diff options
| -rw-r--r-- | include/linux/ftrace.h | 6 | ||||
| -rw-r--r-- | kernel/trace/ftrace.c | 79 |
2 files changed, 84 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index efe3e521aff4..8b37b8105398 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -51,6 +51,7 @@ static inline void early_trace_init(void) { } struct module; struct ftrace_hash; +struct ftrace_direct_func; #if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_MODULES) && \ defined(CONFIG_DYNAMIC_FTRACE) @@ -248,6 +249,7 @@ static inline void ftrace_free_mem(struct module *mod, void *start, void *end) { #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS int register_ftrace_direct(unsigned long ip, unsigned long addr); int unregister_ftrace_direct(unsigned long ip, unsigned long addr); +struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr); #else static inline int register_ftrace_direct(unsigned long ip, unsigned long addr) { @@ -257,6 +259,10 @@ static inline int unregister_ftrace_direct(unsigned long ip, unsigned long addr) { return -ENODEV; } +static inline struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr) +{ + return NULL; +} #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 329a3f3789a1..c4446eabacbe 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4938,6 +4938,46 @@ ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove, } #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS + +struct ftrace_direct_func { + struct list_head next; + unsigned long addr; + int count; +}; + +static LIST_HEAD(ftrace_direct_funcs); + +/** + * ftrace_find_direct_func - test an address if it is a registered direct caller + * @addr: The address of a registered direct caller + * + * This searches to see if a ftrace direct caller has been registered + * at a specific address, and if so, it returns a descriptor for it. + * + * This can be used by architecture code to see if an address is + * a direct caller (trampoline) attached to a fentry/mcount location. + * This is useful for the function_graph tracer, as it may need to + * do adjustments if it traced a location that also has a direct + * trampoline attached to it. + */ +struct ftrace_direct_func *ftrace_find_direct_func(unsigned long addr) +{ + struct ftrace_direct_func *entry; + bool found = false; + + /* May be called by fgraph trampoline (protected by rcu tasks) */ + list_for_each_entry_rcu(entry, &ftrace_direct_funcs, next) { + if (entry->addr == addr) { + found = true; + break; + } + } + if (found) + return entry; + + return NULL; +} + /** * register_ftrace_direct - Call a custom trampoline directly * @ip: The address of the nop at the beginning of a function @@ -4957,6 +4997,7 @@ ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove, */ int register_ftrace_direct(unsigned long ip, unsigned long addr) { + struct ftrace_direct_func *direct; struct ftrace_func_entry *entry; struct ftrace_hash *free_hash = NULL; struct dyn_ftrace *rec; @@ -5005,6 +5046,18 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) if (!entry) goto out_unlock; + direct = ftrace_find_direct_func(addr); + if (!direct) { + direct = kmalloc(sizeof(*direct), GFP_KERNEL); + if (!direct) { + kfree(entry); + goto out_unlock; + } + direct->addr = addr; + direct->count = 0; + list_add_rcu(&direct->next, &ftrace_direct_funcs); + } + entry->ip = ip; entry->direct = addr; __add_hash_entry(direct_functions, entry); @@ -5019,8 +5072,20 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr) ftrace_set_filter_ip(&direct_ops, ip, 1, 0); } - if (ret) + if (ret) { kfree(entry); + if (!direct->count) { + list_del_rcu(&direct->next); + synchronize_rcu_tasks(); + kfree(direct); + if (free_hash) + free_ftrace_hash(free_hash); + free_hash = NULL; + } + } else { + if (!direct->count) + direct->count++; + } out_unlock: mutex_unlock(&direct_mutex); @@ -5036,6 +5101,7 @@ EXPORT_SYMBOL_GPL(register_ftrace_direct); int unregister_ftrace_direct(unsigned long ip, unsigned long addr) { struct ftrace_func_entry *entry; + struct ftrace_direct_func *direct; struct dyn_ftrace *rec; int ret = -ENODEV; @@ -5066,6 +5132,17 @@ int unregister_ftrace_direct(unsigned long ip, unsigned long addr) remove_hash_entry(direct_functions, entry); + direct = ftrace_find_direct_func(addr); + if (!WARN_ON(!direct)) { + /* This is the good path (see the ! before WARN) */ + direct->count--; + WARN_ON(direct->count < 0); + if (!direct->count) { + list_del_rcu(&direct->next); + synchronize_rcu_tasks(); + kfree(direct); + } + } out_unlock: mutex_unlock(&direct_mutex); |