Subject: [PATCH 3/4] kprobes: move kprobe_ftrace_handler() from x86 and make it weak

From: Jisheng Zhang <[email-masked]>
Date: Mon, 19 Aug 2019 11:37:32 +0000

This code could be reused. So move it from x86 to common code.

Signed-off-by: Jisheng Zhang <[email-masked]>
---
 arch/x86/kernel/kprobes/ftrace.c | 44 --------------------------------
 kernel/kprobes.c                 | 44 ++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 44 deletions(-)

diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c
index c2ad0b9259ca..91ae1e3e65f7 100644
--- a/arch/x86/kernel/kprobes/ftrace.c
+++ b/arch/x86/kernel/kprobes/ftrace.c
@@ -12,50 +12,6 @@
 
 #include "common.h"
 
-/* Ftrace callback handler for kprobes -- called under preepmt disabed */
-void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-			   struct ftrace_ops *ops, struct pt_regs *regs)
-{
-	struct kprobe *p;
-	struct kprobe_ctlblk *kcb;
-
-	/* Preempt is disabled by ftrace */
-	p = get_kprobe((kprobe_opcode_t *)ip);
-	if (unlikely(!p) || kprobe_disabled(p))
-		return;
-
-	kcb = get_kprobe_ctlblk();
-	if (kprobe_running()) {
-		kprobes_inc_nmissed_count(p);
-	} else {
-		unsigned long orig_ip = instruction_pointer(regs);
-		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
-		instruction_pointer_set(regs, ip + sizeof(kprobe_opcode_t));
-
-		__this_cpu_write(current_kprobe, p);
-		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
-		if (!p->pre_handler || !p->pre_handler(p, regs)) {
-			/*
-			 * Emulate singlestep (and also recover regs->ip)
-			 * as if there is a 5byte nop
-			 */
-			instruction_pointer_set(regs,
-				(unsigned long)p->addr + MCOUNT_INSN_SIZE);
-			if (unlikely(p->post_handler)) {
-				kcb->kprobe_status = KPROBE_HIT_SSDONE;
-				p->post_handler(p, regs, 0);
-			}
-			instruction_pointer_set(regs, orig_ip);
-		}
-		/*
-		 * If pre_handler returns !0, it changes regs->ip. We have to
-		 * skip emulating post_handler.
-		 */
-		__this_cpu_write(current_kprobe, NULL);
-	}
-}
-NOKPROBE_SYMBOL(kprobe_ftrace_handler);
-
 int arch_prepare_kprobe_ftrace(struct kprobe *p)
 {
 	p->ainsn.insn = NULL;
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f8400753a8a9..479148ee1822 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -960,6 +960,50 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
 #endif /* CONFIG_OPTPROBES */
 
 #ifdef CONFIG_KPROBES_ON_FTRACE
+/* Ftrace callback handler for kprobes -- called under preepmt disabed */
+void __weak kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+				  struct ftrace_ops *ops, struct pt_regs *regs)
+{
+	struct kprobe *p;
+	struct kprobe_ctlblk *kcb;
+
+	/* Preempt is disabled by ftrace */
+	p = get_kprobe((kprobe_opcode_t *)ip);
+	if (unlikely(!p) || kprobe_disabled(p))
+		return;
+
+	kcb = get_kprobe_ctlblk();
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(p);
+	} else {
+		unsigned long orig_ip = instruction_pointer(regs);
+		/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
+		instruction_pointer_set(regs, ip + sizeof(kprobe_opcode_t));
+
+		__this_cpu_write(current_kprobe, p);
+		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+		if (!p->pre_handler || !p->pre_handler(p, regs)) {
+			/*
+			 * Emulate singlestep (and also recover regs->ip)
+			 * as if there is a 5byte nop
+			 */
+			instruction_pointer_set(regs,
+				(unsigned long)p->addr + MCOUNT_INSN_SIZE);
+			if (unlikely(p->post_handler)) {
+				kcb->kprobe_status = KPROBE_HIT_SSDONE;
+				p->post_handler(p, regs, 0);
+			}
+			instruction_pointer_set(regs, orig_ip);
+		}
+		/*
+		 * If pre_handler returns !0, it changes regs->ip. We have to
+		 * skip emulating post_handler.
+		 */
+		__this_cpu_write(current_kprobe, NULL);
+	}
+}
+NOKPROBE_SYMBOL(kprobe_ftrace_handler);
+
 static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
 	.func = kprobe_ftrace_handler,
 	.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
-- 
2.23.0.rc1

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