Date: Thu, 21 May 2020 22:50:10 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: John Baldwin <jhb@freebsd.org> Cc: Mark Johnston <markj@freebsd.org>, Antoine Brodin <antoine@freebsd.org>, src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head@freebsd.org Subject: Re: svn commit: r361303 - in head: lib/libc/gen libexec/rtld-elf sys/sys Message-ID: <20200521195010.GJ64045@kib.kiev.ua> In-Reply-To: <25dcdfaa-fea9-98a1-c731-db37489ccc6b@FreeBSD.org> References: <202005202208.04KM8QPA020707@repo.freebsd.org> <CAALwa8mXfJZyRQ-Gx684mgoeTDZs14tEP26rJNqvh_rEiY18=Q@mail.gmail.com> <20200521134152.GE64045@kib.kiev.ua> <20200521151248.GA85681@raichu> <c7fce441-692e-e4d6-64cb-ae86ef13c6cb@FreeBSD.org> <20200521165646.GF64045@kib.kiev.ua> <25dcdfaa-fea9-98a1-c731-db37489ccc6b@FreeBSD.org>
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On Thu, May 21, 2020 at 12:30:47PM -0700, John Baldwin wrote: > On 5/21/20 9:56 AM, Konstantin Belousov wrote: > > On Thu, May 21, 2020 at 09:03:44AM -0700, John Baldwin wrote: > >> On 5/21/20 8:12 AM, Mark Johnston wrote: > >>> On Thu, May 21, 2020 at 04:41:52PM +0300, Konstantin Belousov wrote: > >>>> On Thu, May 21, 2020 at 03:02:07PM +0200, Antoine Brodin wrote: > >>>>> On Thu, May 21, 2020 at 12:08 AM Konstantin Belousov <kib@freebsd.org> wrote: > >>>>>> > >>>>>> Author: kib > >>>>>> Date: Wed May 20 22:08:26 2020 > >>>>>> New Revision: 361303 > >>>>>> URL: https://svnweb.freebsd.org/changeset/base/361303 > >>>>>> > >>>>>> Log: > >>>>>> Change the samantic of struct link_map l_addr member. > >>>>>> > >>>>>> It previously returned the object map base address, while all other > >>>>>> ELF operating systems return load offset, i.e. the difference between > >>>>>> map base and the link base. > >>>>>> > >>>>>> Explain the meaning of the field in the man page. > >>>>>> > >>>>>> Stop filling the mips-only l_offs member, which is apparently unused. > >>>>>> > >>>>>> PR: 246561 > >>>>>> Requested by: Damjan Jovanovic <damjan.jov@gmail.com> > >>>>>> Reviewed by: emaste, jhb, cem (previous version) > >>>>>> Sponsored by: The FreeBSD Foundation > >>>>>> MFC after: 1 week > >>>>>> Differential revision: https://reviews.freebsd.org/D24918 > >>>>>> > >>>>>> Modified: > >>>>>> head/lib/libc/gen/dlinfo.3 > >>>>>> head/libexec/rtld-elf/rtld.c > >>>>>> head/sys/sys/link_elf.h > >>>>> > >>>>> Hi, > >>>>> > >>>>> After this commit, some ports fail to build with signal 11. > >>>>> For instance lang/perl5.30 fails to build with default options (DTRACE on) > >>>>> Disabling the DTRACE option makes it able to build again. > >>>>> > >>>> I see, thank you for reporting. > >>>> > >>>> So drti.c:dtrace_dof_init() does read l_addr, and the dtrace code assumes > >>>> that l_addr is the base, not relocbase. > >>>> > >>>> Mark, was dofhp_addr initialization changed comparing to Solaris ? > >>> > >>> It appears it has been the same since DTrace was imported. illumos > >>> still has similar code. > >>> > >>> Note that drti.o is linked into any executable and shlib that defines > >>> static probes, so the ABI change affects more than just dtrace(1). > >>> Would it be possible to define a new value for RTLD_DI_LINKMAP, and > >>> preserve the old behaviour for the old value? > >> > >> I think a bigger question is if Solaris/illumos treat l_addr as mapbase > >> (absolute address) or relocbase (relative address). In the discussion > >> in the phabricator I had assumed that all other OS's treated l_addr as > >> the relative offset (relocbase). Does the code for illumos assume an > >> absolute address or does it assume a relative address in l_addr? > > > > It is rather clear, since the dtrace code was pristine, that Solaris > > provides the mapbase. I do not have Solaris/Illumos box anymore > > (for quite some time), so I cannot check directly. > > > > My current PoV is that l_addr semantic must be restored, and relocbase > > provided by newly added member. > > I am fine with reverting the l_addr semantic. I'm still not sure how to > resolve the original PR, though perhaps Wine just has to carry a local > patch forever? GDB will work via the current accident so long as we > never pre-link libraries. As long as PIE binaries have a starting VA of > 0 like our shared libraries then I think GDB will be ok with our PIE > binaries as well. Wine should work without patch now, and after the D24918 is applied, too. I do not intend to revert l_addr to the 'load address' semantic. I am actually trying to find a solaris box to compile the test program.
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