From patchwork Wed Apr 13 18:25:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52867 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 9C797385741A for ; Wed, 13 Apr 2022 18:25:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9C797385741A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874332; bh=1pIo6NV4v1imjLb9rZ/VC/XEKxVKUKTCNqNrNe0UlFk=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=BGlAq2u/cZ18WJaaHoaupkMm3gKoMw0gOeAlozWm+IN9+hfG6Ehx+cE9jmihOBh3Z IriFNkAt6SvEGY64rukEF8Y2uABHGeHKXztnSlflmLtYuV4GWo/WNrYy81skgp3Jvf 0LZpq97CxOHMK3jCa90DtgIngBF8E58XUtnlRkec= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by sourceware.org (Postfix) with ESMTPS id A03473858C53 for ; Wed, 13 Apr 2022 18:25:10 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A03473858C53 Received: by mail-pj1-x102e.google.com with SMTP id e8-20020a17090a118800b001cb13402ea2so3189760pja.0 for ; Wed, 13 Apr 2022 11:25:10 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=1pIo6NV4v1imjLb9rZ/VC/XEKxVKUKTCNqNrNe0UlFk=; b=p6F7RUkoo+XlWea/qoQcuvfAFB9TkvEP0XqB/Ulpxbu3nCJX68we+PvKq9A1ryXkZH AVWhZbhmqnqA0a/9RKyq+/0XM8QvqdtSj42XSnV2cRKbEauslriWpllk6Xw6GRYhg6qC fJuKO/DwJI3tBTqx4CiIDL0AIAkHT0BRYZU05/vlIM6fovTETW7EEjN4RVh4MBAooyyS DiKkijeVeVeqrCxnclCWrq/mhXLNTPmnBvSPZ4aYxBOLgk1iLbm9OMJtrSYV3cpVy4z+ acowOcWQ2A13XysGFYa9Fu2v4lg2V2RPUhHneAQdYmW2efwWUVe3l87NTTlAz9LsV9fZ /J4Q== X-Gm-Message-State: AOAM530s8WVdRBcB4Uem0GfKcrjh3td4/dmEuY4WqGbFN6CojMvmJhom zONXpq6pxchnm0Ck6Mu1MJA= X-Google-Smtp-Source: ABdhPJwGoq+qosuDzn7d60D2AMO4nvdKefZaNSV/DGtSxU1/lPAYW49yT5PwPOBZArjt0bL+0mHFDg== X-Received: by 2002:a17:90b:1642:b0:1c6:c6d0:fbfa with SMTP id il2-20020a17090b164200b001c6c6d0fbfamr41585pjb.218.1649874309602; Wed, 13 Apr 2022 11:25:09 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id h13-20020a056a00230d00b004f427ffd485sm47214067pfh.143.2022.04.13.11.25.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:09 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id C5C19C023F; Wed, 13 Apr 2022 11:25:07 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 1/6] elf: Define DT_RELR related macros and types Date: Wed, 13 Apr 2022 11:25:02 -0700 Message-Id: <20220413182507.896862-2-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3028.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" --- elf/elf.h | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) Reviewed-by: Fangrui Song diff --git a/elf/elf.h b/elf/elf.h index 0735f6b579..0195029188 100644 --- a/elf/elf.h +++ b/elf/elf.h @@ -443,7 +443,8 @@ typedef struct #define SHT_PREINIT_ARRAY 16 /* Array of pre-constructors */ #define SHT_GROUP 17 /* Section group */ #define SHT_SYMTAB_SHNDX 18 /* Extended section indices */ -#define SHT_NUM 19 /* Number of defined types. */ +#define SHT_RELR 19 /* RELR relative relocations */ +#define SHT_NUM 20 /* Number of defined types. */ #define SHT_LOOS 0x60000000 /* Start OS-specific. */ #define SHT_GNU_ATTRIBUTES 0x6ffffff5 /* Object attributes. */ #define SHT_GNU_HASH 0x6ffffff6 /* GNU-style hash table. */ @@ -662,6 +663,11 @@ typedef struct Elf64_Sxword r_addend; /* Addend */ } Elf64_Rela; +/* RELR relocation table entry */ + +typedef Elf32_Word Elf32_Relr; +typedef Elf64_Xword Elf64_Relr; + /* How to extract and insert information held in the r_info field. */ #define ELF32_R_SYM(val) ((val) >> 8) @@ -887,7 +893,10 @@ typedef struct #define DT_PREINIT_ARRAY 32 /* Array with addresses of preinit fct*/ #define DT_PREINIT_ARRAYSZ 33 /* size in bytes of DT_PREINIT_ARRAY */ #define DT_SYMTAB_SHNDX 34 /* Address of SYMTAB_SHNDX section */ -#define DT_NUM 35 /* Number used */ +#define DT_RELRSZ 35 /* Total size of RELR relative relocations */ +#define DT_RELR 36 /* Address of RELR relative relocations */ +#define DT_RELRENT 37 /* Size of one RELR relative relocaction */ +#define DT_NUM 38 /* Number used */ #define DT_LOOS 0x6000000d /* Start of OS-specific */ #define DT_HIOS 0x6ffff000 /* End of OS-specific */ #define DT_LOPROC 0x70000000 /* Start of processor-specific */ From patchwork Wed Apr 13 18:25:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52868 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 073973857405 for ; Wed, 13 Apr 2022 18:26:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 073973857405 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874375; bh=MOi96q2BDCLXw6vfPPxgWYYEjGyj6vv2raliLsmPWhw=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=lpXlQEouegKQd7PDvWEV2IeMS57JwlGhsDxHZYHw/mnnhPddHY/gE+0TH5FN/4Vi6 5olG7j2H8Ci8ZmMsm2AAw+aMRGVOoKDGvu3itrSOT8td97+xa27CqwxW2quoKXC4I2 tMJpeAXvy+vXvv2wXx+fbo3+avZnFEfx+hqwLBcI= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pj1-x102f.google.com (mail-pj1-x102f.google.com [IPv6:2607:f8b0:4864:20::102f]) by sourceware.org (Postfix) with ESMTPS id 98F153858C53 for ; Wed, 13 Apr 2022 18:25:12 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 98F153858C53 Received: by mail-pj1-x102f.google.com with SMTP id h23-20020a17090a051700b001c9c1dd3acbso3146551pjh.3 for ; Wed, 13 Apr 2022 11:25:12 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=MOi96q2BDCLXw6vfPPxgWYYEjGyj6vv2raliLsmPWhw=; b=frhGkSis0597zaTPWIs1svzI4MWxi8LS2gK5L/BiNE9m2gRsrMh8eKMLc+wWu2oX8x P66ZUfjFqPB6AOsSmk73ASB6YUb2dnkR8KKC84y8ig6l0NryTHr1tlwsEfHQLVlN7cB7 +NqGu0jvROIXRPO+69D/JsqN/0aVL+zg74DIwG+dImvyymqoAzB7lrMcBk6EcSuiCOD1 jxGfaSxbN5Ux+/RfOeK9b6UNUc8wdcmlbxpDPA4ZaTEESZUkQipPLXMlEtjGyvinAMvP I0NT+R4Fkr6VtQn2knMDMRaQUxusfiuZxfqOhaiOHNu2f2JZCEsS+nAdsMY547lKs78M wuPQ== X-Gm-Message-State: AOAM533LlomzMtYvdxpORYKnVOSMVq+OaD26rEYy/rpyO697YP73DOhT hu7NEQn7llRYwJh1VjYEjHrJr/yR26Y= X-Google-Smtp-Source: ABdhPJyMe73ohpGioBUor+HImcjVwahqzIWpfqt2shtIFC4ff9PlHp6VgkRnCFar0Mm/agBVm6w0+g== X-Received: by 2002:a17:902:d5cd:b0:156:6263:bbc7 with SMTP id g13-20020a170902d5cd00b001566263bbc7mr45244684plh.160.1649874311553; Wed, 13 Apr 2022 11:25:11 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id f16-20020a056a00229000b004fabe756ba6sm47138492pfe.54.2022.04.13.11.25.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:09 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id D150CC0249; Wed, 13 Apr 2022 11:25:07 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 2/6] Add GLIBC_ABI_DT_RELR for DT_RELR support Date: Wed, 13 Apr 2022 11:25:03 -0700 Message-Id: <20220413182507.896862-3-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3027.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" The EI_ABIVERSION field of the ELF header in executables and shared libraries can be bumped to indicate the minimum ABI requirement on the dynamic linker. However, EI_ABIVERSION in executables isn't checked by the Linux kernel ELF loader nor the existing dynamic linker. Executables will crash mysteriously if the dynamic linker doesn't support the ABI features required by the EI_ABIVERSION field. The dynamic linker should be changed to check EI_ABIVERSION in executables. Add a glibc version, GLIBC_ABI_DT_RELR, to indicate DT_RELR support so that the existing dynamic linkers will issue an error on executables with GLIBC_ABI_DT_RELR dependency. Issue an error if there is a DT_RELR entry without GLIBC_ABI_DT_RELR dependency nor GLIBC_PRIVATE definition. Support __placeholder_only_for_empty_version_map as the placeholder symbol used only for empty version map to generate GLIBC_ABI_DT_RELR without any symbols. Reviewed-by: Fangrui Song --- elf/Makefile | 14 ++++++++++++-- elf/Versions | 5 +++++ elf/dl-version.c | 38 ++++++++++++++++++++++++++++++++------ include/link.h | 6 ++++++ scripts/abilist.awk | 2 ++ scripts/versions.awk | 7 ++++++- 6 files changed, 63 insertions(+), 9 deletions(-) diff --git a/elf/Makefile b/elf/Makefile index c96924e9c2..09d3d88336 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -1105,8 +1105,12 @@ $(eval $(call include_dsosort_tests,dso-sort-tests-1.def)) $(eval $(call include_dsosort_tests,dso-sort-tests-2.def)) endif -check-abi: $(objpfx)check-abi-ld.out -tests-special += $(objpfx)check-abi-ld.out +check-abi: $(objpfx)check-abi-ld.out \ + $(objpfx)check-abi-version-libc.out +tests-special += \ + $(objpfx)check-abi-ld.out \ + $(objpfx)check-abi-version-libc.out \ +# tests-special update-abi: update-abi-ld update-all-abi: update-all-abi-ld @@ -2725,3 +2729,9 @@ $(objpfx)tst-p_align3: $(objpfx)tst-p_alignmod3.so $(objpfx)tst-p_align3.out: tst-p_align3.sh $(objpfx)tst-p_align3 $(SHELL) $< $(common-objpfx) '$(test-program-prefix)'; \ $(evaluate-test) + +$(objpfx)check-abi-version-libc.out: $(common-objpfx)libc.so + LC_ALL=C $(READELF) -V -W $< \ + | sed -ne '/.gnu.version_d/, /.gnu.version_r/ p' \ + | grep GLIBC_ABI_DT_RELR > $@; \ + $(evaluate-test) diff --git a/elf/Versions b/elf/Versions index 8bed855d8c..a9ff278de7 100644 --- a/elf/Versions +++ b/elf/Versions @@ -23,6 +23,11 @@ libc { GLIBC_2.35 { _dl_find_object; } + GLIBC_ABI_DT_RELR { + # This symbol is used only for empty version map and will be removed + # by scripts/versions.awk. + __placeholder_only_for_empty_version_map; + } GLIBC_PRIVATE { # functions used in other libraries __libc_early_init; diff --git a/elf/dl-version.c b/elf/dl-version.c index b47bd91727..0537b1c7de 100644 --- a/elf/dl-version.c +++ b/elf/dl-version.c @@ -214,12 +214,20 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode) while (1) { /* Match the symbol. */ + const char *string = strtab + aux->vna_name; result |= match_symbol (DSO_FILENAME (map->l_name), map->l_ns, aux->vna_hash, - strtab + aux->vna_name, - needed->l_real, verbose, + string, needed->l_real, verbose, aux->vna_flags & VER_FLG_WEAK); + if (map->l_abi_version == lav_none + /* 0xfd0e42: _dl_elf_hash ("GLIBC_ABI_DT_RELR"). */ + && aux->vna_hash == 0xfd0e42 + && __glibc_likely (strcmp (string, + "GLIBC_ABI_DT_RELR") + == 0)) + map->l_abi_version = lav_dt_relr_ref; + /* Compare the version index. */ if ((unsigned int) (aux->vna_other & 0x7fff) > ndx_high) ndx_high = aux->vna_other & 0x7fff; @@ -243,16 +251,23 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode) } /* We also must store the names of the defined versions. Determine - the maximum index here as well. - - XXX We could avoid the loop by just taking the number of definitions - as an upper bound of new indices. */ + the maximum index here as well. */ if (def != NULL) { ElfW(Verdef) *ent; ent = (ElfW(Verdef) *) (map->l_addr + def->d_un.d_ptr); while (1) { + /* 0x0963cf85: _dl_elf_hash ("GLIBC_PRIVATE"). */ + if (ent->vd_hash == 0x0963cf85) + { + ElfW(Verdaux) *aux = (ElfW(Verdaux) *) ((char *) ent + + ent->vd_aux); + if (__glibc_likely (strcmp ("GLIBC_PRIVATE", + strtab + aux->vda_name) == 0)) + map->l_abi_version = lav_private_def; + } + if ((unsigned int) (ent->vd_ndx & 0x7fff) > ndx_high) ndx_high = ent->vd_ndx & 0x7fff; @@ -352,6 +367,17 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode) } } + /* Issue an error if there is a DT_RELR entry without GLIBC_ABI_DT_RELR + dependency nor GLIBC_PRIVATE definition. */ + if (map->l_info[DT_RELR] != NULL + && __glibc_unlikely (map->l_abi_version == lav_none)) + { + _dl_exception_create + (&exception, DSO_FILENAME (map->l_name), + N_("DT_RELR without GLIBC_ABI_DT_RELR dependency")); + goto call_error; + } + return result; } diff --git a/include/link.h b/include/link.h index 03db14c7b0..8ec5e35cf2 100644 --- a/include/link.h +++ b/include/link.h @@ -177,6 +177,12 @@ struct link_map lt_library, /* Library needed by main executable. */ lt_loaded /* Extra run-time loaded shared object. */ } l_type:2; + enum /* ABI dependency of this object. */ + { + lav_none, /* No ABI dependency. */ + lav_dt_relr_ref, /* Need GLIBC_ABI_DT_RELR. */ + lav_private_def /* Define GLIBC_PRIVATE. */ + } l_abi_version:2; unsigned int l_relocated:1; /* Nonzero if object's relocations done. */ unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */ unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */ diff --git a/scripts/abilist.awk b/scripts/abilist.awk index 24a34ccbed..6cc7af6ac8 100644 --- a/scripts/abilist.awk +++ b/scripts/abilist.awk @@ -55,6 +55,8 @@ $2 == "g" || $2 == "w" && (NF == 7 || NF == 8) { # caused STV_HIDDEN symbols to appear in .dynsym, though that is useless. if (NF > 7 && $7 == ".hidden") next; + if (version ~ /^GLIBC_ABI_/ && !include_abi_version) next; + if (version == "GLIBC_PRIVATE" && !include_private) next; desc = ""; diff --git a/scripts/versions.awk b/scripts/versions.awk index 357ad1355e..d70b07bd1a 100644 --- a/scripts/versions.awk +++ b/scripts/versions.awk @@ -185,8 +185,13 @@ END { closeversion(oldver, veryoldver); veryoldver = oldver; } - printf("%s {\n global:\n", $2) > outfile; oldver = $2; + # Skip the placeholder symbol used only for empty version map. + if ($3 == "__placeholder_only_for_empty_version_map;") { + printf("%s {\n", $2) > outfile; + continue; + } + printf("%s {\n global:\n", $2) > outfile; } printf(" ") > outfile; for (n = 3; n <= NF; ++n) { From patchwork Wed Apr 13 18:25:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52873 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 F1F603857C48 for ; Wed, 13 Apr 2022 18:29:50 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F1F603857C48 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874591; bh=Ag6uBEQ2LgEOTSdEqL7cIhGv6TpsCwOdoQTr/HFkh+Y=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=AEQ5gDVYwZwLwQrGhHrE5wooIIclSWoYIfY51tcSWaq4i8oztXYVO7yjfsSVzc7jn oXS/d4Mf6KBoFTm7x955fj1ZeFGFXpZg+HkhA5hOLCItiFC+z5DmHhWwDWK/f/ujVk 1lMRLAb6lxPaVr/j6DlSF1722OrACLOfF4WZD4kA= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by sourceware.org (Postfix) with ESMTPS id 4A58E3857419 for ; Wed, 13 Apr 2022 18:25:16 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4A58E3857419 Received: by mail-pj1-x1033.google.com with SMTP id j8-20020a17090a060800b001cd4fb60dccso3159947pjj.2 for ; Wed, 13 Apr 2022 11:25:16 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=Ag6uBEQ2LgEOTSdEqL7cIhGv6TpsCwOdoQTr/HFkh+Y=; b=YfRlr6mvI/ghcFxKi4misLkXhyzBdB2s/BI+B5/Yo/BJwC3kV1epJ4xwLW6Qzz3RH1 O/d0lW6l1d3H6USTFsIVguStdum85SoqG8AE/sS4QX8ukgJLpHfDBaE25VR/u0TcshDc 7PJ2f5JbRVYzeP/ZX5oV19UHQjN41UQiIgpK78nsTJQgyhsW1A8eBgmV0bctPvoYkkmQ bjLMKPlYzHAnemXAmNOX3xnRTOQpdpn3/W/eXkdDnBtSWm7GTHFcOPPMGjYUoHl6AVnn VnAAS09sTS0GFAfvWAr6XYVJwWIc6CcCKWPt4JjQEokCNj7A1+9LtxGL2mUPL6C+RJMv GAmA== X-Gm-Message-State: AOAM533xOjtuhdbEVflqLUhdCZSU0s5ihBg0SGi2mcuZwhJqoOhsCIUa 7hEU9Zkc4TOMVeQ0+05d7JFpSu7nU44= X-Google-Smtp-Source: ABdhPJylY8InJOyZr0fNWKvx2oooLPOwNRdA/oTSy+UHeEO11SZTFaQFBPEy2p6pGaGll6QDG7mstA== X-Received: by 2002:a17:90a:a509:b0:1ca:c48e:a795 with SMTP id a9-20020a17090aa50900b001cac48ea795mr18207pjq.165.1649874315176; Wed, 13 Apr 2022 11:25:15 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id n43-20020a056a000d6b00b005080953ad41sm1378693pfv.53.2022.04.13.11.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:11 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id 9A701C011C; Wed, 13 Apr 2022 11:25:10 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 3/6] elf: Support DT_RELR relative relocation format [BZ #27924] Date: Wed, 13 Apr 2022 11:25:04 -0700 Message-Id: <20220413182507.896862-4-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3027.7 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE, 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" From: Fangrui Song PIE and shared objects usually have many relative relocations. In 2017/2018, SHT_RELR/DT_RELR was proposed on https://groups.google.com/g/generic-abi/c/bX460iggiKg/m/GxjM0L-PBAAJ ("Proposal for a new section type SHT_RELR") and is a pre-standard. RELR usually takes 3% or smaller space than R_*_RELATIVE relocations. The virtual memory size of a mostly statically linked PIE is typically 5~10% smaller. --- Notes I will not include in the submitted commit: Available on https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/maskray/relr "pre-standard": even Solaris folks are happy with the refined generic-abi proposal. Cary Coutant will apply the change https://sourceware.org/pipermail/libc-alpha/2021-October/131781.html This patch is simpler than Chrome OS's glibc patch and makes ELF_DYNAMIC_DO_RELR available to all ports. I don't think the current glibc implementation supports ia64 in an ELFCLASS32 container. That said, the style I used is works with an ELFCLASS32 container for 64-bit machine if ElfW(Addr) is 64-bit. * Chrome OS folks have carried a local patch since 2018 (latest version: https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/refs/heads/main/sys-libs/glibc/files/local/glibc-2.32). I.e. this feature has been battle tested. * Android bionic supports 2018 and switched to DT_RELR==36 in 2020. * The Linux kernel has supported CONFIG_RELR since 2019-08 (https://git.kernel.org/linus/5cf896fb6be3effd9aea455b22213e27be8bdb1d). * A musl patch (by me) exists but is not applied: https://www.openwall.com/lists/musl/2019/03/06/3 * rtld-elf from FreeBSD 14 will support DT_RELR. I believe upstream glibc should support DT_RELR to benefit all Linux distributions. I filed some feature requests to get their attention: * Gentoo: https://bugs.gentoo.org/818376 * Arch Linux: https://bugs.archlinux.org/task/72433 * Debian https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=996598 * Fedora https://bugzilla.redhat.com/show_bug.cgi?id=2014699 As of linker support (to the best of my knowledge): * LLD support DT_RELR. * https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/refs/heads/main/sys-devel/binutils/files/ has a gold patch. * GNU ld feature request https://sourceware.org/bugzilla/show_bug.cgi?id=27923 Changes from the original patch: 1. Check the linker option, -z pack-relative-relocs, which add a GLIBC_ABI_DT_RELR symbol version dependency on the shared C library if it provides a GLIBC_2.XX symbol version. 2. Change make variale to have-dt-relr. 3. Rename tst-relr-no-pie to tst-relr-pie for --disable-default-pie. 4. Use TEST_VERIFY in tst-relr.c. 5. Add the check-tst-relr-pie.out test to check for linker generated libc.so version dependency on GLIBC_ABI_DT_RELR. 6. Move ELF_DYNAMIC_DO_RELR before ELF_DYNAMIC_DO_REL. --- configure | 37 ++++++++++++++++++++++++ configure.ac | 5 ++++ elf/Makefile | 25 ++++++++++++++++ elf/dynamic-link.h | 34 ++++++++++++++++++++++ elf/get-dynamic-info.h | 3 ++ elf/tst-relr-pie.c | 1 + elf/tst-relr.c | 65 ++++++++++++++++++++++++++++++++++++++++++ 7 files changed, 170 insertions(+) create mode 100644 elf/tst-relr-pie.c create mode 100644 elf/tst-relr.c diff --git a/configure b/configure index d2f413d05d..c0c2246597 100755 --- a/configure +++ b/configure @@ -6076,6 +6076,43 @@ $as_echo "$libc_linker_feature" >&6; } config_vars="$config_vars have-depaudit = $libc_cv_depaudit" +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z pack-relative-relocs" >&5 +$as_echo_n "checking for linker that supports -z pack-relative-relocs... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + cat > conftest.c <&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + if ${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -Wl,-z,pack-relative-relocs -nostdlib \ + -nostartfiles -fPIC -shared -o conftest.so conftest.c 2>&1 \ + | grep "warning: -z pack-relative-relocs ignored" > /dev/null 2>&1; then + true + else + libc_linker_feature=yes + fi + fi + rm -f conftest* +fi +if test $libc_linker_feature = yes; then + libc_cv_dt_relr=yes +else + libc_cv_dt_relr=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-dt-relr = $libc_cv_dt_relr" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index b6a747dece..66cad71431 100644 --- a/configure.ac +++ b/configure.ac @@ -1336,6 +1336,11 @@ LIBC_LINKER_FEATURE([--depaudit], [-Wl,--depaudit,x], [libc_cv_depaudit=yes], [libc_cv_depaudit=no]) LIBC_CONFIG_VAR([have-depaudit], [$libc_cv_depaudit]) +LIBC_LINKER_FEATURE([-z pack-relative-relocs], + [-Wl,-z,pack-relative-relocs], + [libc_cv_dt_relr=yes], [libc_cv_dt_relr=no]) +LIBC_CONFIG_VAR([have-dt-relr], [$libc_cv_dt_relr]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/elf/Makefile b/elf/Makefile index 09d3d88336..979dde046d 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -541,6 +541,25 @@ tests-special += \ # tests-special endif endif +ifeq ($(have-dt-relr),yes) +tests += \ + tst-relr \ +# tests +ifeq ($(have-fpie),yes) +tests += \ + tst-relr-pie \ +# tests +tests-pie += \ + tst-relr-pie \ +# tests-pie +tests-special += \ + $(objpfx)check-tst-relr-pie.out \ +# tests-special +endif +CFLAGS-tst-relr-pie.c += $(pie-ccflag) +LDFLAGS-tst-relr += -Wl,-z,pack-relative-relocs +LDFLAGS-tst-relr-pie += -Wl,-z,pack-relative-relocs +endif endif ifeq ($(run-built-tests),yes) @@ -2735,3 +2754,9 @@ $(objpfx)check-abi-version-libc.out: $(common-objpfx)libc.so | sed -ne '/.gnu.version_d/, /.gnu.version_r/ p' \ | grep GLIBC_ABI_DT_RELR > $@; \ $(evaluate-test) + +$(objpfx)check-tst-relr-pie.out: $(objpfx)tst-relr-pie + LC_ALL=C $(OBJDUMP) -p $< \ + | sed -ne '/required from libc.so/,$$ p' \ + | grep GLIBC_ABI_DT_RELR > $@; \ + $(evaluate-test) diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index 25dd7ca4f2..7325e0d9fc 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -146,12 +146,46 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], # define ELF_DYNAMIC_DO_RELA(map, scope, lazy, skip_ifunc) /* Nothing to do. */ # endif +# define ELF_DYNAMIC_DO_RELR(map) \ + do { \ + ElfW(Addr) l_addr = (map)->l_addr, *where = 0; \ + const ElfW(Relr) *r, *end; \ + if (!(map)->l_info[DT_RELR]) \ + break; \ + r = (const ElfW(Relr) *)D_PTR((map), l_info[DT_RELR]); \ + end = (const ElfW(Relr) *)((const char *)r + \ + (map)->l_info[DT_RELRSZ]->d_un.d_val); \ + for (; r < end; r++) \ + { \ + ElfW(Relr) entry = *r; \ + if ((entry & 1) == 0) \ + { \ + where = (ElfW(Addr) *)(l_addr + entry); \ + *where++ += l_addr; \ + } \ + else \ + { \ + for (long int i = 0; (entry >>= 1) != 0; i++) \ + if ((entry & 1) != 0) \ + where[i] += l_addr; \ + where += CHAR_BIT * sizeof(ElfW(Relr)) - 1; \ + } \ + } \ + } while (0); + /* This can't just be an inline function because GCC is too dumb to inline functions containing inlines themselves. */ +# ifdef RTLD_BOOTSTRAP +# define DO_RTLD_BOOTSTRAP 1 +# else +# define DO_RTLD_BOOTSTRAP 0 +# endif # define ELF_DYNAMIC_RELOCATE(map, scope, lazy, consider_profile, skip_ifunc) \ do { \ int edr_lazy = elf_machine_runtime_setup ((map), (scope), (lazy), \ (consider_profile)); \ + if (((map) != &GL(dl_rtld_map) || DO_RTLD_BOOTSTRAP)) \ + ELF_DYNAMIC_DO_RELR (map); \ ELF_DYNAMIC_DO_REL ((map), (scope), edr_lazy, skip_ifunc); \ ELF_DYNAMIC_DO_RELA ((map), (scope), edr_lazy, skip_ifunc); \ } while (0) diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h index 6c2ccd6db4..6c2a3a12b1 100644 --- a/elf/get-dynamic-info.h +++ b/elf/get-dynamic-info.h @@ -89,6 +89,7 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap, # if ! ELF_MACHINE_NO_REL ADJUST_DYN_INFO (DT_REL); # endif + ADJUST_DYN_INFO (DT_RELR); ADJUST_DYN_INFO (DT_JMPREL); ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM)); ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH)); @@ -113,6 +114,8 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap, if (info[DT_REL] != NULL) assert (info[DT_RELENT]->d_un.d_val == sizeof (ElfW(Rel))); #endif + if (info[DT_RELR] != NULL) + assert (info[DT_RELRENT]->d_un.d_val == sizeof (ElfW(Relr))); if (bootstrap || static_pie_bootstrap) { assert (info[DT_RUNPATH] == NULL); diff --git a/elf/tst-relr-pie.c b/elf/tst-relr-pie.c new file mode 100644 index 0000000000..7df0cdbfd6 --- /dev/null +++ b/elf/tst-relr-pie.c @@ -0,0 +1 @@ +#include "tst-relr.c" diff --git a/elf/tst-relr.c b/elf/tst-relr.c new file mode 100644 index 0000000000..c634ce0d21 --- /dev/null +++ b/elf/tst-relr.c @@ -0,0 +1,65 @@ +/* Basic tests for DT_RELR. + Copyright (C) 2022 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include +#include + +static int o, x; + +#define ELEMS O O O O O O O O X X X X X X X O O X O O X X X E X E E O X O E +#define E 0, + +#define O &o, +#define X &x, +void *arr[] = { ELEMS }; +#undef O +#undef X + +#define O 1, +#define X 2, +static char val[] = { ELEMS }; + +static int +do_test (void) +{ + ElfW(Dyn) *d = _DYNAMIC; + if (d) + { + bool has_relr = false; + for (; d->d_tag != DT_NULL; d++) + if (d->d_tag == DT_RELR) + has_relr = true; + +#if defined __PIE__ || defined __pie__ || defined PIE || defined pie + TEST_VERIFY (has_relr); +#else + TEST_VERIFY (!has_relr); +#endif + } + + for (int i = 0; i < array_length (arr); i++) + TEST_VERIFY ((arr[i] == 0 && val[i] == 0) + || (arr[i] == &o && val[i] == 1) + || (arr[i] == &x && val[i] == 2)); + + return 0; +} + +#include From patchwork Wed Apr 13 18:25:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52869 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 4683B3857811 for ; Wed, 13 Apr 2022 18:26:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4683B3857811 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874417; bh=xKO1p5wpII66g6kHJcRj1E3GE5aEnTBcAXwSFA2fYIg=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=KM/YsmlXHkJAVJ3KCHwSaklDz2KOAankoMoedY+Prkdu8T7rXmrKCbGvlk71sE6sm Ai3q6k3zfAXPgNZ37o19EdAefUvtzy1TpP+nY4dX+DN6n/p0IgCXv2jkcdfW/9Efyq DNsIoC7ffx+f+CeRtyvjO8QH6h70AslrmBqEfEAM= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pf1-x42c.google.com (mail-pf1-x42c.google.com [IPv6:2607:f8b0:4864:20::42c]) by sourceware.org (Postfix) with ESMTPS id 2F2493857C4A for ; Wed, 13 Apr 2022 18:25:14 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2F2493857C4A Received: by mail-pf1-x42c.google.com with SMTP id j17so2712618pfi.9 for ; Wed, 13 Apr 2022 11:25:14 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=xKO1p5wpII66g6kHJcRj1E3GE5aEnTBcAXwSFA2fYIg=; b=biLQ6Uw1KZx43PHOmNXoK8yxKsApZBEQh/jDLwxEYqFr31DHLIsZZPydvbX+EjzOnc cju5B2VdMfalD0lB0w+4d4rvQEKW5L8YOZe6uF9CN6Ep4Tqvhmq8k9F3z7lknX38vPL2 qeiVxiDF1POUQTvLGIQPVMtKkAc1tmeIzvZxrcVDyk9cqUdY8ZallcKXdOIwlSAsP5Xv k/2JgAXo98GpxiQ/WlZImu9puAEMf1XTY5rVnsmvlz7FoIS0ucRnKq+mTfV4LYd9yVNI +xPq7HZzH1RfyBPYOyHUHwAuFuPynphtXt1Aae6JCfXp0cbBp7X9XoV6WsN3wJxcUHth lnLw== X-Gm-Message-State: AOAM530mZgipJYKiOgkesSw4TrKd348yCSuEqzXwRk4vWOxIxBQ/GaFn qV7/CLR1mLs9nkbqoZIz4e8jAOKoBOM= X-Google-Smtp-Source: ABdhPJw6E9iXCLCRhHoBf3Q1NdJTZHLbj3YP9xaDKA9kl3oOAuzg+eL0oVL/t7AW7bf0SJYu0HbqwQ== X-Received: by 2002:a63:da4d:0:b0:39d:353e:64fb with SMTP id l13-20020a63da4d000000b0039d353e64fbmr16547824pgj.34.1649874313164; Wed, 13 Apr 2022 11:25:13 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id m10-20020a17090a414a00b001cb776494a5sm3711941pjg.0.2022.04.13.11.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:11 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id A7E19C023F; Wed, 13 Apr 2022 11:25:10 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 4/6] elf: Properly handle zero DT_RELA/DT_REL values Date: Wed, 13 Apr 2022 11:25:05 -0700 Message-Id: <20220413182507.896862-5-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3028.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" With DT_RELR, there may be no relocations in DT_RELA/DT_REL and their entry values are zero. Don't relocate DT_RELA/DT_REL and update the combined relocation start address if their entry values are zero. --- elf/dynamic-link.h | 6 +++++- elf/get-dynamic-info.h | 24 ++++++++++++++++++------ 2 files changed, 23 insertions(+), 7 deletions(-) diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h index 7325e0d9fc..7dd8f1b1d6 100644 --- a/elf/dynamic-link.h +++ b/elf/dynamic-link.h @@ -84,7 +84,9 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], __typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative; int lazy; } \ ranges[2] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 } }; \ \ - if ((map)->l_info[DT_##RELOC]) \ + /* With DT_RELR, DT_RELA/DT_REL can have zero value. */ \ + if ((map)->l_info[DT_##RELOC] != NULL \ + && (map)->l_info[DT_##RELOC]->d_un.d_ptr != 0) \ { \ ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]); \ ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val; \ @@ -98,6 +100,8 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[], ElfW(Addr) start = D_PTR ((map), l_info[DT_JMPREL]); \ ElfW(Addr) size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val; \ \ + if (ranges[0].start == 0) \ + ranges[0].start = start; \ if (ranges[0].start + ranges[0].size == (start + size)) \ ranges[0].size -= size; \ if (!(do_lazy) \ diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h index 6c2a3a12b1..0314baf020 100644 --- a/elf/get-dynamic-info.h +++ b/elf/get-dynamic-info.h @@ -75,24 +75,36 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap, # define ADJUST_DYN_INFO(tag) \ do \ - if (info[tag] != NULL) \ - info[tag]->d_un.d_ptr += l_addr; \ + { \ + if (info[tag] != NULL) \ + info[tag]->d_un.d_ptr += l_addr; \ + } \ while (0) ADJUST_DYN_INFO (DT_HASH); ADJUST_DYN_INFO (DT_PLTGOT); ADJUST_DYN_INFO (DT_STRTAB); ADJUST_DYN_INFO (DT_SYMTAB); + ADJUST_DYN_INFO (DT_RELR); + ADJUST_DYN_INFO (DT_JMPREL); + ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM)); + ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH)); +# undef ADJUST_DYN_INFO + + /* DT_RELA/DT_REL are mandatory. But they may have zero value if + there is DT_RELR. Don't relocate them if they are zero. */ +# define ADJUST_DYN_INFO(tag) \ + do \ + if (info[tag] != NULL && info[tag]->d_un.d_ptr != 0) \ + info[tag]->d_un.d_ptr += l_addr; \ + while (0) + # if ! ELF_MACHINE_NO_RELA ADJUST_DYN_INFO (DT_RELA); # endif # if ! ELF_MACHINE_NO_REL ADJUST_DYN_INFO (DT_REL); # endif - ADJUST_DYN_INFO (DT_RELR); - ADJUST_DYN_INFO (DT_JMPREL); - ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM)); - ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH)); # undef ADJUST_DYN_INFO } if (info[DT_PLTREL] != NULL) From patchwork Wed Apr 13 18:25:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52870 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 4FAC3385803E for ; Wed, 13 Apr 2022 18:27:39 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4FAC3385803E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874459; bh=oaeF0BZvRmIPuaHxS/nY733QNC354E8ZzcNNLAPI27g=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=Xe9hEOm7aSPuu/a72RG3rcAunIqf368oGv+Ck4fWu6YgOXTKkh5FWphCleDwNCCI1 2ibYsYjucl9Vb+AQBftvJuHURUPx2yjMAZ/cjGiK+/GJSnsJAy5gnm7QtveUXVKUxP XoyC5jfQDzRNKgveYhdxcA+4PiEOa4eMhsmdwfG8= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pf1-x435.google.com (mail-pf1-x435.google.com [IPv6:2607:f8b0:4864:20::435]) by sourceware.org (Postfix) with ESMTPS id C24F5385801B for ; Wed, 13 Apr 2022 18:25:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C24F5385801B Received: by mail-pf1-x435.google.com with SMTP id cw11so2745415pfb.1 for ; Wed, 13 Apr 2022 11:25:13 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=oaeF0BZvRmIPuaHxS/nY733QNC354E8ZzcNNLAPI27g=; b=QJEZ16Ixjxz6AZYScjEdMEky0Ff8xkEsVPG0Kce3NNEUTwrpferFl4qKyXak6mjSEe BdR48TAvnUpceqz4P1PQ36qrNm+6jSSpeELnIgf6CkLFVKFHvPrD1zas86rV2o6aTasr QPPfSIUWSmlAdCkYpyUwakm0v7WJT1cabIonuC4Qwl+U6xaSK5oKMADZX4D2OrBLUqhF YLucz4s8TpVWQ55kqBB6JGYcnyyUsHKtw2yo5h0y8E8aSu2zuOV1DhOo8PKEuDW1h8AD TScAYfMWcptQFKMUBaJZLlbKDjX1gmqofRqMizqZ+0R+IdOKwyi4jCllZmqoEmRfs2ju FKnQ== X-Gm-Message-State: AOAM531w3XooSzSCDsBNI2G/ooiCYas1tCGHZKmTYOQM7v+oC17/q9n4 9HR2KpTImFz2Rmh/pZGN7xc6w/TYdkM= X-Google-Smtp-Source: ABdhPJzFbDIdnu9m6boPguUKLYcJv3H+re7L+dD4vcm+CdjlxiZbNZxX4Ep6eWdz9wPnX48BDQcCuQ== X-Received: by 2002:a62:fb0f:0:b0:4f2:6d3f:5ffb with SMTP id x15-20020a62fb0f000000b004f26d3f5ffbmr103806pfm.55.1649874312738; Wed, 13 Apr 2022 11:25:12 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id r10-20020a17090a454a00b001c96a912aa0sm3830221pjm.3.2022.04.13.11.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:11 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id A946FC0275; Wed, 13 Apr 2022 11:25:10 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 5/6] Add --disable-default-dt-relr Date: Wed, 13 Apr 2022 11:25:06 -0700 Message-Id: <20220413182507.896862-6-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3028.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Enable DT_RELR in glibc shared libraries and position independent executables (PIE) automatically if linker supports -z pack-relative-relocs. Also add a new configuration option, --disable-default-dt-relr, to avoid DT_RELR usage in glibc shared libraries and PIEs. --- INSTALL | 6 ++++++ Makeconfig | 19 +++++++++++++++++++ Makerules | 2 ++ configure | 18 ++++++++++++++++++ configure.ac | 13 +++++++++++++ elf/Makefile | 4 +++- manual/install.texi | 5 +++++ 7 files changed, 66 insertions(+), 1 deletion(-) diff --git a/INSTALL b/INSTALL index 63c022d6b9..4a6506f11f 100644 --- a/INSTALL +++ b/INSTALL @@ -133,6 +133,12 @@ if 'CFLAGS' is specified it must enable optimization. For example: used with the GCC option, -static-pie, which is available with GCC 8 or above, to create static PIE. +'--disable-default-dt-relr' + Don't enable DT_RELR in glibc shared libraries and position + independent executables (PIE). By default, DT_RELR is enabled in + glibc shared libraries and position independent executables on + targets that support it. + '--enable-cet' '--enable-cet=permissive' Enable Intel Control-flow Enforcement Technology (CET) support. diff --git a/Makeconfig b/Makeconfig index 0aa5fb0099..b75f28f837 100644 --- a/Makeconfig +++ b/Makeconfig @@ -358,6 +358,23 @@ else real-static-start-installed-name = $(static-start-installed-name) endif +# Linker option to enable and disable DT-RELR. +ifeq ($(have-dt-relr),yes) +dt-relr-ldflag = -Wl,-z,pack-relative-relocs +no-dt-relr-ldflag = -Wl,-z,nopack-relative-relocs +else +dt-relr-ldflag = +no-dt-relr-ldflag = +endif + +# Default linker option for DT-RELR. +ifeq (yes,$(build-dt-relr-default)) +default-rt-relr-ldflag = $(dt-relr-ldflag) +else +default-rt-relr-ldflag = $(no-dt-relr-ldflag) +endif +LDFLAGS-rtld += $(default-rt-relr-ldflag) + relro-LDFLAGS = -Wl,-z,relro LDFLAGS.so += $(relro-LDFLAGS) LDFLAGS-rtld += $(relro-LDFLAGS) @@ -413,6 +430,7 @@ link-extra-libs-tests = $(libsupport) # Command for linking PIE programs with the C library. ifndef +link-pie +link-pie-before-inputs = $(if $($(@F)-no-pie),$(no-pie-ldflag),-pie) \ + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \ -Wl,-O1 -nostdlib -nostartfiles \ $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \ $(relro-LDFLAGS) $(hashstyle-LDFLAGS) \ @@ -445,6 +463,7 @@ endif ifndef +link-static +link-static-before-inputs = -nostdlib -nostartfiles -static \ $(if $($(@F)-no-pie),$(no-pie-ldflag),$(static-pie-ldflag)) \ + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \ $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \ $(firstword $(CRT-$(@F)) $(csu-objpfx)$(real-static-start-installed-name)) \ $(+preinit) $(+prectorT) diff --git a/Makerules b/Makerules index 428464f092..7c1da551bf 100644 --- a/Makerules +++ b/Makerules @@ -536,6 +536,7 @@ lib%.so: lib%_pic.a $(+preinit) $(+postinit) $(link-libc-deps) define build-shlib-helper $(LINK.o) -shared -static-libgcc -Wl,-O1 $(sysdep-LDFLAGS) \ $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) $(rtld-LDFLAGS) \ + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \ $(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \ $(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \ -Wl,-soname=lib$(libprefix)$(@F:lib%.so=%).so$($(@F)-version) \ @@ -595,6 +596,7 @@ endef define build-module-helper $(LINK.o) -shared -static-libgcc $(sysdep-LDFLAGS) $(rtld-LDFLAGS) \ $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) \ + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \ -B$(csu-objpfx) $(load-map-file) \ $(LDFLAGS.so) $(LDFLAGS-$(@F:%.so=%).so) \ $(link-test-modules-rpath-link) \ diff --git a/configure b/configure index c0c2246597..d230c2c673 100755 --- a/configure +++ b/configure @@ -767,6 +767,7 @@ enable_sanity_checks enable_shared enable_profile enable_default_pie +enable_default_dt_relr enable_timezone_tools enable_hardcoded_path_in_tests enable_hidden_plt @@ -1424,6 +1425,7 @@ Optional Features: --enable-profile build profiled library [default=no] --disable-default-pie Do not build glibc programs and the testsuite as PIE [default=no] + --disable-dt-relr Do not enable DT_RELR in glibc[default=no] --disable-timezone-tools do not install timezone tools [default=install] --enable-hardcoded-path-in-tests @@ -3440,6 +3442,13 @@ else default_pie=yes fi +# Check whether --enable-default-dt-relr was given. +if test "${enable_default_dt_relr+set}" = set; then : + enableval=$enable_default_dt_relr; default_dt_relr=$enableval +else + default_dt_relr=yes +fi + # Check whether --enable-timezone-tools was given. if test "${enable_timezone_tools+set}" = set; then : enableval=$enable_timezone_tools; enable_timezone_tools=$enableval @@ -7092,6 +7101,15 @@ fi config_vars="$config_vars enable-static-pie = $libc_cv_static_pie" +# Disable build-dt-relr-default if linker does not support it or if glibc +# is configured with --disable-default-dt-relr. +build_dt_relr_default=$default_dt_relr +if test "x$build_dt_relr_default" != xno; then + build_dt_relr_default=$libc_cv_dt_relr +fi +config_vars="$config_vars +build-dt-relr-default = $build_dt_relr_default" + # Set the `multidir' variable by grabbing the variable from the compiler. # We do it once and save the result in a generated makefile. libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory` diff --git a/configure.ac b/configure.ac index 66cad71431..1aa152b901 100644 --- a/configure.ac +++ b/configure.ac @@ -197,6 +197,11 @@ AC_ARG_ENABLE([default-pie], [Do not build glibc programs and the testsuite as PIE @<:@default=no@:>@]), [default_pie=$enableval], [default_pie=yes]) +AC_ARG_ENABLE([default-dt-relr], + AS_HELP_STRING([--disable-dt-relr], + [Do not enable DT_RELR in glibc@<:@default=no@:>@]), + [default_dt_relr=$enableval], + [default_dt_relr=yes]) AC_ARG_ENABLE([timezone-tools], AS_HELP_STRING([--disable-timezone-tools], [do not install timezone tools @<:@default=install@:>@]), @@ -1878,6 +1883,14 @@ if test "$libc_cv_static_pie" = "yes"; then fi LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie]) +# Disable build-dt-relr-default if linker does not support it or if glibc +# is configured with --disable-default-dt-relr. +build_dt_relr_default=$default_dt_relr +if test "x$build_dt_relr_default" != xno; then + build_dt_relr_default=$libc_cv_dt_relr +fi +LIBC_CONFIG_VAR([build-dt-relr-default], [$build_dt_relr_default]) + # Set the `multidir' variable by grabbing the variable from the compiler. # We do it once and save the result in a generated makefile. libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory` diff --git a/elf/Makefile b/elf/Makefile index 979dde046d..ac6a73ec5e 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -1580,6 +1580,7 @@ $(objpfx)nodlopen2.out: $(objpfx)nodlopenmod2.so $(objpfx)filtmod1.so: $(objpfx)filtmod1.os $(objpfx)filtmod2.so $(LINK.o) -shared -o $@ -B$(csu-objpfx) $(LDFLAGS.so) \ + $(default-rt-relr-ldflag) \ -L$(subst :, -L,$(rpath-link)) \ -Wl,-rpath-link=$(rpath-link) \ $< -Wl,-F,$(objpfx)filtmod2.so @@ -2379,7 +2380,7 @@ $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so # artificial, large note in tst-big-note-lib.o and invalidate the # test. $(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o - $(LINK.o) -shared -o $@ $(LDFLAGS.so) $< + $(LINK.o) -shared -o $@ $(LDFLAGS.so) $(default-rt-relr-ldflag) $< $(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so @@ -2685,6 +2686,7 @@ $(objpfx)tst-ro-dynamic: $(objpfx)tst-ro-dynamic-mod.so $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \ tst-ro-dynamic-mod.map $(LINK.o) -nostdlib -nostartfiles -shared -o $@ \ + $(default-rt-relr-ldflag) \ -Wl,--script=tst-ro-dynamic-mod.map \ $(objpfx)tst-ro-dynamic-mod.os diff --git a/manual/install.texi b/manual/install.texi index 29c52f2927..04ea996561 100644 --- a/manual/install.texi +++ b/manual/install.texi @@ -161,6 +161,11 @@ and architecture support it, static executables are built as static PIE and the resulting glibc can be used with the GCC option, -static-pie, which is available with GCC 8 or above, to create static PIE. +@item --disable-default-dt-relr +Don't enable DT_RELR in glibc shared libraries and position independent +executables (PIE). By default, DT_RELR is enabled in glibc shared +libraries and position independent executables on targets that support it. + @item --enable-cet @itemx --enable-cet=permissive Enable Intel Control-flow Enforcement Technology (CET) support. When From patchwork Wed Apr 13 18:25:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 52872 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 9BB103857827 for ; Wed, 13 Apr 2022 18:29:08 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9BB103857827 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1649874548; bh=VfdVi8wa/LJolfSfghY+jykT8QLZOf4XLd8T7bejgS4=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=B6s3fAcN1FFkTRHKmw5PiGOAFq5yhWmp7THROp7o4RHF3XnDhT2U2fY057Kyd6XD+ 66hs9uDlDuVX1tEsWf4zOuqfrcEKgSJpFaNxEy4USHeKwyvFvvaUlKnduGXkgx0ICF vuTOCFluTi1qJc6Ji4TJ4Jb2+3sdAT7/jmf9H3oU= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by sourceware.org (Postfix) with ESMTPS id 353723857827 for ; Wed, 13 Apr 2022 18:25:15 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 353723857827 Received: by mail-pf1-x42a.google.com with SMTP id n22so2388563pfa.0 for ; Wed, 13 Apr 2022 11:25:15 -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:in-reply-to :references:mime-version:content-transfer-encoding; bh=VfdVi8wa/LJolfSfghY+jykT8QLZOf4XLd8T7bejgS4=; b=Hs/mhybB3I2YL5quq+zRadzri71YcqkqxUIBWLKELapc6VY3/C2Ne+8xrFroqArvaJ B2u4YnkxzYUqOtM6P4ccNgGgip9xtxTaQJeRjNmL9ucTHtNEzF6IKpWcTvnM9PfS3w1F +jqBCII6wlLL1nvg9eTdBYMqK9JX372nliNPAAxBryUypvlVkONQh4piWWvXTU7Rubxa WeFbFQP6gLCCZVGFgLu8YUz98RSMuWOfYwwwzXNNMQZaPcRS9iECcKNeItfhIKjPvNaQ vn3DxBf8m8/YPzRaVCP8cXfFrI/hwj0t5dn1nnq+GC1g9huD8d1o1EU0GdLKQAIi2mLZ Grlw== X-Gm-Message-State: AOAM530bLjUaLijb87g2Bw2dN4toJtl+y9dRLrp1iBlvBQ7UbwT/gsFV jb7JF+Tg+rPXSvUmNJchpEE= X-Google-Smtp-Source: ABdhPJxX58du/2jcOEG6pXVBO9RVWYXYIz16hDsiUEbGU0W9quiCijTiiZXAU/WtOMr1Ytzp0BLvCw== X-Received: by 2002:a05:6a00:ad0:b0:4e1:2d96:2ab0 with SMTP id c16-20020a056a000ad000b004e12d962ab0mr107505pfl.3.1649874314307; Wed, 13 Apr 2022 11:25:14 -0700 (PDT) Received: from gnu-tgl-3.localdomain ([172.58.35.207]) by smtp.gmail.com with ESMTPSA id ne24-20020a17090b375800b001cb62235013sm3477321pjb.5.2022.04.13.11.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Apr 2022 11:25:11 -0700 (PDT) Received: from gnu-tgl-3.. (localhost [IPv6:::1]) by gnu-tgl-3.localdomain (Postfix) with ESMTP id B4AE3C0323; Wed, 13 Apr 2022 11:25:10 -0700 (PDT) To: libc-alpha@sourceware.org Subject: [PATCH v8 6/6] NEWS: Mention DT_RELR support Date: Wed, 13 Apr 2022 11:25:07 -0700 Message-Id: <20220413182507.896862-7-hjl.tools@gmail.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220413182507.896862-1-hjl.tools@gmail.com> References: <20220413182507.896862-1-hjl.tools@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-3028.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" --- NEWS | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) Reviewed-by: Fangrui Song diff --git a/NEWS b/NEWS index 4b6d9de2b5..ef8ac4acd2 100644 --- a/NEWS +++ b/NEWS @@ -9,7 +9,12 @@ Version 2.36 Major new features: - [Add new features here] +* Support for DT_RELR relative relocation format has been added to + glibc. This is a new ELF dynamic tag that improves the size of + relative relocations in shared object files and position independent + executables (PIE). DT_RELR generation requires linker support for + -z pack-relative-relocs option, which is supported for some targets + in recent binutils versions. Lazy binding doesn't apply to DT_RELR. Deprecated and removed features, and other changes affecting compatibility: