From owner-svn-src-head@freebsd.org Tue Oct 30 22:12:37 2018 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9CAEC100892A for ; Tue, 30 Oct 2018 22:12:37 +0000 (UTC) (envelope-from arichardson.kde@gmail.com) Received: from mail-yb1-f194.google.com (mail-yb1-f194.google.com [209.85.219.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 35BD57D165 for ; Tue, 30 Oct 2018 22:12:37 +0000 (UTC) (envelope-from arichardson.kde@gmail.com) Received: by mail-yb1-f194.google.com with SMTP id d18-v6so5761255yba.4 for ; Tue, 30 Oct 2018 15:12:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9C1ccPKDD1dVgC6TDEEN7XoTIWrykNpFnxvGX7Wnvzo=; b=fD+EeWpwSDNAXG3RmTIYRDCxkKXlmRfg3Ug/a2MH7l7UPp+nts1OgVXmidw+JG3X94 3uRZd5XHEa+R0oilbbj6OCUocedjmASmCxG9Yto5NDCeWWT3BTQZJFxX8hdJdxhyBl6e wKdvQxBKh2kDNbOTHtGqzy9Xqi5Imq7DQSN6CtuH1ChTUtTLkxBLcw7KJ2SaoipzZZZ/ 8Fzvse/jTvR5Fc1R+isjQPrKG+nkj00XXkfGfZy8kU2JPLTwRfFcXUMYf4ImzRx49H/u yamD2dKUpkfIuMHdWreCi9bsEXBKvWDZBTdGa7jXr4qHnZGBDGsOVUcXSt62izwNGobR vS4g== X-Gm-Message-State: AGRZ1gKRAdx0xuX/X3ukjMEfWFgqMf5ZAes1iex+mAYAxVVBkNgG36iI LNmyviLLpvYlkwhgiu8YZTsD2LQQL3o= X-Google-Smtp-Source: AJdET5e60xTiU50Pwfte7xxbP3IGe1Hbkxe02j03QZspksyHqOJmXIx0r7L79GCLOPs5q0SgWaJacw== X-Received: by 2002:a5b:406:: with SMTP id m6-v6mr480571ybp.223.1540935653963; Tue, 30 Oct 2018 14:40:53 -0700 (PDT) Received: from mail-yw1-f54.google.com (mail-yw1-f54.google.com. [209.85.161.54]) by smtp.gmail.com with ESMTPSA id g21-v6sm5927429ywk.5.2018.10.30.14.40.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Oct 2018 14:40:53 -0700 (PDT) Received: by mail-yw1-f54.google.com with SMTP id v77-v6so5586865ywc.4 for ; Tue, 30 Oct 2018 14:40:53 -0700 (PDT) X-Received: by 2002:a0d:d88d:: with SMTP id a135-v6mr476317ywe.75.1540935653400; Tue, 30 Oct 2018 14:40:53 -0700 (PDT) MIME-Version: 1.0 References: <7DC6D9C4-C153-4BCE-851C-22C890AB0D73@yahoo.com> In-Reply-To: From: Alexander Richardson Date: Tue, 30 Oct 2018 21:40:42 +0000 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: svn commit: r339876 - head/libexec/rtld-elf To: marklmi26-fbsd@yahoo.com Cc: svn-src-head@freebsd.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 30 Oct 2018 22:12:37 -0000 On Tue, 30 Oct 2018 at 21:32, Mark Millard wrote: > > > > On 2018-Oct-30, at 2:23 PM, Alexander Richardson wrote: > > > On Tue, 30 Oct 2018 at 18:19, Mark Millard wrote: > >> > >> Alexander Richardson arichardson at freebsd.org wrote on > >> Tue Oct 30 15:33:00 UTC 2018 : > >> > >>> On Tue, 30 Oct 2018 at 10:17, Michael Tuexen > >>> wrote: > >>>> > >>>>> On 29. Oct 2018, at 22:08, Alex Richardson wrote: > >>>>> > >>>>> Author: arichardson > >>>>> Date: Mon Oct 29 21:08:02 2018 > >>>>> New Revision: 339876 > >>>>> URL: https://svnweb.freebsd.org/changeset/base/339876 > >>>>> > >>>>> Log: > >>>>> rtld: set obj->textsize correctly > >>>>> > >>>>> With lld-generated binaries the first PT_LOAD will usually be a read-only > >>>>> segment unless you pass --no-rosegment. For those binaries the textsize is > >>>>> determined by the next PT_LOAD. To allow both LLD and bfd 2.17 binaries to > >>>>> be parsed correctly use the end of the last PT_LOAD that is marked as > >>>>> executable instead. > >>>>> > >>>>> I noticed that the value was wrong while adding some debug prints for some rtld > >>>>> changes for CHERI binaries. `obj->textsize` only seems to be used by PPC so the > >>>>> effect is untested. However, the value before was definitely wrong and the new > >>>>> result matches the phdrs. > >>>> I build kernel and world with a revision later than this on a PPC. Buildword > >>>> ends up with a world where almost all binaries are segfaulting.... Especially gdb > >>>> (but svn, ls or so all segfault). > >>>> > >>>> Best regards > >>>> Michael > >>> > >>> This is rather surprising since if anything the range of the icache > >>> flush should increase rather than decrease after this change. > >>> > >>> I can only see this causing a behaviour change if we actually need to > >>> flush more than just the executable segments. > >>> Is it possible that some binary/library contains a non-executable > >>> segment as the first PT_LOAD? > >>> Or is there some linker script that adds custom PHDRS? > >> > >> The following is based on using devel/powerpc64-xtoolchain-gcc > >> to buildworld buildkernel on/for powerpc64. (I experiment with > >> using fairly modern tools to target powerpc64 and powerpc.) > >> The build context is head -r339076 based, both for what > >> did the build and for what it was building. > >> > >> I report from both elfdump and objdump output > >> because each seems to have some oddities in what > >> it outputs. > >> > >> I start with elfdump (which leaves sh_flags blank > >> and shows a section header with sh_name empty > >> that objdump does not list at all): > >> > >> # elfdump -pc /bin/ls | less > >> > >> . . . > >> > >> As for objdump on the same file (section > >> one less than elfdump listed, no empty sh_name > >> section listed): > >> > >> # objdump -ph /bin/ls | less > >> > >> /bin/ls: file format elf64-powerpc-freebsd > >> > >> Program Header: > >> PHDR off 0x0000000000000040 vaddr 0x0000000010000040 paddr 0x0000000010000040 align 2**3 > >> filesz 0x0000000000000188 memsz 0x0000000000000188 flags r-- > >> INTERP off 0x00000000000001c8 vaddr 0x00000000100001c8 paddr 0x00000000100001c8 align 2**0 > >> filesz 0x0000000000000015 memsz 0x0000000000000015 flags r-- > >> LOAD off 0x0000000000000000 vaddr 0x0000000010000000 paddr 0x0000000010000000 align 2**16 > >> filesz 0x000000000000910c memsz 0x000000000000910c flags r-x > >> LOAD off 0x0000000000009110 vaddr 0x0000000010019110 paddr 0x0000000010019110 align 2**16 > >> filesz 0x0000000000000ee0 memsz 0x00000000000010e8 flags rw- > >> DYNAMIC off 0x0000000000009138 vaddr 0x0000000010019138 paddr 0x0000000010019138 align 2**3 > >> filesz 0x00000000000001c0 memsz 0x00000000000001c0 flags rw- > >> NOTE off 0x00000000000001e0 vaddr 0x00000000100001e0 paddr 0x00000000100001e0 align 2**2 > >> filesz 0x0000000000000030 memsz 0x0000000000000030 flags r-- > >> STACK off 0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**4 > >> filesz 0x0000000000000000 memsz 0x0000000000000000 flags rw- > >> > >> Dynamic Section: > >> NEEDED libutil.so.9 > >> NEEDED libncursesw.so.8 > >> NEEDED libc.so.7 > >> INIT 0x0000000010019328 > >> FINI 0x0000000010019340 > >> HASH 0x0000000010000210 > >> STRTAB 0x0000000010000d00 > >> SYMTAB 0x0000000010000490 > >> STRSZ 0x000000000000035a > >> SYMENT 0x0000000000000018 > >> DEBUG 0x0000000000000000 > >> PLTGOT 0x0000000010019898 > >> PLTRELSZ 0x00000000000006f0 > >> PLTREL 0x0000000000000007 > >> JMPREL 0x00000000100012f8 > >> 0x70000000 0x00000000100089b4 > >> RELA 0x0000000010001160 > >> RELASZ 0x0000000000000198 > >> RELAENT 0x0000000000000018 > >> VERNEED 0x0000000010001110 > >> VERNEEDNUM 0x0000000000000001 > >> VERSYM 0x000000001000105a > >> > >> Version References: > >> required from libc.so.7: > >> 0x077a28b3 0x00 05 FBSD_1.3 > >> 0x077a28b1 0x00 04 FBSD_1.1 > >> 0x077a28b5 0x00 03 FBSD_1.5 > >> 0x077a28b0 0x00 02 FBSD_1.0 > >> private flags = 0x1: [abiv1] > >> > >> Sections: > >> Idx Name Size VMA LMA File off Algn > >> 0 .interp 00000015 00000000100001c8 00000000100001c8 000001c8 2**0 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 1 .note.tag 00000030 00000000100001e0 00000000100001e0 000001e0 2**2 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 2 .hash 0000027c 0000000010000210 0000000010000210 00000210 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 3 .dynsym 00000870 0000000010000490 0000000010000490 00000490 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 4 .dynstr 0000035a 0000000010000d00 0000000010000d00 00000d00 2**0 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 5 .gnu.version 000000b4 000000001000105a 000000001000105a 0000105a 2**1 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 6 .gnu.version_r 00000050 0000000010001110 0000000010001110 00001110 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 7 .rela.dyn 00000198 0000000010001160 0000000010001160 00001160 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 8 .rela.plt 000006f0 00000000100012f8 00000000100012f8 000012f8 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 9 .init 0000002c 00000000100019f0 00000000100019f0 000019f0 2**4 > >> CONTENTS, ALLOC, LOAD, READONLY, CODE > >> 10 .text 00007204 0000000010001a20 0000000010001a20 00001a20 2**5 > >> CONTENTS, ALLOC, LOAD, READONLY, CODE > >> 11 .fini 00000024 0000000010008c30 0000000010008c30 00008c30 2**4 > >> CONTENTS, ALLOC, LOAD, READONLY, CODE > >> 12 .rodata 000004b0 0000000010008c58 0000000010008c58 00008c58 2**3 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 13 .eh_frame 00000004 0000000010009108 0000000010009108 00009108 2**2 > >> CONTENTS, ALLOC, LOAD, READONLY, DATA > >> 14 .ctors 00000010 0000000010019110 0000000010019110 00009110 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 15 .dtors 00000010 0000000010019120 0000000010019120 00009120 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 16 .jcr 00000008 0000000010019130 0000000010019130 00009130 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 17 .dynamic 000001c0 0000000010019138 0000000010019138 00009138 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 18 .opd 00000468 00000000100192f8 00000000100192f8 000092f8 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 19 .got 00000098 0000000010019800 0000000010019800 00009800 2**8 > >> CONTENTS, ALLOC, LOAD, DATA > >> 20 .plt 00000708 0000000010019898 0000000010019898 00009898 2**3 > >> ALLOC > >> 21 .data 00000050 0000000010019fa0 0000000010019fa0 00009fa0 2**3 > >> CONTENTS, ALLOC, LOAD, DATA > >> 22 .bss 00000208 0000000010019ff0 0000000010019ff0 00009ff0 2**3 > >> ALLOC > >> 23 .comment 000002b5 0000000000000000 0000000000000000 00009ff0 2**0 > >> CONTENTS, READONLY > >> 24 .gnu_debuglink 00000010 0000000000000000 0000000000000000 0000a2a8 2**2 > >> CONTENTS, READONLY > >> > >> > > > > The first PT_LOAD is also executable so there will be no be behaviour > > change. It must be one of the library dependencies that is different. > > The difference in section headers output doesn't matter here since all > > that RTLD looks at is the PHDRS. > > > > I think you missed the fact that the .got and .plt are in the > material from the 2nd PT_LOAD: there are writeable code areas > involved for powerpc64. > > So both PT_LOAD's contribute code areas and there is a space > between the two contributions. The first PT_LOAD loads most > code (the readonly code, to be specific). The 2nd contributes > a writable-code area. > > But may be i've misunderstood the assumptions that your change > is based on. Before my change the second PT would also not be included in obj->textsize since we were setting obj->textsize as end of PT_LOAD[0]. After the change it will be end of last executable PT_LOAD (which will usually be PT_LOAD[0] but could also include more now). Since there is only one executable PT_LOAD which happens to be also be PT_LOAD[0], there will be no change to obj->textsize. The only time this commit could change anything is if there is a PT_LOAD that is executable but is not PT_LOAD[0] or if PT_LOAD[0] is not executable. I think it must be the former case since as far as I know ld.bfd will always create a read/execute segment as PT_LOAD[0] unless it is given a custom linker script. Alex