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authorMasami Hiramatsu <mhiramat@kernel.org>2020-05-12 17:02:44 +0900
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-06-16 21:21:01 -0400
commit7e6a71d8e60187726e29b13d9e9b23b77026c17a (patch)
treebb464ab9c2c40fe45d4e877e3c50d984e31dc091 /kernel
parent6743ad432ec92e680cd0d9db86cb17b949cf5a43 (diff)
kprobes: Use non RCU traversal APIs on kprobe_tables if possible
Current kprobes uses RCU traversal APIs on kprobe_tables even if it is safe because kprobe_mutex is locked. Make those traversals to non-RCU APIs where the kprobe_mutex is locked. Link: http://lkml.kernel.org/r/158927056452.27680.9710575332163005121.stgit@devnote2 Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/kprobes.c29
1 files changed, 20 insertions, 9 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 8b2fd4145ab3..ceb0e273bd69 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -46,6 +46,11 @@
static int kprobes_initialized;
+/* kprobe_table can be accessed by
+ * - Normal hlist traversal and RCU add/del under kprobe_mutex is held.
+ * Or
+ * - RCU hlist traversal under disabling preempt (breakpoint handlers)
+ */
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
@@ -850,7 +855,7 @@ static void optimize_all_kprobes(void)
kprobes_allow_optimization = true;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
- hlist_for_each_entry_rcu(p, head, hlist)
+ hlist_for_each_entry(p, head, hlist)
if (!kprobe_disabled(p))
optimize_kprobe(p);
}
@@ -877,7 +882,7 @@ static void unoptimize_all_kprobes(void)
kprobes_allow_optimization = false;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
- hlist_for_each_entry_rcu(p, head, hlist) {
+ hlist_for_each_entry(p, head, hlist) {
if (!kprobe_disabled(p))
unoptimize_kprobe(p, false);
}
@@ -1500,12 +1505,14 @@ static struct kprobe *__get_valid_kprobe(struct kprobe *p)
{
struct kprobe *ap, *list_p;
+ lockdep_assert_held(&kprobe_mutex);
+
ap = get_kprobe(p->addr);
if (unlikely(!ap))
return NULL;
if (p != ap) {
- list_for_each_entry_rcu(list_p, &ap->list, list)
+ list_for_each_entry(list_p, &ap->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid;
@@ -1670,7 +1677,9 @@ static int aggr_kprobe_disabled(struct kprobe *ap)
{
struct kprobe *kp;
- list_for_each_entry_rcu(kp, &ap->list, list)
+ lockdep_assert_held(&kprobe_mutex);
+
+ list_for_each_entry(kp, &ap->list, list)
if (!kprobe_disabled(kp))
/*
* There is an active probe on the list.
@@ -1749,7 +1758,7 @@ static int __unregister_kprobe_top(struct kprobe *p)
else {
/* If disabling probe has special handlers, update aggrprobe */
if (p->post_handler && !kprobe_gone(p)) {
- list_for_each_entry_rcu(list_p, &ap->list, list) {
+ list_for_each_entry(list_p, &ap->list, list) {
if ((list_p != p) && (list_p->post_handler))
goto noclean;
}
@@ -2063,13 +2072,15 @@ static void kill_kprobe(struct kprobe *p)
{
struct kprobe *kp;
+ lockdep_assert_held(&kprobe_mutex);
+
p->flags |= KPROBE_FLAG_GONE;
if (kprobe_aggrprobe(p)) {
/*
* If this is an aggr_kprobe, we have to list all the
* chained probes and mark them GONE.
*/
- list_for_each_entry_rcu(kp, &p->list, list)
+ list_for_each_entry(kp, &p->list, list)
kp->flags |= KPROBE_FLAG_GONE;
p->post_handler = NULL;
kill_optimized_kprobe(p);
@@ -2313,7 +2324,7 @@ static int kprobes_module_callback(struct notifier_block *nb,
mutex_lock(&kprobe_mutex);
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
- hlist_for_each_entry_rcu(p, head, hlist)
+ hlist_for_each_entry(p, head, hlist)
if (within_module_init((unsigned long)p->addr, mod) ||
(checkcore &&
within_module_core((unsigned long)p->addr, mod))) {
@@ -2551,7 +2562,7 @@ static int arm_all_kprobes(void)
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
/* Arm all kprobes on a best-effort basis */
- hlist_for_each_entry_rcu(p, head, hlist) {
+ hlist_for_each_entry(p, head, hlist) {
if (!kprobe_disabled(p)) {
err = arm_kprobe(p);
if (err) {
@@ -2594,7 +2605,7 @@ static int disarm_all_kprobes(void)
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
/* Disarm all kprobes on a best-effort basis */
- hlist_for_each_entry_rcu(p, head, hlist) {
+ hlist_for_each_entry(p, head, hlist) {
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) {
err = disarm_kprobe(p, false);
if (err) {