[PATCH 06/19] ftrace: Add multi direct register/unregister interface

Jiri Olsa
2021-06-05T11:11:04Z

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@kernel.org>
---
include/linux/ftrace.h | 10 ++++
kernel/trace/ftrace.c | 108 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 118 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 40b493908f09..91e8d9534ad7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -316,6 +316,8 @@ 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
# define ftrace_direct_func_count 0
static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
@@ -346,6 +348,14 @@ static inline unsigned long ftrace_find_rec_direct(unsigned long ip)
{
return 0;
}
+int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+ return -ENODEV;
+}
+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 9e584710f542..f1ebee1bfbfe 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5402,6 +5402,114 @@ 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;
+}
+
+int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+ struct ftrace_hash *hash = ops->func_hash->filter_hash;
+ struct ftrace_func_entry *entry, *new;
+ struct ftrace_hash *free_hash = NULL;
+ int err = -EBUSY, size, i;
+
+ if (ops->func || ops->trampoline)
+ return -EINVAL;
+ if (ops->flags & FTRACE_OPS_FL_ENABLED)
+ return -EINVAL;
+ 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) {
+ 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);
+ }
+ }
+ }
+ }
+
+ 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);
+
+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);
+ }
+ }
+ }
+
+ mutex_unlock(&direct_mutex);
+ return err;
+}
+EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

/**
--
2.31.1