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 int runtime_instr_avail(void)
22{
23	return test_facility(64);
24}
25
26static void disable_runtime_instr(void)
27{
28	struct pt_regs *regs = task_pt_regs(current);
29
30	load_runtime_instr_cb(&runtime_instr_empty_cb);
31
32	/*
33	 * Make sure the RI bit is deleted from the PSW. If the user did not
34	 * switch off RI before the system call the process will get a
35	 * specification exception otherwise.
36	 */
37	regs->psw.mask &= ~PSW_MASK_RI;
38}
39
40static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
41{
42	cb->buf_limit = 0xfff;
43	cb->int_requested = 1;
44	cb->pstate = 1;
45	cb->pstate_set_buf = 1;
46	cb->pstate_sample = 1;
47	cb->pstate_collect = 1;
48	cb->key = PAGE_DEFAULT_KEY;
49	cb->valid = 1;
50}
51
52void exit_thread_runtime_instr(void)
53{
54	struct task_struct *task = current;
55
56	if (!task->thread.ri_cb)
57		return;
58	disable_runtime_instr();
59	kfree(task->thread.ri_cb);
60	task->thread.ri_signum = 0;
61	task->thread.ri_cb = NULL;
62}
63
64static void runtime_instr_int_handler(struct ext_code ext_code,
65				unsigned int param32, unsigned long param64)
66{
67	struct siginfo info;
68
69	if (!(param32 & CPU_MF_INT_RI_MASK))
70		return;
71
72	inc_irq_stat(IRQEXT_CMR);
73
74	if (!current->thread.ri_cb)
75		return;
76	if (current->thread.ri_signum < SIGRTMIN ||
77	    current->thread.ri_signum > SIGRTMAX) {
78		WARN_ON_ONCE(1);
79		return;
80	}
81
82	memset(&info, 0, sizeof(info));
83	info.si_signo = current->thread.ri_signum;
84	info.si_code = SI_QUEUE;
85	if (param32 & CPU_MF_INT_RI_BUF_FULL)
86		info.si_int = ENOBUFS;
87	else if (param32 & CPU_MF_INT_RI_HALTED)
88		info.si_int = ECANCELED;
89	else
90		return; /* unknown reason */
91
92	send_sig_info(current->thread.ri_signum, &info, current);
93}
94
95SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
96{
97	struct runtime_instr_cb *cb;
98
99	if (!runtime_instr_avail())
100		return -EOPNOTSUPP;
101
102	if (command == S390_RUNTIME_INSTR_STOP) {
103		preempt_disable();
104		exit_thread_runtime_instr();
105		preempt_enable();
106		return 0;
107	}
108
109	if (command != S390_RUNTIME_INSTR_START ||
110	    (signum < SIGRTMIN || signum > SIGRTMAX))
111		return -EINVAL;
112
113	if (!current->thread.ri_cb) {
114		cb = kzalloc(sizeof(*cb), GFP_KERNEL);
115		if (!cb)
116			return -ENOMEM;
117	} else {
118		cb = current->thread.ri_cb;
119		memset(cb, 0, sizeof(*cb));
120	}
121
122	init_runtime_instr_cb(cb);
123	current->thread.ri_signum = signum;
124
125	/* now load the control block to make it available */
126	preempt_disable();
127	current->thread.ri_cb = cb;
128	load_runtime_instr_cb(cb);
129	preempt_enable();
130	return 0;
131}
132
133static int __init runtime_instr_init(void)
134{
135	int rc;
136
137	if (!runtime_instr_avail())
138		return 0;
139
140	irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
141	rc = register_external_irq(EXT_IRQ_MEASURE_ALERT,
142				   runtime_instr_int_handler);
143	if (rc)
144		irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
145	else
146		pr_info("Runtime instrumentation facility initialized\n");
147	return rc;
148}
149device_initcall(runtime_instr_init);
150