GNU Linux-libre 4.9.288-gnu1
[releases.git] / arch / s390 / kernel / runtime_instr.c
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 */
19 struct runtime_instr_cb runtime_instr_empty_cb;
20
21 void runtime_instr_release(struct task_struct *tsk)
22 {
23         kfree(tsk->thread.ri_cb);
24 }
25
26 static void disable_runtime_instr(void)
27 {
28         struct task_struct *task = current;
29         struct pt_regs *regs;
30
31         if (!task->thread.ri_cb)
32                 return;
33         regs = task_pt_regs(task);
34         preempt_disable();
35         load_runtime_instr_cb(&runtime_instr_empty_cb);
36         kfree(task->thread.ri_cb);
37         task->thread.ri_cb = NULL;
38         preempt_enable();
39
40         /*
41          * Make sure the RI bit is deleted from the PSW. If the user did not
42          * switch off RI before the system call the process will get a
43          * specification exception otherwise.
44          */
45         regs->psw.mask &= ~PSW_MASK_RI;
46 }
47
48 static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
49 {
50         cb->buf_limit = 0xfff;
51         cb->pstate = 1;
52         cb->pstate_set_buf = 1;
53         cb->pstate_sample = 1;
54         cb->pstate_collect = 1;
55         cb->key = PAGE_DEFAULT_KEY;
56         cb->valid = 1;
57 }
58
59 SYSCALL_DEFINE1(s390_runtime_instr, int, command)
60 {
61         struct runtime_instr_cb *cb;
62
63         if (!test_facility(64))
64                 return -EOPNOTSUPP;
65
66         if (command == S390_RUNTIME_INSTR_STOP) {
67                 disable_runtime_instr();
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 }