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ftrace: Add multi direct register/unregister interface 

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, unsigned long addr)

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.

Link: https://lkml.kernel.org/r/20211008091336.33616-7-jolsa@kernel.org

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Jiri Olsa 2021-10-08 11:13:34 +02:00 committed by Steven Rostedt (VMware)
parent 1904a81445
commit f64dd4627e
2 changed files with 153 additions and 0 deletions
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11
include/linux/ftrace.h
View File

@ -324,7 +324,10 @@ 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, unsigned long addr);
#else
struct ftrace_ops;
# define ftrace_direct_func_count 0
static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
{
@ -354,6 +357,14 @@ 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, unsigned long addr)
{
return -ENODEV;
}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

142
kernel/trace/ftrace.c
View File

@ -5401,6 +5401,148 @@ 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;
}
static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long addr)
{
struct ftrace_func_entry *entry, *del;
int size, i;
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 == addr) {
remove_hash_entry(direct_functions, del);
kfree(del);
}
}
}
}
/**
* register_ftrace_direct_multi - Call a custom trampoline directly
* for multiple functions registered in @ops
* @ops: The address of the struct ftrace_ops object
* @addr: The address of the trampoline to call at @ops functions
*
* This is used to connect a direct calls to @addr from the nop locations
* of the functions registered in @ops (with by ftrace_set_filter_ip
* function).
*
* The location that it calls (@addr) must be able to handle a direct call,
* and save the parameters of the function being traced, and restore them
* (or inject new ones if needed), before returning.
*
* Returns:
* 0 on success
* -EINVAL - The @ops object was already registered with this call or
* when there are no functions in @ops object.
* -EBUSY - Another direct function is already attached (there can be only one)
* -ENODEV - @ip does not point to a ftrace nop location (or not supported)
* -ENOMEM - There was an allocation failure.
*/
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)
remove_direct_functions_hash(hash, addr);
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);
/**
* unregister_ftrace_direct_multi - Remove calls to custom trampoline
* previously registered by register_ftrace_direct_multi for @ops object.
* @ops: The address of the struct ftrace_ops object
*
* This is used to remove a direct calls to @addr from the nop locations
* of the functions registered in @ops (with by ftrace_set_filter_ip
* function).
*
* Returns:
* 0 on success
* -EINVAL - The @ops object was not properly registered.
*/
int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
{
struct ftrace_hash *hash = ops->func_hash->filter_hash;
int err;
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);
remove_direct_functions_hash(hash, addr);
mutex_unlock(&direct_mutex);
return err;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
/**