7 files changed, 53 insertions, 77 deletions

diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index 19edcd526ba4..68fe10250486 100644
--- a/arch/i386/kernel/kprobes.c
+++ b/arch/i386/kernel/kprobes.c
@@ -58,13 +58,9 @@ static inline int is_IF_modifier(kprobe_opcode_t opcode)
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
-        return 0;
-}
-
-void __kprobes arch_copy_kprobe(struct kprobe *p)
-{
         memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
         p->opcode = *p->addr;
+        return 0;
 }
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 5368f9c2e6bf..331e169e8629 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -60,13 +60,13 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
                 if (!p->ainsn.insn)
                         ret = -ENOMEM;
         }
-        return ret;
-}
 
-void __kprobes arch_copy_kprobe(struct kprobe *p)
-{
-        memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
-        p->opcode = *p->addr;
+        if (!ret) {
+                memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+                p->opcode = *p->addr;
+        }
+
+        return ret;
 }
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
@@ -85,9 +85,7 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-        down(&kprobe_mutex);
         free_insn_slot(p->ainsn.insn);
-        up(&kprobe_mutex);
 }
 
 static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c
index a97b0f0727ab..bbd5aa6818ea 100644
--- a/arch/sparc64/kernel/kprobes.c
+++ b/arch/sparc64/kernel/kprobes.c
@@ -43,14 +43,10 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
-        return 0;
-}
-
-void __kprobes arch_copy_kprobe(struct kprobe *p)
-{
         p->ainsn.insn[0] = *p->addr;
         p->ainsn.insn[1] = BREAKPOINT_INSTRUCTION_2;
         p->opcode = *p->addr;
+        return 0;
 }
 
 void __kprobes arch_arm_kprobe(struct kprobe *p)
diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index afe11f4fbd1d..8b8943bfb89e 100644
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -42,8 +42,8 @@
 #include <asm/pgtable.h>
 #include <asm/kdebug.h>
 
-static DECLARE_MUTEX(kprobe_mutex);
 void jprobe_return_end(void);
+void __kprobes arch_copy_kprobe(struct kprobe *p);
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
 DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
@@ -69,12 +69,11 @@ static inline int is_IF_modifier(kprobe_opcode_t *insn)
 int __kprobes arch_prepare_kprobe(struct kprobe *p)
 {
         /* insn: must be on special executable page on x86_64. */
-        down(&kprobe_mutex);
         p->ainsn.insn = get_insn_slot();
-        up(&kprobe_mutex);
         if (!p->ainsn.insn) {
                 return -ENOMEM;
         }
+        arch_copy_kprobe(p);
         return 0;
 }
 
@@ -223,9 +222,7 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
-        down(&kprobe_mutex);
         free_insn_slot(p->ainsn.insn);
-        up(&kprobe_mutex);
 }
 
 static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
diff --git a/include/asm-ia64/kprobes.h b/include/asm-ia64/kprobes.h
index 5b26462674a7..12a0b93020da 100644
--- a/include/asm-ia64/kprobes.h
+++ b/include/asm-ia64/kprobes.h
@@ -110,11 +110,6 @@ struct arch_specific_insn {
         unsigned short target_br_reg;
 };
 
-/* ia64 does not need this */
-static inline void arch_copy_kprobe(struct kprobe *p)
-{
-}
-
 extern int kprobe_exceptions_notify(struct notifier_block *self,
                                     unsigned long val, void *data);
 
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index c03f2dc933de..ad6e4fe970fd 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -150,7 +150,6 @@ struct kretprobe_instance {
 
 extern spinlock_t kretprobe_lock;
 extern int arch_prepare_kprobe(struct kprobe *p);
-extern void arch_copy_kprobe(struct kprobe *p);
 extern void arch_arm_kprobe(struct kprobe *p);
 extern void arch_disarm_kprobe(struct kprobe *p);
 extern void arch_remove_kprobe(struct kprobe *p);
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3897630d2335..f14ccd35e9b6 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -48,7 +48,7 @@
 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
 
-static DEFINE_SPINLOCK(kprobe_lock);    /* Protects kprobe_table */
+static DECLARE_MUTEX(kprobe_mutex);     /* Protects kprobe_table */
 DEFINE_SPINLOCK(kretprobe_lock);        /* Protects kretprobe_inst_table */
 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
 
@@ -167,7 +167,7 @@ static inline void reset_kprobe_instance(void)
 
 /*
  * This routine is called either:
- *      - under the kprobe_lock spinlock - during kprobe_[un]register()
+ *      - under the kprobe_mutex - during kprobe_[un]register()
  *                              OR
  *      - with preemption disabled - from arch/xxx/kernel/kprobes.c
  */
@@ -420,7 +420,6 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 /*
  * This is the second or subsequent kprobe at the address - handle
  * the intricacies
- * TODO: Move kcalloc outside the spin_lock
  */
 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
                                           struct kprobe *p)
@@ -442,25 +441,6 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
         return ret;
 }
 
-/* kprobe removal house-keeping routines */
-static inline void cleanup_kprobe(struct kprobe *p, unsigned long flags)
-{
-        arch_disarm_kprobe(p);
-        hlist_del_rcu(&p->hlist);
-        spin_unlock_irqrestore(&kprobe_lock, flags);
-        arch_remove_kprobe(p);
-}
-
-static inline void cleanup_aggr_kprobe(struct kprobe *old_p,
-                struct kprobe *p, unsigned long flags)
-{
-        list_del_rcu(&p->list);
-        if (list_empty(&old_p->list))
-                cleanup_kprobe(old_p, flags);
-        else
-                spin_unlock_irqrestore(&kprobe_lock, flags);
-}
-
 static int __kprobes in_kprobes_functions(unsigned long addr)
 {
         if (addr >= (unsigned long)__kprobes_text_start
@@ -472,7 +452,6 @@ static int __kprobes in_kprobes_functions(unsigned long addr)
 int __kprobes register_kprobe(struct kprobe *p)
 {
         int ret = 0;
-        unsigned long flags = 0;
         struct kprobe *old_p;
         struct module *mod;
 
@@ -484,18 +463,17 @@ int __kprobes register_kprobe(struct kprobe *p)
                         (unlikely(!try_module_get(mod))))
                 return -EINVAL;
 
-        if ((ret = arch_prepare_kprobe(p)) != 0)
-                goto rm_kprobe;
-
         p->nmissed = 0;
-        spin_lock_irqsave(&kprobe_lock, flags);
+        down(&kprobe_mutex);
         old_p = get_kprobe(p->addr);
         if (old_p) {
                 ret = register_aggr_kprobe(old_p, p);
                 goto out;
         }
 
-        arch_copy_kprobe(p);
+        if ((ret = arch_prepare_kprobe(p)) != 0)
+                goto out;
+
         INIT_HLIST_NODE(&p->hlist);
         hlist_add_head_rcu(&p->hlist,
                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
@@ -503,10 +481,8 @@ int __kprobes register_kprobe(struct kprobe *p)
         arch_arm_kprobe(p);
 
 out:
-        spin_unlock_irqrestore(&kprobe_lock, flags);
-rm_kprobe:
-        if (ret == -EEXIST)
-                arch_remove_kprobe(p);
+        up(&kprobe_mutex);
+
         if (ret && mod)
                 module_put(mod);
         return ret;
@@ -514,29 +490,48 @@ rm_kprobe:
 
 void __kprobes unregister_kprobe(struct kprobe *p)
 {
-        unsigned long flags;
-        struct kprobe *old_p;
         struct module *mod;
+        struct kprobe *old_p, *cleanup_p;
 
-        spin_lock_irqsave(&kprobe_lock, flags);
+        down(&kprobe_mutex);
         old_p = get_kprobe(p->addr);
-        if (old_p) {
-                /* cleanup_*_kprobe() does the spin_unlock_irqrestore */
-                if (old_p->pre_handler == aggr_pre_handler)
-                        cleanup_aggr_kprobe(old_p, p, flags);
-                else
-                        cleanup_kprobe(p, flags);
+        if (unlikely(!old_p)) {
+                up(&kprobe_mutex);
+                return;
+        }
 
-                synchronize_sched();
+        if ((old_p->pre_handler == aggr_pre_handler) &&
+                (p->list.next == &old_p->list) &&
+                (p->list.prev == &old_p->list)) {
+                /* Only one element in the aggregate list */
+                arch_disarm_kprobe(p);
+                hlist_del_rcu(&old_p->hlist);
+                cleanup_p = old_p;
+        } else if (old_p == p) {
+                /* Only one kprobe element in the hash list */
+                arch_disarm_kprobe(p);
+                hlist_del_rcu(&p->hlist);
+                cleanup_p = p;
+        } else {
+                list_del_rcu(&p->list);
+                cleanup_p = NULL;
+        }
 
-                if ((mod = module_text_address((unsigned long)p->addr)))
-                        module_put(mod);
+        up(&kprobe_mutex);
 
-                if (old_p->pre_handler == aggr_pre_handler &&
-                                list_empty(&old_p->list))
+        synchronize_sched();
+        if ((mod = module_text_address((unsigned long)p->addr)))
+                module_put(mod);
+
+        if (cleanup_p) {
+                if (cleanup_p->pre_handler == aggr_pre_handler) {
+                        list_del_rcu(&p->list);
                         kfree(old_p);
-        } else
-                spin_unlock_irqrestore(&kprobe_lock, flags);
+                }
+                down(&kprobe_mutex);
+                arch_remove_kprobe(p);
+                up(&kprobe_mutex);
+        }
 }
 
 static struct notifier_block kprobe_exceptions_nb = {