| Message ID | 20231229115134.08dd5174@gandalf.local.home (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | ftrace: Fix modification of direct_function hash while in use | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
Masami and Jiri, This patch made it through all my tests. If I can get an Acked-by by Sunday, I'll include it in my push to Linus (I have a couple of other fixes to send him). -- Steve On Fri, 29 Dec 2023 11:51:34 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Masami Hiramatsu reported a memory leak in register_ftrace_direct() where > if the number of new entries are added is large enough to cause two > allocations in the loop: > > 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; > } > } > > Where ftrace_add_rec_direct() has: > > if (ftrace_hash_empty(direct_functions) || > direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > struct ftrace_hash *new_hash; > int size = ftrace_hash_empty(direct_functions) ? 0 : > direct_functions->count + 1; > > if (size < 32) > size = 32; > > new_hash = dup_hash(direct_functions, size); > if (!new_hash) > return NULL; > > *free_hash = direct_functions; > direct_functions = new_hash; > } > > The "*free_hash = direct_functions;" can happen twice, losing the previous > allocation of direct_functions. > > But this also exposed a more serious bug. > > The modification of direct_functions above is not safe. As > direct_functions can be referenced at any time to find what direct caller > it should call, the time between: > > new_hash = dup_hash(direct_functions, size); > and > direct_functions = new_hash; > > can have a race with another CPU (or even this one if it gets interrupted), > and the entries being moved to the new hash are not referenced. > > That's because the "dup_hash()" is really misnamed and is really a > "move_hash()". It moves the entries from the old hash to the new one. > > Now even if that was changed, this code is not proper as direct_functions > should not be updated until the end. That is the best way to handle > function reference changes, and is the way other parts of ftrace handles > this. > > The following is done: > > 1. Change add_hash_entry() to return the entry it created and inserted > into the hash, and not just return success or not. > > 2. Replace ftrace_add_rec_direct() with add_hash_entry(), and remove > the former. > > 3. Allocate a "new_hash" at the start that is made for holding both the > new hash entries as well as the existing entries in direct_functions. > > 4. Copy (not move) the direct_function entries over to the new_hash. > > 5. Copy the entries of the added hash to the new_hash. > > 6. If everything succeeds, then use rcu_pointer_assign() to update the > direct_functions with the new_hash. > > This simplifies the code and fixes both the memory leak as well as the > race condition mentioned above. > > Link: https://lore.kernel.org/all/170368070504.42064.8960569647118388081.stgit@devnote2/ > > Cc: stable@vger.kernel.org > Fixes: 763e34e74bb7d ("ftrace: Add register_ftrace_direct()") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > kernel/trace/ftrace.c | 100 ++++++++++++++++++++---------------------- > 1 file changed, 47 insertions(+), 53 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 8de8bec5f366..b01ae7d36021 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1183,18 +1183,19 @@ static void __add_hash_entry(struct ftrace_hash *hash, > hash->count++; > } > > -static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > +static struct ftrace_func_entry * > +add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > { > struct ftrace_func_entry *entry; > > entry = kmalloc(sizeof(*entry), GFP_KERNEL); > if (!entry) > - return -ENOMEM; > + return NULL; > > entry->ip = ip; > __add_hash_entry(hash, entry); > > - return 0; > + return entry; > } > > static void > @@ -1349,7 +1350,6 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > struct ftrace_func_entry *entry; > struct ftrace_hash *new_hash; > int size; > - int ret; > int i; > > new_hash = alloc_ftrace_hash(size_bits); > @@ -1366,8 +1366,7 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > size = 1 << hash->size_bits; > for (i = 0; i < size; i++) { > hlist_for_each_entry(entry, &hash->buckets[i], hlist) { > - ret = add_hash_entry(new_hash, entry->ip); > - if (ret < 0) > + if (add_hash_entry(new_hash, entry->ip) == NULL) > goto free_hash; > } > } > @@ -2536,7 +2535,7 @@ ftrace_find_unique_ops(struct dyn_ftrace *rec) > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > /* Protected by rcu_tasks for reading, and direct_mutex for writing */ > -static struct ftrace_hash *direct_functions = EMPTY_HASH; > +static struct ftrace_hash __rcu *direct_functions = EMPTY_HASH; > static DEFINE_MUTEX(direct_mutex); > int ftrace_direct_func_count; > > @@ -2555,39 +2554,6 @@ unsigned long ftrace_find_rec_direct(unsigned long ip) > return entry->direct; > } > > -static struct ftrace_func_entry* > -ftrace_add_rec_direct(unsigned long ip, unsigned long addr, > - struct ftrace_hash **free_hash) > -{ > - struct ftrace_func_entry *entry; > - > - if (ftrace_hash_empty(direct_functions) || > - direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > - struct ftrace_hash *new_hash; > - int size = ftrace_hash_empty(direct_functions) ? 0 : > - direct_functions->count + 1; > - > - if (size < 32) > - size = 32; > - > - new_hash = dup_hash(direct_functions, size); > - if (!new_hash) > - return NULL; > - > - *free_hash = direct_functions; > - direct_functions = new_hash; > - } > - > - entry = kmalloc(sizeof(*entry), GFP_KERNEL); > - if (!entry) > - return NULL; > - > - entry->ip = ip; > - entry->direct = addr; > - __add_hash_entry(direct_functions, entry); > - return entry; > -} > - > static void call_direct_funcs(unsigned long ip, unsigned long pip, > struct ftrace_ops *ops, struct ftrace_regs *fregs) > { > @@ -4223,8 +4189,8 @@ enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter) > /* Do nothing if it exists */ > if (entry) > return 0; > - > - ret = add_hash_entry(hash, rec->ip); > + if (add_hash_entry(hash, rec->ip) == NULL) > + ret = -ENOMEM; > } > return ret; > } > @@ -5266,7 +5232,8 @@ __ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) > return 0; > } > > - return add_hash_entry(hash, ip); > + entry = add_hash_entry(hash, ip); > + return entry ? 0 : -ENOMEM; > } > > static int > @@ -5410,7 +5377,7 @@ static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long > */ > int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > { > - struct ftrace_hash *hash, *free_hash = NULL; > + struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL; > struct ftrace_func_entry *entry, *new; > int err = -EBUSY, size, i; > > @@ -5436,17 +5403,44 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > } > } > > - /* ... and insert them to direct_functions hash. */ > err = -ENOMEM; > + > + /* Make a copy hash to place the new and the old entries in */ > + size = hash->count + direct_functions->count; > + if (size > 32) > + size = 32; > + new_hash = alloc_ftrace_hash(fls(size)); > + if (!new_hash) > + goto out_unlock; > + > + /* Now copy over the existing direct entries */ > + size = 1 << direct_functions->size_bits; > + for (i = 0; i < size; i++) { > + hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) { > + new = add_hash_entry(new_hash, entry->ip); > + if (!new) > + goto out_unlock; > + new->direct = entry->direct; > + } > + } > + > + /* ... and add the new entries */ > + size = 1 << hash->size_bits; > 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); > + new = add_hash_entry(new_hash, entry->ip); > if (!new) > - goto out_remove; > + goto out_unlock; > + /* Update both the copy and the hash entry */ > + new->direct = addr; > entry->direct = addr; > } > } > > + free_hash = direct_functions; > + rcu_assign_pointer(direct_functions, new_hash); > + new_hash = NULL; > + > ops->func = call_direct_funcs; > ops->flags = MULTI_FLAGS; > ops->trampoline = FTRACE_REGS_ADDR; > @@ -5454,17 +5448,17 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > > err = register_ftrace_function_nolock(ops); > > - out_remove: > - if (err) > - remove_direct_functions_hash(hash, addr); > - > out_unlock: > mutex_unlock(&direct_mutex); > > - if (free_hash) { > + if (free_hash && free_hash != EMPTY_HASH) { > synchronize_rcu_tasks(); > free_ftrace_hash(free_hash); > } > + > + if (new_hash) > + free_ftrace_hash(new_hash); > + > return err; > } > EXPORT_SYMBOL_GPL(register_ftrace_direct); > @@ -6309,7 +6303,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer) > > if (entry) > continue; > - if (add_hash_entry(hash, rec->ip) < 0) > + if (add_hash_entry(hash, rec->ip) == NULL) > goto out; > } else { > if (entry) {
On Fri, 29 Dec 2023 11:51:34 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Masami Hiramatsu reported a memory leak in register_ftrace_direct() where > if the number of new entries are added is large enough to cause two > allocations in the loop: > > 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; > } > } > > Where ftrace_add_rec_direct() has: > > if (ftrace_hash_empty(direct_functions) || > direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > struct ftrace_hash *new_hash; > int size = ftrace_hash_empty(direct_functions) ? 0 : > direct_functions->count + 1; > > if (size < 32) > size = 32; > > new_hash = dup_hash(direct_functions, size); > if (!new_hash) > return NULL; > > *free_hash = direct_functions; > direct_functions = new_hash; > } > > The "*free_hash = direct_functions;" can happen twice, losing the previous > allocation of direct_functions. > > But this also exposed a more serious bug. > > The modification of direct_functions above is not safe. As > direct_functions can be referenced at any time to find what direct caller > it should call, the time between: > > new_hash = dup_hash(direct_functions, size); > and > direct_functions = new_hash; > > can have a race with another CPU (or even this one if it gets interrupted), > and the entries being moved to the new hash are not referenced. > > That's because the "dup_hash()" is really misnamed and is really a > "move_hash()". It moves the entries from the old hash to the new one. > > Now even if that was changed, this code is not proper as direct_functions > should not be updated until the end. That is the best way to handle > function reference changes, and is the way other parts of ftrace handles > this. Oops, I also misunderstood. > > The following is done: > > 1. Change add_hash_entry() to return the entry it created and inserted > into the hash, and not just return success or not. > > 2. Replace ftrace_add_rec_direct() with add_hash_entry(), and remove > the former. > > 3. Allocate a "new_hash" at the start that is made for holding both the > new hash entries as well as the existing entries in direct_functions. > > 4. Copy (not move) the direct_function entries over to the new_hash. > > 5. Copy the entries of the added hash to the new_hash. > > 6. If everything succeeds, then use rcu_pointer_assign() to update the > direct_functions with the new_hash. > > This simplifies the code and fixes both the memory leak as well as the > race condition mentioned above. This looks good to me. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you, > > Link: https://lore.kernel.org/all/170368070504.42064.8960569647118388081.stgit@devnote2/ > > Cc: stable@vger.kernel.org > Fixes: 763e34e74bb7d ("ftrace: Add register_ftrace_direct()") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > kernel/trace/ftrace.c | 100 ++++++++++++++++++++---------------------- > 1 file changed, 47 insertions(+), 53 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 8de8bec5f366..b01ae7d36021 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1183,18 +1183,19 @@ static void __add_hash_entry(struct ftrace_hash *hash, > hash->count++; > } > > -static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > +static struct ftrace_func_entry * > +add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > { > struct ftrace_func_entry *entry; > > entry = kmalloc(sizeof(*entry), GFP_KERNEL); > if (!entry) > - return -ENOMEM; > + return NULL; > > entry->ip = ip; > __add_hash_entry(hash, entry); > > - return 0; > + return entry; > } > > static void > @@ -1349,7 +1350,6 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > struct ftrace_func_entry *entry; > struct ftrace_hash *new_hash; > int size; > - int ret; > int i; > > new_hash = alloc_ftrace_hash(size_bits); > @@ -1366,8 +1366,7 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > size = 1 << hash->size_bits; > for (i = 0; i < size; i++) { > hlist_for_each_entry(entry, &hash->buckets[i], hlist) { > - ret = add_hash_entry(new_hash, entry->ip); > - if (ret < 0) > + if (add_hash_entry(new_hash, entry->ip) == NULL) > goto free_hash; > } > } > @@ -2536,7 +2535,7 @@ ftrace_find_unique_ops(struct dyn_ftrace *rec) > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > /* Protected by rcu_tasks for reading, and direct_mutex for writing */ > -static struct ftrace_hash *direct_functions = EMPTY_HASH; > +static struct ftrace_hash __rcu *direct_functions = EMPTY_HASH; > static DEFINE_MUTEX(direct_mutex); > int ftrace_direct_func_count; > > @@ -2555,39 +2554,6 @@ unsigned long ftrace_find_rec_direct(unsigned long ip) > return entry->direct; > } > > -static struct ftrace_func_entry* > -ftrace_add_rec_direct(unsigned long ip, unsigned long addr, > - struct ftrace_hash **free_hash) > -{ > - struct ftrace_func_entry *entry; > - > - if (ftrace_hash_empty(direct_functions) || > - direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > - struct ftrace_hash *new_hash; > - int size = ftrace_hash_empty(direct_functions) ? 0 : > - direct_functions->count + 1; > - > - if (size < 32) > - size = 32; > - > - new_hash = dup_hash(direct_functions, size); > - if (!new_hash) > - return NULL; > - > - *free_hash = direct_functions; > - direct_functions = new_hash; > - } > - > - entry = kmalloc(sizeof(*entry), GFP_KERNEL); > - if (!entry) > - return NULL; > - > - entry->ip = ip; > - entry->direct = addr; > - __add_hash_entry(direct_functions, entry); > - return entry; > -} > - > static void call_direct_funcs(unsigned long ip, unsigned long pip, > struct ftrace_ops *ops, struct ftrace_regs *fregs) > { > @@ -4223,8 +4189,8 @@ enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter) > /* Do nothing if it exists */ > if (entry) > return 0; > - > - ret = add_hash_entry(hash, rec->ip); > + if (add_hash_entry(hash, rec->ip) == NULL) > + ret = -ENOMEM; > } > return ret; > } > @@ -5266,7 +5232,8 @@ __ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) > return 0; > } > > - return add_hash_entry(hash, ip); > + entry = add_hash_entry(hash, ip); > + return entry ? 0 : -ENOMEM; > } > > static int > @@ -5410,7 +5377,7 @@ static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long > */ > int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > { > - struct ftrace_hash *hash, *free_hash = NULL; > + struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL; > struct ftrace_func_entry *entry, *new; > int err = -EBUSY, size, i; > > @@ -5436,17 +5403,44 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > } > } > > - /* ... and insert them to direct_functions hash. */ > err = -ENOMEM; > + > + /* Make a copy hash to place the new and the old entries in */ > + size = hash->count + direct_functions->count; > + if (size > 32) > + size = 32; > + new_hash = alloc_ftrace_hash(fls(size)); > + if (!new_hash) > + goto out_unlock; > + > + /* Now copy over the existing direct entries */ > + size = 1 << direct_functions->size_bits; > + for (i = 0; i < size; i++) { > + hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) { > + new = add_hash_entry(new_hash, entry->ip); > + if (!new) > + goto out_unlock; > + new->direct = entry->direct; > + } > + } > + > + /* ... and add the new entries */ > + size = 1 << hash->size_bits; > 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); > + new = add_hash_entry(new_hash, entry->ip); > if (!new) > - goto out_remove; > + goto out_unlock; > + /* Update both the copy and the hash entry */ > + new->direct = addr; > entry->direct = addr; > } > } > > + free_hash = direct_functions; > + rcu_assign_pointer(direct_functions, new_hash); > + new_hash = NULL; > + > ops->func = call_direct_funcs; > ops->flags = MULTI_FLAGS; > ops->trampoline = FTRACE_REGS_ADDR; > @@ -5454,17 +5448,17 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > > err = register_ftrace_function_nolock(ops); > > - out_remove: > - if (err) > - remove_direct_functions_hash(hash, addr); > - > out_unlock: > mutex_unlock(&direct_mutex); > > - if (free_hash) { > + if (free_hash && free_hash != EMPTY_HASH) { > synchronize_rcu_tasks(); > free_ftrace_hash(free_hash); > } > + > + if (new_hash) > + free_ftrace_hash(new_hash); > + > return err; > } > EXPORT_SYMBOL_GPL(register_ftrace_direct); > @@ -6309,7 +6303,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer) > > if (entry) > continue; > - if (add_hash_entry(hash, rec->ip) < 0) > + if (add_hash_entry(hash, rec->ip) == NULL) > goto out; > } else { > if (entry) { > -- > 2.42.0 >
On Fri, Dec 29, 2023 at 11:51:34AM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Masami Hiramatsu reported a memory leak in register_ftrace_direct() where > if the number of new entries are added is large enough to cause two > allocations in the loop: > > 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; > } > } > > Where ftrace_add_rec_direct() has: > > if (ftrace_hash_empty(direct_functions) || > direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > struct ftrace_hash *new_hash; > int size = ftrace_hash_empty(direct_functions) ? 0 : > direct_functions->count + 1; > > if (size < 32) > size = 32; > > new_hash = dup_hash(direct_functions, size); > if (!new_hash) > return NULL; > > *free_hash = direct_functions; > direct_functions = new_hash; > } > > The "*free_hash = direct_functions;" can happen twice, losing the previous > allocation of direct_functions. nice catch, I'm running bpf CI on this and it looks good so far [1] Acked-by: Jiri Olsa <jolsa@kernel.org> jirka [1] https://github.com/kernel-patches/bpf/pull/6202 > > But this also exposed a more serious bug. > > The modification of direct_functions above is not safe. As > direct_functions can be referenced at any time to find what direct caller > it should call, the time between: > > new_hash = dup_hash(direct_functions, size); > and > direct_functions = new_hash; > > can have a race with another CPU (or even this one if it gets interrupted), > and the entries being moved to the new hash are not referenced. > > That's because the "dup_hash()" is really misnamed and is really a > "move_hash()". It moves the entries from the old hash to the new one. > > Now even if that was changed, this code is not proper as direct_functions > should not be updated until the end. That is the best way to handle > function reference changes, and is the way other parts of ftrace handles > this. > > The following is done: > > 1. Change add_hash_entry() to return the entry it created and inserted > into the hash, and not just return success or not. > > 2. Replace ftrace_add_rec_direct() with add_hash_entry(), and remove > the former. > > 3. Allocate a "new_hash" at the start that is made for holding both the > new hash entries as well as the existing entries in direct_functions. > > 4. Copy (not move) the direct_function entries over to the new_hash. > > 5. Copy the entries of the added hash to the new_hash. > > 6. If everything succeeds, then use rcu_pointer_assign() to update the > direct_functions with the new_hash. > > This simplifies the code and fixes both the memory leak as well as the > race condition mentioned above. > > Link: https://lore.kernel.org/all/170368070504.42064.8960569647118388081.stgit@devnote2/ > > Cc: stable@vger.kernel.org > Fixes: 763e34e74bb7d ("ftrace: Add register_ftrace_direct()") > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > kernel/trace/ftrace.c | 100 ++++++++++++++++++++---------------------- > 1 file changed, 47 insertions(+), 53 deletions(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 8de8bec5f366..b01ae7d36021 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -1183,18 +1183,19 @@ static void __add_hash_entry(struct ftrace_hash *hash, > hash->count++; > } > > -static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > +static struct ftrace_func_entry * > +add_hash_entry(struct ftrace_hash *hash, unsigned long ip) > { > struct ftrace_func_entry *entry; > > entry = kmalloc(sizeof(*entry), GFP_KERNEL); > if (!entry) > - return -ENOMEM; > + return NULL; > > entry->ip = ip; > __add_hash_entry(hash, entry); > > - return 0; > + return entry; > } > > static void > @@ -1349,7 +1350,6 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > struct ftrace_func_entry *entry; > struct ftrace_hash *new_hash; > int size; > - int ret; > int i; > > new_hash = alloc_ftrace_hash(size_bits); > @@ -1366,8 +1366,7 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) > size = 1 << hash->size_bits; > for (i = 0; i < size; i++) { > hlist_for_each_entry(entry, &hash->buckets[i], hlist) { > - ret = add_hash_entry(new_hash, entry->ip); > - if (ret < 0) > + if (add_hash_entry(new_hash, entry->ip) == NULL) > goto free_hash; > } > } > @@ -2536,7 +2535,7 @@ ftrace_find_unique_ops(struct dyn_ftrace *rec) > > #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS > /* Protected by rcu_tasks for reading, and direct_mutex for writing */ > -static struct ftrace_hash *direct_functions = EMPTY_HASH; > +static struct ftrace_hash __rcu *direct_functions = EMPTY_HASH; > static DEFINE_MUTEX(direct_mutex); > int ftrace_direct_func_count; > > @@ -2555,39 +2554,6 @@ unsigned long ftrace_find_rec_direct(unsigned long ip) > return entry->direct; > } > > -static struct ftrace_func_entry* > -ftrace_add_rec_direct(unsigned long ip, unsigned long addr, > - struct ftrace_hash **free_hash) > -{ > - struct ftrace_func_entry *entry; > - > - if (ftrace_hash_empty(direct_functions) || > - direct_functions->count > 2 * (1 << direct_functions->size_bits)) { > - struct ftrace_hash *new_hash; > - int size = ftrace_hash_empty(direct_functions) ? 0 : > - direct_functions->count + 1; > - > - if (size < 32) > - size = 32; > - > - new_hash = dup_hash(direct_functions, size); > - if (!new_hash) > - return NULL; > - > - *free_hash = direct_functions; > - direct_functions = new_hash; > - } > - > - entry = kmalloc(sizeof(*entry), GFP_KERNEL); > - if (!entry) > - return NULL; > - > - entry->ip = ip; > - entry->direct = addr; > - __add_hash_entry(direct_functions, entry); > - return entry; > -} > - > static void call_direct_funcs(unsigned long ip, unsigned long pip, > struct ftrace_ops *ops, struct ftrace_regs *fregs) > { > @@ -4223,8 +4189,8 @@ enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter) > /* Do nothing if it exists */ > if (entry) > return 0; > - > - ret = add_hash_entry(hash, rec->ip); > + if (add_hash_entry(hash, rec->ip) == NULL) > + ret = -ENOMEM; > } > return ret; > } > @@ -5266,7 +5232,8 @@ __ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) > return 0; > } > > - return add_hash_entry(hash, ip); > + entry = add_hash_entry(hash, ip); > + return entry ? 0 : -ENOMEM; > } > > static int > @@ -5410,7 +5377,7 @@ static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long > */ > int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > { > - struct ftrace_hash *hash, *free_hash = NULL; > + struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL; > struct ftrace_func_entry *entry, *new; > int err = -EBUSY, size, i; > > @@ -5436,17 +5403,44 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > } > } > > - /* ... and insert them to direct_functions hash. */ > err = -ENOMEM; > + > + /* Make a copy hash to place the new and the old entries in */ > + size = hash->count + direct_functions->count; > + if (size > 32) > + size = 32; > + new_hash = alloc_ftrace_hash(fls(size)); > + if (!new_hash) > + goto out_unlock; > + > + /* Now copy over the existing direct entries */ > + size = 1 << direct_functions->size_bits; > + for (i = 0; i < size; i++) { > + hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) { > + new = add_hash_entry(new_hash, entry->ip); > + if (!new) > + goto out_unlock; > + new->direct = entry->direct; > + } > + } > + > + /* ... and add the new entries */ > + size = 1 << hash->size_bits; > 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); > + new = add_hash_entry(new_hash, entry->ip); > if (!new) > - goto out_remove; > + goto out_unlock; > + /* Update both the copy and the hash entry */ > + new->direct = addr; > entry->direct = addr; > } > } > > + free_hash = direct_functions; > + rcu_assign_pointer(direct_functions, new_hash); > + new_hash = NULL; > + > ops->func = call_direct_funcs; > ops->flags = MULTI_FLAGS; > ops->trampoline = FTRACE_REGS_ADDR; > @@ -5454,17 +5448,17 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) > > err = register_ftrace_function_nolock(ops); > > - out_remove: > - if (err) > - remove_direct_functions_hash(hash, addr); > - > out_unlock: > mutex_unlock(&direct_mutex); > > - if (free_hash) { > + if (free_hash && free_hash != EMPTY_HASH) { > synchronize_rcu_tasks(); > free_ftrace_hash(free_hash); > } > + > + if (new_hash) > + free_ftrace_hash(new_hash); > + > return err; > } > EXPORT_SYMBOL_GPL(register_ftrace_direct); > @@ -6309,7 +6303,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer) > > if (entry) > continue; > - if (add_hash_entry(hash, rec->ip) < 0) > + if (add_hash_entry(hash, rec->ip) == NULL) > goto out; > } else { > if (entry) { > -- > 2.42.0 >
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 8de8bec5f366..b01ae7d36021 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1183,18 +1183,19 @@ static void __add_hash_entry(struct ftrace_hash *hash, hash->count++; } -static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip) +static struct ftrace_func_entry * +add_hash_entry(struct ftrace_hash *hash, unsigned long ip) { struct ftrace_func_entry *entry; entry = kmalloc(sizeof(*entry), GFP_KERNEL); if (!entry) - return -ENOMEM; + return NULL; entry->ip = ip; __add_hash_entry(hash, entry); - return 0; + return entry; } static void @@ -1349,7 +1350,6 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) struct ftrace_func_entry *entry; struct ftrace_hash *new_hash; int size; - int ret; int i; new_hash = alloc_ftrace_hash(size_bits); @@ -1366,8 +1366,7 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) size = 1 << hash->size_bits; for (i = 0; i < size; i++) { hlist_for_each_entry(entry, &hash->buckets[i], hlist) { - ret = add_hash_entry(new_hash, entry->ip); - if (ret < 0) + if (add_hash_entry(new_hash, entry->ip) == NULL) goto free_hash; } } @@ -2536,7 +2535,7 @@ ftrace_find_unique_ops(struct dyn_ftrace *rec) #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS /* Protected by rcu_tasks for reading, and direct_mutex for writing */ -static struct ftrace_hash *direct_functions = EMPTY_HASH; +static struct ftrace_hash __rcu *direct_functions = EMPTY_HASH; static DEFINE_MUTEX(direct_mutex); int ftrace_direct_func_count; @@ -2555,39 +2554,6 @@ unsigned long ftrace_find_rec_direct(unsigned long ip) return entry->direct; } -static struct ftrace_func_entry* -ftrace_add_rec_direct(unsigned long ip, unsigned long addr, - struct ftrace_hash **free_hash) -{ - struct ftrace_func_entry *entry; - - if (ftrace_hash_empty(direct_functions) || - direct_functions->count > 2 * (1 << direct_functions->size_bits)) { - struct ftrace_hash *new_hash; - int size = ftrace_hash_empty(direct_functions) ? 0 : - direct_functions->count + 1; - - if (size < 32) - size = 32; - - new_hash = dup_hash(direct_functions, size); - if (!new_hash) - return NULL; - - *free_hash = direct_functions; - direct_functions = new_hash; - } - - entry = kmalloc(sizeof(*entry), GFP_KERNEL); - if (!entry) - return NULL; - - entry->ip = ip; - entry->direct = addr; - __add_hash_entry(direct_functions, entry); - return entry; -} - static void call_direct_funcs(unsigned long ip, unsigned long pip, struct ftrace_ops *ops, struct ftrace_regs *fregs) { @@ -4223,8 +4189,8 @@ enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter) /* Do nothing if it exists */ if (entry) return 0; - - ret = add_hash_entry(hash, rec->ip); + if (add_hash_entry(hash, rec->ip) == NULL) + ret = -ENOMEM; } return ret; } @@ -5266,7 +5232,8 @@ __ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) return 0; } - return add_hash_entry(hash, ip); + entry = add_hash_entry(hash, ip); + return entry ? 0 : -ENOMEM; } static int @@ -5410,7 +5377,7 @@ static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long */ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) { - struct ftrace_hash *hash, *free_hash = NULL; + struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL; struct ftrace_func_entry *entry, *new; int err = -EBUSY, size, i; @@ -5436,17 +5403,44 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) } } - /* ... and insert them to direct_functions hash. */ err = -ENOMEM; + + /* Make a copy hash to place the new and the old entries in */ + size = hash->count + direct_functions->count; + if (size > 32) + size = 32; + new_hash = alloc_ftrace_hash(fls(size)); + if (!new_hash) + goto out_unlock; + + /* Now copy over the existing direct entries */ + size = 1 << direct_functions->size_bits; + for (i = 0; i < size; i++) { + hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) { + new = add_hash_entry(new_hash, entry->ip); + if (!new) + goto out_unlock; + new->direct = entry->direct; + } + } + + /* ... and add the new entries */ + size = 1 << hash->size_bits; 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); + new = add_hash_entry(new_hash, entry->ip); if (!new) - goto out_remove; + goto out_unlock; + /* Update both the copy and the hash entry */ + new->direct = addr; entry->direct = addr; } } + free_hash = direct_functions; + rcu_assign_pointer(direct_functions, new_hash); + new_hash = NULL; + ops->func = call_direct_funcs; ops->flags = MULTI_FLAGS; ops->trampoline = FTRACE_REGS_ADDR; @@ -5454,17 +5448,17 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) err = register_ftrace_function_nolock(ops); - out_remove: - if (err) - remove_direct_functions_hash(hash, addr); - out_unlock: mutex_unlock(&direct_mutex); - if (free_hash) { + if (free_hash && free_hash != EMPTY_HASH) { synchronize_rcu_tasks(); free_ftrace_hash(free_hash); } + + if (new_hash) + free_ftrace_hash(new_hash); + return err; } EXPORT_SYMBOL_GPL(register_ftrace_direct); @@ -6309,7 +6303,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer) if (entry) continue; - if (add_hash_entry(hash, rec->ip) < 0) + if (add_hash_entry(hash, rec->ip) == NULL) goto out; } else { if (entry) {