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Diffstat (limited to 'kernel/trace/trace_kprobe.c')
-rw-r--r--kernel/trace/trace_kprobe.c230
1 files changed, 89 insertions, 141 deletions
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 9f46e98ba8f2..243f6834d026 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -35,12 +35,17 @@ struct trace_probe {
const char *symbol; /* symbol name */
struct ftrace_event_class class;
struct ftrace_event_call call;
- struct ftrace_event_file * __rcu *files;
+ struct list_head files;
ssize_t size; /* trace entry size */
unsigned int nr_args;
struct probe_arg args[];
};
+struct event_file_link {
+ struct ftrace_event_file *file;
+ struct list_head list;
+};
+
#define SIZEOF_TRACE_PROBE(n) \
(offsetof(struct trace_probe, args) + \
(sizeof(struct probe_arg) * (n)))
@@ -90,7 +95,7 @@ static __kprobes bool trace_probe_is_on_module(struct trace_probe *tp)
}
static int register_probe_event(struct trace_probe *tp);
-static void unregister_probe_event(struct trace_probe *tp);
+static int unregister_probe_event(struct trace_probe *tp);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);
@@ -150,6 +155,7 @@ static struct trace_probe *alloc_trace_probe(const char *group,
goto error;
INIT_LIST_HEAD(&tp->list);
+ INIT_LIST_HEAD(&tp->files);
return tp;
error:
kfree(tp->call.name);
@@ -183,25 +189,6 @@ static struct trace_probe *find_trace_probe(const char *event,
return NULL;
}
-static int trace_probe_nr_files(struct trace_probe *tp)
-{
- struct ftrace_event_file **file;
- int ret = 0;
-
- /*
- * Since all tp->files updater is protected by probe_enable_lock,
- * we don't need to lock an rcu_read_lock.
- */
- file = rcu_dereference_raw(tp->files);
- if (file)
- while (*(file++))
- ret++;
-
- return ret;
-}
-
-static DEFINE_MUTEX(probe_enable_lock);
-
/*
* Enable trace_probe
* if the file is NULL, enable "perf" handler, or enable "trace" handler.
@@ -211,67 +198,42 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
int ret = 0;
- mutex_lock(&probe_enable_lock);
-
if (file) {
- struct ftrace_event_file **new, **old;
- int n = trace_probe_nr_files(tp);
-
- old = rcu_dereference_raw(tp->files);
- /* 1 is for new one and 1 is for stopper */
- new = kzalloc((n + 2) * sizeof(struct ftrace_event_file *),
- GFP_KERNEL);
- if (!new) {
+ struct event_file_link *link;
+
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (!link) {
ret = -ENOMEM;
- goto out_unlock;
+ goto out;
}
- memcpy(new, old, n * sizeof(struct ftrace_event_file *));
- new[n] = file;
- /* The last one keeps a NULL */
- rcu_assign_pointer(tp->files, new);
- tp->flags |= TP_FLAG_TRACE;
+ link->file = file;
+ list_add_tail_rcu(&link->list, &tp->files);
- if (old) {
- /* Make sure the probe is done with old files */
- synchronize_sched();
- kfree(old);
- }
+ tp->flags |= TP_FLAG_TRACE;
} else
tp->flags |= TP_FLAG_PROFILE;
- if (trace_probe_is_enabled(tp) && trace_probe_is_registered(tp) &&
- !trace_probe_has_gone(tp)) {
+ if (trace_probe_is_registered(tp) && !trace_probe_has_gone(tp)) {
if (trace_probe_is_return(tp))
ret = enable_kretprobe(&tp->rp);
else
ret = enable_kprobe(&tp->rp.kp);
}
-
- out_unlock:
- mutex_unlock(&probe_enable_lock);
-
+ out:
return ret;
}
-static int
-trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
+static struct event_file_link *
+find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
{
- struct ftrace_event_file **files;
- int i;
+ struct event_file_link *link;
- /*
- * Since all tp->files updater is protected by probe_enable_lock,
- * we don't need to lock an rcu_read_lock.
- */
- files = rcu_dereference_raw(tp->files);
- if (files) {
- for (i = 0; files[i]; i++)
- if (files[i] == file)
- return i;
- }
+ list_for_each_entry(link, &tp->files, list)
+ if (link->file == file)
+ return link;
- return -1;
+ return NULL;
}
/*
@@ -281,43 +243,23 @@ trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
static int
disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
+ struct event_file_link *link = NULL;
+ int wait = 0;
int ret = 0;
- mutex_lock(&probe_enable_lock);
-
if (file) {
- struct ftrace_event_file **new, **old;
- int n = trace_probe_nr_files(tp);
- int i, j;
-
- old = rcu_dereference_raw(tp->files);
- if (n == 0 || trace_probe_file_index(tp, file) < 0) {
+ link = find_event_file_link(tp, file);
+ if (!link) {
ret = -EINVAL;
- goto out_unlock;
+ goto out;
}
- if (n == 1) { /* Remove the last file */
- tp->flags &= ~TP_FLAG_TRACE;
- new = NULL;
- } else {
- new = kzalloc(n * sizeof(struct ftrace_event_file *),
- GFP_KERNEL);
- if (!new) {
- ret = -ENOMEM;
- goto out_unlock;
- }
-
- /* This copy & check loop copies the NULL stopper too */
- for (i = 0, j = 0; j < n && i < n + 1; i++)
- if (old[i] != file)
- new[j++] = old[i];
- }
-
- rcu_assign_pointer(tp->files, new);
+ list_del_rcu(&link->list);
+ wait = 1;
+ if (!list_empty(&tp->files))
+ goto out;
- /* Make sure the probe is done with old files */
- synchronize_sched();
- kfree(old);
+ tp->flags &= ~TP_FLAG_TRACE;
} else
tp->flags &= ~TP_FLAG_PROFILE;
@@ -326,10 +268,21 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
+ wait = 1;
+ }
+ out:
+ if (wait) {
+ /*
+ * Synchronize with kprobe_trace_func/kretprobe_trace_func
+ * to ensure disabled (all running handlers are finished).
+ * This is not only for kfree(), but also the caller,
+ * trace_remove_event_call() supposes it for releasing
+ * event_call related objects, which will be accessed in
+ * the kprobe_trace_func/kretprobe_trace_func.
+ */
+ synchronize_sched();
+ kfree(link); /* Ignored if link == NULL */
}
-
- out_unlock:
- mutex_unlock(&probe_enable_lock);
return ret;
}
@@ -398,9 +351,12 @@ static int unregister_trace_probe(struct trace_probe *tp)
if (trace_probe_is_enabled(tp))
return -EBUSY;
+ /* Will fail if probe is being used by ftrace or perf */
+ if (unregister_probe_event(tp))
+ return -EBUSY;
+
__unregister_trace_probe(tp);
list_del(&tp->list);
- unregister_probe_event(tp);
return 0;
}
@@ -679,7 +635,9 @@ static int release_all_trace_probes(void)
/* TODO: Use batch unregistration */
while (!list_empty(&probe_list)) {
tp = list_entry(probe_list.next, struct trace_probe, list);
- unregister_trace_probe(tp);
+ ret = unregister_trace_probe(tp);
+ if (ret)
+ goto end;
free_trace_probe(tp);
}
@@ -885,20 +843,10 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
static __kprobes void
kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
{
- /*
- * Note: preempt is already disabled around the kprobe handler.
- * However, we still need an smp_read_barrier_depends() corresponding
- * to smp_wmb() in rcu_assign_pointer() to access the pointer.
- */
- struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
-
- if (unlikely(!file))
- return;
+ struct event_file_link *link;
- while (*file) {
- __kprobe_trace_func(tp, regs, *file);
- file++;
- }
+ list_for_each_entry_rcu(link, &tp->files, list)
+ __kprobe_trace_func(tp, regs, link->file);
}
/* Kretprobe handler */
@@ -945,20 +893,10 @@ static __kprobes void
kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
- /*
- * Note: preempt is already disabled around the kprobe handler.
- * However, we still need an smp_read_barrier_depends() corresponding
- * to smp_wmb() in rcu_assign_pointer() to access the pointer.
- */
- struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
-
- if (unlikely(!file))
- return;
+ struct event_file_link *link;
- while (*file) {
- __kretprobe_trace_func(tp, ri, regs, *file);
- file++;
- }
+ list_for_each_entry_rcu(link, &tp->files, list)
+ __kretprobe_trace_func(tp, ri, regs, link->file);
}
/* Event entry printers */
@@ -1157,13 +1095,14 @@ kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
int size, __size, dsize;
int rctx;
+ head = this_cpu_ptr(call->perf_events);
+ if (hlist_empty(head))
+ return;
+
dsize = __get_data_size(tp, regs);
__size = sizeof(*entry) + tp->size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
- if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
- "profile buffer not large enough"))
- return;
entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
if (!entry)
@@ -1172,10 +1111,7 @@ kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
entry->ip = (unsigned long)tp->rp.kp.addr;
memset(&entry[1], 0, dsize);
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
-
- head = this_cpu_ptr(call->perf_events);
- perf_trace_buf_submit(entry, size, rctx,
- entry->ip, 1, regs, head, NULL);
+ perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
}
/* Kretprobe profile handler */
@@ -1189,13 +1125,14 @@ kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
int size, __size, dsize;
int rctx;
+ head = this_cpu_ptr(call->perf_events);
+ if (hlist_empty(head))
+ return;
+
dsize = __get_data_size(tp, regs);
__size = sizeof(*entry) + tp->size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
- if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
- "profile buffer not large enough"))
- return;
entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
if (!entry)
@@ -1204,13 +1141,16 @@ kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
-
- head = this_cpu_ptr(call->perf_events);
- perf_trace_buf_submit(entry, size, rctx,
- entry->ret_ip, 1, regs, head, NULL);
+ perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
}
#endif /* CONFIG_PERF_EVENTS */
+/*
+ * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
+ *
+ * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
+ * lockless, but we can't race with this __init function.
+ */
static __kprobes
int kprobe_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
@@ -1312,11 +1252,15 @@ static int register_probe_event(struct trace_probe *tp)
return ret;
}
-static void unregister_probe_event(struct trace_probe *tp)
+static int unregister_probe_event(struct trace_probe *tp)
{
+ int ret;
+
/* tp->event is unregistered in trace_remove_event_call() */
- trace_remove_event_call(&tp->call);
- kfree(tp->call.print_fmt);
+ ret = trace_remove_event_call(&tp->call);
+ if (!ret)
+ kfree(tp->call.print_fmt);
+ return ret;
}
/* Make a debugfs interface for controlling probe points */
@@ -1376,6 +1320,10 @@ find_trace_probe_file(struct trace_probe *tp, struct trace_array *tr)
return NULL;
}
+/*
+ * Nobody but us can call enable_trace_probe/disable_trace_probe at this
+ * stage, we can do this lockless.
+ */
static __init int kprobe_trace_self_tests_init(void)
{
int ret, warn = 0;