From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20103 invoked by alias); 11 Jul 2012 00:04:28 -0000 Received: (qmail 20078 invoked by uid 22791); 11 Jul 2012 00:04:22 -0000 X-SWARE-Spam-Status: No, hits=-0.5 required=5.0 tests=AWL,BAYES_50,KAM_STOCKGEN,KHOP_THREADED,TW_BJ,TW_JS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from eddie.linux-mips.org (HELO cvs.linux-mips.org) (78.24.191.182) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 11 Jul 2012 00:04:06 +0000 Received: from localhost.localdomain ([127.0.0.1]:39071 "EHLO localhost.localdomain" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S1903675Ab2GKAEE (ORCPT ); Wed, 11 Jul 2012 02:04:04 +0200 Date: Wed, 11 Jul 2012 00:04:00 -0000 From: "Maciej W. Rozycki" To: Hans-Peter Nilsson cc: Jan-Benedict Glaw , binutils@sourceware.org Subject: Re: [PATCH] VAX/BFD: Omit PLT slots for local symbols In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-IsSubscribed: yes Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org X-SW-Source: 2012-07/txt/msg00103.txt.bz2 On Tue, 8 May 2012, Hans-Peter Nilsson wrote: > > ld/testsuite/ > > * ld-vax-elf/plt-local-lib.dd: New test. > > * ld-vax-elf/plt-local-lib.ld: New test linker script. > > * ld-vax-elf/plt-local-lib.s: New test source. > > * ld-vax-elf/plt-local.dd: New test. > > * ld-vax-elf/plt-local.ld:New test linker script. > > * ld-vax-elf/plt-local.s: New test source. > > * ld-vax-elf/plt-local-hidden-pic.s: New test source. > > * ld-vax-elf/plt-local-rehidden-pic.s: New test source. > > * ld-vax-elf/vax-elf.exp: New test script. > > > Index: binutils/ld/testsuite/ld-vax-elf/vax-elf.exp > > =================================================================== > > --- /dev/null > > +++ binutils/ld/testsuite/ld-vax-elf/vax-elf.exp > > @@ -0,0 +1,50 @@ > > +# Expect script for VAX ELF linker tests > > ... > > + > > +run_ld_link_tests [list \ > > + [list "PLT test (shared library)" \ > > + "-shared -T plt-local-lib.ld" \ > > + "-k" \ > > + { plt-local-lib.s } \ > > + { { objdump -d plt-local-lib.dd } } \ > > + "plt-local-lib.so"] \ > > + [list "PLT test (object 1)" \ > > + "-r" \ > > ... (pruned for brevity) > > Ouch, another one of those tables-of-lists-of-tables and in a > brand-new .exp. > > Let me suggest instead using a mechanism such as run_dump_test > with depended parts (DSO's linked against) sorted before others. > This'd give easy drop-in of new tests without having to add to a > separate table entry somewhere. See ld-cris/cris.exp. Similar > new test: ld-arm/gc-hidden-1.d (unfortunately there's no > file-name iterator in arm-elf.exp, entries are still added > manually). So I have found some time to look into your suggestion, and frankly, I am not happy with it at all. In my opinion your approach merely avoids the shortcomings of the LD test framework in a different way. If I could honestly say it is a solution, then I would certainly be eager to adopt it. I find it to be a workaround because: 1. The dependency between the final executable and any shared libraries is not expressed anywhere except from the linker flags in the ld: specifier. Of course keeping the dependency in a single place is good, but the way it works in your scheme it doesn't actually cause the framework to take it into account in any way, it just depends on building all the shared libraries first. 2. Test cases are not grouped together anymore, if for example a test case consists of a bunch of shared libraries and a bunch of executables linked against them, then the shared libraries are tested at a different stage than the executables. That may make following the dependencies a bit more difficult. 3. Test cases are run implicitly -- you see it as an advantage, I do not. I find such test suites harder to follow and prefer being able to add any extra commentary or other arrangements in .exp files (cf. the MIPS test suite and the "foreach { abi flag emul } $abis { ... }" loop there). 4. It resorts to some fragile file shuffling code so that proper .so objects are created. On the contrary my proposal makes it clearly a self-contained test case, it is easily readable and the only drawback is it uses an unnecessary incremental link because run_ld_link_tests does not support stopping after assembly for intermediate steps. So yes, it has shortcomings, but your proposal has no clear advantage to me I am afraid. NB the first shared-library dump is not strictly necessary and does not check anything related to this bug, I just added it to have extra coverage, because -- as you must have undoubtedly noticed -- current one for the VAX ELF target is particularly poor. Your proposal does not address cases where a dump of any intermediate shared libraries is not required and in my version you can just remove the "objdump" clause. So I think the test case is as good as it could be as it stands. That said however, I do not object discussing any improvement to the LD test framework. Including in particular a way to pull shared library dependencies automatically from .d files. I have a vague shape of how this might look like in my mind, but let's leave it to sharpen for now; I don't think any prospect of a test suite improvement should be holding this obvious bug fix. So taking the above consideration into account would anyone with the power to approve this submission please review my proposal and say whether it is OK or not? I have repeated it below to save you digging through mailing list archives. Thanks. > The change below fixes a problem with the creation of the PLT on the VAX > target, where entries are made where they should not for local symbols, > leading to unneeded or even empty slots. The conditions for the latters > are a bit obscure, for such a slot to be created a dynamic symbol has to > be preempted in the link with a static hidden symbol referred to by a PLT > relocation (i.e. from a PIC relocatable). This is covered by the test > case provided. Executables with empty PLT slots are invalid and rejected > by the dynamic linker. > > There is some code duplication in the area affected, so I have merged the > two pieces (that deal with local and garbage-collected symbols, > respectively) into one, similarly to how some other targets do it. Also > the attempt to make a symbol whose h->dynindx is -1 dynamic is incorrect > here -- such symbols will have qualified as local in SYMBOL_CALLS_LOCAL > and shouldn't be produced. > > No regressions with this change. OK to apply? 2012-07-11 Maciej W. Rozycki bfd/ * elf32-vax.c (elf_vax_adjust_dynamic_symbol): Don't allocate PLT slots for local symbols. ld/testsuite/ * ld-vax-elf/plt-local-lib.dd: New test. * ld-vax-elf/plt-local-lib.ld: New test linker script. * ld-vax-elf/plt-local-lib.s: New test source. * ld-vax-elf/plt-local.dd: New test. * ld-vax-elf/plt-local.ld:New test linker script. * ld-vax-elf/plt-local.s: New test source. * ld-vax-elf/plt-local-hidden-pic.s: New test source. * ld-vax-elf/plt-local-rehidden-pic.s: New test source. * ld-vax-elf/vax-elf.exp: New test script. Maciej binutils-vax-plt-local.patch Index: binutils/bfd/elf32-vax.c =================================================================== --- binutils.orig/bfd/elf32-vax.c +++ binutils/bfd/elf32-vax.c @@ -934,39 +934,21 @@ elf_vax_adjust_dynamic_symbol (info, h) if (h->type == STT_FUNC || h->needs_plt) { - if (! info->shared - && !h->def_dynamic - && !h->ref_dynamic - /* We must always create the plt entry if it was referenced - by a PLTxxO relocation. In this case we already recorded - it as a dynamic symbol. */ - && h->dynindx == -1) + if (h->plt.refcount <= 0 + || SYMBOL_CALLS_LOCAL (info, h) + || (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT + && h->root.type == bfd_link_hash_undefweak)) { /* This case can occur if we saw a PLTxx reloc in an input file, but the symbol was never referred to by a dynamic - object. In such a case, we don't actually need to build - a procedure linkage table, and we can just do a PCxx - reloc instead. */ - BFD_ASSERT (h->needs_plt); + object, or if all references were garbage collected. In + such a case, we don't actually need to build a procedure + linkage table, and we can just do a PCxx reloc instead. */ h->plt.offset = (bfd_vma) -1; - return TRUE; - } - - /* GC may have rendered this entry unused. */ - if (h->plt.refcount <= 0) - { h->needs_plt = 0; - h->plt.offset = (bfd_vma) -1; return TRUE; } - /* Make sure this symbol is output as a dynamic symbol. */ - if (h->dynindx == -1) - { - if (! bfd_elf_link_record_dynamic_symbol (info, h)) - return FALSE; - } - s = bfd_get_section_by_name (dynobj, ".plt"); BFD_ASSERT (s != NULL); Index: binutils/ld/testsuite/ld-vax-elf/plt-local-hidden-pic.s =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local-hidden-pic.s @@ -0,0 +1,14 @@ + .text + + .hidden foo_hidden + .globl foo_hidden + .type foo_hidden, @function +foo_hidden: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_hidden, . - foo_hidden Index: binutils/ld/testsuite/ld-vax-elf/plt-local-lib.dd =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local-lib.dd @@ -0,0 +1,91 @@ +.*: +file format .*vax.* + +Disassembly of section \.plt: + +00001000 : + 1000: dd ef 76 20 pushl 307c <_GLOBAL_OFFSET_TABLE_\+0x4> + 1004: 00 00 + 1006: 17 ff 74 20 jmp \*3080 <_GLOBAL_OFFSET_TABLE_\+0x8> + 100a: 00 00 + +0000100c : + 100c: fc 0f \.word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > + 100e: 16 ef ec ff jsb 1000 + 1012: ff ff + 1014: 00 00 00 00 \.long 0x00000000 + +00001018 : + 1018: fc 0f \.word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > + 101a: 16 ef e0 ff jsb 1000 + 101e: ff ff + 1020: 0c 00 00 00 \.long 0x0000000c + +00001024 : + 1024: fc 0f \.word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > + 1026: 16 ef d4 ff jsb 1000 + 102a: ff ff + 102c: 18 00 00 00 \.long 0x00000018 + +00001030 : + 1030: fc 0f \.word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > + 1032: 16 ef c8 ff jsb 1000 + 1036: ff ff + 1038: 24 00 00 00 \.long 0x00000024 + +Disassembly of section \.text: + +00002000 : + 2000: 00 00 \.word 0x0000 # Entry mask: < > + 2002: fb 00 ff 7f calls \$0x0,\*3088 <_GLOBAL_OFFSET_TABLE_\+0x10> + 2006: 10 00 00 + 2009: fb 00 ff 80 calls \$0x0,\*3090 <_GLOBAL_OFFSET_TABLE_\+0x18> + 200d: 10 00 00 + 2010: fb 00 ff 6d calls \$0x0,\*3084 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2014: 10 00 00 + 2017: fb 00 ef 2e calls \$0x0,204c + 201b: 00 00 00 + 201e: fb 00 ff 67 calls \$0x0,\*308c <_GLOBAL_OFFSET_TABLE_\+0x14> + 2022: 10 00 00 + 2025: 04 ret + +00002026 : + 2026: 00 00 \.word 0x0000 # Entry mask: < > + 2028: fb 00 ff 59 calls \$0x0,\*3088 <_GLOBAL_OFFSET_TABLE_\+0x10> + 202c: 10 00 00 + 202f: fb 00 ff 5a calls \$0x0,\*3090 <_GLOBAL_OFFSET_TABLE_\+0x18> + 2033: 10 00 00 + 2036: fb 00 ff 47 calls \$0x0,\*3084 <_GLOBAL_OFFSET_TABLE_\+0xc> + 203a: 10 00 00 + 203d: fb 00 ef 08 calls \$0x0,204c + 2041: 00 00 00 + 2044: fb 00 ff 41 calls \$0x0,\*308c <_GLOBAL_OFFSET_TABLE_\+0x14> + 2048: 10 00 00 + 204b: 04 ret + +0000204c : + 204c: 00 00 \.word 0x0000 # Entry mask: < > + 204e: fb 00 ff 33 calls \$0x0,\*3088 <_GLOBAL_OFFSET_TABLE_\+0x10> + 2052: 10 00 00 + 2055: fb 00 ff 34 calls \$0x0,\*3090 <_GLOBAL_OFFSET_TABLE_\+0x18> + 2059: 10 00 00 + 205c: fb 00 ff 21 calls \$0x0,\*3084 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2060: 10 00 00 + 2063: fb 00 ef e2 calls \$0x0,204c + 2067: ff ff ff + 206a: fb 00 ff 1b calls \$0x0,\*308c <_GLOBAL_OFFSET_TABLE_\+0x14> + 206e: 10 00 00 + 2071: 04 ret + +00002072 : + 2072: 00 00 \.word 0x0000 # Entry mask: < > + 2074: fb 00 ff 0d calls \$0x0,\*3088 <_GLOBAL_OFFSET_TABLE_\+0x10> + 2078: 10 00 00 + 207b: fb 00 ff 0e calls \$0x0,\*3090 <_GLOBAL_OFFSET_TABLE_\+0x18> + 207f: 10 00 00 + 2082: fb 00 ff fb calls \$0x0,\*3084 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2086: 0f 00 00 + 2089: fb 00 ef bc calls \$0x0,204c + 208d: ff ff ff + 2090: fb 00 ff f5 calls \$0x0,\*308c <_GLOBAL_OFFSET_TABLE_\+0x14> + 2094: 0f 00 00 + 2097: 04 ret Index: binutils/ld/testsuite/ld-vax-elf/plt-local-lib.ld =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local-lib.ld @@ -0,0 +1,18 @@ +SECTIONS +{ + . = 0; + .hash : { *(.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .rela.plt : { *(.rela.plt) } + + . = 0x1000; + .plt : { *(.plt) } + + . = 0x2000; + .text : { *(.text) } + + . = 0x3000; + .dynamic : { *(.dynamic) } + .got : { *(.got.plt) } +} Index: binutils/ld/testsuite/ld-vax-elf/plt-local-lib.s =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local-lib.s @@ -0,0 +1,50 @@ + .text + + .globl foo_extern + .type foo_extern, @function +foo_extern: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_extern, . - foo_extern + + .globl foo_local + .type foo_local, @function +foo_local: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_local, . - foo_local + + .hidden foo_hidden + .globl foo_hidden + .type foo_hidden, @function +foo_hidden: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_hidden, . - foo_hidden + + .globl foo_rehidden + .type foo_rehidden, @function +foo_rehidden: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_rehidden, . - foo_rehidden Index: binutils/ld/testsuite/ld-vax-elf/plt-local-rehidden-pic.s =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local-rehidden-pic.s @@ -0,0 +1,14 @@ + .text + + .hidden foo_rehidden + .globl foo_rehidden + .type foo_rehidden, @function +foo_rehidden: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_rehidden, . - foo_rehidden Index: binutils/ld/testsuite/ld-vax-elf/plt-local.dd =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local.dd @@ -0,0 +1,73 @@ +.*: +file format .*vax.* + +Disassembly of section \.plt: + +00001000 : + 1000: dd ef 86 20 pushl 308c <_GLOBAL_OFFSET_TABLE_\+0x4> + 1004: 00 00 + 1006: 17 ff 84 20 jmp \*3090 <_GLOBAL_OFFSET_TABLE_\+0x8> + 100a: 00 00 + +0000100c : + 100c: fc 0f \.word 0x0ffc # Entry mask: < r11 r10 r9 r8 r7 r6 r5 r4 r3 r2 > + 100e: 16 ef ec ff jsb 1000 + 1012: ff ff + 1014: 00 00 00 00 \.long 0x00000000 + +Disassembly of section \.text: + +00002000 : + 2000: 00 00 \.word 0x0000 # Entry mask: < > + 2002: fb 00 ff 8b calls \$0x0,\*3094 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2006: 10 00 00 + 2009: fb 00 ef 3c calls \$0x0,204c + 200d: 00 00 00 + 2010: fb 00 ef 5b calls \$0x0,2072 + 2014: 00 00 00 + 2017: fb 00 ef e2 calls \$0x0,2000 + 201b: ff ff ff + 201e: fb 00 ef 01 calls \$0x0,2026 + 2022: 00 00 00 + 2025: 04 ret + +00002026 : + 2026: 00 00 \.word 0x0000 # Entry mask: < > + 2028: fb 00 ff 65 calls \$0x0,\*3094 <_GLOBAL_OFFSET_TABLE_\+0xc> + 202c: 10 00 00 + 202f: fb 00 ef 16 calls \$0x0,204c + 2033: 00 00 00 + 2036: fb 00 ef 35 calls \$0x0,2072 + 203a: 00 00 00 + 203d: fb 00 ef bc calls \$0x0,2000 + 2041: ff ff ff + 2044: fb 00 ef db calls \$0x0,2026 + 2048: ff ff ff + 204b: 04 ret + +0000204c : + 204c: 00 00 \.word 0x0000 # Entry mask: < > + 204e: fb 00 ff 3f calls \$0x0,\*3094 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2052: 10 00 00 + 2055: fb 00 ef f0 calls \$0x0,204c + 2059: ff ff ff + 205c: fb 00 ef 0f calls \$0x0,2072 + 2060: 00 00 00 + 2063: fb 00 ef 96 calls \$0x0,2000 + 2067: ff ff ff + 206a: fb 00 ef b5 calls \$0x0,2026 + 206e: ff ff ff + 2071: 04 ret + +00002072 : + 2072: 00 00 \.word 0x0000 # Entry mask: < > + 2074: fb 00 ff 19 calls \$0x0,\*3094 <_GLOBAL_OFFSET_TABLE_\+0xc> + 2078: 10 00 00 + 207b: fb 00 ef ca calls \$0x0,204c + 207f: ff ff ff + 2082: fb 00 ef e9 calls \$0x0,2072 + 2086: ff ff ff + 2089: fb 00 ef 70 calls \$0x0,2000 + 208d: ff ff ff + 2090: fb 00 ef 8f calls \$0x0,2026 + 2094: ff ff ff + 2097: 04 ret Index: binutils/ld/testsuite/ld-vax-elf/plt-local.ld =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local.ld @@ -0,0 +1,34 @@ +ENTRY (foo_global) +SECTIONS +{ + . = 0; + .interp : { *(.interp) } + .hash : { *(.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .gnu.version : { *(.gnu.version) } + .gnu.version_d : { *(.gnu.version_d) } + .rela.plt : { *(.rela.plt) } + + . = 0x1000; + .plt : { *(.plt) } + + . = 0x2000; + .text : { *(.text) } + + . = 0x3000; + .dynamic : { *(.dynamic) } + .got : { *(.got.plt) } +}; +VERSION +{ + { + global: + foo_extern; + foo_global; + foo_hidden; + foo_rehidden; + local: + foo_local; + }; +} Index: binutils/ld/testsuite/ld-vax-elf/plt-local.s =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/plt-local.s @@ -0,0 +1,25 @@ + .text + + .globl foo_global + .type foo_global, @function +foo_global: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_global, . - foo_global + + .globl foo_local + .type foo_local, @function +foo_local: + .word 0 + calls $0, foo_extern + calls $0, foo_global + calls $0, foo_local + calls $0, foo_hidden + calls $0, foo_rehidden + ret + .size foo_local, . - foo_local Index: binutils/ld/testsuite/ld-vax-elf/vax-elf.exp =================================================================== --- /dev/null +++ binutils/ld/testsuite/ld-vax-elf/vax-elf.exp @@ -0,0 +1,50 @@ +# Expect script for VAX ELF linker tests +# Copyright 2012 Free Software Foundation, Inc. +# +# This file is part of the GNU Binutils. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write to the Free Software +# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, +# MA 02110-1301, USA. +# + +if { ![istarget vax-*-*] || ![is_elf_format] } { + return +} + +run_ld_link_tests [list \ + [list "PLT test (shared library)" \ + "-shared -T plt-local-lib.ld" \ + "-k" \ + { plt-local-lib.s } \ + { { objdump -d plt-local-lib.dd } } \ + "plt-local-lib.so"] \ + [list "PLT test (object 1)" \ + "-r" \ + "-k" \ + { plt-local-hidden-pic.s } \ + {} \ + "plt-local-hidden-pic-r.o"] \ + [list "PLT test (object 2)" \ + "-r" \ + "-k" \ + { plt-local-rehidden-pic.s } \ + {} \ + "plt-local-rehidden-pic-r.o"] \ + [list "PLT test (executable)" \ + "-T plt-local.ld tmpdir/plt-local-hidden-pic-r.o tmpdir/plt-local-rehidden-pic-r.o tmpdir/plt-local-lib.so" \ + "" \ + { plt-local.s } \ + { { objdump -d plt-local.dd } } \ + "plt-local"]]