From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C740C433B4 for ; Thu, 20 May 2021 10:29:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7CE14613AC for ; Thu, 20 May 2021 10:29:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236677AbhETKbN (ORCPT ); Thu, 20 May 2021 06:31:13 -0400 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]:48829 "EHLO out30-45.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236716AbhETK3M (ORCPT ); Thu, 20 May 2021 06:29:12 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=chengshuyi@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0UZVBzqP_1621506468; Received: from B-39YZML7H-2200.local(mailfrom:chengshuyi@linux.alibaba.com fp:SMTPD_---0UZVBzqP_1621506468) by smtp.aliyun-inc.com(127.0.0.1); Thu, 20 May 2021 18:27:49 +0800 Subject: Re: [PATCH v2] pahole: Add --kabi_prefix flag To: Jiri Olsa Cc: Andrii Nakryiko , Arnaldo Carvalho de Melo , dwarves@vger.kernel.org, wenan.mao@linux.alibaba.com, Jiri Olsa References: From: Shuyi Cheng Message-ID: <30cc773d-779f-9440-2f79-1fd642287cc4@linux.alibaba.com> Date: Thu, 20 May 2021 18:27:48 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org On 5/20/21 4:07 AM, Jiri Olsa wrote: > On Wed, May 19, 2021 at 10:44:44AM +0800, Shuyi Cheng wrote: >> To solve problems similar to _RH_KABI_REPLACE. The _RH_KABI_REPLACE(_orig, >> _new) macros perserve size alignment and kabi agreement between _orig and >> _new.Below is the definition of this macro: >> >> # define _RH_KABI_REPLACE(_orig, _new) \ >> union { \ >> _new; \ >> struct { \ >> _orig; \ >> } __UNIQUE_ID(rh_kabi_hide); \ >> __RH_KABI_CHECK_SIZE_ALIGN(_orig, _new); \ >> } > > hi, > that macro sounds familiar ;-) I think this should be already > solved directly in the header file by this one: > > https://gitlab.com/cki-project/kernel-ark/-/commit/331be9c5a436057ee852075c102d9d90a9046a30 > > jirka > Well, this patch solves this problem very well from the kernel level. But there are many mirrors [here](http://debuginfo.centos.org/7/x86_64/) that still have this problem. And these mirrors support ebpf, so it is very important to effectively extract the btf segment from these mirrors. :-) >> >> >> __UNIQUE_ID uses the __COUNTER__ macro, and the __COUNTER__ macro is >> automatically incremented by 1 every time it is precompiled. Therefore, in >> different compilation units, the same structure has different names.Here is >> a concrete example: >> >> struct acpi_dev_node { >> union { >> struct acpi_device *companion; >> struct { >> void *handle; >> } __UNIQUE_ID_rh_kabi_hide29; >> union { }; >> }; >> }; >> struct acpi_dev_node { >> union { >> struct acpi_device *companion; >> struct { >> void *handle; >> } __UNIQUE_ID_rh_kabi_hide31; >> union { }; >> }; >> }; >> >> Finally, it will cause the btf algorithm to de-duplication efficiency is not >> high, and time-consuming. For example, running ./pahole -J >> vmlinux-3.10.0-1160.el7.x86_64 without --kabi_prefix flag, the running time >> is: >> real 8m28.912s >> user 8m27.271s >> sys 0m1.471s >> And the size of the generated btf segment is 30678240 bytes. >> >> After adding the patch, running ./pahole >> --kabi_prefix=__UNIQUE_ID_rh_kabi_hide -J vmlinux-3.10.0-1160.el7.x86_64. >> The running time of the command is: >> real 0m19.634s >> user 0m18.457s >> sys 0m1.169s >> And the size of the generated btf segment is 3117719 bytes. >> >> --- >> >> v1:https://lore.kernel.org/dwarves/CAEf4Bzazh4RNCY3rGRRXfO2wJ7DSiMx8w+61B_hjhu9FrOffpQ@mail.gmail.com >> v1->v2: >> --Change btf_prefix to --kabi_prefix. >> --Add man page. >> --Add space after if and comma. >> >> man-pages/pahole.1 | 4 ++++ >> pahole.c | 10 ++++++++++ >> pahole_strings.h | 2 ++ >> strings.c | 9 ++++++++- >> 4 files changed, 24 insertions(+), 1 deletion(-) >> >> diff --git a/man-pages/pahole.1 b/man-pages/pahole.1 >> index a10738f..2659fe6 100644 >> --- a/man-pages/pahole.1 >> +++ b/man-pages/pahole.1 >> @@ -340,6 +340,10 @@ Show a traditional string version, i.e.: "v1.18". >> Show a numeric only version, suitable for use in Makefiles and scripts >> where >> one wants to know what if the installed version has some feature, i.e.: 118 >> instead of "v1.18". >> >> +.TP >> +.B \-\-kabi_prefix=STRING >> +When the prefix of the string is STRING, treat the string as STRING. >> + >> .SH NOTES >> >> To enable the generation of debugging information in the Linux kernel build >> diff --git a/pahole.c b/pahole.c >> index dc40ccf..6a700d9 100644 >> --- a/pahole.c >> +++ b/pahole.c >> @@ -24,6 +24,7 @@ >> #include "btf_encoder.h" >> #include "libbtf.h" >> #include "lib/bpf/src/libbpf.h" >> +#include "pahole_strings.h" >> >> static bool btf_encode; >> static bool ctf_encode; >> @@ -855,6 +856,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version; >> #define ARGP_btf_gen_floats 322 >> #define ARGP_btf_gen_all 323 >> #define ARGP_with_flexible_array 324 >> +#define ARGP_kabi_prefix 325 >> >> static const struct argp_option pahole__options[] = { >> { >> @@ -1140,6 +1142,12 @@ static const struct argp_option pahole__options[] = { >> .doc = "Path to the base BTF file", >> }, >> { >> + .name = "kabi_prefix", >> + .key = ARGP_kabi_prefix, >> + .arg = "STRING", >> + .doc = "When the prefix of the string is STRING, treat the string as >> STRING.", >> + }, >> + { >> .name = "btf_encode", >> .key = 'J', >> .doc = "Encode as BTF", >> @@ -1297,6 +1305,8 @@ static error_t pahole__options_parser(int key, char >> *arg, >> btf_encode_force = true; break; >> case ARGP_btf_base: >> base_btf_file = arg; break; >> + case ARGP_kabi_prefix: >> + kabi_prefix = arg; break; >> case ARGP_numeric_version: >> print_numeric_version = true; break; >> case ARGP_btf_gen_floats: >> diff --git a/pahole_strings.h b/pahole_strings.h >> index 522fbf2..a836ba8 100644 >> --- a/pahole_strings.h >> +++ b/pahole_strings.h >> @@ -14,6 +14,8 @@ struct strings { >> struct btf *btf; >> }; >> >> +extern const char *kabi_prefix; >> + >> struct strings *strings__new(void); >> >> void strings__delete(struct strings *strings); >> diff --git a/strings.c b/strings.c >> index d37f49d..d1a54ec 100644 >> --- a/strings.c >> +++ b/strings.c >> @@ -17,6 +17,8 @@ >> #include "dutil.h" >> #include "lib/bpf/src/libbpf.h" >> >> +const char *kabi_prefix; >> + >> struct strings *strings__new(void) >> { >> struct strings *strs = malloc(sizeof(*strs)); >> @@ -48,7 +50,12 @@ strings_t strings__add(struct strings *strs, const char >> *str) >> if (str == NULL) >> return 0; >> >> - index = btf__add_str(strs->btf, str); >> + if (kabi_prefix && >> + strncmp(str, kabi_prefix, strlen(kabi_prefix)) == 0) >> + index = btf__add_str(strs->btf, kabi_prefix); >> + else >> + index = btf__add_str(strs->btf, str); >> + >> if (index < 0) >> return 0; >> >> -- >> 1.8.3.1 >>