Messages in this thread Patch in this message | | | Date | Tue, 04 Aug 2020 16:57:49 -0400 | From | Steven Rostedt <> | Subject | [for-linus][PATCH 06/17] ftrace: Do not let direct or IPMODIFY ftrace_ops be added to module and set trampolines |
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From: Chengming Zhou <zhouchengming@bytedance.com>
When inserting a module, we find all ftrace_ops referencing it on the ftrace_ops_list. But FTRACE_OPS_FL_DIRECT and FTRACE_OPS_FL_IPMODIFY flags are special, and should not be set automatically. So warn and skip ftrace_ops that have these two flags set and adding new code. Also check if only one ftrace_ops references the module, in which case we can use a trampoline as an optimization.
Link: https://lkml.kernel.org/r/20200728180554.65203-2-zhouchengming@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- kernel/trace/ftrace.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index d052f856f1cf..f433cb44300a 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6199,9 +6199,17 @@ static int referenced_filters(struct dyn_ftrace *rec) for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) { if (ops_references_rec(ops, rec)) { + if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_DIRECT)) + continue; + if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_IPMODIFY)) + continue; cnt++; if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) rec->flags |= FTRACE_FL_REGS; + if (cnt == 1 && ops->trampoline) + rec->flags |= FTRACE_FL_TRAMP; + else + rec->flags &= ~FTRACE_FL_TRAMP; } } -- 2.26.2
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