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Various tracing fixes:

Browse Source 
- Fix a function comparison warning for a xen trace event macro
  - Fix a double perf_event linking to a trace_uprobe_filter for multiple events
  - Fix suspicious RCU warnings in trace event code for using
     list_for_each_entry_rcu() when the "_rcu" portion wasn't needed.
  - Fix a bug in the histogram code when using the same variable
  - Fix a NULL pointer dereference when tracefs lockdown enabled and calling
     trace_set_default_clock()
 
 This v2 version contains:
 
  - A fix to a bug found with the double perf_event linking patch
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Merge tag 'trace-v5.5-rc6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Various tracing fixes:

   - Fix a function comparison warning for a xen trace event macro

   - Fix a double perf_event linking to a trace_uprobe_filter for
     multiple events

   - Fix suspicious RCU warnings in trace event code for using
     list_for_each_entry_rcu() when the "_rcu" portion wasn't needed.

   - Fix a bug in the histogram code when using the same variable

   - Fix a NULL pointer dereference when tracefs lockdown enabled and
     calling trace_set_default_clock()

   - A fix to a bug found with the double perf_event linking patch"

* tag 'trace-v5.5-rc6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing/uprobe: Fix to make trace_uprobe_filter alignment safe
  tracing: Do not set trace clock if tracefs lockdown is in effect
  tracing: Fix histogram code when expression has same var as value
  tracing: trigger: Replace unneeded RCU-list traversals
  tracing/uprobe: Fix double perf_event linking on multiprobe uprobe
  tracing: xen: Ordered comparison of function pointers
This commit is contained in:
Linus Torvalds 2020-01-23 11:23:37 -08:00
commit 34597c85be
8 changed files with 163 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/trace/events/xen.h
View File

@ -66,7 +66,11 @@ TRACE_EVENT(xen_mc_callback,
TP_PROTO(xen_mc_callback_fn_t fn, void *data),
TP_ARGS(fn, data),
TP_STRUCT__entry(
__field(xen_mc_callback_fn_t, fn)
/*
* Use field_struct to avoid is_signed_type()
* comparison of a function pointer.
*/
__field_struct(xen_mc_callback_fn_t, fn)
__field(void *, data)
),
TP_fast_assign(

5
kernel/trace/trace.c
View File

@ -9420,6 +9420,11 @@ __init static int tracing_set_default_clock(void)
{
/* sched_clock_stable() is determined in late_initcall */
if (!trace_boot_clock && !sched_clock_stable()) {
if (security_locked_down(LOCKDOWN_TRACEFS)) {
pr_warn("Can not set tracing clock due to lockdown\n");
return -EPERM;
}
printk(KERN_WARNING
"Unstable clock detected, switching default tracing clock to \"global\"\n"
"If you want to keep using the local clock, then add:\n"

63
kernel/trace/trace_events_hist.c
View File

@ -116,6 +116,7 @@ struct hist_field {
struct ftrace_event_field *field;
unsigned long flags;
hist_field_fn_t fn;
unsigned int ref;
unsigned int size;
unsigned int offset;
unsigned int is_signed;
@ -1766,11 +1767,13 @@ static struct hist_field *find_var(struct hist_trigger_data *hist_data,
struct event_trigger_data *test;
struct hist_field *hist_field;
lockdep_assert_held(&event_mutex);
hist_field = find_var_field(hist_data, var_name);
if (hist_field)
return hist_field;
list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
test_data = test->private_data;
hist_field = find_var_field(test_data, var_name);
@ -1820,7 +1823,9 @@ static struct hist_field *find_file_var(struct trace_event_file *file,
struct event_trigger_data *test;
struct hist_field *hist_field;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
test_data = test->private_data;
hist_field = find_var_field(test_data, var_name);
@ -2423,8 +2428,16 @@ static int contains_operator(char *str)
return field_op;
}
static void get_hist_field(struct hist_field *hist_field)
{
hist_field->ref++;
}
static void __destroy_hist_field(struct hist_field *hist_field)
{
if (--hist_field->ref > 1)
return;
kfree(hist_field->var.name);
kfree(hist_field->name);
kfree(hist_field->type);
@ -2466,6 +2479,8 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
if (!hist_field)
return NULL;
hist_field->ref = 1;
hist_field->hist_data = hist_data;
if (flags & HIST_FIELD_FL_EXPR || flags & HIST_FIELD_FL_ALIAS)
@ -2661,6 +2676,17 @@ static struct hist_field *create_var_ref(struct hist_trigger_data *hist_data,
{
unsigned long flags = HIST_FIELD_FL_VAR_REF;
struct hist_field *ref_field;
int i;
/* Check if the variable already exists */
for (i = 0; i < hist_data->n_var_refs; i++) {
ref_field = hist_data->var_refs[i];
if (ref_field->var.idx == var_field->var.idx &&
ref_field->var.hist_data == var_field->hist_data) {
get_hist_field(ref_field);
return ref_field;
}
}
ref_field = create_hist_field(var_field->hist_data, NULL, flags, NULL);
if (ref_field) {
@ -3115,7 +3141,9 @@ static char *find_trigger_filter(struct hist_trigger_data *hist_data,
{
struct event_trigger_data *test;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (test->private_data == hist_data)
return test->filter_str;
@ -3166,9 +3194,11 @@ find_compatible_hist(struct hist_trigger_data *target_hist_data,
struct event_trigger_data *test;
unsigned int n_keys;
lockdep_assert_held(&event_mutex);
n_keys = target_hist_data->n_fields - target_hist_data->n_vals;
list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
hist_data = test->private_data;
@ -5528,7 +5558,7 @@ static int hist_show(struct seq_file *m, void *v)
goto out_unlock;
}
list_for_each_entry_rcu(data, &event_file->triggers, list) {
list_for_each_entry(data, &event_file->triggers, list) {
if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
hist_trigger_show(m, data, n++);
}
@ -5921,7 +5951,9 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
if (hist_data->attrs->name && !named_data)
goto new;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (!hist_trigger_match(data, test, named_data, false))
continue;
@ -6005,10 +6037,12 @@ static bool have_hist_trigger_match(struct event_trigger_data *data,
struct event_trigger_data *test, *named_data = NULL;
bool match = false;
lockdep_assert_held(&event_mutex);
if (hist_data->attrs->name)
named_data = find_named_trigger(hist_data->attrs->name);
list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (hist_trigger_match(data, test, named_data, false)) {
match = true;
@ -6026,10 +6060,12 @@ static bool hist_trigger_check_refs(struct event_trigger_data *data,
struct hist_trigger_data *hist_data = data->private_data;
struct event_trigger_data *test, *named_data = NULL;
lockdep_assert_held(&event_mutex);
if (hist_data->attrs->name)
named_data = find_named_trigger(hist_data->attrs->name);
list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (!hist_trigger_match(data, test, named_data, false))
continue;
@ -6051,10 +6087,12 @@ static void hist_unregister_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *test, *named_data = NULL;
bool unregistered = false;
lockdep_assert_held(&event_mutex);
if (hist_data->attrs->name)
named_data = find_named_trigger(hist_data->attrs->name);
list_for_each_entry_rcu(test, &file->triggers, list) {
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (!hist_trigger_match(data, test, named_data, false))
continue;
@ -6080,7 +6118,9 @@ static bool hist_file_check_refs(struct trace_event_file *file)
struct hist_trigger_data *hist_data;
struct event_trigger_data *test;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
hist_data = test->private_data;
if (check_var_refs(hist_data))
@ -6323,7 +6363,8 @@ hist_enable_trigger(struct event_trigger_data *data, void *rec,
struct enable_trigger_data *enable_data = data->private_data;
struct event_trigger_data *test;
list_for_each_entry_rcu(test, &enable_data->file->triggers, list) {
list_for_each_entry_rcu(test, &enable_data->file->triggers, list,
lockdep_is_held(&event_mutex)) {
if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
if (enable_data->enable)
test->paused = false;

20
kernel/trace/trace_events_trigger.c
View File

@ -501,7 +501,9 @@ void update_cond_flag(struct trace_event_file *file)
struct event_trigger_data *data;
bool set_cond = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(data, &file->triggers, list) {
if (data->filter || event_command_post_trigger(data->cmd_ops) ||
event_command_needs_rec(data->cmd_ops)) {
set_cond = true;
@ -536,7 +538,9 @@ static int register_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *test;
int ret = 0;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
ret = -EEXIST;
goto out;
@ -581,7 +585,9 @@ static void unregister_trigger(char *glob, struct event_trigger_ops *ops,
struct event_trigger_data *data;
bool unregistered = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(data, &file->triggers, list) {
if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
unregistered = true;
list_del_rcu(&data->list);
@ -1497,7 +1503,9 @@ int event_enable_register_trigger(char *glob,
struct event_trigger_data *test;
int ret = 0;
list_for_each_entry_rcu(test, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(test, &file->triggers, list) {
test_enable_data = test->private_data;
if (test_enable_data &&
(test->cmd_ops->trigger_type ==
@ -1537,7 +1545,9 @@ void event_enable_unregister_trigger(char *glob,
struct event_trigger_data *data;
bool unregistered = false;
list_for_each_entry_rcu(data, &file->triggers, list) {
lockdep_assert_held(&event_mutex);
list_for_each_entry(data, &file->triggers, list) {
enable_data = data->private_data;
if (enable_data &&
(data->cmd_ops->trigger_type ==

2
kernel/trace/trace_kprobe.c
View File

@ -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, false);
if (ret < 0)
goto error;

8
kernel/trace/trace_probe.c
View File

@ -984,15 +984,19 @@ 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, bool alloc_filter)
{
struct trace_event_call *call;
size_t size = sizeof(struct trace_probe_event);
int ret = 0;
if (!event || !group)
return -EINVAL;
tp->event = kzalloc(sizeof(struct trace_probe_event), GFP_KERNEL);
if (alloc_filter)
size += sizeof(struct trace_uprobe_filter);
tp->event = kzalloc(size, GFP_KERNEL);
if (!tp->event)
return -ENOMEM;

9
kernel/trace/trace_probe.h
View File

@ -223,6 +223,12 @@ struct probe_arg {
const struct fetch_type *type; /* Type of this argument */
};
struct trace_uprobe_filter {
rwlock_t rwlock;
int nr_systemwide;
struct list_head perf_events;
};
/* Event call and class holder */
struct trace_probe_event {
unsigned int flags; /* For TP_FLAG_* */
@ -230,6 +236,7 @@ struct trace_probe_event {
struct trace_event_call call;
struct list_head files;
struct list_head probes;
struct trace_uprobe_filter filter[0];
};
struct trace_probe {
@ -322,7 +329,7 @@ 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, bool alloc_filter);
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);

121
kernel/trace/trace_uprobe.c
View File

@ -34,12 +34,6 @@ struct uprobe_trace_entry_head {
#define DATAOF_TRACE_ENTRY(entry, is_return) \
((void*)(entry) + SIZEOF_TRACE_ENTRY(is_return))
struct trace_uprobe_filter {
rwlock_t rwlock;
int nr_systemwide;
struct list_head perf_events;
};
static int trace_uprobe_create(int argc, const char **argv);
static int trace_uprobe_show(struct seq_file *m, struct dyn_event *ev);
static int trace_uprobe_release(struct dyn_event *ev);
@ -60,7 +54,6 @@ 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;
@ -351,7 +344,7 @@ 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, true);
if (ret < 0)
goto error;
@ -359,7 +352,7 @@ 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(tu->tp.event->filter);
return tu;
error:
@ -1067,13 +1060,14 @@ 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(tu->tp.event->filter));
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 +1102,7 @@ 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(tu->tp.event->filter));
if (enabled)
return 0;
@ -1205,39 +1199,39 @@ __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);
write_unlock(&filter->rwlock);
if (!done)
return uprobe_apply(tu->inode, tu->offset, &tu->consumer, false);
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 +1241,21 @@ 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 +1265,59 @@ 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(tu->tp.event->filter, 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(tu->tp.event->filter, 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 = tu->tp.event->filter;
read_lock(&filter->rwlock);
ret = __uprobe_perf_filter(filter, mm);
read_unlock(&filter->rwlock);
return ret;
}
@ -1419,10 +1440,10 @@ 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: