From: "Steven Rostedt (VMware)" <rost...@goodmis.org>
This is the start of the infrastructure work to allow for tracing module
functions before it is loaded.
Currently the following command:
# echo :mod:some-mod > set_ftrace_filter
will enable tracing of all functions within the module "some-mod" if it is
loaded. What we want, is if the module is not loaded, that line will be
saved. When the module is loaded, then the "some-mod" will have that line
executed on it, so that the functions within it starts being traced.
Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org>
---
kernel/trace/ftrace.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++---
kernel/trace/trace.h | 12 +++++
2 files changed, 148 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 9e5841dc14b5..1867edec6269 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1293,6 +1293,28 @@ static void ftrace_hash_clear(struct ftrace_hash *hash)
FTRACE_WARN_ON(hash->count);
}
+static void free_ftrace_mod(struct ftrace_mod_load *ftrace_mod)
+{
+ list_del(&ftrace_mod->list);
+ kfree(ftrace_mod->module);
+ kfree(ftrace_mod->func);
+ kfree(ftrace_mod);
+}
+
+static void clear_ftrace_mod_list(struct list_head *head)
+{
+ struct ftrace_mod_load *p, *n;
+
+ /* stack tracer isn't supported yet */
+ if (!head)
+ return;
+
+ mutex_lock(&ftrace_lock);
+ list_for_each_entry_safe(p, n, head, list)
+ free_ftrace_mod(p);
+ mutex_unlock(&ftrace_lock);
+}
+
static void free_ftrace_hash(struct ftrace_hash *hash)
{
if (!hash || hash == EMPTY_HASH)
@@ -1346,6 +1368,35 @@ static struct ftrace_hash *alloc_ftrace_hash(int
size_bits)
return hash;
}
+
+static int ftrace_add_mod(struct trace_array *tr,
+ const char *func, const char *module,
+ int enable)
+{
+ struct ftrace_mod_load *ftrace_mod;
+ struct list_head *mod_head = enable ? &tr->mod_trace : &tr->mod_notrace;
+
+ ftrace_mod = kzalloc(sizeof(*ftrace_mod), GFP_KERNEL);
+ if (!ftrace_mod)
+ return -ENOMEM;
+
+ ftrace_mod->func = kstrdup(func, GFP_KERNEL);
+ ftrace_mod->module = kstrdup(module, GFP_KERNEL);
+ ftrace_mod->enable = enable;
+
+ if (!ftrace_mod->func || !ftrace_mod->module)
+ goto out_free;
+
+ list_add(&ftrace_mod->list, mod_head);
+
+ return 0;
+
+ out_free:
+ free_ftrace_mod(ftrace_mod);
+
+ return -ENOMEM;
+}
+
static struct ftrace_hash *
alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
{
@@ -3457,6 +3508,8 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
{
struct ftrace_iterator *iter;
struct ftrace_hash *hash;
+ struct list_head *mod_head;
+ struct trace_array *tr = ops->private;
int ret = 0;
ftrace_ops_init(ops);
@@ -3478,18 +3531,23 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
mutex_lock(&ops->func_hash->regex_lock);
- if (flag & FTRACE_ITER_NOTRACE)
+ if (flag & FTRACE_ITER_NOTRACE) {
hash = ops->func_hash->notrace_hash;
- else
+ mod_head = tr ? &tr->mod_trace : NULL;
+ } else {
hash = ops->func_hash->filter_hash;
+ mod_head = tr ? &tr->mod_notrace : NULL;
+ }
if (file->f_mode & FMODE_WRITE) {
const int size_bits = FTRACE_HASH_DEFAULT_BITS;
- if (file->f_flags & O_TRUNC)
+ if (file->f_flags & O_TRUNC) {
iter->hash = alloc_ftrace_hash(size_bits);
- else
+ clear_ftrace_mod_list(mod_head);
+ } else {
iter->hash = alloc_and_copy_ftrace_hash(size_bits,
hash);
+ }
if (!iter->hash) {
trace_parser_put(&iter->parser);
@@ -3761,6 +3819,68 @@ static int ftrace_hash_move_and_update_ops(struct
ftrace_ops *ops,
return ret;
}
+static bool module_exists(const char *module)
+{
+ /* All modules have the symbol __this_module */
+ const char this_mod[] = "__this_module";
+ const int modname_size = MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 1;
+ char modname[modname_size + 1];
+ unsigned long val;
+ int n;
+
+ n = snprintf(modname, modname_size + 1, "%s:%s", module, this_mod);
+
+ if (n > modname_size)
+ return false;
+
+ val = module_kallsyms_lookup_name(modname);
+ return val != 0;
+}
+
+static int cache_mod(struct trace_array *tr,
+ const char *func, char *module, int enable)
+{
+ struct ftrace_mod_load *ftrace_mod, *n;
+ struct list_head *head = enable ? &tr->mod_trace : &tr->mod_notrace;
+ int ret;
+
+ mutex_lock(&ftrace_lock);
+
+ /* We do not cache inverse filters */
+ if (func[0] == '!') {
+ func++;
+ ret = -EINVAL;
+
+ /* Look to remove this hash */
+ list_for_each_entry_safe(ftrace_mod, n, head, list) {
+ if (strcmp(ftrace_mod->module, module) != 0)
+ continue;
+
+ /* no func matches all */
+ if (!func || strcmp(func, "*") == 0 ||
+ (ftrace_mod->func &&
+ strcmp(ftrace_mod->func, func) == 0)) {
+ ret = 0;
+ free_ftrace_mod(ftrace_mod);
+ continue;
+ }
+ }
+ goto out;
+ }
+
+ ret = -EINVAL;
+ /* We only care about modules that have not been loaded yet */
+ if (module_exists(module))
+ goto out;
+
+ /* Save this string off, and execute it when the module is loaded */
+ ret = ftrace_add_mod(tr, func, module, enable);
+ out:
+ mutex_unlock(&ftrace_lock);
+
+ return ret;
+}
+
/*
* We register the module command as a template to show others how
* to register the a command as well.
@@ -3768,10 +3888,16 @@ static int ftrace_hash_move_and_update_ops(struct
ftrace_ops *ops,
static int
ftrace_mod_callback(struct trace_array *tr, struct ftrace_hash *hash,
- char *func, char *cmd, char *module, int enable)
+ char *func_orig, char *cmd, char *module, int enable)
{
+ char *func;
int ret;
+ /* match_records() modifies func, and we need the original */
+ func = kstrdup(func_orig, GFP_KERNEL);
+ if (!func)
+ return -ENOMEM;
+
/*
* cmd == 'mod' because we only registered this func
* for the 'mod' ftrace_func_command.
@@ -3780,8 +3906,10 @@ ftrace_mod_callback(struct trace_array *tr, struct
ftrace_hash *hash,
* parameter.
*/
ret = match_records(hash, func, strlen(func), module);
+ kfree(func);
+
if (!ret)
- return -EINVAL;
+ return cache_mod(tr, func_orig, module, enable);
if (ret < 0)
return ret;
return 0;
@@ -5570,6 +5698,8 @@ static void ftrace_update_trampoline(struct ftrace_ops
*ops)
void ftrace_init_trace_array(struct trace_array *tr)
{
INIT_LIST_HEAD(&tr->func_probes);
+ INIT_LIST_HEAD(&tr->mod_trace);
+ INIT_LIST_HEAD(&tr->mod_notrace);
}
#else
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 69a3ab3ee4f5..d63550cdbdfa 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -263,7 +263,10 @@ struct trace_array {
struct ftrace_ops *ops;
struct trace_pid_list __rcu *function_pids;
#ifdef CONFIG_DYNAMIC_FTRACE
+ /* All of these are protected by the ftrace_lock */
struct list_head func_probes;
+ struct list_head mod_trace;
+ struct list_head mod_notrace;
#endif
/* function tracing enabled */
int function_enabled;
@@ -761,6 +764,15 @@ enum print_line_t print_trace_line(struct trace_iterator
*iter);
extern char trace_find_mark(unsigned long long duration);
+struct ftrace_hash;
+
+struct ftrace_mod_load {
+ struct list_head list;
+ char *func;
+ char *module;
+ int enable;
+};
+
struct ftrace_hash {
unsigned long size_bits;
struct hlist_head *buckets;
--
2.10.2
