));
+	}
+
+	init_runtime_instr_cb(cb);
+
+	/* now load the control block to make it available */
+	preempt_disable();
+	current->thread.ri_cb = cb;
+	load_runtime_instr_cb(cb);
+	preempt_enable();
+	return 0;
+}