netdev - Re: [PATCH v6 bpf-next 06/11] tracepoint: compute num

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Message-ID: <20180327111559.2abb9981@gandalf.local.home>
Date:   Tue, 27 Mar 2018 11:15:59 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Alexei Starovoitov <ast@...com>
Cc:     <davem@...emloft.net>, <daniel@...earbox.net>,
        <torvalds@...ux-foundation.org>, <peterz@...radead.org>,
        <netdev@...r.kernel.org>, <kernel-team@...com>,
        <linux-api@...r.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH v6 bpf-next 06/11] tracepoint: compute num_args at build
 time

On Mon, 26 Mar 2018 19:47:01 -0700
Alexei Starovoitov <ast@...com> wrote:

> From: Alexei Starovoitov <ast@...nel.org>
> 
> compute number of arguments passed into tracepoint
> at compile time and store it as part of 'struct tracepoint'.
> The number is necessary to check safety of bpf program access that
> is coming in subsequent patch.
> 
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>

Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

-- Steve

> ---
>  include/linux/tracepoint-defs.h |  1 +
>  include/linux/tracepoint.h      | 12 ++++++------
>  include/trace/define_trace.h    | 14 +++++++-------
>  3 files changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
> index 64ed7064f1fa..39a283c61c51 100644
> --- a/include/linux/tracepoint-defs.h
> +++ b/include/linux/tracepoint-defs.h
> @@ -33,6 +33,7 @@ struct tracepoint {
>  	int (*regfunc)(void);
>  	void (*unregfunc)(void);
>  	struct tracepoint_func __rcu *funcs;
> +	u32 num_args;
>  };
>  
>  #endif
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index c94f466d57ef..c92f4adbc0d7 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -230,18 +230,18 @@ extern void syscall_unregfunc(void);
>   * structures, so we create an array of pointers that will be used for iteration
>   * on the tracepoints.
>   */
> -#define DEFINE_TRACE_FN(name, reg, unreg)				 \
> +#define DEFINE_TRACE_FN(name, reg, unreg, num_args)			 \
>  	static const char __tpstrtab_##name[]				 \
>  	__attribute__((section("__tracepoints_strings"))) = #name;	 \
>  	struct tracepoint __tracepoint_##name				 \
>  	__attribute__((section("__tracepoints"))) =			 \
> -		{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
> +		{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL, num_args };\
>  	static struct tracepoint * const __tracepoint_ptr_##name __used	 \
>  	__attribute__((section("__tracepoints_ptrs"))) =		 \
>  		&__tracepoint_##name;
>  
> -#define DEFINE_TRACE(name)						\
> -	DEFINE_TRACE_FN(name, NULL, NULL);
> +#define DEFINE_TRACE(name, num_args)					\
> +	DEFINE_TRACE_FN(name, NULL, NULL, num_args);
>  
>  #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
>  	EXPORT_SYMBOL_GPL(__tracepoint_##name)
> @@ -275,8 +275,8 @@ extern void syscall_unregfunc(void);
>  		return false;						\
>  	}
>  
> -#define DEFINE_TRACE_FN(name, reg, unreg)
> -#define DEFINE_TRACE(name)
> +#define DEFINE_TRACE_FN(name, reg, unreg, num_args)
> +#define DEFINE_TRACE(name, num_args)
>  #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
>  #define EXPORT_TRACEPOINT_SYMBOL(name)
>  
> diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h
> index d9e3d4aa3f6e..96b22ace9ae7 100644
> --- a/include/trace/define_trace.h
> +++ b/include/trace/define_trace.h
> @@ -25,7 +25,7 @@
>  
>  #undef TRACE_EVENT
>  #define TRACE_EVENT(name, proto, args, tstruct, assign, print)	\
> -	DEFINE_TRACE(name)
> +	DEFINE_TRACE(name, COUNT_ARGS(args))
>  
>  #undef TRACE_EVENT_CONDITION
>  #define TRACE_EVENT_CONDITION(name, proto, args, cond, tstruct, assign, print) \
> @@ -39,24 +39,24 @@
>  #undef TRACE_EVENT_FN
>  #define TRACE_EVENT_FN(name, proto, args, tstruct,		\
>  		assign, print, reg, unreg)			\
> -	DEFINE_TRACE_FN(name, reg, unreg)
> +	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
>  
>  #undef TRACE_EVENT_FN_COND
>  #define TRACE_EVENT_FN_COND(name, proto, args, cond, tstruct,		\
>  		assign, print, reg, unreg)			\
> -	DEFINE_TRACE_FN(name, reg, unreg)
> +	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
>  
>  #undef DEFINE_EVENT
>  #define DEFINE_EVENT(template, name, proto, args) \
> -	DEFINE_TRACE(name)
> +	DEFINE_TRACE(name, COUNT_ARGS(args))
>  
>  #undef DEFINE_EVENT_FN
>  #define DEFINE_EVENT_FN(template, name, proto, args, reg, unreg) \
> -	DEFINE_TRACE_FN(name, reg, unreg)
> +	DEFINE_TRACE_FN(name, reg, unreg, COUNT_ARGS(args))
>  
>  #undef DEFINE_EVENT_PRINT
>  #define DEFINE_EVENT_PRINT(template, name, proto, args, print)	\
> -	DEFINE_TRACE(name)
> +	DEFINE_TRACE(name, COUNT_ARGS(args))
>  
>  #undef DEFINE_EVENT_CONDITION
>  #define DEFINE_EVENT_CONDITION(template, name, proto, args, cond) \
> @@ -64,7 +64,7 @@
>  
>  #undef DECLARE_TRACE
>  #define DECLARE_TRACE(name, proto, args)	\
> -	DEFINE_TRACE(name)
> +	DEFINE_TRACE(name, COUNT_ARGS(args))
>  
>  #undef TRACE_INCLUDE
>  #undef __TRACE_INCLUDE