1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * CIO inject interface
4 *
5 * Copyright IBM Corp. 2021
6 * Author(s): Vineeth Vijayan <vneethv@linux.ibm.com>
7 */
8
9 #define KMSG_COMPONENT "cio"
10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
11
12 #include <linux/slab.h>
13 #include <linux/spinlock.h>
14 #include <linux/mm.h>
15 #include <linux/debugfs.h>
16 #include <asm/chpid.h>
17
18 #include "cio_inject.h"
19 #include "cio_debug.h"
20
21 static DEFINE_SPINLOCK(crw_inject_lock);
22 DEFINE_STATIC_KEY_FALSE(cio_inject_enabled);
23 static struct crw *crw_inject_data;
24
25 /**
26 * crw_inject : Initiate the artificial CRW inject
27 * @crw: The data which needs to be injected as new CRW.
28 *
29 * The CRW handler is called, which will use the provided artificial
30 * data instead of the CRW from the underlying hardware.
31 *
32 * Return: 0 on success
33 */
crw_inject(struct crw * crw)34 static int crw_inject(struct crw *crw)
35 {
36 int rc = 0;
37 struct crw *copy;
38 unsigned long flags;
39
40 copy = kmemdup(crw, sizeof(*crw), GFP_KERNEL);
41 if (!copy)
42 return -ENOMEM;
43
44 spin_lock_irqsave(&crw_inject_lock, flags);
45 if (crw_inject_data) {
46 kfree(copy);
47 rc = -EBUSY;
48 } else {
49 crw_inject_data = copy;
50 }
51 spin_unlock_irqrestore(&crw_inject_lock, flags);
52
53 if (!rc)
54 crw_handle_channel_report();
55
56 return rc;
57 }
58
59 /**
60 * stcrw_get_injected: Copy the artificial CRW data to CRW struct.
61 * @crw: The target CRW pointer.
62 *
63 * Retrieve an injected CRW data. Return 0 on success, 1 if no
64 * injected-CRW is available. The function reproduces the return
65 * code of the actual STCRW function.
66 */
stcrw_get_injected(struct crw * crw)67 int stcrw_get_injected(struct crw *crw)
68 {
69 int rc = 1;
70 unsigned long flags;
71
72 spin_lock_irqsave(&crw_inject_lock, flags);
73 if (crw_inject_data) {
74 memcpy(crw, crw_inject_data, sizeof(*crw));
75 kfree(crw_inject_data);
76 crw_inject_data = NULL;
77 rc = 0;
78 }
79 spin_unlock_irqrestore(&crw_inject_lock, flags);
80
81 return rc;
82 }
83
84 /* The debugfs write handler for crw_inject nodes operation */
crw_inject_write(struct file * file,const char __user * buf,size_t lbuf,loff_t * ppos)85 static ssize_t crw_inject_write(struct file *file, const char __user *buf,
86 size_t lbuf, loff_t *ppos)
87 {
88 u32 slct, oflw, chn, rsc, anc, erc, rsid;
89 struct crw crw;
90 char *buffer;
91 int rc;
92
93 if (!static_branch_likely(&cio_inject_enabled)) {
94 pr_warn("CIO inject is not enabled - ignoring CRW inject\n");
95 return -EINVAL;
96 }
97
98 buffer = memdup_user_nul(buf, lbuf);
99 if (IS_ERR(buffer))
100 return -ENOMEM;
101
102 rc = sscanf(buffer, "%x %x %x %x %x %x %x", &slct, &oflw, &chn, &rsc, &anc,
103 &erc, &rsid);
104
105 kvfree(buffer);
106 if (rc != 7) {
107 pr_warn("crw_inject: Invalid format (need <solicited> <overflow> <chaining> <rsc> <ancillary> <erc> <rsid>)\n");
108 return -EINVAL;
109 }
110
111 memset(&crw, 0, sizeof(crw));
112 crw.slct = slct;
113 crw.oflw = oflw;
114 crw.chn = chn;
115 crw.rsc = rsc;
116 crw.anc = anc;
117 crw.erc = erc;
118 crw.rsid = rsid;
119
120 rc = crw_inject(&crw);
121 if (rc)
122 return rc;
123
124 return lbuf;
125 }
126
127 /* Debugfs write handler for inject_enable node*/
enable_inject_write(struct file * file,const char __user * buf,size_t lbuf,loff_t * ppos)128 static ssize_t enable_inject_write(struct file *file, const char __user *buf,
129 size_t lbuf, loff_t *ppos)
130 {
131 unsigned long en = 0;
132 int rc;
133
134 rc = kstrtoul_from_user(buf, lbuf, 10, &en);
135 if (rc)
136 return rc;
137
138 switch (en) {
139 case 0:
140 static_branch_disable(&cio_inject_enabled);
141 break;
142 case 1:
143 static_branch_enable(&cio_inject_enabled);
144 break;
145 }
146
147 return lbuf;
148 }
149
150 static const struct file_operations crw_fops = {
151 .owner = THIS_MODULE,
152 .write = crw_inject_write,
153 };
154
155 static const struct file_operations cio_en_fops = {
156 .owner = THIS_MODULE,
157 .write = enable_inject_write,
158 };
159
cio_inject_init(void)160 static int __init cio_inject_init(void)
161 {
162 /* enable_inject node enables the static branching */
163 debugfs_create_file("enable_inject", 0200, cio_debugfs_dir,
164 NULL, &cio_en_fops);
165
166 debugfs_create_file("crw_inject", 0200, cio_debugfs_dir,
167 NULL, &crw_fops);
168 return 0;
169 }
170
171 device_initcall(cio_inject_init);
172