For now, we can change the address of a direct ftrace_ops with modify_ftrace_direct(). However, we can't change the functions to filter for a direct ftrace_ops. Therefore, we introduce the function reset_ftrace_direct_ips() to do such things, and this function will reset the functions to filter for a direct ftrace_ops.
This function do such thing in following steps: 1. filter out the new functions from ips that don't exist in the ops->func_hash->filter_hash and add them to the new hash. 2. add all the functions in the new ftrace_hash to direct_functions by ftrace_direct_update(). 3. reset the functions to filter of the ftrace_ops to the ips with ftrace_set_filter_ips(). 4. remove the functions that in the old ftrace_hash, but not in the new ftrace_hash from direct_functions. Signed-off-by: Menglong Dong <[email protected]> --- include/linux/ftrace.h | 7 ++++ kernel/trace/ftrace.c | 75 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 82 insertions(+) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index b672ca15f265..b7c60f5a4120 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -528,6 +528,8 @@ int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr); void ftrace_stub_direct_tramp(void); +int reset_ftrace_direct_ips(struct ftrace_ops *ops, unsigned long *ips, + unsigned int cnt); #else struct ftrace_ops; static inline unsigned long ftrace_find_rec_direct(unsigned long ip) @@ -551,6 +553,11 @@ static inline int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned l { return -ENODEV; } +static inline int reset_ftrace_direct_ips(struct ftrace_ops *ops, unsigned long *ips, + unsigned int cnt) +{ + return -ENODEV; +} /* * This must be implemented by the architecture. diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f5f6d7bc26f0..db3aa61889d3 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6224,6 +6224,81 @@ int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) return err; } EXPORT_SYMBOL_GPL(modify_ftrace_direct); + +/* reset the ips for a direct ftrace (add or remove) */ +int reset_ftrace_direct_ips(struct ftrace_ops *ops, unsigned long *ips, + unsigned int cnt) +{ + struct ftrace_hash *hash, *free_hash; + struct ftrace_func_entry *entry, *del; + unsigned long ip; + int err, size; + + if (check_direct_multi(ops)) + return -EINVAL; + if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) + return -EINVAL; + + mutex_lock(&direct_mutex); + hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS); + if (!hash) { + err = -ENOMEM; + goto out_unlock; + } + + /* find out the new functions from ips and add to hash */ + for (int i = 0; i < cnt; i++) { + ip = ftrace_location(ips[i]); + if (!ip) { + err = -ENOENT; + goto out_unlock; + } + if (__ftrace_lookup_ip(ops->func_hash->filter_hash, ip)) + continue; + err = __ftrace_match_addr(hash, ip, 0); + if (err) + goto out_unlock; + } + + free_hash = direct_functions; + /* add the new ips to direct hash. */ + err = ftrace_direct_update(hash, ops->direct_call); + if (err) + goto out_unlock; + + if (free_hash && free_hash != EMPTY_HASH) + call_rcu_tasks(&free_hash->rcu, register_ftrace_direct_cb); + + free_ftrace_hash(hash); + hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, + ops->func_hash->filter_hash); + if (!hash) { + err = -ENOMEM; + goto out_unlock; + } + err = ftrace_set_filter_ips(ops, ips, cnt, 0, 1); + + /* remove the entries that don't exist in our filter_hash anymore + * from the direct_functions. + */ + size = 1 << hash->size_bits; + for (int i = 0; i < size; i++) { + hlist_for_each_entry(entry, &hash->buckets[i], hlist) { + if (__ftrace_lookup_ip(ops->func_hash->filter_hash, entry->ip)) + continue; + del = __ftrace_lookup_ip(direct_functions, entry->ip); + if (del && del->direct == ops->direct_call) { + remove_hash_entry(direct_functions, del); + kfree(del); + } + } + } +out_unlock: + mutex_unlock(&direct_mutex); + if (hash) + free_ftrace_hash(hash); + return err; +} #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ /** -- 2.39.5
