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Message-Id: <20211008091336.33616-7-jolsa@kernel.org>
Date: Fri, 8 Oct 2021 11:13:34 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andriin@...com>
Subject: [PATCH 6/8] 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.
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
include/linux/ftrace.h | 11 ++++
kernel/trace/ftrace.c | 142 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 153 insertions(+)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1ca60ee70fb0..ba5d02ba8166 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, 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)
{
@@ -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, unsigned long addr)
+{
+ 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 6032a5441770..f9df7bffb770 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5405,6 +5405,148 @@ 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 */
/**
--
2.31.1
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