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-rw-r--r--kernel/printk/index.c195
1 files changed, 195 insertions, 0 deletions
diff --git a/kernel/printk/index.c b/kernel/printk/index.c
new file mode 100644
index 000000000000..d3709408debe
--- /dev/null
+++ b/kernel/printk/index.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Userspace indexing of printk formats
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/string_helpers.h>
+
+#include "internal.h"
+
+extern struct pi_entry *__start_printk_index[];
+extern struct pi_entry *__stop_printk_index[];
+
+/* The base dir for module formats, typically debugfs/printk/index/ */
+static struct dentry *dfs_index;
+
+static struct pi_entry *pi_get_entry(const struct module *mod, loff_t pos)
+{
+ struct pi_entry **entries;
+ unsigned int nr_entries;
+
+#ifdef CONFIG_MODULES
+ if (mod) {
+ entries = mod->printk_index_start;
+ nr_entries = mod->printk_index_size;
+ }
+#endif
+
+ if (!mod) {
+ /* vmlinux, comes from linker symbols */
+ entries = __start_printk_index;
+ nr_entries = __stop_printk_index - __start_printk_index;
+ }
+
+ if (pos >= nr_entries)
+ return NULL;
+
+ return entries[pos];
+}
+
+static void *pi_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ const struct module *mod = s->file->f_inode->i_private;
+ struct pi_entry *entry = pi_get_entry(mod, *pos);
+
+ (*pos)++;
+
+ return entry;
+}
+
+static void *pi_start(struct seq_file *s, loff_t *pos)
+{
+ /*
+ * Make show() print the header line. Do not update *pos because
+ * pi_next() still has to return the entry at index 0 later.
+ */
+ if (*pos == 0)
+ return SEQ_START_TOKEN;
+
+ return pi_next(s, NULL, pos);
+}
+
+/*
+ * We need both ESCAPE_ANY and explicit characters from ESCAPE_SPECIAL in @only
+ * because otherwise ESCAPE_NAP will cause double quotes and backslashes to be
+ * ignored for quoting.
+ */
+#define seq_escape_printf_format(s, src) \
+ seq_escape_str(s, src, ESCAPE_ANY | ESCAPE_NAP | ESCAPE_APPEND, "\"\\")
+
+static int pi_show(struct seq_file *s, void *v)
+{
+ const struct pi_entry *entry = v;
+ int level = LOGLEVEL_DEFAULT;
+ enum printk_info_flags flags = 0;
+ u16 prefix_len = 0;
+
+ if (v == SEQ_START_TOKEN) {
+ seq_puts(s, "# <level/flags> filename:line function \"format\"\n");
+ return 0;
+ }
+
+ if (!entry->fmt)
+ return 0;
+
+ if (entry->level)
+ printk_parse_prefix(entry->level, &level, &flags);
+ else
+ prefix_len = printk_parse_prefix(entry->fmt, &level, &flags);
+
+
+ if (flags & LOG_CONT) {
+ /*
+ * LOGLEVEL_DEFAULT here means "use the same level as the
+ * message we're continuing from", not the default message
+ * loglevel, so don't display it as such.
+ */
+ if (level == LOGLEVEL_DEFAULT)
+ seq_puts(s, "<c>");
+ else
+ seq_printf(s, "<%d,c>", level);
+ } else
+ seq_printf(s, "<%d>", level);
+
+ seq_printf(s, " %s:%d %s \"", entry->file, entry->line, entry->func);
+ if (entry->subsys_fmt_prefix)
+ seq_escape_printf_format(s, entry->subsys_fmt_prefix);
+ seq_escape_printf_format(s, entry->fmt + prefix_len);
+ seq_puts(s, "\"\n");
+
+ return 0;
+}
+
+static void pi_stop(struct seq_file *p, void *v) { }
+
+static const struct seq_operations dfs_index_sops = {
+ .start = pi_start,
+ .next = pi_next,
+ .show = pi_show,
+ .stop = pi_stop,
+};
+
+DEFINE_SEQ_ATTRIBUTE(dfs_index);
+
+#ifdef CONFIG_MODULES
+static const char *pi_get_module_name(struct module *mod)
+{
+ return mod ? mod->name : "vmlinux";
+}
+#else
+static const char *pi_get_module_name(struct module *mod)
+{
+ return "vmlinux";
+}
+#endif
+
+static void pi_create_file(struct module *mod)
+{
+ debugfs_create_file(pi_get_module_name(mod), 0444, dfs_index,
+ mod, &dfs_index_fops);
+}
+
+#ifdef CONFIG_MODULES
+static void pi_remove_file(struct module *mod)
+{
+ debugfs_remove(debugfs_lookup(pi_get_module_name(mod), dfs_index));
+}
+
+static int pi_module_notify(struct notifier_block *nb, unsigned long op,
+ void *data)
+{
+ struct module *mod = data;
+
+ switch (op) {
+ case MODULE_STATE_COMING:
+ pi_create_file(mod);
+ break;
+ case MODULE_STATE_GOING:
+ pi_remove_file(mod);
+ break;
+ default: /* we don't care about other module states */
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block module_printk_fmts_nb = {
+ .notifier_call = pi_module_notify,
+};
+
+static void __init pi_setup_module_notifier(void)
+{
+ register_module_notifier(&module_printk_fmts_nb);
+}
+#else
+static inline void __init pi_setup_module_notifier(void) { }
+#endif
+
+static int __init pi_init(void)
+{
+ struct dentry *dfs_root = debugfs_create_dir("printk", NULL);
+
+ dfs_index = debugfs_create_dir("index", dfs_root);
+ pi_setup_module_notifier();
+ pi_create_file(NULL);
+
+ return 0;
+}
+
+/* debugfs comes up on core and must be initialised first */
+postcore_initcall(pi_init);