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33701557 CD |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Userspace indexing of printk formats | |
4 | */ | |
5 | ||
6 | #include <linux/debugfs.h> | |
7 | #include <linux/module.h> | |
8 | #include <linux/printk.h> | |
9 | #include <linux/slab.h> | |
10 | #include <linux/string_helpers.h> | |
11 | ||
12 | #include "internal.h" | |
13 | ||
14 | extern struct pi_entry *__start_printk_index[]; | |
15 | extern struct pi_entry *__stop_printk_index[]; | |
16 | ||
17 | /* The base dir for module formats, typically debugfs/printk/index/ */ | |
18 | static struct dentry *dfs_index; | |
19 | ||
20 | static struct pi_entry *pi_get_entry(const struct module *mod, loff_t pos) | |
21 | { | |
22 | struct pi_entry **entries; | |
23 | unsigned int nr_entries; | |
24 | ||
25 | #ifdef CONFIG_MODULES | |
26 | if (mod) { | |
27 | entries = mod->printk_index_start; | |
28 | nr_entries = mod->printk_index_size; | |
5aa7eea9 | 29 | } else |
33701557 | 30 | #endif |
5aa7eea9 | 31 | { |
33701557 CD |
32 | /* vmlinux, comes from linker symbols */ |
33 | entries = __start_printk_index; | |
34 | nr_entries = __stop_printk_index - __start_printk_index; | |
35 | } | |
36 | ||
37 | if (pos >= nr_entries) | |
38 | return NULL; | |
39 | ||
40 | return entries[pos]; | |
41 | } | |
42 | ||
43 | static void *pi_next(struct seq_file *s, void *v, loff_t *pos) | |
44 | { | |
45 | const struct module *mod = s->file->f_inode->i_private; | |
46 | struct pi_entry *entry = pi_get_entry(mod, *pos); | |
47 | ||
48 | (*pos)++; | |
49 | ||
50 | return entry; | |
51 | } | |
52 | ||
53 | static void *pi_start(struct seq_file *s, loff_t *pos) | |
54 | { | |
55 | /* | |
56 | * Make show() print the header line. Do not update *pos because | |
57 | * pi_next() still has to return the entry at index 0 later. | |
58 | */ | |
59 | if (*pos == 0) | |
60 | return SEQ_START_TOKEN; | |
61 | ||
62 | return pi_next(s, NULL, pos); | |
63 | } | |
64 | ||
65 | /* | |
66 | * We need both ESCAPE_ANY and explicit characters from ESCAPE_SPECIAL in @only | |
67 | * because otherwise ESCAPE_NAP will cause double quotes and backslashes to be | |
68 | * ignored for quoting. | |
69 | */ | |
70 | #define seq_escape_printf_format(s, src) \ | |
71 | seq_escape_str(s, src, ESCAPE_ANY | ESCAPE_NAP | ESCAPE_APPEND, "\"\\") | |
72 | ||
73 | static int pi_show(struct seq_file *s, void *v) | |
74 | { | |
75 | const struct pi_entry *entry = v; | |
76 | int level = LOGLEVEL_DEFAULT; | |
77 | enum printk_info_flags flags = 0; | |
78 | u16 prefix_len = 0; | |
79 | ||
80 | if (v == SEQ_START_TOKEN) { | |
81 | seq_puts(s, "# <level/flags> filename:line function \"format\"\n"); | |
82 | return 0; | |
83 | } | |
84 | ||
85 | if (!entry->fmt) | |
86 | return 0; | |
87 | ||
88 | if (entry->level) | |
89 | printk_parse_prefix(entry->level, &level, &flags); | |
90 | else | |
91 | prefix_len = printk_parse_prefix(entry->fmt, &level, &flags); | |
92 | ||
93 | ||
94 | if (flags & LOG_CONT) { | |
95 | /* | |
96 | * LOGLEVEL_DEFAULT here means "use the same level as the | |
97 | * message we're continuing from", not the default message | |
98 | * loglevel, so don't display it as such. | |
99 | */ | |
100 | if (level == LOGLEVEL_DEFAULT) | |
101 | seq_puts(s, "<c>"); | |
102 | else | |
103 | seq_printf(s, "<%d,c>", level); | |
104 | } else | |
105 | seq_printf(s, "<%d>", level); | |
106 | ||
107 | seq_printf(s, " %s:%d %s \"", entry->file, entry->line, entry->func); | |
108 | if (entry->subsys_fmt_prefix) | |
109 | seq_escape_printf_format(s, entry->subsys_fmt_prefix); | |
110 | seq_escape_printf_format(s, entry->fmt + prefix_len); | |
111 | seq_puts(s, "\"\n"); | |
112 | ||
113 | return 0; | |
114 | } | |
115 | ||
116 | static void pi_stop(struct seq_file *p, void *v) { } | |
117 | ||
118 | static const struct seq_operations dfs_index_sops = { | |
119 | .start = pi_start, | |
120 | .next = pi_next, | |
121 | .show = pi_show, | |
122 | .stop = pi_stop, | |
123 | }; | |
124 | ||
125 | DEFINE_SEQ_ATTRIBUTE(dfs_index); | |
126 | ||
127 | #ifdef CONFIG_MODULES | |
128 | static const char *pi_get_module_name(struct module *mod) | |
129 | { | |
130 | return mod ? mod->name : "vmlinux"; | |
131 | } | |
132 | #else | |
133 | static const char *pi_get_module_name(struct module *mod) | |
134 | { | |
135 | return "vmlinux"; | |
136 | } | |
137 | #endif | |
138 | ||
0f0aa848 | 139 | static void pi_create_file(struct module *mod) |
33701557 CD |
140 | { |
141 | debugfs_create_file(pi_get_module_name(mod), 0444, dfs_index, | |
142 | mod, &dfs_index_fops); | |
143 | } | |
144 | ||
bc17bed5 | 145 | #ifdef CONFIG_MODULES |
0f0aa848 | 146 | static void pi_remove_file(struct module *mod) |
33701557 | 147 | { |
55bf243c | 148 | debugfs_lookup_and_remove(pi_get_module_name(mod), dfs_index); |
33701557 CD |
149 | } |
150 | ||
33701557 CD |
151 | static int pi_module_notify(struct notifier_block *nb, unsigned long op, |
152 | void *data) | |
153 | { | |
154 | struct module *mod = data; | |
155 | ||
156 | switch (op) { | |
157 | case MODULE_STATE_COMING: | |
158 | pi_create_file(mod); | |
159 | break; | |
160 | case MODULE_STATE_GOING: | |
161 | pi_remove_file(mod); | |
162 | break; | |
163 | default: /* we don't care about other module states */ | |
164 | break; | |
165 | } | |
166 | ||
167 | return NOTIFY_OK; | |
168 | } | |
169 | ||
170 | static struct notifier_block module_printk_fmts_nb = { | |
171 | .notifier_call = pi_module_notify, | |
172 | }; | |
173 | ||
174 | static void __init pi_setup_module_notifier(void) | |
175 | { | |
176 | register_module_notifier(&module_printk_fmts_nb); | |
177 | } | |
178 | #else | |
179 | static inline void __init pi_setup_module_notifier(void) { } | |
180 | #endif | |
181 | ||
182 | static int __init pi_init(void) | |
183 | { | |
184 | struct dentry *dfs_root = debugfs_create_dir("printk", NULL); | |
185 | ||
186 | dfs_index = debugfs_create_dir("index", dfs_root); | |
187 | pi_setup_module_notifier(); | |
188 | pi_create_file(NULL); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | /* debugfs comes up on core and must be initialised first */ | |
194 | postcore_initcall(pi_init); |