Dwarves Archive on lore.kernel.org
 help / color / Atom feed
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Hao Luo <haoluo@google.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	daniel@iogearbox.net, dwarves@vger.kernel.org, yhs@fb.com
Subject: Re: [PATCH 1/2] btf_encoder: Make encoding vars into BTF optional.
Date: Fri, 18 Sep 2020 18:24:02 -0300
Message-ID: <20200918212402.GE1996959@kernel.org> (raw)
In-Reply-To: <20200918204058.1030519-2-haoluo@google.com>

Em Fri, Sep 18, 2020 at 01:40:57PM -0700, Hao Luo escreveu:
> Introduce an option --btf_encode_symbols to pahole so that pahole
> will only encode global symbols upon request. On the kernel side,
> we can add a Kconfig to turn on this feature. This would make the
> rollout of pahole v1.18 safe against potential bugs in the feature
> introduced in commit f3d9054ba8ff ("btf_encoder: Teach pahole to
> store percpu variables in vmlinux BTF.").

'encode_symbols' is too generic, please rename it to
encode_global_symbols or something like that.

- Arnaldo
 
> Signed-off-by: Hao Luo <haoluo@google.com>
> ---
>  btf_encoder.c |  5 ++++-
>  btf_encoder.h |  2 +-
>  pahole.c      | 11 ++++++++++-
>  3 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/btf_encoder.c b/btf_encoder.c
> index 982f59d..54ffdd1 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -237,7 +237,7 @@ static struct variable *hashaddr__find_variable(const struct hlist_head hashtabl
>  	return NULL;
>  }
>  
> -int cu__encode_btf(struct cu *cu, int verbose, bool force)
> +int cu__encode_btf(struct cu *cu, int verbose, bool force, bool encode_symbols)
>  {
>  	bool add_index_type = false;
>  	uint32_t type_id_off;
> @@ -314,6 +314,9 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force)
>  		}
>  	}
>  
> +	/* if there is no request to encode symbols, just finish. */
> +	if (!encode_symbols)
> +		goto out;
>  
>  	if (btfe->percpu_shndx == 0 || !btfe->symtab)
>  		goto out;
> diff --git a/btf_encoder.h b/btf_encoder.h
> index bca2348..f2e95fe 100644
> --- a/btf_encoder.h
> +++ b/btf_encoder.h
> @@ -13,6 +13,6 @@ struct cu;
>  
>  int btf_encoder__encode();
>  
> -int cu__encode_btf(struct cu *cu, int verbose, bool force);
> +int cu__encode_btf(struct cu *cu, int verbose, bool force, bool encode_symbols);
>  
>  #endif /* _BTF_ENCODER_H_ */
> diff --git a/pahole.c b/pahole.c
> index e1cde61..079d951 100644
> --- a/pahole.c
> +++ b/pahole.c
> @@ -26,6 +26,7 @@
>  static bool btf_encode;
>  static bool ctf_encode;
>  static bool first_obj_only;
> +static bool btf_encode_symbols;
>  
>  static uint8_t class__include_anonymous;
>  static uint8_t class__include_nested_anonymous;
> @@ -809,6 +810,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
>  #define ARGP_header_type	   314
>  #define ARGP_size_bytes		   315
>  #define ARGP_range		   316
> +#define ARGP_btf_encode_symbols	   317
>  
>  static const struct argp_option pahole__options[] = {
>  	{
> @@ -1087,6 +1089,11 @@ static const struct argp_option pahole__options[] = {
>  		.key  = 'J',
>  		.doc  = "Encode as BTF",
>  	},
> +	{
> +		.name = "btf_encode_symbols",
> +		.key  = ARGP_btf_encode_symbols,
> +		.doc  = "Encode global symbols in BTF. Off by default."
> +	},
>  	{
>  		.name = "force",
>  		.key  = 'j',
> @@ -1207,6 +1214,8 @@ static error_t pahole__options_parser(int key, char *arg,
>  		conf.range = arg;			break;
>  	case ARGP_header_type:
>  		conf.header_type = arg;			break;
> +	case ARGP_btf_encode_symbols:
> +		btf_encode_symbols = true;		break;
>  	default:
>  		return ARGP_ERR_UNKNOWN;
>  	}
> @@ -2352,7 +2361,7 @@ static enum load_steal_kind pahole_stealer(struct cu *cu,
>  		goto filter_it;
>  
>  	if (btf_encode) {
> -		cu__encode_btf(cu, global_verbose, force);
> +		cu__encode_btf(cu, global_verbose, force, btf_encode_symbols);
>  		return LSK__KEEPIT;
>  	}
>  
> -- 
> 2.28.0.681.g6f77f65b4e-goog
> 

-- 

- Arnaldo

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-18 20:40 [PATCH 0/2] pahole: Make encoding percpu " Hao Luo
2020-09-18 20:40 ` [PATCH 1/2] btf_encoder: Make encoding " Hao Luo
2020-09-18 21:24   ` Arnaldo Carvalho de Melo [this message]
2020-09-18 21:26     ` Hao Luo
2020-09-18 21:40       ` Arnaldo Carvalho de Melo
2020-09-18 20:40 ` [PATCH 2/2] btf_encoder: Introduce option '--btf_encode_force' Hao Luo
2020-09-19  0:57 ` [PATCH 0/2] pahole: Make encoding percpu vars into BTF optional Alexei Starovoitov
2020-09-19  4:00   ` Hao Luo
2020-09-21 12:27     ` Arnaldo Carvalho de Melo

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200918212402.GE1996959@kernel.org \
    --to=acme@kernel.org \
    --cc=alexei.starovoitov@gmail.com \
    --cc=andrii.nakryiko@gmail.com \
    --cc=arnaldo.melo@gmail.com \
    --cc=daniel@iogearbox.net \
    --cc=dwarves@vger.kernel.org \
    --cc=haoluo@google.com \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Dwarves Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dwarves/0 dwarves/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dwarves dwarves/ https://lore.kernel.org/dwarves \
		dwarves@vger.kernel.org
	public-inbox-index dwarves

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.dwarves


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git