在 2020/7/28 下午9:02, Steven Rostedt 写道: > On Tue, 28 Jul 2020 18:27:20 +0800 > Chengming Zhou <zhouchengm...@bytedance.com> wrote: > >> When module loaded and enabled, we will use __ftrace_replace_code >> for module if any ftrace_ops referenced it found. But we will get >> wrong ftrace_addr for module rec in ftrace_get_addr_new, because >> rec->flags has not been setup correctly. >> So setup correct rec->flags when we call referenced_filters to find >> ftrace_ops references it. > This is somewhat correct ;-) > >> Signed-off-by: Chengming Zhou <zhouchengm...@bytedance.com> >> Signed-off-by: Muchun Song <songmuc...@bytedance.com> >> --- >> kernel/trace/ftrace.c | 16 +++++++++++++--- >> 1 file changed, 13 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c >> index fca01a168ae5..00087dea0174 100644 >> --- a/kernel/trace/ftrace.c >> +++ b/kernel/trace/ftrace.c >> @@ -6190,8 +6190,17 @@ static int referenced_filters(struct dyn_ftrace *rec) >> int cnt = 0; >> >> for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) { >> - if (ops_references_rec(ops, rec)) >> - cnt++; >> + if (ops_references_rec(ops, rec)) { >> + cnt++; >> + if (ops->flags & FTRACE_OPS_FL_DIRECT) >> + rec->flags |= FTRACE_FL_DIRECT; > The above should be: > > if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_DIRECT)) > continue; > cnt++; > > The direct flag is *very* special, and should not be set automatically > like this. > > Probably should add the same kind of warning and skip for > FTRACE_OPS_FL_IPMODIFY. Ok, I think it's fine to warn and skip these ops. >> + if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) >> + rec->flags |= FTRACE_FL_REGS; > The above is definitely a bug fix. I'm thinking this patch should be > broken up into two. One with just this update (and the clear below), > and the rest later. As this should be backported to stable.
Yes, this bug cause a kernel crash on our server... So I will send a bugfix patch just including this update and the clear below. >> + if (cnt == 1 && ops->trampoline) >> + rec->flags |= FTRACE_FL_TRAMP; >> + else >> + rec->flags &= ~FTRACE_FL_TRAMP; > The above is correct, but not critical that it would need to be > backported. I will put the rest in the second patch later. Thanks! > > Thanks! > > -- Steve > >> + } >> } >> >> return cnt; >> @@ -6373,7 +6382,8 @@ void ftrace_module_enable(struct module *mod) >> cnt += referenced_filters(rec); >> >> /* This clears FTRACE_FL_DISABLED */ >> - rec->flags = cnt; >> + rec->flags &= ~FTRACE_FL_DISABLED; >> + rec->flags += cnt; >> >> if (ftrace_start_up && cnt) { >> int failed = __ftrace_replace_code(rec, 1);