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Commit 892fd363 authored by Chengming Zhou's avatar Chengming Zhou Committed by Greg Kroah-Hartman
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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: 8c4f3c3f ("ftrace: Check module functions being traced on reload")
Signed-off-by: default avatarChengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: default avatarMuchun Song <songmuchun@bytedance.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e88a72e8

kernel/trace/ftrace.c

+7 −4
Original line number Diff line number Diff line
@@ -5665,8 +5665,11 @@ 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))

		if (ops_references_rec(ops, rec)) {

			cnt++;

			if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)

				rec->flags |= FTRACE_FL_REGS;

		}

	}



	return cnt;
@@ -5843,8 +5846,8 @@ 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);