1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright IBM Corp. 2012
4 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/syscalls.h>
9 #include <linux/signal.h>
10 #include <linux/mm.h>
11 #include <linux/slab.h>
12 #include <linux/init.h>
13 #include <linux/errno.h>
14 #include <linux/kernel_stat.h>
15 #include <linux/sched/task_stack.h>
16
17 #include <asm/runtime_instr.h>
18 #include <asm/cpu_mf.h>
19 #include <asm/irq.h>
20
21 #include "entry.h"
22
23 /* empty control block to disable RI by loading it */
24 struct runtime_instr_cb runtime_instr_empty_cb;
25
26 void runtime_instr_release(struct task_struct *tsk)
27 {
28 kfree(tsk->thread.ri_cb);
29 }
30
31 static void disable_runtime_instr(void)
32 {
33 struct task_struct *task = current;
34 struct pt_regs *regs;
35
36 if (!task->thread.ri_cb)
37 return;
38 regs = task_pt_regs(task);
39 preempt_disable();
40 load_runtime_instr_cb(&runtime_instr_empty_cb);
41 kfree(task->thread.ri_cb);
42 task->thread.ri_cb = NULL;
43 preempt_enable();
44
45 /*
46 * Make sure the RI bit is deleted from the PSW. If the user did not
47 * switch off RI before the system call the process will get a
48 * specification exception otherwise.
49 */
50 regs->psw.mask &= ~PSW_MASK_RI;
51 }
52
53 static void init_runtime_instr_cb(struct runtime_instr_cb *cb)
54 {
55 cb->rla = 0xfff;
56 cb->s = 1;
57 cb->k = 1;
58 cb->ps = 1;
59 cb->pc = 1;
60 cb->key = PAGE_DEFAULT_KEY >> 4;
61 cb->v = 1;
62 }
63
64 /*
65 * The signum argument is unused. In older kernels it was used to
66 * specify a real-time signal. For backwards compatibility user space
67 * should pass a valid real-time signal number (the signum argument
68 * was checked in older kernels).
69 */
70 SYSCALL_DEFINE2(s390_runtime_instr, int, command, int, signum)
71 {
72 struct runtime_instr_cb *cb;
73
74 if (!test_facility(64))
75 return -EOPNOTSUPP;
76
77 if (command == S390_RUNTIME_INSTR_STOP) {
78 disable_runtime_instr();
79 return 0;
80 }
81
82 if (command != S390_RUNTIME_INSTR_START)
83 return -EINVAL;
84
85 if (!current->thread.ri_cb) {
86 cb = kzalloc(sizeof(*cb), GFP_KERNEL);
87 if (!cb)
88 return -ENOMEM;
89 } else {
90 cb = current->thread.ri_cb;
91 memset(cb, 0, sizeof(*cb));
92 }
93
94 init_runtime_instr_cb(cb);
95
96 /* now load the control block to make it available */
97 preempt_disable();
98 current->thread.ri_cb = cb;
99 load_runtime_instr_cb(cb);
100 preempt_enable();
101 return 0;
102 }
103
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