From owner-freebsd-current@FreeBSD.ORG Fri Feb 15 10:02:51 2008 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8CA6216A46C; Fri, 15 Feb 2008 10:02:51 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from relay02.kiev.sovam.com (relay02.kiev.sovam.com [62.64.120.197]) by mx1.freebsd.org (Postfix) with ESMTP id CDCB813C506; Fri, 15 Feb 2008 10:02:50 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from [212.82.216.226] (helo=skuns.kiev.zoral.com.ua) by relay02.kiev.sovam.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.67) (envelope-from ) id 1JPxP5-000Gvd-BH; Fri, 15 Feb 2008 12:02:49 +0200 Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by skuns.kiev.zoral.com.ua (8.14.1/8.14.1) with ESMTP id m1FA2MY5065511 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 15 Feb 2008 12:02:23 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2) with ESMTP id m1FA2iOF042690; Fri, 15 Feb 2008 12:02:44 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.14.2/8.14.2/Submit) id m1FA2hFt042644; Fri, 15 Feb 2008 12:02:43 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 15 Feb 2008 12:02:43 +0200 From: Kostik Belousov To: Ruslan Ermilov Message-ID: <20080215100243.GF57756@deviant.kiev.zoral.com.ua> References: <200802122009.m1CK94Y8026959@repoman.freebsd.org> <20080212200911.B49F416A51C@hub.freebsd.org> <20080212204803.GT57756@deviant.kiev.zoral.com.ua> <20080213113530.GB45243@team.vega.ru> <20080214173850.GB57756@deviant.kiev.zoral.com.ua> <20080214211744.GA80604@team.vega.ru> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="5Q2zYvwyseWqYgH3" Content-Disposition: inline In-Reply-To: <20080214211744.GA80604@team.vega.ru> User-Agent: Mutt/1.4.2.3i X-Virus-Scanned: ClamAV version 0.91.2, clamav-milter version 0.91.2 on skuns.kiev.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.2.3 X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on skuns.kiev.zoral.com.ua X-Scanner-Signature: fd47f7ed058f8bb752f6c36e497d0305 X-DrWeb-checked: yes X-SpamTest-Envelope-From: kostikbel@gmail.com X-SpamTest-Group-ID: 00000000 X-SpamTest-Header: Not Detected X-SpamTest-Info: Profiles 2240 [Feb 15 2008] X-SpamTest-Info: helo_type=3 X-SpamTest-Method: none X-SpamTest-Rate: 0 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0278], KAS30/Release Cc: current@freebsd.org Subject: Re: [src] cvs commit: src/include unistd.h src/lib/libc/sys readlink.2 src/sys/compat/freebsd32 syscalls.master src/sys/kern syscalls.master vfs_syscalls.c src/sys/sys syscallsubr.h X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Feb 2008 10:02:51 -0000 --5Q2zYvwyseWqYgH3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Feb 15, 2008 at 12:17:47AM +0300, Ruslan Ermilov wrote: > On Thu, Feb 14, 2008 at 07:38:50PM +0200, Kostik Belousov wrote: > > On Wed, Feb 13, 2008 at 02:35:30PM +0300, Ruslan Ermilov wrote: > > > [ Replying to the list. ] > > >=20 > > > On Tue, Feb 12, 2008 at 10:48:04PM +0200, Kostik Belousov wrote: > > > > > -int readlink(const char *, char *, int); > > > > > +ssize_t readlink(const char *, char *, size_t); > > > > You do understand that this changes the ABI ? size_t and int have d= ifferent > > > > sizes on 64-bit arches, and now upper-half of the register used to = pass > > > > the third arg is used. Amd64, fortunately, makes very hard to load= a > > > > non-zero into the upper half, I am not so sure about IA64/sparc64. > > >=20 > > > I considered that. I've tested locally on amd64 and sparc64, and > > > ia64 on pluto2.freebsd.org. Since this is only a third argument, > > > it's passed in a 64-bit register, and for any meaningful value of it > > > (0 .. INT_MAX), there's no ABI change at all. I compared .s files. > > >=20 > > > : // cc -S a.c ; mv a.s a.s~ ; cc -S -DNEW a.c ; diff -u a.s~ a.s > > > : #include > > > : #include > > > :=20 > > > : #ifdef NEW > > > : ssize_t readlink(const char *, char *, size_t); > > > : #else > > > : int readlink(const char *, char *, int); > > > : #endif > > > :=20 > > > : void > > > : foo(void) > > > : { > > > : int i; > > > : char buf[1024]; > > > :=20 > > > : i =3D readlink("foo", buf, INT_MAX); > > > : } > > >=20 > > > > This change, IMHO, requires symbol version compat shims. > > >=20 > > > I don't think so. > > >=20 > >=20 > > The slightly contrived example below works on RELENG_7 amd64, relevant > > output from the truss is > > readlink("/usr/X11R6","l",1) =3D 1 (0x1) > > on the CURRENT gives > > readlink("/usr/X11R6","l",1) =3D -4294967295 (0xff= ffffff00000001) > > [also please note wrong output for the third readlink arg; ktrace/kdump= works > > ok]. > >=20 > > .text > > .globl main > > main: movq $0xffffffff00000001, %rax > > movq %rax, %rdx > > movq $buf, %rax > > movq %rax, %rsi > > movq $path, %rax > > movq %rax, %rdi > > call readlink > > xorl %edi, %edi > > call exit > > =09 > > .section .rodata > > path: .asciz "/usr/X11R6" > >=20 > > .data > > .comm buf, 0x80 >=20 > This is because uio_resid is still "int". >=20 > : int > : kern_readlink(struct thread *td, char *path, enum uio_seg pathseg, char= *buf, > : enum uio_seg bufseg, size_t count) > [...] > : auio.uio_resid =3D count; > [...] > : td->td_retval[0] =3D count - auio.uio_resid; >=20 > uio_resid gets the (truncated) value of "1", VOP_READLINK() > reads 1 char, td_retval[0] gets the value 0xffffffff00000001. > Any meaningful value of the third argument will work OTOH. The point of the conversation I started is exactly this: the domain of the _reasonable_ values for the third arg is changed after your commit. The value that was perfectly acceptable before the commit now causes wrong effects. I consider this to be the ABI change. --5Q2zYvwyseWqYgH3 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (FreeBSD) iEYEARECAAYFAke1Y0MACgkQC3+MBN1Mb4g9fACdGDAI5oXOQ+QeEa+A2CQ8Yk1N bHQAn2AiV/bAKvcQ3UcLfGyYcACH6sf/ =Mulk -----END PGP SIGNATURE----- --5Q2zYvwyseWqYgH3--