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// 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;
}
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