// 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_obj(*cb);		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;}