Re: [RFC PATCH 1/4] trace: Simplify kprobe overridable function check

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

On Thu,  2 Apr 2026 17:26:04 +0800
Yafang Shao <laoar.shao@gmail.com> wrote:

> Simplify the logic for checking overridable kprobe functions by removing
> redundant code.
> 
> No functional change.

NACK.

trace_kprobe must be hidden inside the trace_kprobe.c. It is not
designed to be exposed. 

Thank you,

> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> ---
>  kernel/trace/bpf_trace.c    | 13 ++++++---
>  kernel/trace/trace_kprobe.c | 40 +++++----------------------
>  kernel/trace/trace_probe.h  | 54 ++++++++++++++++++++++++++-----------
>  3 files changed, 54 insertions(+), 53 deletions(-)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 0b040a417442..c901ace836cb 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1929,10 +1929,15 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
>  	 * Kprobe override only works if they are on the function entry,
>  	 * and only if they are on the opt-in list.
>  	 */
> -	if (prog->kprobe_override &&
> -	    (!trace_kprobe_on_func_entry(event->tp_event) ||
> -	     !trace_kprobe_error_injectable(event->tp_event)))
> -		return -EINVAL;
> +	if (prog->kprobe_override) {
> +		struct trace_kprobe *tp = trace_kprobe_primary_from_call(event->tp_event);
> +
> +		if (!tp)
> +			return -EINVAL;
> +		if (!trace_kprobe_on_func_entry(tp) ||
> +		    !trace_kprobe_error_injectable(tp))
> +			return -EINVAL;
> +	}
>  
>  	mutex_lock(&bpf_event_mutex);
>  
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index a5dbb72528e0..768702674a5c 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -53,17 +53,6 @@ static struct dyn_event_operations trace_kprobe_ops = {
>  	.match = trace_kprobe_match,
>  };
>  
> -/*
> - * Kprobe event core functions
> - */
> -struct trace_kprobe {
> -	struct dyn_event	devent;
> -	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
> -	unsigned long __percpu *nhit;
> -	const char		*symbol;	/* symbol name */
> -	struct trace_probe	tp;
> -};
> -
>  static bool is_trace_kprobe(struct dyn_event *ev)
>  {
>  	return ev->ops == &trace_kprobe_ops;
> @@ -212,33 +201,16 @@ unsigned long trace_kprobe_address(struct trace_kprobe *tk)
>  	return addr;
>  }
>  
> -static nokprobe_inline struct trace_kprobe *
> -trace_kprobe_primary_from_call(struct trace_event_call *call)
> -{
> -	struct trace_probe *tp;
> -
> -	tp = trace_probe_primary_from_call(call);
> -	if (WARN_ON_ONCE(!tp))
> -		return NULL;
> -
> -	return container_of(tp, struct trace_kprobe, tp);
> -}
> -
> -bool trace_kprobe_on_func_entry(struct trace_event_call *call)
> +bool trace_kprobe_on_func_entry(struct trace_kprobe *tp)
>  {
> -	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
> -
> -	return tk ? (kprobe_on_func_entry(tk->rp.kp.addr,
> -			tk->rp.kp.addr ? NULL : tk->rp.kp.symbol_name,
> -			tk->rp.kp.addr ? 0 : tk->rp.kp.offset) == 0) : false;
> +	return !kprobe_on_func_entry(tp->rp.kp.addr,
> +			tp->rp.kp.addr ? NULL : tp->rp.kp.symbol_name,
> +			tp->rp.kp.addr ? 0 : tp->rp.kp.offset);
>  }
>  
> -bool trace_kprobe_error_injectable(struct trace_event_call *call)
> +bool trace_kprobe_error_injectable(struct trace_kprobe *tp)
>  {
> -	struct trace_kprobe *tk = trace_kprobe_primary_from_call(call);
> -
> -	return tk ? within_error_injection_list(trace_kprobe_address(tk)) :
> -	       false;
> +	return within_error_injection_list(trace_kprobe_address(tp));
>  }
>  
>  static int register_kprobe_event(struct trace_kprobe *tk);
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 9fc56c937130..958eb78a9068 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -30,6 +30,7 @@
>  
>  #include "trace.h"
>  #include "trace_output.h"
> +#include "trace_dynevent.h"
>  
>  #define MAX_TRACE_ARGS		128
>  #define MAX_ARGSTR_LEN		63
> @@ -210,21 +211,6 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
>  #define ASSIGN_FETCH_TYPE_END {}
>  #define MAX_ARRAY_LEN	64
>  
> -#ifdef CONFIG_KPROBE_EVENTS
> -bool trace_kprobe_on_func_entry(struct trace_event_call *call);
> -bool trace_kprobe_error_injectable(struct trace_event_call *call);
> -#else
> -static inline bool trace_kprobe_on_func_entry(struct trace_event_call *call)
> -{
> -	return false;
> -}
> -
> -static inline bool trace_kprobe_error_injectable(struct trace_event_call *call)
> -{
> -	return false;
> -}
> -#endif /* CONFIG_KPROBE_EVENTS */
> -
>  struct probe_arg {
>  	struct fetch_insn	*code;
>  	bool			dynamic;/* Dynamic array (string) is used */
> @@ -271,6 +257,32 @@ struct event_file_link {
>  	struct list_head		list;
>  };
>  
> +/*
> + * Kprobe event core functions
> + */
> +struct trace_kprobe {
> +	struct dyn_event	devent;
> +	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
> +	unsigned long __percpu	*nhit;
> +	const char		*symbol;	/* symbol name */
> +	struct trace_probe	tp;
> +};
> +
> +#ifdef CONFIG_KPROBE_EVENTS
> +bool trace_kprobe_on_func_entry(struct trace_kprobe *tp);
> +bool trace_kprobe_error_injectable(struct trace_kprobe *tp);
> +#else
> +static inline bool trace_kprobe_on_func_entry(struct trace_kprobe *tp)
> +{
> +	return false;
> +}
> +
> +static inline bool trace_kprobe_error_injectable(struct trace_kprobe *tp)
> +{
> +	return false;
> +}
> +#endif /* CONFIG_KPROBE_EVENTS */
> +
>  static inline unsigned int trace_probe_load_flag(struct trace_probe *tp)
>  {
>  	return smp_load_acquire(&tp->event->flags);
> @@ -329,6 +341,18 @@ trace_probe_primary_from_call(struct trace_event_call *call)
>  	return list_first_entry_or_null(&tpe->probes, struct trace_probe, list);
>  }
>  
> +static nokprobe_inline struct trace_kprobe *
> +trace_kprobe_primary_from_call(struct trace_event_call *call)
> +{
> +	struct trace_probe *tp;
> +
> +	tp = trace_probe_primary_from_call(call);
> +	if (WARN_ON_ONCE(!tp))
> +		return NULL;
> +
> +	return container_of(tp, struct trace_kprobe, tp);
> +}
> +
>  static inline struct list_head *trace_probe_probe_list(struct trace_probe *tp)
>  {
>  	return &tp->event->probes;
> -- 
> 2.47.3
> 


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