On Tue, 31 Aug 2021 11:50:15 +0200
Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> Adding interface to register multiple direct functions
> within single call. Adding following functions:
>
> register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
> unregister_ftrace_direct_multi(struct ftrace_ops *ops)
>
> The register_ftrace_direct_multi registers direct function (addr)
> with all functions in ops filter. The ops filter can be updated
> before with ftrace_set_filter_ip calls.
>
> All requested functions must not have direct function currently
> registered, otherwise register_ftrace_direct_multi will fail.
>
> The unregister_ftrace_direct_multi unregisters ops related direct
> functions.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> include/linux/ftrace.h | 11 ++++
> kernel/trace/ftrace.c | 111 +++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 122 insertions(+)
>
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index d399621a67ee..e40b5201c16e 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -316,7 +316,10 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
> unsigned long old_addr,
> unsigned long new_addr);
> unsigned long ftrace_find_rec_direct(unsigned long ip);
> +int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
> +int unregister_ftrace_direct_multi(struct ftrace_ops *ops);
> #else
> +struct ftrace_ops;
> # define ftrace_direct_func_count 0
> static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
> {
> @@ -346,6 +349,14 @@ static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
> {
> return 0;
> }
> +static inline int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
> +{
> + return -ENODEV;
> +}
> +static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops)
> +{
> + return -ENODEV;
> +}
> #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 c60217d81040..7243769493c9 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -5407,6 +5407,117 @@ int modify_ftrace_direct(unsigned long ip,
> return ret;
> }
> EXPORT_SYMBOL_GPL(modify_ftrace_direct);
> +
> +#define MULTI_FLAGS (FTRACE_OPS_FL_IPMODIFY | FTRACE_OPS_FL_DIRECT | \
> + FTRACE_OPS_FL_SAVE_REGS)
> +
> +static int check_direct_multi(struct ftrace_ops *ops)
> +{
> + if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
> + return -EINVAL;
> + if ((ops->flags & MULTI_FLAGS) != MULTI_FLAGS)
> + return -EINVAL;
> + return 0;
> +}
> +
Needs kernel doc comments as this is an interface outside this file.
> +int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
> +{
> + struct ftrace_hash *hash, *free_hash = NULL;
> + struct ftrace_func_entry *entry, *new;
> + int err = -EBUSY, size, i;
> +
> + if (ops->func || ops->trampoline)
> + return -EINVAL;
> + if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
> + return -EINVAL;
> + if (ops->flags & FTRACE_OPS_FL_ENABLED)
> + return -EINVAL;
> +
> + hash = ops->func_hash->filter_hash;
> + if (ftrace_hash_empty(hash))
> + return -EINVAL;
> +
> + mutex_lock(&direct_mutex);
> +
> + /* Make sure requested entries are not already registered.. */
> + size = 1 << hash->size_bits;
> + for (i = 0; i < size; i++) {
> + hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
> + if (ftrace_find_rec_direct(entry->ip))
> + goto out_unlock;
> + }
> + }
> +
> + /* ... and insert them to direct_functions hash. */
> + err = -ENOMEM;
> + for (i = 0; i < size; i++) {
> + hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
> + new = ftrace_add_rec_direct(entry->ip, addr, &free_hash);
> + if (!new)
> + goto out_remove;
> + entry->direct = addr;
> + }
> + }
> +
> + ops->func = call_direct_funcs;
> + ops->flags = MULTI_FLAGS;
> + ops->trampoline = FTRACE_REGS_ADDR;
> +
> + err = register_ftrace_function(ops);
> +
> + out_remove:
> + if (err) {
The below code:
> + for (i = 0; i < size; i++) {
> + hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
> + new = __ftrace_lookup_ip(direct_functions, entry->ip);
> + if (new) {
> + remove_hash_entry(direct_functions, new);
> + kfree(new);
> + }
> + }
> + }
is identical to code below.
> + }
> +
> + out_unlock:
> + mutex_unlock(&direct_mutex);
> +
> + if (free_hash) {
> + synchronize_rcu_tasks();
> + free_ftrace_hash(free_hash);
> + }
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(register_ftrace_direct_multi);
> +
Should have kernel doc as well.
> +int unregister_ftrace_direct_multi(struct ftrace_ops *ops)
> +{
> + struct ftrace_hash *hash = ops->func_hash->filter_hash;
> + struct ftrace_func_entry *entry, *new;
> + int err, size, i;
> +
> + if (check_direct_multi(ops))
> + return -EINVAL;
> + if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
> + return -EINVAL;
> +
> + mutex_lock(&direct_mutex);
> + err = unregister_ftrace_function(ops);
> +
> + size = 1 << hash->size_bits;
> + for (i = 0; i < size; i++) {
> + hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
> + new = __ftrace_lookup_ip(direct_functions, entry->ip);
> + if (new) {
> + remove_hash_entry(direct_functions, new);
> + kfree(new);
> + }
> + }
> + }
Would probably make sense to turn this into a static inline helper.
-- Steve
> +
> + mutex_unlock(&direct_mutex);
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
> #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
>
> /**
