From nobody Sat Dec 04 18:10:45 2021 X-Original-To: freebsd-current@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id BEBFC18C8BE3 for ; Sat, 4 Dec 2021 18:10:55 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "gate2.funkthat.com", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4J5yRd42R5z4x1S; Sat, 4 Dec 2021 18:10:53 +0000 (UTC) (envelope-from jmg@gold.funkthat.com) Received: from gold.funkthat.com (localhost [127.0.0.1]) by gold.funkthat.com (8.15.2/8.15.2) with ESMTPS id 1B4IAjRh041368 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Sat, 4 Dec 2021 10:10:45 -0800 (PST) (envelope-from jmg@gold.funkthat.com) Received: (from jmg@localhost) by gold.funkthat.com (8.15.2/8.15.2/Submit) id 1B4IAjPU041367; Sat, 4 Dec 2021 10:10:45 -0800 (PST) (envelope-from jmg) Date: Sat, 4 Dec 2021 10:10:45 -0800 From: John-Mark Gurney To: David Chisnall , freebsd-current@freebsd.org Subject: Re: failure of pructl (atexit/_Block_copy/--no-allow-shlib-undefined) Message-ID: <20211204181045.GW35602@funkthat.com> Mail-Followup-To: David Chisnall , freebsd-current@freebsd.org References: <20211202020326.GU35602@funkthat.com> <75CCC6A8-F777-48F9-9AC7-5A08FA9CCD25@FreeBSD.org> <20211202234350.GV35602@funkthat.com> List-Id: Discussions about the use of FreeBSD-current List-Archive: https://lists.freebsd.org/archives/freebsd-current List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-current@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211202234350.GV35602@funkthat.com> X-Operating-System: FreeBSD 11.3-STABLE amd64 X-PGP-Fingerprint: D87A 235F FB71 1F3F 55B7 ED9B D5FF 5A51 C0AC 3D65 X-Files: The truth is out there X-URL: https://www.funkthat.com/ X-Resume: https://www.funkthat.com/~jmg/resume.html X-TipJar: bitcoin:13Qmb6AeTgQecazTWph4XasEsP7nGRbAPE X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? User-Agent: Mutt/1.6.1 (2016-04-27) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (gold.funkthat.com [127.0.0.1]); Sat, 04 Dec 2021 10:10:45 -0800 (PST) X-Rspamd-Queue-Id: 4J5yRd42R5z4x1S X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of jmg@gold.funkthat.com has no SPF policy when checking 208.87.223.18) smtp.mailfrom=jmg@gold.funkthat.com X-Spamd-Result: default: False [0.22 / 15.00]; MID_RHS_MATCH_FROM(0.00)[]; ARC_NA(0.00)[]; FREEFALL_USER(0.00)[jmg]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-0.999]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[funkthat.com]; AUTH_NA(1.00)[]; NEURAL_SPAM_SHORT(1.00)[1.000]; NEURAL_HAM_MEDIUM(-0.98)[-0.979]; RCPT_COUNT_TWO(0.00)[2]; R_SPF_NA(0.00)[no SPF record]; FORGED_SENDER(0.30)[jmg@funkthat.com,jmg@gold.funkthat.com]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:32354, ipnet:208.87.216.0/21, country:US]; FROM_NEQ_ENVFROM(0.00)[jmg@funkthat.com,jmg@gold.funkthat.com]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-ThisMailContainsUnwantedMimeParts: N John-Mark Gurney wrote this message on Thu, Dec 02, 2021 at 15:43 -0800: > David Chisnall wrote this message on Thu, Dec 02, 2021 at 10:34 +0000: > > On 02/12/2021 09:51, Dimitry Andric wrote: > > > Apparently the "block runtime" is supposed to provide the actual object, > > > so I guess you have to explicitly link to that runtime? > > > > The block runtime provides this symbol. You use this libc API, you must > > be compiling with a toolchain that supports blocks and must be providing > > the blocks symbols. If you don't use `atexit_b` or any of the other > > `_b` APIs then you don't need to link the blocks runtime. > > > > I am not sure why this is causing linker failures - if it's a weak > > symbol and it's not defined then that's entirely expected: the point of > > a weak symbol is that it might not be defined. This avoids the need to > > link libc to the blocks runtime for code that doesn't use blocks (i.e. > > most code that doesn't come from macOS). > > > > This code is not using `atexit_b`, but because it is using `atexit` the > > linker is complaining that the compilation unit containing `atexit` is > > referring to a symbol that isn't defined. > > I assume that this failure was due to a recent llvm change, because I > haven't received any failures about pructl until Nov 16th, 2021, > despite the port and code being untouched since 2020-09-22. > > Digging in a bit more, it looks like libpru is compiled w/ -fblocks, > and so depending upon the _Block_copy symbol, the atexit is just the > "closest" symbol that's defined". pructl is not, but even compiling > pructl w/ -fblocks, doesn't fix the link error, as it looks like the > block runtime isn't linked. If I manually include > /usr/lib/libBlocksRuntime.so, then pructl is able to link. > > I can't seem to find any docs on clang about how to properly compile > code that uses blocks, so, unless someone points me to docs on how to > compile blocks enable programs, I'll just patch libpru to not use > blocks since it seems like blocks is well supported. I don't want > to fix this code every few years when things change. Thanks to some off-list comms, it appears that this was a regression in lld 13, and will be fixed by: https://reviews.llvm.org/D115041 Thanks to jrtc27 for [helping] tracking this down! -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."