diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2019-12-08 16:01:12 -0800 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-12-10 13:53:59 -0500 |
| commit | ff205766dbbee024a4a716638868d98ffb17748a (patch) | |
| tree | 503d0cfaaecf515dd179e6e0c6a8c0ef57f2b3cb /kernel/trace/fgraph.c | |
| parent | a61f810567be0ef101d8bbb65b89ffeac7d62103 (diff) | |
ftrace: Fix function_graph tracer interaction with BPF trampoline
Depending on type of BPF programs served by BPF trampoline it can call original
function. In such case the trampoline will skip one stack frame while
returning. That will confuse function_graph tracer and will cause crashes with
bad RIP. Teach graph tracer to skip functions that have BPF trampoline attached.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/fgraph.c')
| -rw-r--r-- | kernel/trace/fgraph.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 67e0c462b059..a2659735db73 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -101,6 +101,15 @@ int function_graph_enter(unsigned long ret, unsigned long func, { struct ftrace_graph_ent trace; + /* + * Skip graph tracing if the return location is served by direct trampoline, + * since call sequence and return addresses is unpredicatable anymore. + * Ex: BPF trampoline may call original function and may skip frame + * depending on type of BPF programs attached. + */ + if (ftrace_direct_func_count && + ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE)) + return -EBUSY; trace.func = func; trace.depth = ++current->curr_ret_depth; |