1 files changed, 6 insertions, 19 deletions

diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c
index 6cb40d1..9bef2c8 100644
--- a/arch/x86_64/kernel/kprobes.c
+++ b/arch/x86_64/kernel/kprobes.c
@@ -34,7 +34,6 @@
 #include <linux/config.h>
 #include <linux/kprobes.h>
 #include <linux/ptrace.h>
-#include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/slab.h>
 #include <linux/preempt.h>
@@ -266,6 +265,7 @@ static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
 		regs->rip = (unsigned long)p->ainsn.insn;
 }
 
+/* Called with kretprobe_lock held */
 void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
 				      struct pt_regs *regs)
 {
@@ -299,15 +299,12 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 
 	/* Check we're not actually recursing */
 	if (kprobe_running()) {
-		/* We *are* holding lock here, so this is safe.
-		   Disarm the probe we just hit, and ignore it. */
 		p = get_kprobe(addr);
 		if (p) {
 			if (kcb->kprobe_status == KPROBE_HIT_SS &&
 				*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
 				regs->eflags &= ~TF_MASK;
 				regs->eflags |= kcb->kprobe_saved_rflags;
-				unlock_kprobes();
 				goto no_kprobe;
 			} else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) {
 				/* TODO: Provide re-entrancy from
@@ -340,14 +337,11 @@ int __kprobes kprobe_handler(struct pt_regs *regs)
 				goto ss_probe;
 			}
 		}
-		/* If it's not ours, can't be delete race, (we hold lock). */
 		goto no_kprobe;
 	}
 
-	lock_kprobes();
 	p = get_kprobe(addr);
 	if (!p) {
-		unlock_kprobes();
 		if (*addr != BREAKPOINT_INSTRUCTION) {
 			/*
 			 * The breakpoint instruction was removed right
@@ -406,9 +400,10 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
         struct kretprobe_instance *ri = NULL;
         struct hlist_head *head;
         struct hlist_node *node, *tmp;
-	unsigned long orig_ret_address = 0;
+	unsigned long flags, orig_ret_address = 0;
 	unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
 
+	spin_lock_irqsave(&kretprobe_lock, flags);
         head = kretprobe_inst_table_head(current);
 
 	/*
@@ -448,7 +443,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 	regs->rip = orig_ret_address;
 
 	reset_current_kprobe();
-	unlock_kprobes();
+	spin_unlock_irqrestore(&kretprobe_lock, flags);
 	preempt_enable_no_resched();
 
         /*
@@ -536,10 +531,6 @@ static void __kprobes resume_execution(struct kprobe *p,
 	}
 }
 
-/*
- * Interrupts are disabled on entry as trap1 is an interrupt gate and they
- * remain disabled thoroughout this function.  And we hold kprobe lock.
- */
 int __kprobes post_kprobe_handler(struct pt_regs *regs)
 {
 	struct kprobe *cur = kprobe_running();
@@ -560,8 +551,6 @@ int __kprobes post_kprobe_handler(struct pt_regs *regs)
 	if (kcb->kprobe_status == KPROBE_REENTER) {
 		restore_previous_kprobe(kcb);
 		goto out;
-	} else {
-		unlock_kprobes();
 	}
 	reset_current_kprobe();
 out:
@@ -578,7 +567,6 @@ out:
 	return 1;
 }
 
-/* Interrupts disabled, kprobe_lock held. */
 int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 {
 	struct kprobe *cur = kprobe_running();
@@ -592,7 +580,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
 		regs->eflags |= kcb->kprobe_old_rflags;
 
 		reset_current_kprobe();
-		unlock_kprobes();
 		preempt_enable_no_resched();
 	}
 	return 0;
@@ -607,7 +594,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 	struct die_args *args = (struct die_args *)data;
 	int ret = NOTIFY_DONE;
 
-	preempt_disable();
+	rcu_read_lock();
 	switch (val) {
 	case DIE_INT3:
 		if (kprobe_handler(args->regs))
@@ -626,7 +613,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 	default:
 		break;
 	}
-	preempt_enable();
+	rcu_read_unlock();
 	return ret;
 }