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
21static DEFINE_SPINLOCK(crw_inject_lock);
22DEFINE_STATIC_KEY_FALSE(cio_inject_enabled);
23static 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 */
34static 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 */
67int 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 */
85static 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 = vmemdup_user(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*/
128static 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
150static const struct file_operations crw_fops = {
151	.owner = THIS_MODULE,
152	.write = crw_inject_write,
153};
154
155static const struct file_operations cio_en_fops = {
156	.owner = THIS_MODULE,
157	.write = enable_inject_write,
158};
159
160static 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
171device_initcall(cio_inject_init);
172