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ftrace: Implement cached modules tracing on module load 

If a module is cached in the set_ftrace_filter, and that module is loaded,
then enable tracing on that module as if the cached module text was written
into set_ftrace_filter just as the module is loaded.

  # echo ":mod:kvm_intel" >
  # cat /sys/kernel/tracing/set_ftrace_filter
 #### all functions enabled ####
 :mod:kvm_intel
  # modprobe kvm_intel
  # cat /sys/kernel/tracing/set_ftrace_filter
 vmx_get_rflags [kvm_intel]
 vmx_get_pkru [kvm_intel]
 vmx_get_interrupt_shadow [kvm_intel]
 vmx_rdtscp_supported [kvm_intel]
 vmx_invpcid_supported [kvm_intel]
 [..]

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2017-06-26 10:57:21 -04:00
parent 5985ea8bd5
commit d7fbf8df7c
1 changed files with 93 additions and 0 deletions
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93
kernel/trace/ftrace.c
View File

@ -3969,6 +3969,97 @@ static int cache_mod(struct trace_array *tr,
return ret;
}
static int
ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
int reset, int enable);
static void process_mod_list(struct list_head *head, struct ftrace_ops *ops,
char *mod, bool enable)
{
struct ftrace_mod_load *ftrace_mod, *n;
struct ftrace_hash **orig_hash, *new_hash;
LIST_HEAD(process_mods);
char *func;
int ret;
mutex_lock(&ops->func_hash->regex_lock);
if (enable)
orig_hash = &ops->func_hash->filter_hash;
else
orig_hash = &ops->func_hash->notrace_hash;
new_hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS,
*orig_hash);
if (!new_hash)
return; /* Warn? */
mutex_lock(&ftrace_lock);
list_for_each_entry_safe(ftrace_mod, n, head, list) {
if (strcmp(ftrace_mod->module, mod) != 0)
continue;
if (ftrace_mod->func)
func = kstrdup(ftrace_mod->func, GFP_KERNEL);
else
func = kstrdup("*", GFP_KERNEL);
if (!func) /* warn? */
continue;
list_del(&ftrace_mod->list);
list_add(&ftrace_mod->list, &process_mods);
/* Use the newly allocated func, as it may be "*" */
kfree(ftrace_mod->func);
ftrace_mod->func = func;
}
mutex_unlock(&ftrace_lock);
list_for_each_entry_safe(ftrace_mod, n, &process_mods, list) {
func = ftrace_mod->func;
/* Grabs ftrace_lock, which is why we have this extra step */
match_records(new_hash, func, strlen(func), mod);
free_ftrace_mod(ftrace_mod);
}
mutex_lock(&ftrace_lock);
ret = ftrace_hash_move_and_update_ops(ops, orig_hash,
new_hash, enable);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ops->func_hash->regex_lock);
free_ftrace_hash(new_hash);
}
static void process_cached_mods(const char *mod_name)
{
struct trace_array *tr;
char *mod;
mod = kstrdup(mod_name, GFP_KERNEL);
if (!mod)
return;
mutex_lock(&trace_types_lock);
list_for_each_entry(tr, &ftrace_trace_arrays, list) {
if (!list_empty(&tr->mod_trace))
process_mod_list(&tr->mod_trace, tr->ops, mod, true);
if (!list_empty(&tr->mod_notrace))
process_mod_list(&tr->mod_notrace, tr->ops, mod, false);
}
mutex_unlock(&trace_types_lock);
kfree(mod);
}
/*
* We register the module command as a template to show others how
* to register the a command as well.
@ -5682,6 +5773,8 @@ void ftrace_module_enable(struct module *mod)
out_unlock:
mutex_unlock(&ftrace_lock);
process_cached_mods(mod->name);
}
void ftrace_module_init(struct module *mod)