On Wed, 19 Aug 2020 14:29:11 +0200 <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > The patch below does not apply to the 4.4-stable tree. > If someone wants it applied there, or to any other stable or longterm > tree, then please email the backport, including the original git commit > id to <stable@xxxxxxxxxxxxxxx>. This should be the fix for 4.4. -- Steve >From 8a224ffb3f52b0027f6b7279854c71a31c48fc97 Mon Sep 17 00:00:00 2001 From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> Date: Wed, 29 Jul 2020 02:05:53 +0800 Subject: [PATCH] ftrace: Setup correct FTRACE_FL_REGS flags for module 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@xxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Fixes: 8c4f3c3fa9681 ("ftrace: Check module functions being traced on reload") Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Index: linux-test.git/kernel/trace/ftrace.c =================================================================== --- linux-test.git.orig/kernel/trace/ftrace.c +++ linux-test.git/kernel/trace/ftrace.c @@ -2823,8 +2823,11 @@ static int referenced_filters(struct dyn 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; @@ -2874,7 +2877,7 @@ static int ftrace_update_code(struct mod p = &pg->records[i]; if (test) cnt += referenced_filters(p); - p->flags = cnt; + p->flags += cnt; /* * Do the initial record conversion from mcount jump
