| From 8a224ffb3f52b0027f6b7279854c71a31c48fc97 Mon Sep 17 00:00:00 2001 |
| From: Chengming Zhou <zhouchengming@bytedance.com> |
| Date: Wed, 29 Jul 2020 02:05:53 +0800 |
| Subject: [PATCH] ftrace: Setup correct FTRACE_FL_REGS flags for module |
| |
| commit 8a224ffb3f52b0027f6b7279854c71a31c48fc97 upstream. |
| |
| 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. It can cause the callback |
| function of a ftrace_ops has FTRACE_OPS_FL_SAVE_REGS to be called |
| with pt_regs set to NULL. |
| So setup correct FTRACE_FL_REGS flags for rec when we call |
| referenced_filters to find ftrace_ops references it. |
| |
| Link: https://lkml.kernel.org/r/20200728180554.65203-1-zhouchengming@bytedance.com |
| |
| Cc: stable@vger.kernel.org |
| Fixes: 8c4f3c3fa9681 ("ftrace: Check module functions being traced on reload") |
| 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> |
| |
| diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c |
| index c141d347f71a..d052f856f1cf 100644 |
| --- a/kernel/trace/ftrace.c |
| +++ b/kernel/trace/ftrace.c |
| @@ -6198,8 +6198,11 @@ 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_SAVE_REGS) |
| + rec->flags |= FTRACE_FL_REGS; |
| + } |
| } |
| |
| return cnt; |
| @@ -6378,8 +6381,8 @@ void ftrace_module_enable(struct module *mod) |
| if (ftrace_start_up) |
| 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); |
| -- |
| 2.27.0 |
| |