1 files changed, 283 insertions, 0 deletions
diff --git a/lib/codetag.c b/lib/codetag.c
new file mode 100644
index 000000000000..5ace625f2328
--- /dev/null
+++ b/lib/codetag.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/codetag.h>
+#include <linux/idr.h>
+#include <linux/kallsyms.h>
+#include <linux/module.h>
+#include <linux/seq_buf.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+struct codetag_type {
+	struct list_head link;
+	unsigned int count;
+	struct idr mod_idr;
+	struct rw_semaphore mod_lock; /* protects mod_idr */
+	struct codetag_type_desc desc;
+};
+
+struct codetag_range {
+	struct codetag *start;
+	struct codetag *stop;
+};
+
+struct codetag_module {
+	struct module *mod;
+	struct codetag_range range;
+};
+
+static DEFINE_MUTEX(codetag_lock);
+static LIST_HEAD(codetag_types);
+
+void codetag_lock_module_list(struct codetag_type *cttype, bool lock)
+{
+	if (lock)
+		down_read(&cttype->mod_lock);
+	else
+		up_read(&cttype->mod_lock);
+}
+
+bool codetag_trylock_module_list(struct codetag_type *cttype)
+{
+	return down_read_trylock(&cttype->mod_lock) != 0;
+}
+
+struct codetag_iterator codetag_get_ct_iter(struct codetag_type *cttype)
+{
+	struct codetag_iterator iter = {
+		.cttype = cttype,
+		.cmod = NULL,
+		.mod_id = 0,
+		.ct = NULL,
+	};
+
+	return iter;
+}
+
+static inline struct codetag *get_first_module_ct(struct codetag_module *cmod)
+{
+	return cmod->range.start < cmod->range.stop ? cmod->range.start : NULL;
+}
+
+static inline
+struct codetag *get_next_module_ct(struct codetag_iterator *iter)
+{
+	struct codetag *res = (struct codetag *)
+			((char *)iter->ct + iter->cttype->desc.tag_size);
+
+	return res < iter->cmod->range.stop ? res : NULL;
+}
+
+struct codetag *codetag_next_ct(struct codetag_iterator *iter)
+{
+	struct codetag_type *cttype = iter->cttype;
+	struct codetag_module *cmod;
+	struct codetag *ct;
+
+	lockdep_assert_held(&cttype->mod_lock);
+
+	if (unlikely(idr_is_empty(&cttype->mod_idr)))
+		return NULL;
+
+	ct = NULL;
+	while (true) {
+		cmod = idr_find(&cttype->mod_idr, iter->mod_id);
+
+		/* If module was removed move to the next one */
+		if (!cmod)
+			cmod = idr_get_next_ul(&cttype->mod_idr,
+					       &iter->mod_id);
+
+		/* Exit if no more modules */
+		if (!cmod)
+			break;
+
+		if (cmod != iter->cmod) {
+			iter->cmod = cmod;
+			ct = get_first_module_ct(cmod);
+		} else
+			ct = get_next_module_ct(iter);
+
+		if (ct)
+			break;
+
+		iter->mod_id++;
+	}
+
+	iter->ct = ct;
+	return ct;
+}
+
+void codetag_to_text(struct seq_buf *out, struct codetag *ct)
+{
+	if (ct->modname)
+		seq_buf_printf(out, "%s:%u [%s] func:%s",
+			       ct->filename, ct->lineno,
+			       ct->modname, ct->function);
+	else
+		seq_buf_printf(out, "%s:%u func:%s",
+			       ct->filename, ct->lineno, ct->function);
+}
+
+static inline size_t range_size(const struct codetag_type *cttype,
+				const struct codetag_range *range)
+{
+	return ((char *)range->stop - (char *)range->start) /
+			cttype->desc.tag_size;
+}
+
+#ifdef CONFIG_MODULES
+static void *get_symbol(struct module *mod, const char *prefix, const char *name)
+{
+	DECLARE_SEQ_BUF(sb, KSYM_NAME_LEN);
+	const char *buf;
+	void *ret;
+
+	seq_buf_printf(&sb, "%s%s", prefix, name);
+	if (seq_buf_has_overflowed(&sb))
+		return NULL;
+
+	buf = seq_buf_str(&sb);
+	preempt_disable();
+	ret = mod ?
+		(void *)find_kallsyms_symbol_value(mod, buf) :
+		(void *)kallsyms_lookup_name(buf);
+	preempt_enable();
+
+	return ret;
+}
+
+static struct codetag_range get_section_range(struct module *mod,
+					      const char *section)
+{
+	return (struct codetag_range) {
+		get_symbol(mod, "__start_", section),
+		get_symbol(mod, "__stop_", section),
+	};
+}
+
+static int codetag_module_init(struct codetag_type *cttype, struct module *mod)
+{
+	struct codetag_range range;
+	struct codetag_module *cmod;
+	int err;
+
+	range = get_section_range(mod, cttype->desc.section);
+	if (!range.start || !range.stop) {
+		pr_warn("Failed to load code tags of type %s from the module %s\n",
+			cttype->desc.section,
+			mod ? mod->name : "(built-in)");
+		return -EINVAL;
+	}
+
+	/* Ignore empty ranges */
+	if (range.start == range.stop)
+		return 0;
+
+	BUG_ON(range.start > range.stop);
+
+	cmod = kmalloc(sizeof(*cmod), GFP_KERNEL);
+	if (unlikely(!cmod))
+		return -ENOMEM;
+
+	cmod->mod = mod;
+	cmod->range = range;
+
+	down_write(&cttype->mod_lock);
+	err = idr_alloc(&cttype->mod_idr, cmod, 0, 0, GFP_KERNEL);
+	if (err >= 0) {
+		cttype->count += range_size(cttype, &range);
+		if (cttype->desc.module_load)
+			cttype->desc.module_load(cttype, cmod);
+	}
+	up_write(&cttype->mod_lock);
+
+	if (err < 0) {
+		kfree(cmod);
+		return err;
+	}
+
+	return 0;
+}
+
+void codetag_load_module(struct module *mod)
+{
+	struct codetag_type *cttype;
+
+	if (!mod)
+		return;
+
+	mutex_lock(&codetag_lock);
+	list_for_each_entry(cttype, &codetag_types, link)
+		codetag_module_init(cttype, mod);
+	mutex_unlock(&codetag_lock);
+}
+
+bool codetag_unload_module(struct module *mod)
+{
+	struct codetag_type *cttype;
+	bool unload_ok = true;
+
+	if (!mod)
+		return true;
+
+	mutex_lock(&codetag_lock);
+	list_for_each_entry(cttype, &codetag_types, link) {
+		struct codetag_module *found = NULL;
+		struct codetag_module *cmod;
+		unsigned long mod_id, tmp;
+
+		down_write(&cttype->mod_lock);
+		idr_for_each_entry_ul(&cttype->mod_idr, cmod, tmp, mod_id) {
+			if (cmod->mod && cmod->mod == mod) {
+				found = cmod;
+				break;
+			}
+		}
+		if (found) {
+			if (cttype->desc.module_unload)
+				if (!cttype->desc.module_unload(cttype, cmod))
+					unload_ok = false;
+
+			cttype->count -= range_size(cttype, &cmod->range);
+			idr_remove(&cttype->mod_idr, mod_id);
+			kfree(cmod);
+		}
+		up_write(&cttype->mod_lock);
+	}
+	mutex_unlock(&codetag_lock);
+
+	return unload_ok;
+}
+
+#else /* CONFIG_MODULES */
+static int codetag_module_init(struct codetag_type *cttype, struct module *mod) { return 0; }
+#endif /* CONFIG_MODULES */
+
+struct codetag_type *
+codetag_register_type(const struct codetag_type_desc *desc)
+{
+	struct codetag_type *cttype;
+	int err;
+
+	BUG_ON(desc->tag_size <= 0);
+
+	cttype = kzalloc(sizeof(*cttype), GFP_KERNEL);
+	if (unlikely(!cttype))
+		return ERR_PTR(-ENOMEM);
+
+	cttype->desc = *desc;
+	idr_init(&cttype->mod_idr);
+	init_rwsem(&cttype->mod_lock);
+
+	err = codetag_module_init(cttype, NULL);
+	if (unlikely(err)) {
+		kfree(cttype);
+		return ERR_PTR(err);
+	}
+
+	mutex_lock(&codetag_lock);
+	list_add_tail(&cttype->link, &codetag_types);
+	mutex_unlock(&codetag_lock);
+
+	return cttype;
+}