[PATCH v2 05/12] tracing/uprobe: Add multi-probe per uprobe event support

Masami Hiramatsu
2019-06-19T15:08:05Z

Allow user to define several probes on one uprobe event.
Note that this only support appending method. So deleting
event will delete all probes on the event.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/trace/trace.c | 2 +
kernel/trace/trace_uprobe.c | 60 ++++++++++++++++++++++++++++++-------------
2 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8f5455046504..73fbe3b0dd08 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4821,7 +4821,7 @@ static const char readme_msg[] =
"\t\t\t Write into this file to define/undefine new trace events.\n"
#endif
#ifdef CONFIG_UPROBE_EVENTS
- " uprobe_events\t\t- Add/remove/show the userspace dynamic events\n"
+ " uprobe_events\t\t- Create/append/remove/show the userspace dynamic events\n"
"\t\t\t Write into this file to define/undefine new trace events.\n"
#endif
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 437dddeca8bf..c568f7b16f5c 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -364,15 +364,32 @@ static int unregister_trace_uprobe(struct trace_uprobe *tu)
{
int ret;

+ if (trace_probe_has_sibling(&tu->tp))
+ goto unreg;
+
ret = unregister_uprobe_event(tu);
if (ret)
return ret;

+unreg:
dyn_event_remove(&tu->devent);
+ trace_probe_unlink(&tu->tp);
free_trace_uprobe(tu);
return 0;
}

+static int append_trace_uprobe(struct trace_uprobe *tu, struct trace_uprobe *to)
+{
+ int ret;
+
+ /* Append to existing event */
+ ret = trace_probe_append(&tu->tp, &to->tp);
+ if (!ret)
+ dyn_event_add(&tu->devent);
+
+ return ret;
+}
+
/*
* Uprobe with multiple reference counter is not allowed. i.e.
* If inode and offset matches, reference counter offset *must*
@@ -382,25 +399,21 @@ static int unregister_trace_uprobe(struct trace_uprobe *tu)
* as the new one does not conflict with any other existing
* ones.
*/
-static struct trace_uprobe *find_old_trace_uprobe(struct trace_uprobe *new)
+static int validate_ref_ctr_offset(struct trace_uprobe *new)
{
struct dyn_event *pos;
- struct trace_uprobe *tmp, *old = NULL;
+ struct trace_uprobe *tmp;
struct inode *new_inode = d_real_inode(new->path.dentry);

- old = find_probe_event(trace_probe_name(&new->tp),
- trace_probe_group_name(&new->tp));
-
for_each_trace_uprobe(tmp, pos) {
- if ((old ? old != tmp : true) &&
- new_inode == d_real_inode(tmp->path.dentry) &&
+ if (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 -EINVAL;
}
}
- return old;
+ return 0;
}

/* Register a trace_uprobe and probe_event */
@@ -411,18 +424,29 @@ static int register_trace_uprobe(struct trace_uprobe *tu)

mutex_lock(&event_mutex);

- /* register as an event */
- old_tu = find_old_trace_uprobe(tu);
- if (IS_ERR(old_tu)) {
- ret = PTR_ERR(old_tu);
+ ret = validate_ref_ctr_offset(tu);
+ if (ret)
goto end;
- }

+ /* register as an event */
+ old_tu = find_probe_event(trace_probe_name(&tu->tp),
+ trace_probe_group_name(&tu->tp));
if (old_tu) {
- /* delete old event */
- ret = unregister_trace_uprobe(old_tu);
- if (ret)
- goto end;
+ if (is_ret_probe(tu) != is_ret_probe(old_tu)) {
+ trace_probe_log_set_index(0);
+ trace_probe_log_err(0, DIFF_PROBE_TYPE);
+ ret = -EEXIST;
+ } else {
+ ret = trace_probe_compare_arg_type(&tu->tp, &old_tu->tp);
+ if (ret) {
+ /* Note that argument starts index = 2 */
+ trace_probe_log_set_index(ret + 1);
+ trace_probe_log_err(0, DIFF_ARG_TYPE);
+ ret = -EEXIST;
+ } else
+ ret = append_trace_uprobe(tu, old_tu);
+ }
+ goto end;
}

ret = register_uprobe_event(tu);