1/*
 2 * Copyright IBM Corp. 2012
 3 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
 4 */
 5
 6#include <linux/kernel.h>
 7#include <linux/syscalls.h>
 8#include <linux/signal.h>
 9#include <linux/mm.h>
10#include <linux/slab.h>
11#include <linux/init.h>
12#include <linux/errno.h>
13#include <linux/kernel_stat.h>
14#include <asm/runtime_instr.h>
15#include <asm/cpu_mf.h>
16#include <asm/irq.h>
17
18/* empty control block to disable RI by loading it */
19struct runtime_instr_cb runtime_instr_empty_cb;
20
21static void disable_runtime_instr(void)
22{
23	struct pt_regs *regs = task_pt_regs(current);
24
25	load_runtime_instr_cb(&runtime_instr_empty_cb);
26
27	/*
28	 * Make sure the RI bit is deleted from the PSW. If the user did not
29	 * switch off RI before the system call the process will get a
30	 * specification exception otherwise.
31	 */
32	regs->psw.mask &= ~PSW_MASK_RI;
33}
34
35static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
36{
37	cb->buf_limit = 0xfff;
38	cb->pstate = 1;
39	cb->pstate_set_buf = 1;
40	cb->pstate_sample = 1;
41	cb->pstate_collect = 1;
42	cb->key = PAGE_DEFAULT_KEY;
43	cb->valid = 1;
44}
45
46void exit_thread_runtime_instr(void)
47{
48	struct task_struct *task = current;
49
50	if (!task->thread.ri_cb)
51		return;
52	disable_runtime_instr();
53	kfree(task->thread.ri_cb);
54	task->thread.ri_cb = NULL;
55}
56
57SYSCALL_DEFINE1(s390_runtime_instr, int, command)
58{
59	struct runtime_instr_cb *cb;
60
61	if (!test_facility(64))
62		return -EOPNOTSUPP;
63
64	if (command == S390_RUNTIME_INSTR_STOP) {
65		preempt_disable();
66		exit_thread_runtime_instr();
67		preempt_enable();
68		return 0;
69	}
70
71	if (command != S390_RUNTIME_INSTR_START)
72		return -EINVAL;
73
74	if (!current->thread.ri_cb) {
75		cb = kzalloc(sizeof(*cb), GFP_KERNEL);
76		if (!cb)
77			return -ENOMEM;
78	} else {
79		cb = current->thread.ri_cb;
80		memset(cb, 0, sizeof(*cb));
81	}
82
83	init_runtime_instr_cb(cb);
84
85	/* now load the control block to make it available */
86	preempt_disable();
87	current->thread.ri_cb = cb;
88	load_runtime_instr_cb(cb);
89	preempt_enable();
90	return 0;
91}