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// 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>
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);
}
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;
seq_buf_printf(&sb, "%s%s", prefix, name);
if (seq_buf_has_overflowed(&sb))
return NULL;
buf = seq_buf_str(&sb);
return mod ?
(void *)find_kallsyms_symbol_value(mod, buf) :
(void *)kallsyms_lookup_name(buf);
}
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);
up_write(&cttype->mod_lock);
if (err < 0) {
kfree(cmod);
return err;
}
return 0;
}
#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;
}
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