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ftrace: Add multi direct modify interface 

Adding interface to modify registered direct function
for ftrace_ops. Adding following function:

   modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

The function changes the currently registered direct
function for all attached functions.

Link: https://lkml.kernel.org/r/20211008091336.33616-8-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 11:13:35 +02:00 committed by Steven Rostedt (VMware)
parent f64dd4627e
commit ccf5a89efd
2 changed files with 68 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/ftrace.h
View File

@ -326,6 +326,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
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);
int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
#else
struct ftrace_ops;
# define ftrace_direct_func_count 0
@ -365,6 +367,10 @@ static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigne
{
return -ENODEV;
}
static inline int modify_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

62
kernel/trace/ftrace.c
View File

@ -5543,6 +5543,68 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
return err;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
/**
* modify_ftrace_direct_multi - Modify an existing direct 'multi' call
* to call something else
* @ops: The address of the struct ftrace_ops object
* @addr: The address of the new trampoline to call at @ops functions
*
* This is used to unregister currently registered direct caller and
* register new one @addr on functions registered in @ops object.
*
* Note there's window between ftrace_shutdown and ftrace_startup calls
* where there will be no callbacks called.
*
* Returns: zero on success. Non zero on error, which includes:
* -EINVAL - The @ops object was not properly registered.
*/
int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
{
struct ftrace_hash *hash = ops->func_hash->filter_hash;
struct ftrace_func_entry *entry, *iter;
int i, size;
int err;
if (check_direct_multi(ops))
return -EINVAL;
if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
return -EINVAL;
mutex_lock(&direct_mutex);
mutex_lock(&ftrace_lock);
/*
* Shutdown the ops, change 'direct' pointer for each
* ops entry in direct_functions hash and startup the
* ops back again.
*
* Note there is no callback called for @ops object after
* this ftrace_shutdown call until ftrace_startup is called
* later on.
*/
err = ftrace_shutdown(ops, 0);
if (err)
goto out_unlock;
size = 1 << hash->size_bits;
for (i = 0; i < size; i++) {
hlist_for_each_entry(iter, &hash->buckets[i], hlist) {
entry = __ftrace_lookup_ip(direct_functions, iter->ip);
if (!entry)
continue;
entry->direct = addr;
}
}
err = ftrace_startup(ops, 0);
out_unlock:
mutex_unlock(&ftrace_lock);
mutex_unlock(&direct_mutex);
return err;
}
EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi);
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
/**