1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2023 Red Hat
4 */
5
6 #include "logger.h"
7
8 #include <asm/current.h>
9 #include <linux/delay.h>
10 #include <linux/hardirq.h>
11 #include <linux/module.h>
12 #include <linux/printk.h>
13 #include <linux/sched.h>
14
15 #include "errors.h"
16 #include "thread-device.h"
17 #include "thread-utils.h"
18
19 int vdo_log_level = VDO_LOG_DEFAULT;
20
vdo_get_log_level(void)21 int vdo_get_log_level(void)
22 {
23 int log_level_latch = READ_ONCE(vdo_log_level);
24
25 if (unlikely(log_level_latch > VDO_LOG_MAX)) {
26 log_level_latch = VDO_LOG_DEFAULT;
27 WRITE_ONCE(vdo_log_level, log_level_latch);
28 }
29 return log_level_latch;
30 }
31
get_current_interrupt_type(void)32 static const char *get_current_interrupt_type(void)
33 {
34 if (in_nmi())
35 return "NMI";
36
37 if (in_irq())
38 return "HI";
39
40 if (in_softirq())
41 return "SI";
42
43 return "INTR";
44 }
45
46 /**
47 * emit_log_message_to_kernel() - Emit a log message to the kernel at the specified priority.
48 *
49 * @priority: The priority at which to log the message
50 * @fmt: The format string of the message
51 */
emit_log_message_to_kernel(int priority,const char * fmt,...)52 static void emit_log_message_to_kernel(int priority, const char *fmt, ...)
53 {
54 va_list args;
55 struct va_format vaf;
56
57 if (priority > vdo_get_log_level())
58 return;
59
60 va_start(args, fmt);
61 vaf.fmt = fmt;
62 vaf.va = &args;
63
64 switch (priority) {
65 case VDO_LOG_EMERG:
66 case VDO_LOG_ALERT:
67 case VDO_LOG_CRIT:
68 pr_crit("%pV", &vaf);
69 break;
70 case VDO_LOG_ERR:
71 pr_err("%pV", &vaf);
72 break;
73 case VDO_LOG_WARNING:
74 pr_warn("%pV", &vaf);
75 break;
76 case VDO_LOG_NOTICE:
77 case VDO_LOG_INFO:
78 pr_info("%pV", &vaf);
79 break;
80 case VDO_LOG_DEBUG:
81 pr_debug("%pV", &vaf);
82 break;
83 default:
84 printk(KERN_DEFAULT "%pV", &vaf);
85 break;
86 }
87
88 va_end(args);
89 }
90
91 /**
92 * emit_log_message() - Emit a log message to the kernel log in a format suited to the current
93 * thread context.
94 *
95 * Context info formats:
96 *
97 * interrupt: uds[NMI]: blah
98 * kvdo thread: kvdo12:foobarQ: blah
99 * thread w/device id: kvdo12:myprog: blah
100 * other thread: uds: myprog: blah
101 *
102 * Fields: module name, interrupt level, process name, device ID.
103 *
104 * @priority: the priority at which to log the message
105 * @module: The name of the module doing the logging
106 * @prefix: The prefix of the log message
107 * @vaf1: The first message format descriptor
108 * @vaf2: The second message format descriptor
109 */
emit_log_message(int priority,const char * module,const char * prefix,const struct va_format * vaf1,const struct va_format * vaf2)110 static void emit_log_message(int priority, const char *module, const char *prefix,
111 const struct va_format *vaf1, const struct va_format *vaf2)
112 {
113 int device_instance;
114
115 /*
116 * In interrupt context, identify the interrupt type and module. Ignore the process/thread
117 * since it could be anything.
118 */
119 if (in_interrupt()) {
120 const char *type = get_current_interrupt_type();
121
122 emit_log_message_to_kernel(priority, "%s[%s]: %s%pV%pV\n", module, type,
123 prefix, vaf1, vaf2);
124 return;
125 }
126
127 /* Not at interrupt level; we have a process we can look at, and might have a device ID. */
128 device_instance = vdo_get_thread_device_id();
129 if (device_instance >= 0) {
130 emit_log_message_to_kernel(priority, "%s%u:%s: %s%pV%pV\n", module,
131 device_instance, current->comm, prefix, vaf1,
132 vaf2);
133 return;
134 }
135
136 /*
137 * If it's a kernel thread and the module name is a prefix of its name, assume it is ours
138 * and only identify the thread.
139 */
140 if (((current->flags & PF_KTHREAD) != 0) &&
141 (strncmp(module, current->comm, strlen(module)) == 0)) {
142 emit_log_message_to_kernel(priority, "%s: %s%pV%pV\n", current->comm,
143 prefix, vaf1, vaf2);
144 return;
145 }
146
147 /* Identify the module and the process. */
148 emit_log_message_to_kernel(priority, "%s: %s: %s%pV%pV\n", module, current->comm,
149 prefix, vaf1, vaf2);
150 }
151
152 /*
153 * vdo_log_embedded_message() - Log a message embedded within another message.
154 * @priority: the priority at which to log the message
155 * @module: the name of the module doing the logging
156 * @prefix: optional string prefix to message, may be NULL
157 * @fmt1: format of message first part (required)
158 * @args1: arguments for message first part (required)
159 * @fmt2: format of message second part
160 */
vdo_log_embedded_message(int priority,const char * module,const char * prefix,const char * fmt1,va_list args1,const char * fmt2,...)161 void vdo_log_embedded_message(int priority, const char *module, const char *prefix,
162 const char *fmt1, va_list args1, const char *fmt2, ...)
163 {
164 va_list args1_copy;
165 va_list args2;
166 struct va_format vaf1, vaf2;
167
168 va_start(args2, fmt2);
169
170 if (module == NULL)
171 module = VDO_LOGGING_MODULE_NAME;
172
173 if (prefix == NULL)
174 prefix = "";
175
176 /*
177 * It is implementation dependent whether va_list is defined as an array type that decays
178 * to a pointer when passed as an argument. Copy args1 and args2 with va_copy so that vaf1
179 * and vaf2 get proper va_list pointers irrespective of how va_list is defined.
180 */
181 va_copy(args1_copy, args1);
182 vaf1.fmt = fmt1;
183 vaf1.va = &args1_copy;
184
185 vaf2.fmt = fmt2;
186 vaf2.va = &args2;
187
188 emit_log_message(priority, module, prefix, &vaf1, &vaf2);
189
190 va_end(args1_copy);
191 va_end(args2);
192 }
193
vdo_vlog_strerror(int priority,int errnum,const char * module,const char * format,va_list args)194 int vdo_vlog_strerror(int priority, int errnum, const char *module, const char *format,
195 va_list args)
196 {
197 char errbuf[VDO_MAX_ERROR_MESSAGE_SIZE];
198 const char *message = uds_string_error(errnum, errbuf, sizeof(errbuf));
199
200 vdo_log_embedded_message(priority, module, NULL, format, args, ": %s (%d)",
201 message, errnum);
202 return errnum;
203 }
204
__vdo_log_strerror(int priority,int errnum,const char * module,const char * format,...)205 int __vdo_log_strerror(int priority, int errnum, const char *module, const char *format, ...)
206 {
207 va_list args;
208
209 va_start(args, format);
210 vdo_vlog_strerror(priority, errnum, module, format, args);
211 va_end(args);
212 return errnum;
213 }
214
vdo_log_backtrace(int priority)215 void vdo_log_backtrace(int priority)
216 {
217 if (priority > vdo_get_log_level())
218 return;
219
220 dump_stack();
221 }
222
__vdo_log_message(int priority,const char * module,const char * format,...)223 void __vdo_log_message(int priority, const char *module, const char *format, ...)
224 {
225 va_list args;
226
227 va_start(args, format);
228 vdo_log_embedded_message(priority, module, NULL, format, args, "%s", "");
229 va_end(args);
230 }
231
232 /*
233 * Sleep or delay a few milliseconds in an attempt to allow the log buffers to be flushed lest they
234 * be overrun.
235 */
vdo_pause_for_logger(void)236 void vdo_pause_for_logger(void)
237 {
238 fsleep(4000);
239 }
240