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5de363b6 | 1 | // SPDX-License-Identifier: GPL-2.0 |
eb71c87a LT |
2 | /* |
3 | * drivers/base/power/trace.c | |
4 | * | |
5 | * Copyright (C) 2006 Linus Torvalds | |
6 | * | |
7 | * Trace facility for suspend/resume problems, when none of the | |
8 | * devices may be working. | |
9 | */ | |
7a5bd127 JP |
10 | #define pr_fmt(fmt) "PM: " fmt |
11 | ||
431d452a | 12 | #include <linux/pm-trace.h> |
1b6bc32f | 13 | #include <linux/export.h> |
eb71c87a | 14 | #include <linux/rtc.h> |
ba58d102 | 15 | #include <linux/suspend.h> |
0560204b | 16 | #include <linux/init.h> |
eb71c87a | 17 | |
463a8630 | 18 | #include <linux/mc146818rtc.h> |
eb71c87a LT |
19 | |
20 | #include "power.h" | |
21 | ||
22 | /* | |
23 | * Horrid, horrid, horrid. | |
24 | * | |
25 | * It turns out that the _only_ piece of hardware that actually | |
26 | * keeps its value across a hard boot (and, more importantly, the | |
27 | * POST init sequence) is literally the realtime clock. | |
28 | * | |
29 | * Never mind that an RTC chip has 114 bytes (and often a whole | |
30 | * other bank of an additional 128 bytes) of nice SRAM that is | |
31 | * _designed_ to keep data - the POST will clear it. So we literally | |
32 | * can just use the few bytes of actual time data, which means that | |
33 | * we're really limited. | |
34 | * | |
35 | * It means, for example, that we can't use the seconds at all | |
36 | * (since the time between the hang and the boot might be more | |
37 | * than a minute), and we'd better not depend on the low bits of | |
38 | * the minutes either. | |
39 | * | |
40 | * There are the wday fields etc, but I wouldn't guarantee those | |
41 | * are dependable either. And if the date isn't valid, either the | |
42 | * hw or POST will do strange things. | |
43 | * | |
44 | * So we're left with: | |
45 | * - year: 0-99 | |
46 | * - month: 0-11 | |
47 | * - day-of-month: 1-28 | |
48 | * - hour: 0-23 | |
49 | * - min: (0-30)*2 | |
50 | * | |
51 | * Giving us a total range of 0-16128000 (0xf61800), ie less | |
52 | * than 24 bits of actual data we can save across reboots. | |
53 | * | |
54 | * And if your box can't boot in less than three minutes, | |
55 | * you're screwed. | |
56 | * | |
57 | * Now, almost 24 bits of data is pitifully small, so we need | |
58 | * to be pretty dense if we want to use it for anything nice. | |
59 | * What we do is that instead of saving off nice readable info, | |
60 | * we save off _hashes_ of information that we can hopefully | |
61 | * regenerate after the reboot. | |
62 | * | |
63 | * In particular, this means that we might be unlucky, and hit | |
64 | * a case where we have a hash collision, and we end up not | |
65 | * being able to tell for certain exactly which case happened. | |
66 | * But that's hopefully unlikely. | |
67 | * | |
68 | * What we do is to take the bits we can fit, and split them | |
69 | * into three parts (16*997*1009 = 16095568), and use the values | |
70 | * for: | |
71 | * - 0-15: user-settable | |
72 | * - 0-996: file + line number | |
73 | * - 0-1008: device | |
74 | */ | |
75 | #define USERHASH (16) | |
76 | #define FILEHASH (997) | |
77 | #define DEVHASH (1009) | |
78 | ||
79 | #define DEVSEED (7919) | |
80 | ||
ba58d102 CY |
81 | bool pm_trace_rtc_abused __read_mostly; |
82 | EXPORT_SYMBOL_GPL(pm_trace_rtc_abused); | |
83 | ||
eb71c87a LT |
84 | static unsigned int dev_hash_value; |
85 | ||
86 | static int set_magic_time(unsigned int user, unsigned int file, unsigned int device) | |
87 | { | |
88 | unsigned int n = user + USERHASH*(file + FILEHASH*device); | |
89 | ||
90 | // June 7th, 2006 | |
91 | static struct rtc_time time = { | |
92 | .tm_sec = 0, | |
93 | .tm_min = 0, | |
94 | .tm_hour = 0, | |
95 | .tm_mday = 7, | |
96 | .tm_mon = 5, // June - counting from zero | |
97 | .tm_year = 106, | |
98 | .tm_wday = 3, | |
99 | .tm_yday = 160, | |
100 | .tm_isdst = 1 | |
101 | }; | |
102 | ||
103 | time.tm_year = (n % 100); | |
104 | n /= 100; | |
105 | time.tm_mon = (n % 12); | |
106 | n /= 12; | |
107 | time.tm_mday = (n % 28) + 1; | |
108 | n /= 28; | |
109 | time.tm_hour = (n % 24); | |
110 | n /= 24; | |
111 | time.tm_min = (n % 20) * 3; | |
112 | n /= 20; | |
463a8630 | 113 | mc146818_set_time(&time); |
ba58d102 | 114 | pm_trace_rtc_abused = true; |
eb71c87a LT |
115 | return n ? -1 : 0; |
116 | } | |
117 | ||
118 | static unsigned int read_magic_time(void) | |
119 | { | |
120 | struct rtc_time time; | |
121 | unsigned int val; | |
122 | ||
0dd8d6cb MJ |
123 | if (mc146818_get_time(&time) < 0) { |
124 | pr_err("Unable to read current time from RTC\n"); | |
125 | return 0; | |
126 | } | |
127 | ||
a07995be | 128 | pr_info("RTC time: %ptRt, date: %ptRd\n", &time, &time); |
eb71c87a LT |
129 | val = time.tm_year; /* 100 years */ |
130 | if (val > 100) | |
131 | val -= 100; | |
132 | val += time.tm_mon * 100; /* 12 months */ | |
133 | val += (time.tm_mday-1) * 100 * 12; /* 28 month-days */ | |
134 | val += time.tm_hour * 100 * 12 * 28; /* 24 hours */ | |
135 | val += (time.tm_min / 3) * 100 * 12 * 28 * 24; /* 20 3-minute intervals */ | |
136 | return val; | |
137 | } | |
138 | ||
139 | /* | |
140 | * This is just the sdbm hash function with a user-supplied | |
141 | * seed and final size parameter. | |
142 | */ | |
143 | static unsigned int hash_string(unsigned int seed, const char *data, unsigned int mod) | |
144 | { | |
145 | unsigned char c; | |
146 | while ((c = *data++) != 0) { | |
147 | seed = (seed << 16) + (seed << 6) - seed + c; | |
148 | } | |
149 | return seed % mod; | |
150 | } | |
151 | ||
152 | void set_trace_device(struct device *dev) | |
153 | { | |
1e0b2cf9 | 154 | dev_hash_value = hash_string(DEVSEED, dev_name(dev), DEVHASH); |
eb71c87a | 155 | } |
44bf4cea | 156 | EXPORT_SYMBOL(set_trace_device); |
eb71c87a LT |
157 | |
158 | /* | |
159 | * We could just take the "tracedata" index into the .tracedata | |
160 | * section instead. Generating a hash of the data gives us a | |
161 | * chance to work across kernel versions, and perhaps more | |
162 | * importantly it also gives us valid/invalid check (ie we will | |
163 | * likely not give totally bogus reports - if the hash matches, | |
164 | * it's not any guarantee, but it's a high _likelihood_ that | |
165 | * the match is valid). | |
166 | */ | |
431d452a | 167 | void generate_pm_trace(const void *tracedata, unsigned int user) |
eb71c87a LT |
168 | { |
169 | unsigned short lineno = *(unsigned short *)tracedata; | |
170 | const char *file = *(const char **)(tracedata + 2); | |
171 | unsigned int user_hash_value, file_hash_value; | |
172 | ||
0560204b JG |
173 | if (!x86_platform.legacy.rtc) |
174 | return; | |
175 | ||
eb71c87a LT |
176 | user_hash_value = user % USERHASH; |
177 | file_hash_value = hash_string(lineno, file, FILEHASH); | |
178 | set_magic_time(user_hash_value, file_hash_value, dev_hash_value); | |
179 | } | |
431d452a | 180 | EXPORT_SYMBOL(generate_pm_trace); |
eb71c87a | 181 | |
f9723837 | 182 | extern char __tracedata_start[], __tracedata_end[]; |
eb71c87a LT |
183 | static int show_file_hash(unsigned int value) |
184 | { | |
185 | int match; | |
186 | char *tracedata; | |
187 | ||
188 | match = 0; | |
f9723837 | 189 | for (tracedata = __tracedata_start ; tracedata < __tracedata_end ; |
44bf4cea | 190 | tracedata += 2 + sizeof(unsigned long)) { |
eb71c87a LT |
191 | unsigned short lineno = *(unsigned short *)tracedata; |
192 | const char *file = *(const char **)(tracedata + 2); | |
193 | unsigned int hash = hash_string(lineno, file, FILEHASH); | |
194 | if (hash != value) | |
195 | continue; | |
0295a34d | 196 | pr_info(" hash matches %s:%u\n", file, lineno); |
eb71c87a LT |
197 | match++; |
198 | } | |
199 | return match; | |
200 | } | |
201 | ||
202 | static int show_dev_hash(unsigned int value) | |
203 | { | |
204 | int match = 0; | |
2ac21c6b | 205 | struct list_head *entry; |
eb71c87a | 206 | |
2ac21c6b JH |
207 | device_pm_lock(); |
208 | entry = dpm_list.prev; | |
1eede070 | 209 | while (entry != &dpm_list) { |
eb71c87a | 210 | struct device * dev = to_device(entry); |
1e0b2cf9 | 211 | unsigned int hash = hash_string(DEVSEED, dev_name(dev), DEVHASH); |
eb71c87a | 212 | if (hash == value) { |
fc3a8828 | 213 | dev_info(dev, "hash matches\n"); |
eb71c87a LT |
214 | match++; |
215 | } | |
216 | entry = entry->prev; | |
217 | } | |
2ac21c6b | 218 | device_pm_unlock(); |
eb71c87a LT |
219 | return match; |
220 | } | |
221 | ||
222 | static unsigned int hash_value_early_read; | |
223 | ||
d33ac60b JH |
224 | int show_trace_dev_match(char *buf, size_t size) |
225 | { | |
226 | unsigned int value = hash_value_early_read / (USERHASH * FILEHASH); | |
227 | int ret = 0; | |
228 | struct list_head *entry; | |
229 | ||
230 | /* | |
231 | * It's possible that multiple devices will match the hash and we can't | |
232 | * tell which is the culprit, so it's best to output them all. | |
233 | */ | |
234 | device_pm_lock(); | |
235 | entry = dpm_list.prev; | |
236 | while (size && entry != &dpm_list) { | |
237 | struct device *dev = to_device(entry); | |
238 | unsigned int hash = hash_string(DEVSEED, dev_name(dev), | |
239 | DEVHASH); | |
240 | if (hash == value) { | |
241 | int len = snprintf(buf, size, "%s\n", | |
242 | dev_driver_string(dev)); | |
243 | if (len > size) | |
244 | len = size; | |
245 | buf += len; | |
246 | ret += len; | |
247 | size -= len; | |
248 | } | |
249 | entry = entry->prev; | |
250 | } | |
251 | device_pm_unlock(); | |
252 | return ret; | |
253 | } | |
254 | ||
ba58d102 CY |
255 | static int |
256 | pm_trace_notify(struct notifier_block *nb, unsigned long mode, void *_unused) | |
257 | { | |
258 | switch (mode) { | |
259 | case PM_POST_HIBERNATION: | |
260 | case PM_POST_SUSPEND: | |
261 | if (pm_trace_rtc_abused) { | |
262 | pm_trace_rtc_abused = false; | |
263 | pr_warn("Possible incorrect RTC due to pm_trace, please use 'ntpdate' or 'rdate' to reset it.\n"); | |
264 | } | |
265 | break; | |
266 | default: | |
267 | break; | |
268 | } | |
269 | return 0; | |
270 | } | |
271 | ||
272 | static struct notifier_block pm_trace_nb = { | |
273 | .notifier_call = pm_trace_notify, | |
274 | }; | |
275 | ||
0659d420 | 276 | static int __init early_resume_init(void) |
eb71c87a | 277 | { |
0560204b JG |
278 | if (!x86_platform.legacy.rtc) |
279 | return 0; | |
280 | ||
eb71c87a | 281 | hash_value_early_read = read_magic_time(); |
ba58d102 | 282 | register_pm_notifier(&pm_trace_nb); |
eb71c87a LT |
283 | return 0; |
284 | } | |
285 | ||
0659d420 | 286 | static int __init late_resume_init(void) |
eb71c87a LT |
287 | { |
288 | unsigned int val = hash_value_early_read; | |
289 | unsigned int user, file, dev; | |
290 | ||
0560204b JG |
291 | if (!x86_platform.legacy.rtc) |
292 | return 0; | |
293 | ||
eb71c87a LT |
294 | user = val % USERHASH; |
295 | val = val / USERHASH; | |
296 | file = val % FILEHASH; | |
297 | val = val / FILEHASH; | |
298 | dev = val /* % DEVHASH */; | |
299 | ||
0295a34d | 300 | pr_info(" Magic number: %d:%d:%d\n", user, file, dev); |
eb71c87a LT |
301 | show_file_hash(file); |
302 | show_dev_hash(dev); | |
303 | return 0; | |
304 | } | |
305 | ||
306 | core_initcall(early_resume_init); | |
307 | late_initcall(late_resume_init); |