From patchwork Mon Nov 1 20:23:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella X-Patchwork-Id: 46924 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 33665385842E for ; Mon, 1 Nov 2021 20:27:19 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 33665385842E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1635798439; bh=NPb1ZDObW8I9EZKILtI78HPd5ooZ4GFlctmCz30U7fU=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=og1ZA4mvMHiMoARkXy1iqhamFIxr7GnURjR7bZsORR6J8XB8qiu+bwakKaz/IOTsS 7AwT/HVnEXdFpIuElyQdWeu/S2MVOdVYnFuVOIlicOZqVU2S86OghRQ7ed55EkfA/y pRjjkpExZjfYvWWc+AA8+3AIzB0vQzQT5h0sQQck= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-qk1-x732.google.com (mail-qk1-x732.google.com [IPv6:2607:f8b0:4864:20::732]) by sourceware.org (Postfix) with ESMTPS id C7BCC3858023 for ; Mon, 1 Nov 2021 20:23:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C7BCC3858023 Received: by mail-qk1-x732.google.com with SMTP id bq14so6274060qkb.1 for ; Mon, 01 Nov 2021 13:23:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=NPb1ZDObW8I9EZKILtI78HPd5ooZ4GFlctmCz30U7fU=; b=Ztn7UeOdxVMn2Gc0ItitbwvBrHPT2iTUNYZ1qjgGDvutipl1cEISsObK6FeT4mYJZW PdUjGOtNN0JcGAoov4Rb+FyLWug+f0JvP8h0ElzfD9WDOPHEVWyW4fIIe6dPWqVJRMPQ wP5cyN7LbdvL/rMjk2q2jpw5fmQjTczU7TSF7Cecf8N4jsFNGlkuOGSzt7UFQR6x95nI Y+i1uP0m3wkx//mnnuSg68eO+JVVW3A2VRPLmi2EUWmnGTJlLYznddgMcYNMfvX23T9b 1l9fT9/4i3ZR1KOt99s+6psH3WW03+emKOn5MeJm5XTJ05EFEXaRXSIzB32CZVoNA3Lk /QXw== X-Gm-Message-State: AOAM532HGuClXU8rXBP1ozJSoxU9AHWpqrWl05o/Cni49SsByg12WVjt 5UFDSxtdUsrGH73qRPV2vLl7dgt/9F0bsA== X-Google-Smtp-Source: ABdhPJyFHxfr4IxbmN2lBtKQuYhU/FpovgmOAbFyCjxsZjxwohk6pB/AlMe3nsEFrBdANnq5jjD4tw== X-Received: by 2002:a05:620a:424b:: with SMTP id w11mr24507873qko.179.1635798218276; Mon, 01 Nov 2021 13:23:38 -0700 (PDT) Received: from birita.. ([2804:431:c7cb:b64f:7c54:165f:8728:a193]) by smtp.gmail.com with ESMTPSA id x16sm4857139qkp.56.2021.11.01.13.23.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Nov 2021 13:23:38 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v2] elf: Assume disjointed .rela.dyn and .rela.plt for loader Date: Mon, 1 Nov 2021 17:23:34 -0300 Message-Id: <20211101202334.1026714-1-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 X-Spam-Status: No, score=-11.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, URIBL_BLACK autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Adhemerval Zanella via Libc-alpha From: Adhemerval Zanella Reply-To: Adhemerval Zanella Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" The patch removes the the ELF_DURING_STARTUP optimization and assume both .rel.dyn and .rel.plt might not be subsequent. This allows some code simplification since relocation will be handled independently where it is done on bootstrap. At least on x86_64_64, I can not measure any performance implications. Running 10000 time the command LD_DEBUG=statistics ./elf/ld.so ./libc.so And filtering the "total startup time in dynamic loader" result, the geometric mean is: patched master Ryzen 7 5900x 24140 24952 i7-4510U 45957 45982 (The results do show some variation, I did not make any statistical analysis). It also allows build arm with lld, since it inserts ".ARM.exidx" between ".rel.dyn" and ".rel.plt" for the loader. Checked on x86_64-linux-gnu and arm-linux-gnueabihf. Reviewed-by: H.J. Lu --- elf/dynamic-link.h | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index ac4cc70dea..f619615e5c 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -65,12 +65,6 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], #ifdef RESOLVE_MAP -# if defined RTLD_BOOTSTRAP || defined STATIC_PIE_BOOTSTRAP -# define ELF_DURING_STARTUP (1) -# else -# define ELF_DURING_STARTUP (0) -# endif - /* Get the definitions of `elf_dynamic_do_rel' and `elf_dynamic_do_rela'. These functions are almost identical, so we use cpp magic to avoid duplicating their code. It cannot be done in a more general function @@ -106,9 +100,8 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], \ if (ranges[0].start + ranges[0].size == (start + size)) \ ranges[0].size -= size; \ - if (ELF_DURING_STARTUP \ - || (!(do_lazy) \ - && (ranges[0].start + ranges[0].size) == start)) \ + if (!(do_lazy) \ + && (ranges[0].start + ranges[0].size) == start) \ { \ /* Combine processing the sections. */ \ ranges[0].size += size; \ @@ -121,20 +114,13 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], } \ } \ \ - if (ELF_DURING_STARTUP) \ - elf_dynamic_do_##reloc ((map), scope, ranges[0].start, ranges[0].size, \ - ranges[0].nrelative, 0, skip_ifunc); \ - else \ - { \ - int ranges_index; \ - for (ranges_index = 0; ranges_index < 2; ++ranges_index) \ - elf_dynamic_do_##reloc ((map), scope, \ - ranges[ranges_index].start, \ - ranges[ranges_index].size, \ - ranges[ranges_index].nrelative, \ - ranges[ranges_index].lazy, \ - skip_ifunc); \ - } \ + for (int ranges_index = 0; ranges_index < 2; ++ranges_index) \ + elf_dynamic_do_##reloc ((map), scope, \ + ranges[ranges_index].start, \ + ranges[ranges_index].size, \ + ranges[ranges_index].nrelative, \ + ranges[ranges_index].lazy, \ + skip_ifunc); \ } while (0) # if ELF_MACHINE_NO_REL || ELF_MACHINE_NO_RELA