Adding update_ftrace_direct_del function that removes all entries (ip -> addr) provided in hash argument to direct ftrace ops and updates its attachments.
The difference to current unregister_ftrace_direct is - hash argument that allows to unregister multiple ip -> direct entries at once - we can call update_ftrace_direct_del multiple times on the same ftrace_ops object, becase we do not need to unregister all entries at once, we can do it gradualy with the help of ftrace_update_ops function This change will allow us to have simple ftrace_ops for all bpf direct interface users in following changes. Signed-off-by: Jiri Olsa <[email protected]> --- include/linux/ftrace.h | 6 +++ kernel/trace/ftrace.c | 99 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 105 insertions(+) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ded3a306a8b2..433c36c3af3b 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -543,6 +543,7 @@ int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr); int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr); int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash); +int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash); void ftrace_stub_direct_tramp(void); @@ -575,6 +576,11 @@ int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash) return -ENODEV; } +int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash) +{ + return -ENODEV; +} + /* * This must be implemented by the architecture. * It is the way the ftrace direct_ops helper, when called diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 0b6e1af8f922..3dd1e69aceca 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6376,6 +6376,105 @@ int update_ftrace_direct_add(struct ftrace_ops *ops, struct ftrace_hash *hash) return err; } +/** + * hash_sub - substracts @b from @a and returns the result + * @a: struct ftrace_hash object + * @b: struct ftrace_hash object + * + * Returns struct ftrace_hash object on success, NULL on error. + */ +static struct ftrace_hash *hash_sub(struct ftrace_hash *a, struct ftrace_hash *b) +{ + struct ftrace_func_entry *entry, *del; + struct ftrace_hash *sub; + int size, i; + + sub = alloc_and_copy_ftrace_hash(a->size_bits, a); + if (!sub) + goto error; + + size = 1 << b->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(entry, &b->buckets[i], hlist) { + del = __ftrace_lookup_ip(sub, entry->ip); + if (WARN_ON_ONCE(!del)) + goto error; + remove_hash_entry(sub, del); + kfree(del); + } + } + return sub; + + error: + free_ftrace_hash(sub); + return NULL; +} + +int update_ftrace_direct_del(struct ftrace_ops *ops, struct ftrace_hash *hash) +{ + struct ftrace_hash *new_hash = NULL, *filter_hash = NULL, *free_hash = NULL; + struct ftrace_func_entry *del, *entry; + unsigned long size, i; + int err = -EINVAL; + + if (!hash_count(hash)) + return 0; + if (check_direct_multi(ops)) + return -EINVAL; + if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) + return -EINVAL; + if (direct_functions == EMPTY_HASH) + return -EINVAL; + + mutex_lock(&direct_mutex); + + /* Make sure requested entries are already registered. */ + size = 1 << hash->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(entry, &hash->buckets[i], hlist) { + del = __ftrace_lookup_ip(direct_functions, entry->ip); + if (!del || del->direct != entry->direct) + goto out_unlock; + } + } + + err = -ENOMEM; + filter_hash = hash_sub(ops->func_hash->filter_hash, hash); + if (!filter_hash) + goto out_unlock; + + new_hash = hash_sub(direct_functions, hash); + if (!new_hash) + goto out_unlock; + + /* If there's nothing left, we need to unregister the ops. */ + if (ftrace_hash_empty(filter_hash)) { + err = unregister_ftrace_function(ops); + /* cleanup for possible another register call */ + ops->func = NULL; + ops->trampoline = 0; + ftrace_free_filter(ops); + ops->func_hash->filter_hash = NULL; + } else { + err = ftrace_update_ops(ops, filter_hash, EMPTY_HASH); + } + + if (!err) { + free_hash = direct_functions; + rcu_assign_pointer(direct_functions, new_hash); + } + + out_unlock: + mutex_unlock(&direct_mutex); + + if (free_hash && free_hash != EMPTY_HASH) + call_rcu_tasks(&free_hash->rcu, register_ftrace_direct_cb); + if (filter_hash) + free_ftrace_hash(filter_hash); + + return err; +} + #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */ /** -- 2.51.1
