Kernel/linux-next
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git synced 2025-01-15 11:37:47 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Fixes for ftrace in v6.13:

Browse Source 
- Add needed READ_ONCE() around access to the fgraph array element
 
   The updates to the fgraph array can happen when callbacks are registered
   and unregistered. The __ftrace_return_to_handler() can handle reading
   either the old value or the new value. But once it reads that value
   it must stay consistent otherwise the check that looks to see if the
   value is a stub may show false, but if the compiler decides to re-read
   after that check, it can be true which can cause the code to crash
   later on.
 
 - Make function profiler use the top level ops for filtering again
 
   When function graph became available for instances, its filter ops became
   independent from the top level set_ftrace_filter. In the process the
   function profiler received its own filter ops as well. But the function
   profiler uses the top level set_ftrace_filter file and does not have one
   of its own. In giving it its own filter ops, it lost any user interface
   it once had. Make it use the top level set_ftrace_filter file again.
   This fixes a regression.
 -----BEGIN PGP SIGNATURE-----
 
 iIoEABYIADIWIQRRSw7ePDh/lE+zeZMp5XQQmuv6qgUCZ3cR4RQccm9zdGVkdEBn
 b29kbWlzLm9yZwAKCRAp5XQQmuv6qjxfAQCPhNztdmGmEYmuBtONPHwejidWnuJ6
 Rl2mQxEbp40OUgD+JvSWofhRsvtXWlymqZ9j+dKMegLqMeq834hB0LK4NAg=
 =+KqV
 -----END PGP SIGNATURE-----

Merge tag 'ftrace-v6.13-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull ftrace fixes from Steven Rostedt:

 - Add needed READ_ONCE() around access to the fgraph array element

   The updates to the fgraph array can happen when callbacks are
   registered and unregistered. The __ftrace_return_to_handler() can
   handle reading either the old value or the new value. But once it
   reads that value it must stay consistent otherwise the check that
   looks to see if the value is a stub may show false, but if the
   compiler decides to re-read after that check, it can be true which
   can cause the code to crash later on.

 - Make function profiler use the top level ops for filtering again

   When function graph became available for instances, its filter ops
   became independent from the top level set_ftrace_filter. In the
   process the function profiler received its own filter ops as well.
   But the function profiler uses the top level set_ftrace_filter file
   and does not have one of its own. In giving it its own filter ops, it
   lost any user interface it once had. Make it use the top level
   set_ftrace_filter file again. This fixes a regression.

* tag 'ftrace-v6.13-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Fix function profiler's filtering functionality
  fgraph: Add READ_ONCE() when accessing fgraph_array[]
This commit is contained in:
Linus Torvalds 2025-01-03 10:04:43 -08:00
commit e30dd219c7
2 changed files with 3 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/trace/fgraph.c
View File

@ -833,7 +833,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
#endif
{
for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
struct fgraph_ops *gops = fgraph_array[i];
struct fgraph_ops *gops = READ_ONCE(fgraph_array[i]);
if (gops == &fgraph_stub)
continue;

8
kernel/trace/ftrace.c
View File

@ -902,16 +902,13 @@ static void profile_graph_return(struct ftrace_graph_ret *trace,
}
static struct fgraph_ops fprofiler_ops = {
.ops = {
.flags = FTRACE_OPS_FL_INITIALIZED,
INIT_OPS_HASH(fprofiler_ops.ops)
},
.entryfunc = &profile_graph_entry,
.retfunc = &profile_graph_return,
};
static int register_ftrace_profiler(void)
{
ftrace_ops_set_global_filter(&fprofiler_ops.ops);
return register_ftrace_graph(&fprofiler_ops);
}
@ -922,12 +919,11 @@ static void unregister_ftrace_profiler(void)
#else
static struct ftrace_ops ftrace_profile_ops __read_mostly = {
.func = function_profile_call,
.flags = FTRACE_OPS_FL_INITIALIZED,
INIT_OPS_HASH(ftrace_profile_ops)
};
static int register_ftrace_profiler(void)
{
ftrace_ops_set_global_filter(&ftrace_profile_ops);
return register_ftrace_function(&ftrace_profile_ops);
}