[PATCH 2/2] kprobes: modify the copy_kprobe to make more clearly

[PATCH 2/2] kprobes: modify the copy_kprobe to make more clearly

[zhangduo]

From: zhangduo <zhangduo@kylinos.cn>

  copy_kprobe() are called in init_aggr_kprobe() to copy opcode
  and insn from 'p' to 'ap',but in copy_kprobe(p,ap) implemtation
  'p' pass to 'struct kprobe *ap' , 'ap' pass to 'struct kprobe *p',
  it looks strange, because p means orig kprobe instance, ap
  means aggregator kprobe, not the same.  and before the add_new_kprobe()
  calling used the opposite copy from 'ap' to 'p', so modify copy_kprobe's
  parameter name as 'p_src' and 'p_dst' to fit all.

Signed-off-by: zhangduo <zhangduo@kylinos.cn>
---
 kernel/kprobes.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 4f3e84343..8bcef7d3c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -405,10 +405,10 @@ static inline bool kprobe_unused(struct kprobe *p)
 }
 
 /* Keep all fields in the kprobe consistent. */
-static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
+static inline void copy_kprobe(struct kprobe *p_dst, struct kprobe *p_src)
 {
-	memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
-	memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
+	memcpy(&p_dst->opcode, &p_src->opcode, sizeof(kprobe_opcode_t));
+	memcpy(&p_dst->ainsn, &p_src->ainsn, sizeof(struct arch_specific_insn));
 }
 
 #ifdef CONFIG_OPTPROBES
@@ -1277,7 +1277,7 @@ static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
 static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
 {
 	/* Copy the insn slot of 'p' to 'ap'. */
-	copy_kprobe(p, ap);
+	copy_kprobe(ap, p);
 	flush_insn_slot(ap);
 	ap->addr = p->addr;
 	ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
@@ -1350,7 +1350,7 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
 	}
 
 	/* Copy the insn slot of 'ap' to 'p'. */
-	copy_kprobe(ap, p);
+	copy_kprobe(p, ap);
 	ret = add_new_kprobe(ap, p);
 
 out:
-- 
2.25.1

Re: [PATCH 2/2] kprobes: modify the copy_kprobe to make more clearly

[Masami Hiramatsu]

On Thu, 28 Jul 2022 20:45:16 +0800
zhangduo <zduo006@163.com> wrote:

> From: zhangduo <zhangduo@kylinos.cn>
> 
>   copy_kprobe() are called in init_aggr_kprobe() to copy opcode
>   and insn from 'p' to 'ap',but in copy_kprobe(p,ap) implemtation
>   'p' pass to 'struct kprobe *ap' , 'ap' pass to 'struct kprobe *p',
>   it looks strange, because p means orig kprobe instance, ap
>   means aggregator kprobe, not the same.  and before the add_new_kprobe()
>   calling used the opposite copy from 'ap' to 'p', so modify copy_kprobe's
>   parameter name as 'p_src' and 'p_dst' to fit all.

Agreed, that was confusing.

This doesn not change the behavior, but better to be read
(the arguments are sorted as same as memcpy(dst, src))

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks!

> 
> Signed-off-by: zhangduo <zhangduo@kylinos.cn>
> ---
>  kernel/kprobes.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 4f3e84343..8bcef7d3c 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -405,10 +405,10 @@ static inline bool kprobe_unused(struct kprobe *p)
>  }
>  
>  /* Keep all fields in the kprobe consistent. */
> -static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
> +static inline void copy_kprobe(struct kprobe *p_dst, struct kprobe *p_src)
>  {
> -	memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
> -	memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
> +	memcpy(&p_dst->opcode, &p_src->opcode, sizeof(kprobe_opcode_t));
> +	memcpy(&p_dst->ainsn, &p_src->ainsn, sizeof(struct arch_specific_insn));
>  }
>  
>  #ifdef CONFIG_OPTPROBES
> @@ -1277,7 +1277,7 @@ static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
>  static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
>  {
>  	/* Copy the insn slot of 'p' to 'ap'. */
> -	copy_kprobe(p, ap);
> +	copy_kprobe(ap, p);
>  	flush_insn_slot(ap);
>  	ap->addr = p->addr;
>  	ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
> @@ -1350,7 +1350,7 @@ static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
>  	}
>  
>  	/* Copy the insn slot of 'ap' to 'p'. */
> -	copy_kprobe(ap, p);
> +	copy_kprobe(p, ap);
>  	ret = add_new_kprobe(ap, p);
>  
>  out:
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>