Merge tag 'perf-kprobes-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf/kprobes updates from Ingo Molnar:
 "This prepares to unify the kretprobe trampoline handler and make
  kretprobe lockless (those patches are still work in progress)"

* tag 'perf-kprobes-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  kprobes: Fix to check probe enabled before disarm_kprobe_ftrace()
  kprobes: Make local functions static
  kprobes: Free kretprobe_instance with RCU callback
  kprobes: Remove NMI context check
  sparc: kprobes: Use generic kretprobe trampoline handler
  sh: kprobes: Use generic kretprobe trampoline handler
  s390: kprobes: Use generic kretprobe trampoline handler
  powerpc: kprobes: Use generic kretprobe trampoline handler
  parisc: kprobes: Use generic kretprobe trampoline handler
  mips: kprobes: Use generic kretprobe trampoline handler
  ia64: kprobes: Use generic kretprobe trampoline handler
  csky: kprobes: Use generic kretprobe trampoline handler
  arc: kprobes: Use generic kretprobe trampoline handler
  arm64: kprobes: Use generic kretprobe trampoline handler
  arm: kprobes: Use generic kretprobe trampoline handler
  x86/kprobes: Use generic kretprobe trampoline handler
  kprobes: Add generic kretprobe trampoline handler

1 files changed, 31 insertions, 20 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 8aab327b5539..629abaf25681 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -156,7 +156,10 @@ struct kretprobe {
 };
 
 struct kretprobe_instance {
-	struct hlist_node hlist;
+	union {
+		struct hlist_node hlist;
+		struct rcu_head rcu;
+	};
 	struct kretprobe *rp;
 	kprobe_opcode_t *ret_addr;
 	struct task_struct *task;
@@ -187,10 +190,37 @@ static inline int kprobes_built_in(void)
 	return 1;
 }
 
+extern void kprobe_busy_begin(void);
+extern void kprobe_busy_end(void);
+
 #ifdef CONFIG_KRETPROBES
 extern void arch_prepare_kretprobe(struct kretprobe_instance *ri,
 				   struct pt_regs *regs);
 extern int arch_trampoline_kprobe(struct kprobe *p);
+
+/* If the trampoline handler called from a kprobe, use this version */
+unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
+				void *trampoline_address,
+				void *frame_pointer);
+
+static nokprobe_inline
+unsigned long kretprobe_trampoline_handler(struct pt_regs *regs,
+				void *trampoline_address,
+				void *frame_pointer)
+{
+	unsigned long ret;
+	/*
+	 * Set a dummy kprobe for avoiding kretprobe recursion.
+	 * Since kretprobe never runs in kprobe handler, no kprobe must
+	 * be running at this point.
+	 */
+	kprobe_busy_begin();
+	ret = __kretprobe_trampoline_handler(regs, trampoline_address, frame_pointer);
+	kprobe_busy_end();
+
+	return ret;
+}
+
 #else /* CONFIG_KRETPROBES */
 static inline void arch_prepare_kretprobe(struct kretprobe *rp,
 					struct pt_regs *regs)
@@ -204,16 +234,6 @@ static inline int arch_trampoline_kprobe(struct kprobe *p)
 
 extern struct kretprobe_blackpoint kretprobe_blacklist[];
 
-static inline void kretprobe_assert(struct kretprobe_instance *ri,
-	unsigned long orig_ret_address, unsigned long trampoline_address)
-{
-	if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
-		printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
-				ri->rp, ri->rp->kp.addr);
-		BUG();
-	}
-}
-
 #ifdef CONFIG_KPROBES_SANITY_TEST
 extern int init_test_probes(void);
 #else
@@ -333,10 +353,6 @@ int arch_check_ftrace_location(struct kprobe *p);
 
 /* Get the kprobe at this addr (if any) - called with preemption disabled */
 struct kprobe *get_kprobe(void *addr);
-void kretprobe_hash_lock(struct task_struct *tsk,
-			 struct hlist_head **head, unsigned long *flags);
-void kretprobe_hash_unlock(struct task_struct *tsk, unsigned long *flags);
-struct hlist_head * kretprobe_inst_table_head(struct task_struct *tsk);
 
 /* kprobe_running() will just return the current_kprobe on this CPU */
 static inline struct kprobe *kprobe_running(void)
@@ -354,10 +370,6 @@ static inline struct kprobe_ctlblk *get_kprobe_ctlblk(void)
 	return this_cpu_ptr(&kprobe_ctlblk);
 }
 
-extern struct kprobe kprobe_busy;
-void kprobe_busy_begin(void);
-void kprobe_busy_end(void);
-
 kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset);
 int register_kprobe(struct kprobe *p);
 void unregister_kprobe(struct kprobe *p);
@@ -371,7 +383,6 @@ int register_kretprobes(struct kretprobe **rps, int num);
 void unregister_kretprobes(struct kretprobe **rps, int num);
 
 void kprobe_flush_task(struct task_struct *tk);
-void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
 
 void kprobe_free_init_mem(void);