[for-linus][PATCH 2/5] tracing/uprobe: Fix double perf_event linking on multiprobe uprobe

Steven Rostedt
2020-01-21T14:40:05Z

From: Masami Hiramatsu <mhiramat@kernel.org>

Fix double perf_event linking to trace_uprobe_filter on
multiple uprobe event by moving trace_uprobe_filter under
trace_probe_event.

In uprobe perf event, trace_uprobe_filter data structure is
managing target mm filters (in perf_event) related to each
uprobe event.

Since commit 60d53e2c3b75 ("tracing/probe: Split trace_event
related data from trace_probe") left the trace_uprobe_filter
data structure in trace_uprobe, if a trace_probe_event has
multiple trace_uprobe (multi-probe event), a perf_event is
added to different trace_uprobe_filter on each trace_uprobe.
This leads a linked list corruption.

To fix this issue, move trace_uprobe_filter to trace_probe_event
and link it once on each event instead of each probe.

Link: http://lkml.kernel.org/r/157862073931.1800.3800576241181489174.stgit@devnote2

Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S . Miller" <davem@davemloft.net>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: =?utf-8?q?Toke_H=C3=B8iland-J?= =?utf-8?b?w7hyZ2Vuc2Vu?= <thoiland@redhat.com>
Cc: Jean-Tsung Hsiao <jhsiao@redhat.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe")
Link: https://lkml.kernel.org/r/20200108171611.GA8472@kernel.org
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 2 +-
kernel/trace/trace_probe.c | 5 +-
kernel/trace/trace_probe.h | 3 +-
kernel/trace/trace_uprobe.c | 124 +++++++++++++++++++++++-------------
4 files changed, 86 insertions(+), 48 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7f890262c8a3..3e5f9c7d939c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -290,7 +290,7 @@ static struct trace_kprobe *alloc_trace_kprobe(const char *group,
INIT_HLIST_NODE(&tk->rp.kp.hlist);
INIT_LIST_HEAD(&tk->rp.kp.list);

- ret = trace_probe_init(&tk->tp, event, group);
+ ret = trace_probe_init(&tk->tp, event, group, 0);
if (ret < 0)
goto error;

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 905b10af5d5c..bba18cf44a30 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -984,7 +984,7 @@ void trace_probe_cleanup(struct trace_probe *tp)
}

int trace_probe_init(struct trace_probe *tp, const char *event,
- const char *group)
+ const char *group, size_t event_data_size)
{
struct trace_event_call *call;
int ret = 0;
@@ -992,7 +992,8 @@ int trace_probe_init(struct trace_probe *tp, const char *event,
if (!event || !group)
return -EINVAL;

- tp->event = kzalloc(sizeof(struct trace_probe_event), GFP_KERNEL);
+ tp->event = kzalloc(sizeof(struct trace_probe_event) + event_data_size,
+ GFP_KERNEL);
if (!tp->event)
return -ENOMEM;

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 4ee703728aec..03e4e180058d 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -230,6 +230,7 @@ struct trace_probe_event {
struct trace_event_call call;
struct list_head files;
struct list_head probes;
+ char data[0];
};

struct trace_probe {
@@ -322,7 +323,7 @@ static inline bool trace_probe_has_single_file(struct trace_probe *tp)
}

int trace_probe_init(struct trace_probe *tp, const char *event,
- const char *group);
+ const char *group, size_t event_data_size);
void trace_probe_cleanup(struct trace_probe *tp);
int trace_probe_append(struct trace_probe *tp, struct trace_probe *to);
void trace_probe_unlink(struct trace_probe *tp);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 352073d36585..f66e202fec13 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -60,7 +60,6 @@ static struct dyn_event_operations trace_uprobe_ops = {
*/
struct trace_uprobe {
struct dyn_event devent;
- struct trace_uprobe_filter filter;
struct uprobe_consumer consumer;
struct path path;
struct inode *inode;
@@ -264,6 +263,14 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
}
NOKPROBE_SYMBOL(process_fetch_insn)

+static struct trace_uprobe_filter *
+trace_uprobe_get_filter(struct trace_uprobe *tu)
+{
+ struct trace_probe_event *event = tu->tp.event;
+
+ return (struct trace_uprobe_filter *)&event->data[0];
+}
+
static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
rwlock_init(&filter->rwlock);
@@ -351,7 +358,8 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
if (!tu)
return ERR_PTR(-ENOMEM);

- ret = trace_probe_init(&tu->tp, event, group);
+ ret = trace_probe_init(&tu->tp, event, group,
+ sizeof(struct trace_uprobe_filter));
if (ret < 0)
goto error;

@@ -359,7 +367,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
tu->consumer.handler = uprobe_dispatcher;
if (is_ret)
tu->consumer.ret_handler = uretprobe_dispatcher;
- init_trace_uprobe_filter(&tu->filter);
+ init_trace_uprobe_filter(trace_uprobe_get_filter(tu));
return tu;

error:
@@ -1067,13 +1075,14 @@ static void __probe_event_disable(struct trace_probe *tp)
struct trace_probe *pos;
struct trace_uprobe *tu;

+ tu = container_of(tp, struct trace_uprobe, tp);
+ WARN_ON(!uprobe_filter_is_empty(trace_uprobe_get_filter(tu)));
+
list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
tu = container_of(pos, struct trace_uprobe, tp);
if (!tu->inode)
continue;

- WARN_ON(!uprobe_filter_is_empty(&tu->filter));
-
uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
tu->inode = NULL;
}
@@ -1108,7 +1117,7 @@ static int probe_event_enable(struct trace_event_call *call,
}

tu = container_of(tp, struct trace_uprobe, tp);
- WARN_ON(!uprobe_filter_is_empty(&tu->filter));
+ WARN_ON(!uprobe_filter_is_empty(trace_uprobe_get_filter(tu)));

if (enabled)
return 0;
@@ -1205,39 +1214,39 @@ __uprobe_perf_filter(struct trace_uprobe_filter *filter, struct mm_struct *mm)
}

static inline bool
-uprobe_filter_event(struct trace_uprobe *tu, struct perf_event *event)
+trace_uprobe_filter_event(struct trace_uprobe_filter *filter,
+ struct perf_event *event)
{
- return __uprobe_perf_filter(&tu->filter, event->hw.target->mm);
+ return __uprobe_perf_filter(filter, event->hw.target->mm);
}

-static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
+static bool trace_uprobe_filter_remove(struct trace_uprobe_filter *filter,
+ struct perf_event *event)
{
bool done;

- write_lock(&tu->filter.rwlock);
+ write_lock(&filter->rwlock);
if (event->hw.target) {
list_del(&event->hw.tp_list);
- done = tu->filter.nr_systemwide ||
+ done = filter->nr_systemwide ||
(event->hw.target->flags & PF_EXITING) ||
- uprobe_filter_event(tu, event);
+ trace_uprobe_filter_event(filter, event);
} else {
- tu->filter.nr_systemwide--;
- done = tu->filter.nr_systemwide;
+ filter->nr_systemwide--;
+ done = filter->nr_systemwide;
}
- write_unlock(&tu->filter.rwlock);
-
- if (!done)
- return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
+ write_unlock(&filter->rwlock);

- return 0;
+ return done;
}

-static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
+/* This returns true if the filter always covers target mm */
+static bool trace_uprobe_filter_add(struct trace_uprobe_filter *filter,
+ struct perf_event *event)
{
bool done;
- int err;

- write_lock(&tu->filter.rwlock);
+ write_lock(&filter->rwlock);
if (event->hw.target) {
/*
* event->parent != NULL means copy_process(), we can avoid
@@ -1247,28 +1256,21 @@ static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
* attr.enable_on_exec means that exec/mmap will install the
* breakpoints we need.
*/
- done = tu->filter.nr_systemwide ||
+ done = filter->nr_systemwide ||
event->parent || event->attr.enable_on_exec ||
- uprobe_filter_event(tu, event);
- list_add(&event->hw.tp_list, &tu->filter.perf_events);
+ trace_uprobe_filter_event(filter, event);
+ list_add(&event->hw.tp_list, &filter->perf_events);
} else {
- done = tu->filter.nr_systemwide;
- tu->filter.nr_systemwide++;
+ done = filter->nr_systemwide;
+ filter->nr_systemwide++;
}
- write_unlock(&tu->filter.rwlock);
+ write_unlock(&filter->rwlock);

- err = 0;
- if (!done) {
- err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
- if (err)
- uprobe_perf_close(tu, event);
- }
- return err;
+ return done;
}

-static int uprobe_perf_multi_call(struct trace_event_call *call,
- struct perf_event *event,
- int (*op)(struct trace_uprobe *tu, struct perf_event *event))
+static int uprobe_perf_close(struct trace_event_call *call,
+ struct perf_event *event)
{
struct trace_probe *pos, *tp;
struct trace_uprobe *tu;
@@ -1278,25 +1280,59 @@ static int uprobe_perf_multi_call(struct trace_event_call *call,
if (WARN_ON_ONCE(!tp))
return -ENODEV;

+ tu = container_of(tp, struct trace_uprobe, tp);
+ if (trace_uprobe_filter_remove(trace_uprobe_get_filter(tu), event))
+ return 0;
+
list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
tu = container_of(pos, struct trace_uprobe, tp);
- ret = op(tu, event);
+ ret = uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
if (ret)
break;
}

return ret;
}
+
+static int uprobe_perf_open(struct trace_event_call *call,
+ struct perf_event *event)
+{
+ struct trace_probe *pos, *tp;
+ struct trace_uprobe *tu;
+ int err = 0;
+
+ tp = trace_probe_primary_from_call(call);
+ if (WARN_ON_ONCE(!tp))
+ return -ENODEV;
+
+ tu = container_of(tp, struct trace_uprobe, tp);
+ if (trace_uprobe_filter_add(trace_uprobe_get_filter(tu), event))
+ return 0;
+
+ list_for_each_entry(pos, trace_probe_probe_list(tp), list) {
+ err = uprobe_apply(tu->inode, tu->offset, &tu->consumer, true);
+ if (err) {
+ uprobe_perf_close(call, event);
+ break;
+ }
+ }
+
+ return err;
+}
+
static bool uprobe_perf_filter(struct uprobe_consumer *uc,
enum uprobe_filter_ctx ctx, struct mm_struct *mm)
{
+ struct trace_uprobe_filter *filter;
struct trace_uprobe *tu;
int ret;

tu = container_of(uc, struct trace_uprobe, consumer);
- read_lock(&tu->filter.rwlock);
- ret = __uprobe_perf_filter(&tu->filter, mm);
- read_unlock(&tu->filter.rwlock);
+ filter = trace_uprobe_get_filter(tu);
+
+ read_lock(&filter->rwlock);
+ ret = __uprobe_perf_filter(filter, mm);
+ read_unlock(&filter->rwlock);

return ret;
}
@@ -1419,10 +1455,10 @@ trace_uprobe_register(struct trace_event_call *event, enum trace_reg type,
return 0;

case TRACE_REG_PERF_OPEN:
- return uprobe_perf_multi_call(event, data, uprobe_perf_open);
+ return uprobe_perf_open(event, data);

case TRACE_REG_PERF_CLOSE:
- return uprobe_perf_multi_call(event, data, uprobe_perf_close);
+ return uprobe_perf_close(event, data);

#endif
default:
--
2.24.1