1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
// SPDX-License-Identifier: GPL-2.0
/*
* Dummy EDAC driver
*
* A minimal EDAC device driver that registers its own platform device
* unconditionally, so it probes successfully on any system -- including
* VMs and guests that have no real ECC-capable cache/memory hardware
* exposed to them. Useful for exercising the EDAC core, sysfs interface,
* and userspace tooling (edac-utils, mcelog, etc.) without needing the
* physical hardware the "real" drivers depend on.
*
* Modeled after drivers/edac/a72_edac.c (Cortex A72 EDAC L1/L2 cache
* error detection), but with all of the hardware-specific bits (system
* register reads, SMP cross-calls, devicetree compatible matching)
* replaced by a software-only error source that can be poked from
* debugfs or left to generate nothing at all.
*/
#include <linux/cpu.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include "edac_module.h"
#define DRVNAME "dummy-edac"
#define MESSAGE_SIZE 64
/*
* Simulated "error syndrome". In real hardware drivers this would be
* read out of a per-CPU system/MMIO register. Here userspace (via
* debugfs) or nothing at all drives it, which is exactly the point:
* the driver has no dependency on any physical error source.
*/
struct dummy_edac_priv {
struct dentry *debugfs_dir;
atomic_t inject_ce;
atomic_t inject_ue;
};
static void dummy_edac_check(struct edac_device_ctl_info *edac_ctl)
{
struct dummy_edac_priv *priv = edac_ctl->pvt_info;
int cpu = raw_smp_processor_id();
char msg[MESSAGE_SIZE];
if (atomic_xchg(&priv->inject_ce, 0)) {
snprintf(msg, MESSAGE_SIZE,
"simulated correctable error on CPU %d", cpu);
edac_device_handle_ce(edac_ctl, cpu, 0, msg);
}
if (atomic_xchg(&priv->inject_ue, 0)) {
snprintf(msg, MESSAGE_SIZE,
"simulated uncorrectable error on CPU %d", cpu);
edac_device_handle_ue(edac_ctl, cpu, 0, msg);
}
}
/*
* debugfs knobs so you can drive the driver from userspace inside the
* guest, e.g.:
* echo 1 > /sys/kernel/debug/dummy-edac/inject_ce
* echo 1 > /sys/kernel/debug/dummy-edac/inject_ue
*/
static int inject_ce_set(void *data, u64 val)
{
struct dummy_edac_priv *priv = data;
if (val)
atomic_set(&priv->inject_ce, 1);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(inject_ce_fops, NULL, inject_ce_set, "%llu\n");
static int inject_ue_set(void *data, u64 val)
{
struct dummy_edac_priv *priv = data;
if (val)
atomic_set(&priv->inject_ue, 1);
return 0;
}
DEFINE_DEBUGFS_ATTRIBUTE(inject_ue_fops, NULL, inject_ue_set, "%llu\n");
static int dummy_edac_probe(struct platform_device *pdev)
{
struct edac_device_ctl_info *edac_ctl;
struct dummy_edac_priv *priv;
struct device *dev = &pdev->dev;
int rc;
edac_ctl = edac_device_alloc_ctl_info(sizeof(*priv), "cpu",
num_possible_cpus(), "L", 1, 1,
edac_device_alloc_index());
if (!edac_ctl)
return -ENOMEM;
priv = edac_ctl->pvt_info;
atomic_set(&priv->inject_ce, 0);
atomic_set(&priv->inject_ue, 0);
edac_ctl->edac_check = dummy_edac_check;
edac_ctl->dev = dev;
edac_ctl->mod_name = dev_name(dev);
edac_ctl->dev_name = dev_name(dev);
edac_ctl->ctl_name = DRVNAME;
/* Poll fairly slowly; this is a software source, not real hardware. */
edac_ctl->poll_msec = 1000;
dev_set_drvdata(dev, edac_ctl);
rc = edac_device_add_device(edac_ctl);
if (rc)
goto out_dev;
priv->debugfs_dir = debugfs_create_dir(DRVNAME, NULL);
debugfs_create_file_unsafe("inject_ce", 0200, priv->debugfs_dir,
priv, &inject_ce_fops);
debugfs_create_file_unsafe("inject_ue", 0200, priv->debugfs_dir,
priv, &inject_ue_fops);
return 0;
out_dev:
edac_device_free_ctl_info(edac_ctl);
return rc;
}
static void dummy_edac_remove(struct platform_device *pdev)
{
struct edac_device_ctl_info *edac_ctl = dev_get_drvdata(&pdev->dev);
struct dummy_edac_priv *priv = edac_ctl->pvt_info;
debugfs_remove_recursive(priv->debugfs_dir);
edac_device_del_device(edac_ctl->dev);
edac_device_free_ctl_info(edac_ctl);
}
static struct platform_driver dummy_edac_driver = {
.probe = dummy_edac_probe,
.remove = dummy_edac_remove,
.driver = {
.name = DRVNAME,
},
};
/*
* No devicetree/ACPI match table, and no scan of CPU nodes for a "compatible"
* + enable property: simply register a platform device unconditionally so
* probe() always runs. There is nothing here that depends on the underlying
* platform actually exposing the corresponding hardware, so it loads fine
* under QEMU/KVM, containers-with-a-kernel, or any other guest environment.
*/
static struct platform_device *dummy_pdev;
static int __init dummy_edac_driver_init(void)
{
int rc;
dummy_pdev = platform_device_register_simple(DRVNAME, -1, NULL, 0);
if (IS_ERR(dummy_pdev)) {
pr_err(DRVNAME ": failed to register dummy platform device\n");
return PTR_ERR(dummy_pdev);
}
rc = platform_driver_register(&dummy_edac_driver);
if (rc) {
platform_device_unregister(dummy_pdev);
return rc;
}
pr_info("Loading %s\n", DRVNAME);
return 0;
}
static void __exit dummy_edac_driver_exit(void)
{
platform_driver_unregister(&dummy_edac_driver);
platform_device_unregister(dummy_pdev);
pr_info("Removing %s\n", DRVNAME);
}
module_init(dummy_edac_driver_init);
module_exit(dummy_edac_driver_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Dummy EDAC driver for testing without real ECC hardware");
|
