1 files changed, 89 insertions, 38 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 1485ca8d0e00..cb0b3bde3617 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -62,6 +62,7 @@
         addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
 #endif
 
+static int kprobes_initialized;
 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
 
@@ -69,8 +70,15 @@ static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
 static bool kprobe_enabled;
 
 DEFINE_MUTEX(kprobe_mutex);             /* Protects kprobe_table */
-DEFINE_SPINLOCK(kretprobe_lock);        /* Protects kretprobe_inst_table */
 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
+static struct {
+        spinlock_t lock ____cacheline_aligned;
+} kretprobe_table_locks[KPROBE_TABLE_SIZE];
+
+static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
+{
+        return &(kretprobe_table_locks[hash].lock);
+}
 
 /*
  * Normally, functions that we'd want to prohibit kprobes in, are marked
@@ -368,26 +376,53 @@ void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
         return;
 }
 
-/* Called with kretprobe_lock held */
 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
                                 struct hlist_head *head)
 {
+        struct kretprobe *rp = ri->rp;
+
         /* remove rp inst off the rprobe_inst_table */
         hlist_del(&ri->hlist);
-        if (ri->rp) {
-                /* remove rp inst off the used list */
-                hlist_del(&ri->uflist);
-                /* put rp inst back onto the free list */
-                INIT_HLIST_NODE(&ri->uflist);
-                hlist_add_head(&ri->uflist, &ri->rp->free_instances);
+        INIT_HLIST_NODE(&ri->hlist);
+        if (likely(rp)) {
+                spin_lock(&rp->lock);
+                hlist_add_head(&ri->hlist, &rp->free_instances);
+                spin_unlock(&rp->lock);
         } else
                 /* Unregistering */
                 hlist_add_head(&ri->hlist, head);
 }
 
-struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
+void kretprobe_hash_lock(struct task_struct *tsk,
+                         struct hlist_head **head, unsigned long *flags)
+{
+        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
+        spinlock_t *hlist_lock;
+
+        *head = &kretprobe_inst_table[hash];
+        hlist_lock = kretprobe_table_lock_ptr(hash);
+        spin_lock_irqsave(hlist_lock, *flags);
+}
+
+void kretprobe_table_lock(unsigned long hash, unsigned long *flags)
 {
-        return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
+        spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
+        spin_lock_irqsave(hlist_lock, *flags);
+}
+
+void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags)
+{
+        unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
+        spinlock_t *hlist_lock;
+
+        hlist_lock = kretprobe_table_lock_ptr(hash);
+        spin_unlock_irqrestore(hlist_lock, *flags);
+}
+
+void kretprobe_table_unlock(unsigned long hash, unsigned long *flags)
+{
+        spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
+        spin_unlock_irqrestore(hlist_lock, *flags);
 }
 
 /*
@@ -401,17 +436,21 @@ void __kprobes kprobe_flush_task(struct task_struct *tk)
         struct kretprobe_instance *ri;
         struct hlist_head *head, empty_rp;
         struct hlist_node *node, *tmp;
-        unsigned long flags = 0;
+        unsigned long hash, flags = 0;
 
-        INIT_HLIST_HEAD(&empty_rp);
-        spin_lock_irqsave(&kretprobe_lock, flags);
-        head = kretprobe_inst_table_head(tk);
+        if (unlikely(!kprobes_initialized))
+                /* Early boot.  kretprobe_table_locks not yet initialized. */
+                return;
+
+        hash = hash_ptr(tk, KPROBE_HASH_BITS);
+        head = &kretprobe_inst_table[hash];
+        kretprobe_table_lock(hash, &flags);
         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
                 if (ri->task == tk)
                         recycle_rp_inst(ri, &empty_rp);
         }
-        spin_unlock_irqrestore(&kretprobe_lock, flags);
-
+        kretprobe_table_unlock(hash, &flags);
+        INIT_HLIST_HEAD(&empty_rp);
         hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
                 hlist_del(&ri->hlist);
                 kfree(ri);
@@ -423,24 +462,29 @@ static inline void free_rp_inst(struct kretprobe *rp)
         struct kretprobe_instance *ri;
         struct hlist_node *pos, *next;
 
-        hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) {
-                hlist_del(&ri->uflist);
+        hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, hlist) {
+                hlist_del(&ri->hlist);
                 kfree(ri);
         }
 }
 
 static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
 {
-        unsigned long flags;
+        unsigned long flags, hash;
         struct kretprobe_instance *ri;
         struct hlist_node *pos, *next;
+        struct hlist_head *head;
+
         /* No race here */
-        spin_lock_irqsave(&kretprobe_lock, flags);
-        hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) {
-                ri->rp = NULL;
-                hlist_del(&ri->uflist);
+        for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
+                kretprobe_table_lock(hash, &flags);
+                head = &kretprobe_inst_table[hash];
+                hlist_for_each_entry_safe(ri, pos, next, head, hlist) {
+                        if (ri->rp == rp)
+                                ri->rp = NULL;
+                }
+                kretprobe_table_unlock(hash, &flags);
         }
-        spin_unlock_irqrestore(&kretprobe_lock, flags);
         free_rp_inst(rp);
 }
 
@@ -831,32 +875,37 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
                                            struct pt_regs *regs)
 {
         struct kretprobe *rp = container_of(p, struct kretprobe, kp);
-        unsigned long flags = 0;
+        unsigned long hash, flags = 0;
+        struct kretprobe_instance *ri;
 
         /*TODO: consider to only swap the RA after the last pre_handler fired */
-        spin_lock_irqsave(&kretprobe_lock, flags);
+        hash = hash_ptr(current, KPROBE_HASH_BITS);
+        spin_lock_irqsave(&rp->lock, flags);
         if (!hlist_empty(&rp->free_instances)) {
-                struct kretprobe_instance *ri;
-
                 ri = hlist_entry(rp->free_instances.first,
-                                 struct kretprobe_instance, uflist);
+                                struct kretprobe_instance, hlist);
+                hlist_del(&ri->hlist);
+                spin_unlock_irqrestore(&rp->lock, flags);
+
                 ri->rp = rp;
                 ri->task = current;
 
                 if (rp->entry_handler && rp->entry_handler(ri, regs)) {
-                        spin_unlock_irqrestore(&kretprobe_lock, flags);
+                        spin_unlock_irqrestore(&rp->lock, flags);
                         return 0;
                 }
 
                 arch_prepare_kretprobe(ri, regs);
 
                 /* XXX(hch): why is there no hlist_move_head? */
-                hlist_del(&ri->uflist);
-                hlist_add_head(&ri->uflist, &ri->rp->used_instances);
-                hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task));
-        } else
+                INIT_HLIST_NODE(&ri->hlist);
+                kretprobe_table_lock(hash, &flags);
+                hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
+                kretprobe_table_unlock(hash, &flags);
+        } else {
                 rp->nmissed++;
-        spin_unlock_irqrestore(&kretprobe_lock, flags);
+                spin_unlock_irqrestore(&rp->lock, flags);
+        }
         return 0;
 }
 
@@ -892,7 +941,7 @@ static int __kprobes __register_kretprobe(struct kretprobe *rp,
                 rp->maxactive = NR_CPUS;
 #endif
         }
-        INIT_HLIST_HEAD(&rp->used_instances);
+        spin_lock_init(&rp->lock);
         INIT_HLIST_HEAD(&rp->free_instances);
         for (i = 0; i < rp->maxactive; i++) {
                 inst = kmalloc(sizeof(struct kretprobe_instance) +
@@ -901,8 +950,8 @@ static int __kprobes __register_kretprobe(struct kretprobe *rp,
                         free_rp_inst(rp);
                         return -ENOMEM;
                 }
-                INIT_HLIST_NODE(&inst->uflist);
-                hlist_add_head(&inst->uflist, &rp->free_instances);
+                INIT_HLIST_NODE(&inst->hlist);
+                hlist_add_head(&inst->hlist, &rp->free_instances);
         }
 
         rp->nmissed = 0;
@@ -1009,6 +1058,7 @@ static int __init init_kprobes(void)
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 INIT_HLIST_HEAD(&kprobe_table[i]);
                 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
+                spin_lock_init(&(kretprobe_table_locks[i].lock));
         }
 
         /*
@@ -1050,6 +1100,7 @@ static int __init init_kprobes(void)
         err = arch_init_kprobes();
         if (!err)
                 err = register_die_notifier(&kprobe_exceptions_nb);
+        kprobes_initialized = (err == 0);
 
         if (!err)
                 init_test_probes();