Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git

Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 79 insertions, 58 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 3bb71e63a37e..3ea6325228da 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -48,10 +48,11 @@
 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 */
+DECLARE_MUTEX(kprobe_mutex);            /* Protects kprobe_table */
 DEFINE_SPINLOCK(kretprobe_lock);        /* Protects kretprobe_inst_table */
 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
 
+#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 /*
  * kprobe->ainsn.insn points to the copy of the instruction to be
  * single-stepped. x86_64, POWER4 and above have no-exec support and
@@ -151,6 +152,7 @@ void __kprobes free_insn_slot(kprobe_opcode_t *slot)
                 }
         }
 }
+#endif
 
 /* We have preemption disabled.. so it is safe to use __ versions */
 static inline void set_kprobe_instance(struct kprobe *kp)
@@ -165,7 +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
  */
@@ -418,7 +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)
@@ -430,7 +431,7 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
                 copy_kprobe(old_p, p);
                 ret = add_new_kprobe(old_p, p);
         } else {
-                ap = kcalloc(1, sizeof(struct kprobe), GFP_ATOMIC);
+                ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
                 if (!ap)
                         return -ENOMEM;
                 add_aggr_kprobe(ap, old_p);
@@ -440,25 +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
@@ -467,33 +449,44 @@ static int __kprobes in_kprobes_functions(unsigned long addr)
         return 0;
 }
 
-int __kprobes register_kprobe(struct kprobe *p)
+static int __kprobes __register_kprobe(struct kprobe *p,
+        unsigned long called_from)
 {
         int ret = 0;
-        unsigned long flags = 0;
         struct kprobe *old_p;
-        struct module *mod;
+        struct module *probed_mod;
 
         if ((!kernel_text_address((unsigned long) p->addr)) ||
                 in_kprobes_functions((unsigned long) p->addr))
                 return -EINVAL;
 
-        if ((mod = module_text_address((unsigned long) p->addr)) &&
-                        (unlikely(!try_module_get(mod))))
-                return -EINVAL;
-
-        if ((ret = arch_prepare_kprobe(p)) != 0)
-                goto rm_kprobe;
+        p->mod_refcounted = 0;
+        /* Check are we probing a module */
+        if ((probed_mod = module_text_address((unsigned long) p->addr))) {
+                struct module *calling_mod = module_text_address(called_from);
+                /* We must allow modules to probe themself and
+                 * in this case avoid incrementing the module refcount,
+                 * so as to allow unloading of self probing modules.
+                 */
+                if (calling_mod && (calling_mod != probed_mod)) {
+                        if (unlikely(!try_module_get(probed_mod)))
+                                return -EINVAL;
+                        p->mod_refcounted = 1;
+                } else
+                        probed_mod = NULL;
+        }
 
         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)]);
@@ -501,40 +494,66 @@ 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);
-        if (ret && mod)
-                module_put(mod);
+        up(&kprobe_mutex);
+
+        if (ret && probed_mod)
+                module_put(probed_mod);
         return ret;
 }
 
+int __kprobes register_kprobe(struct kprobe *p)
+{
+        return __register_kprobe(p,
+                (unsigned long)__builtin_return_address(0));
+}
+
 void __kprobes unregister_kprobe(struct kprobe *p)
 {
-        unsigned long flags;
-        struct kprobe *old_p;
         struct module *mod;
+        struct kprobe *old_p, *list_p;
+        int 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;
+        }
+        if (p != old_p) {
+                list_for_each_entry_rcu(list_p, &old_p->list, list)
+                        if (list_p == p)
+                        /* kprobe p is a valid probe */
+                                goto valid_p;
+                up(&kprobe_mutex);
+                return;
+        }
+valid_p:
+        if ((old_p == p) || ((old_p->pre_handler == aggr_pre_handler) &&
+                (p->list.next == &old_p->list) &&
+                (p->list.prev == &old_p->list))) {
+                /* Only probe on the hash list */
+                arch_disarm_kprobe(p);
+                hlist_del_rcu(&old_p->hlist);
+                cleanup_p = 1;
+        } else {
+                list_del_rcu(&p->list);
+                cleanup_p = 0;
+        }
 
-                synchronize_sched();
+        up(&kprobe_mutex);
 
-                if ((mod = module_text_address((unsigned long)p->addr)))
-                        module_put(mod);
+        synchronize_sched();
+        if (p->mod_refcounted &&
+            (mod = module_text_address((unsigned long)p->addr)))
+                module_put(mod);
 
-                if (old_p->pre_handler == aggr_pre_handler &&
-                                list_empty(&old_p->list))
+        if (cleanup_p) {
+                if (p != old_p) {
+                        list_del_rcu(&p->list);
                         kfree(old_p);
-        } else
-                spin_unlock_irqrestore(&kprobe_lock, flags);
+                }
+                arch_remove_kprobe(p);
+        }
 }
 
 static struct notifier_block kprobe_exceptions_nb = {
@@ -548,7 +567,8 @@ int __kprobes register_jprobe(struct jprobe *jp)
         jp->kp.pre_handler = setjmp_pre_handler;
         jp->kp.break_handler = longjmp_break_handler;
 
-        return register_kprobe(&jp->kp);
+        return __register_kprobe(&jp->kp,
+                (unsigned long)__builtin_return_address(0));
 }
 
 void __kprobes unregister_jprobe(struct jprobe *jp)
@@ -588,7 +608,8 @@ int __kprobes register_kretprobe(struct kretprobe *rp)
 
         rp->nmissed = 0;
         /* Establish function entry probe point */
-        if ((ret = register_kprobe(&rp->kp)) != 0)
+        if ((ret = __register_kprobe(&rp->kp,
+                (unsigned long)__builtin_return_address(0))) != 0)
                 free_rp_inst(rp);
         return ret;
 }