trace_uprobe/sdt: Prevent multiple reference counter for same uprobe (ccea8727) · Commits · 戴 / test

We assume to have only one reference counter for one uprobe. Don't allow user to add multiple trace_uprobe entries having same inode+offset but different reference counter. Ex, # echo "p:sdt_tick/loop2 /home/ravi/tick:0x6e4(0x10036)" > uprobe_events # echo "p:sdt_tick/loop2_1 /home/ravi/tick:0x6e4(0xfffff)" >> uprobe_events bash: echo: write error: Invalid argument # dmesg trace_kprobe: Reference counter offset mismatch. There is one exception though: When user is trying to replace the old entry with the new one, we allow this if the new entry does not conflict with any other existing entries. Link: http://lkml.kernel.org/r/20180820044250.11659-4-ravi.bangoria@linux.ibm.com Acked-by:

Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by:

Song Liu <songliubraving@fb.com> Reviewed-by:

Oleg Nesterov <oleg@redhat.com> Tested-by:

Song Liu <songliubraving@fb.com> Signed-off-by:

Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by:

Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_uprobe.c

+35 −2

Original line number	Diff line number	Diff line
		@@ -312,6 +312,35 @@ static int unregister_trace_uprobe(struct trace_uprobe *tu)
		return 0;
		}

		/*
		* Uprobe with multiple reference counter is not allowed. i.e.
		* If inode and offset matches, reference counter offset must
		* match as well. Though, there is one exception: If user is
		* replacing old trace_uprobe with new one(same group/event),
		* then we allow same uprobe with new reference counter as far
		* as the new one does not conflict with any other existing
		* ones.
		*/
		static struct trace_uprobe find_old_trace_uprobe(struct trace_uprobe new)
		{
		struct trace_uprobe tmp, old = NULL;
		struct inode *new_inode = d_real_inode(new->path.dentry);

		old = find_probe_event(trace_event_name(&new->tp.call),
		new->tp.call.class->system);

		list_for_each_entry(tmp, &uprobe_list, list) {
		if ((old ? old != tmp : true) &&
		new_inode == d_real_inode(tmp->path.dentry) &&
		new->offset == tmp->offset &&
		new->ref_ctr_offset != tmp->ref_ctr_offset) {
		pr_warn("Reference counter offset mismatch.");
		return ERR_PTR(-EINVAL);
		}
		}
		return old;
		}

		/* Register a trace_uprobe and probe_event */
		static int register_trace_uprobe(struct trace_uprobe *tu)
		{
		@@ -321,8 +350,12 @@ static int register_trace_uprobe(struct trace_uprobe *tu)
		mutex_lock(&uprobe_lock);

		/* register as an event */
		old_tu = find_probe_event(trace_event_name(&tu->tp.call),
		tu->tp.call.class->system);
		old_tu = find_old_trace_uprobe(tu);
		if (IS_ERR(old_tu)) {
		ret = PTR_ERR(old_tu);
		goto end;
		}

		if (old_tu) {
		/* delete old event */
		ret = unregister_trace_uprobe(old_tu);

Admin message