From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f174.google.com (mail-pf1-f174.google.com [209.85.210.174]) by sourceware.org (Postfix) with ESMTPS id 370E93858C51 for ; Sun, 26 Jun 2022 19:03:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 370E93858C51 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=maskray.me Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pf1-f174.google.com with SMTP id x4so7119891pfq.2 for ; Sun, 26 Jun 2022 12:03:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cF3wrl0OG+k3k50d/f+NQ3J5b8j96DR5KDUqxQxNnkA=; b=aZL6Ou9/jZjMZ+mOlOhzMwcJQaaayt0SYg0AuJ8ui7q8RHehyXVt0XJFzq8+7lh6eG D0HZ3UmaGG08WswF5T20oRH3nH+A/RaxdW0iQWIqJxt5wE4NSZp2W3nxLrfcQe1QwD1y zfySnMJcHEC2Us/lyIJgZL6bvQrWK8nKGh5HC5Q8bmxClI5WZCf8Iqo+pEX9E6xSE4FX kxc4D8Ba4U9nwRDsIjmKyZXE+PzXQsojoTAtzcS3bu6XfsUdwrb4cOnCmPACdXYXnr8O 7XEQV22g7uuyl3vXDYTRhNtCpidvhMWdN/RymHqeOv0aWxw0DSx8ljIYpuaOPuevvgmM l4Yw== X-Gm-Message-State: AJIora949BLT2XQDi49innWauT7jTNaZ1D5xzmtQiPmJ56U1qgbilfPS zFaG+V76M1PlLSbhUjZEtx33FLqiHqs= X-Google-Smtp-Source: AGRyM1t0/v+N/TFcdDX/MicLotpTIc1/biR0VqiBZkpd8a6ApSrFdYyk99M9IxjllIHB+pX6xFHY0Q== X-Received: by 2002:a62:ab05:0:b0:525:9105:58c7 with SMTP id p5-20020a62ab05000000b00525910558c7mr7595224pff.32.1656270183090; Sun, 26 Jun 2022 12:03:03 -0700 (PDT) Received: from localhost ([2601:647:6300:b760:896d:43da:187f:15b5]) by smtp.gmail.com with ESMTPSA id v10-20020a17090a00ca00b001ea5d9ae7d9sm7683028pjd.40.2022.06.26.12.03.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 26 Jun 2022 12:03:02 -0700 (PDT) Date: Sun, 26 Jun 2022 12:03:01 -0700 From: Fangrui Song To: "H.J. Lu" Cc: Binutils Subject: Re: [PATCH] x86: Make protected symbols local for -shared Message-ID: <20220626190301.44tptog54cqex4re@gmail.com> References: <20220625174426.1475218-1-i@maskray.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-8.1 required=5.0 tests=BAYES_00, FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM, GIT_PATCH_0, HEADER_FROM_DIFFERENT_DOMAINS, KAM_DMARC_STATUS, KAM_INFOUSMEBIZ, KAM_STOCKGEN, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: binutils@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Binutils mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Jun 2022 19:03:06 -0000 On 2022-06-26, H.J. Lu wrote: >On Sat, Jun 25, 2022 at 10:44 AM Fangrui Song wrote: >> >> Call _bfd_elf_symbol_refs_local_p with local_protected==true. This has >> 2 noticeable effects for -shared: >> >> * GOT-generating relocations referencing a protected data symbol no >> longer lead to a GLOB_DAT (similar to a hidden symbol). >> * Direct access relocations (e.g. R_X86_64_PC32) no longer has the >> confusing diagnostic below. >> >> __attribute__((visibility("protected"))) void *foo() { >> return (void *)foo; >> } >> >> // gcc -fpic -shared -fuse-ld=bfd >> relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object >> >> The new behavior matches arm, aarch64 (commit >> 83c325007c5599fa9b60b8d5f7b84842160e1d1b), and powerpc ports, and other >> linkers: gold and ld.lld. >> >> Note: if some code tries to use direct access relocations to take the >> address of foo, the pointer equality will break, but the error should be >> reported on the executable link, not on the innocent shared object link. >> glibc 2.36 will give a warning at relocation resolving time. > >It should be controlled by -z [no]indirect-extern-access. Can you enable >-z indirect-extern-access with -shared by default instead? If I set `link_info.indirect_extern_access = 1;` in ld/ldmain.c, bfd/elf-properties.c:654 will create a GNU_PROPERTY_1_NEEDED_INDIRECT_EXTERN_ACCESS note. This will probably be unexpected (and check-ld will have 280+ failures). >> With this change, `#define elf_backend_extern_protected_data 1` is no >> longer effective. Just remove it. >> >> Remove the test "Run protected-func-1 without PIE" since -fno-pic >> address taken operation in the executable doesn't work with protected >> symbol in a shared object by default. Similarly, remove >> protected-data-1a and protected-data-1b. protected-data-1b can be made >> working by removing HAVE_LD_PIE_COPYRELOC from GCC >> (https://sourceware.org/pipermail/gcc-patches/2022-June/596678.html). >> --- >> bfd/elf32-i386.c | 1 - >> bfd/elf64-x86-64.c | 1 - >> bfd/elfxx-x86.c | 2 +- >> ld/testsuite/ld-i386/protected1.d | 4 +++- >> ld/testsuite/ld-i386/protected3.d | 2 +- >> ld/testsuite/ld-i386/protected6a.d | 4 +++- >> ld/testsuite/ld-x86-64/pr24151a-x32.d | 4 +++- >> ld/testsuite/ld-x86-64/pr24151a.d | 4 +++- >> ld/testsuite/ld-x86-64/protected1.d | 4 +++- >> ld/testsuite/ld-x86-64/protected3.d | 2 +- >> ld/testsuite/ld-x86-64/protected6a.d | 4 +++- >> ld/testsuite/ld-x86-64/protected7a.d | 4 +++- >> ld/testsuite/ld-x86-64/x86-64.exp | 27 --------------------------- >> 13 files changed, 24 insertions(+), 39 deletions(-) >> >> diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c >> index e4106d9fd3b..c3c46795731 100644 >> --- a/bfd/elf32-i386.c >> +++ b/bfd/elf32-i386.c >> @@ -4424,7 +4424,6 @@ elf_i386_link_setup_gnu_properties (struct bfd_link_info *info) >> #define elf_backend_got_header_size 12 >> #define elf_backend_plt_alignment 4 >> #define elf_backend_dtrel_excludes_plt 1 >> -#define elf_backend_extern_protected_data 1 >> #define elf_backend_caches_rawsize 1 >> #define elf_backend_want_dynrelro 1 >> >> diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c >> index 6154a70bdd7..aaa5f1496b9 100644 >> --- a/bfd/elf64-x86-64.c >> +++ b/bfd/elf64-x86-64.c >> @@ -5275,7 +5275,6 @@ elf_x86_64_special_sections[]= >> #define elf_backend_got_header_size (GOT_ENTRY_SIZE*3) >> #define elf_backend_rela_normal 1 >> #define elf_backend_plt_alignment 4 >> -#define elf_backend_extern_protected_data 1 >> #define elf_backend_caches_rawsize 1 >> #define elf_backend_dtrel_excludes_plt 1 >> #define elf_backend_want_dynrelro 1 >> diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c >> index acb2cc8528d..18f3d335458 100644 >> --- a/bfd/elfxx-x86.c >> +++ b/bfd/elfxx-x86.c >> @@ -3094,7 +3094,7 @@ _bfd_x86_elf_link_symbol_references_local (struct bfd_link_info *info, >> 2. When building executable, there is no dynamic linker. Or >> 3. or "-z nodynamic-undefined-weak" is used. >> */ >> - if (SYMBOL_REFERENCES_LOCAL (info, h) >> + if (_bfd_elf_symbol_refs_local_p (h, info, 1) >> || (h->root.type == bfd_link_hash_undefweak >> && (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT >> || (bfd_link_executable (info) >> diff --git a/ld/testsuite/ld-i386/protected1.d b/ld/testsuite/ld-i386/protected1.d >> index a3cb5cef140..531645b8fe8 100644 >> --- a/ld/testsuite/ld-i386/protected1.d >> +++ b/ld/testsuite/ld-i386/protected1.d >> @@ -1,3 +1,5 @@ >> #as: --32 >> #ld: -shared -melf_i386 >> -#error: .*relocation R_386_GOTOFF against protected function `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-i386/protected3.d b/ld/testsuite/ld-i386/protected3.d >> index c3a6888d900..77367c4738f 100644 >> --- a/ld/testsuite/ld-i386/protected3.d >> +++ b/ld/testsuite/ld-i386/protected3.d >> @@ -8,7 +8,7 @@ >> Disassembly of section .text: >> >> 0+[a-f0-9]+ : >> -[ ]*[a-f0-9]+: 8b 81 [a-f0-9][a-f0-9] [a-f0-9][a-f0-9] ff ff mov -0x[a-f0-9]+\(%ecx\),%eax >> +[ ]*[a-f0-9]+: 8d 81 00 00 00 00 lea 0x0\(%ecx\),%eax >> [ ]*[a-f0-9]+: 8b 00 mov \(%eax\),%eax >> [ ]*[a-f0-9]+: c3 ret >> #pass >> diff --git a/ld/testsuite/ld-i386/protected6a.d b/ld/testsuite/ld-i386/protected6a.d >> index 7dc350432f4..4d3873239f9 100644 >> --- a/ld/testsuite/ld-i386/protected6a.d >> +++ b/ld/testsuite/ld-i386/protected6a.d >> @@ -1,4 +1,6 @@ >> #source: protected6.s >> #as: --32 >> #ld: -shared -melf_i386 >> -#error: .*relocation R_386_GOTOFF against protected data `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/pr24151a-x32.d b/ld/testsuite/ld-x86-64/pr24151a-x32.d >> index 130611ddf49..1f49b655f7d 100644 >> --- a/ld/testsuite/ld-x86-64/pr24151a-x32.d >> +++ b/ld/testsuite/ld-x86-64/pr24151a-x32.d >> @@ -1,4 +1,6 @@ >> #source: pr24151a.s >> #as: --x32 >> #ld: -shared -melf32_x86_64 >> -#error: .*relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/pr24151a.d b/ld/testsuite/ld-x86-64/pr24151a.d >> index 783b85a1a6f..6c48e383e01 100644 >> --- a/ld/testsuite/ld-x86-64/pr24151a.d >> +++ b/ld/testsuite/ld-x86-64/pr24151a.d >> @@ -1,3 +1,5 @@ >> #as: --64 >> #ld: -shared -melf_x86_64 >> -#error: .*relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/protected1.d b/ld/testsuite/ld-x86-64/protected1.d >> index 783b85a1a6f..6c48e383e01 100644 >> --- a/ld/testsuite/ld-x86-64/protected1.d >> +++ b/ld/testsuite/ld-x86-64/protected1.d >> @@ -1,3 +1,5 @@ >> #as: --64 >> #ld: -shared -melf_x86_64 >> -#error: .*relocation R_X86_64_PC32 against protected symbol `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/protected3.d b/ld/testsuite/ld-x86-64/protected3.d >> index 57950e4d6b6..ba63991582f 100644 >> --- a/ld/testsuite/ld-x86-64/protected3.d >> +++ b/ld/testsuite/ld-x86-64/protected3.d >> @@ -8,7 +8,7 @@ >> Disassembly of section .text: >> >> 0+[a-f0-9]+ : >> -[ ]*[a-f0-9]+: 48 8b 05 ([0-9a-f]{2} ){4} * mov 0x[a-f0-9]+\(%rip\),%rax # [a-f0-9]+ <.*> >> +[ ]*[a-f0-9]+: 48 8d 05 ([0-9a-f]{2} ){4} * lea 0x[a-f0-9]+\(%rip\),%rax # [a-f0-9]+ <.*> >> [ ]*[a-f0-9]+: 8b 00 mov \(%rax\),%eax >> [ ]*[a-f0-9]+: c3 ret >> #pass >> diff --git a/ld/testsuite/ld-x86-64/protected6a.d b/ld/testsuite/ld-x86-64/protected6a.d >> index 3a7963ffd2f..50d6430b577 100644 >> --- a/ld/testsuite/ld-x86-64/protected6a.d >> +++ b/ld/testsuite/ld-x86-64/protected6a.d >> @@ -1,4 +1,6 @@ >> #source: protected6.s >> #as: --64 >> #ld: -shared -melf_x86_64 >> -#error: .*relocation R_X86_64_GOTOFF64 against protected data `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/protected7a.d b/ld/testsuite/ld-x86-64/protected7a.d >> index 3082084a7b8..3974246a2a8 100644 >> --- a/ld/testsuite/ld-x86-64/protected7a.d >> +++ b/ld/testsuite/ld-x86-64/protected7a.d >> @@ -1,4 +1,6 @@ >> #source: protected7.s >> #as: --64 >> #ld: -shared -melf_x86_64 >> -#error: .*relocation R_X86_64_GOTOFF64 against protected function `foo' can not be used when making a shared object >> +#readelf: -rW >> +#... >> +There are no relocations in this file. >> diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp >> index 5e5636bcebe..a096c0b9d0f 100644 >> --- a/ld/testsuite/ld-x86-64/x86-64.exp >> +++ b/ld/testsuite/ld-x86-64/x86-64.exp >> @@ -1832,15 +1832,6 @@ if { [isnative] && [check_compiler_available] } { >> "pr23997" \ >> "pass.out" \ >> ] \ >> - [list \ >> - "Run protected-func-1 without PIE" \ >> - "$NOPIE_LDFLAGS -Wl,--no-as-needed tmpdir/libprotected-func-1.so" \ >> - "-Wa,-mx86-used-note=yes" \ >> - { protected-func-1b.c } \ >> - "protected-func-1a" \ >> - "pass.out" \ >> - "$NOPIE_CFLAGS" \ >> - ] \ >> [list \ >> "Run protected-func-1 with PIE" \ >> "-Wl,--no-as-needed -pie tmpdir/libprotected-func-1.so" \ >> @@ -1904,24 +1895,6 @@ if { [isnative] && [check_compiler_available] } { >> "pass.out" \ >> "-fPIE" \ >> ] \ >> - [list \ >> - "Run protected-data-1a without PIE" \ >> - "$NOPIE_LDFLAGS -Wl,--no-as-needed tmpdir/libprotected-data-1a.so" \ >> - "-Wa,-mx86-used-note=yes" \ >> - { protected-data-1b.c } \ >> - "protected-data-1a" \ >> - "pass.out" \ >> - "$NOPIE_CFLAGS" \ >> - ] \ >> - [list \ >> - "Run protected-data-1b with PIE" \ >> - "-Wl,--no-as-needed -pie tmpdir/libprotected-data-1a.so" \ >> - "-Wa,-mx86-used-note=yes" \ >> - { protected-data-1b.c } \ >> - "protected-data-1b" \ >> - "pass.out" \ >> - "-fPIE" \ >> - ] \ >> [list \ >> "Run protected-data-2a without PIE" \ >> "$NOPIE_LDFLAGS -Wl,--no-as-needed tmpdir/libprotected-data-2a.so" \ >> -- >> 2.37 >> > > >-- >H.J.