linux-kernel - Re: [RFC PATCH 05/13] bpf tools: Save engine type in bpf

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Message-ID: <20160420192315.GU3677@kernel.org>
Date:	Wed, 20 Apr 2016 16:23:15 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	jolsa@...hat.com, brendan.d.gregg@...il.com,
	linux-kernel@...r.kernel.org, pi3orama@....com,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Jiri Olsa <jolsa@...nel.org>, Li Zefan <lizefan@...wei.com>
Subject: Re: [RFC PATCH 05/13] bpf tools: Save engine type in bpf_program

Em Wed, Apr 20, 2016 at 06:01:45PM +0000, Wang Nan escreveu:
> Add an 'engine' field in bpf_program to indicate whether a program is a
> ubpf program or kernel bpf program. For compatibility, the default
> engine is kernel bpf, unless explicitly set to ubpf using
> bpf_program__set_ubpf().
> 
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Brendan Gregg <brendan.d.gregg@...il.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Li Zefan <lizefan@...wei.com>
> ---
>  tools/lib/bpf/libbpf.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  tools/lib/bpf/libbpf.h |  4 ++++
>  2 files changed, 44 insertions(+)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index dd5a107..3755846 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -80,6 +80,7 @@ static const char *libbpf_strerror_table[NR_ERRNO] = {
>  	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
>  	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
>  	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
> +	[ERRCODE_OFFSET(NOUBPF)]	= "UBPF support is not compiled",
>  };
>  
>  int libbpf_strerror(int err, char *buf, size_t size)
> @@ -147,6 +148,11 @@ union prog_instance {
>   * linux/filter.h.
>   */
>  struct bpf_program {
> +	enum {
> +		ENGINE_UNKNOWN,
> +		ENGINE_KBPF,
> +		ENGINE_UBPF,
> +	} engine;
>  	/* Index in elf obj file, for relocation use. */
>  	int idx;
>  	char *section_name;
> @@ -291,6 +297,7 @@ bpf_program__init(void *data, size_t size, char *name, int idx,
>  	memcpy(prog->insns, data,
>  	       prog->insns_cnt * sizeof(struct bpf_insn));
>  	prog->idx = idx;
> +	prog->engine = ENGINE_UNKNOWN;
>  	prog->instances.array = NULL;
>  	prog->instances.nr = -1;
>  
> @@ -941,6 +948,11 @@ bpf_program__load(struct bpf_program *prog,
>  {
>  	int err = 0, fd, i;
>  
> +	if (prog->engine == ENGINE_UNKNOWN)
> +		prog->engine = ENGINE_KBPF;
> +	if (prog->engine != ENGINE_KBPF)

	else if (prog->engine != ENGINE_KBPF)

Nitpicking a bit :-)

> +		return -EINVAL;
> +
>  	if (prog->instances.nr < 0 || !prog->instances.array) {
>  		if (prog->preprocessor) {
>  			pr_warning("Internal error: can't load program '%s'\n",
> @@ -1318,6 +1330,34 @@ int bpf_program__nth_fd(struct bpf_program *prog, int n)
>  	return fd;
>  }
>  
> +#ifdef HAVE_UBPF_SUPPORT
> +int bpf_program__set_ubpf(struct bpf_program *prog)
> +{
> +	if (prog->engine != ENGINE_UNKNOWN) {
> +		pr_warning("Can't set program %s to ubpf\n",
> +			   prog->section_name);
> +		return -EINVAL;
> +	}
> +	prog->engine = ENGINE_UBPF;
> +	return 0;
> +}
> +
> +bool bpf_program__is_ubpf(struct bpf_program *prog)
> +{
> +	return prog->engine == ENGINE_UBPF;
> +}
> +#else
> +int bpf_program__set_ubpf(struct bpf_program *prog __maybe_unused)
> +{
> +	return -LIBBPF_ERRNO__NOUBPF;
> +}
> +
> +bool bpf_program__is_ubpf(struct bpf_program *prog __maybe_unused)
> +{
> +	return false;
> +}
> +#endif
> +
>  int bpf_map__get_fd(struct bpf_map *map)
>  {
>  	if (!map)
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index a51594c..f6965ce 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -26,6 +26,7 @@ enum libbpf_errno {
>  	LIBBPF_ERRNO__VERIFY,	/* Kernel verifier blocks program loading */
>  	LIBBPF_ERRNO__PROG2BIG,	/* Program too big */
>  	LIBBPF_ERRNO__KVER,	/* Incorrect kernel version */
> +	LIBBPF_ERRNO__NOUBPF,	/* UBPF support is not compiled */
>  	__LIBBPF_ERRNO__END,
>  };
>  
> @@ -86,6 +87,9 @@ int bpf_program__get_private(struct bpf_program *prog,
>  
>  const char *bpf_program__title(struct bpf_program *prog, bool needs_copy);
>  
> +int bpf_program__set_ubpf(struct bpf_program *prog);
> +bool bpf_program__is_ubpf(struct bpf_program *prog);
> +
>  int bpf_program__fd(struct bpf_program *prog);
>  
>  struct bpf_insn;
> -- 
> 1.8.3.4