From owner-freebsd-current@freebsd.org Wed Jul 5 18:47:18 2017 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 9E379D8D2D7 for ; Wed, 5 Jul 2017 18:47:18 +0000 (UTC) (envelope-from guyyur@gmail.com) Received: from mail-wm0-x22c.google.com (mail-wm0-x22c.google.com [IPv6:2a00:1450:400c:c09::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3741867403; Wed, 5 Jul 2017 18:47:18 +0000 (UTC) (envelope-from guyyur@gmail.com) Received: by mail-wm0-x22c.google.com with SMTP id f67so122110018wmh.1; Wed, 05 Jul 2017 11:47:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=JAjfu8Y/O+FUF6adHbJ729roLU7frdfISkbZrpE8+p8=; b=A8l0jvlgmejSwT5Gpj1SqHLLibqC/z8CyIqox5qRsHL8wi62rRjsbODGG97MJMXFgR 8GPI4ZKc53mJS4d8PqMgdr1ymVvUT8G82q8WYE/1k4Bvz7VwSkwASvpn89MPwuVCFC9H EFFY8dAkzsJn/ROmm56yXpC7R4msDPUkw1RDrIAuUUZNb1D2V4XfIKdWHq+T1VY0zT9C FjvVrD+E8jhi5HT6eYHvWJF6LUYFtRyAXgdJMfTmCOG0onB4bR89YrUvWZVuAgJ8/DbO earhrlJp4k3VPUYWF+BJ2uYr1nyZNkbvQ2mAqmss73APOupA4A2ysGIycPohT3d97dJa 1xBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=JAjfu8Y/O+FUF6adHbJ729roLU7frdfISkbZrpE8+p8=; b=tFzQPOia5SLj3AZ3jNoUNmSTV0x6qboYWO+QPuXnHbMl7sM6nAmSPT8goGK+9LN3Jg OEOhP2PBmO6HaQHUeAfDzVIa52l41+vDFMENE6R4mDNBioqSrDl0giyYLegqn8aZY1H8 qYje0TemEl0rnHD1YbKcUrMOFoFyLpnaTzmSBLzGHlXZE8A0/aRoNItu4kkfGcV6m3t2 zLLn/5griAbcaVszbs+fLeAyhTqmbOWYS+gFsxg7i63LPEFHMwVTmcE6sqkaayfFxS40 rq041Vy3AzZQe28A77KLcmeH6aykaxkGKORuEyV/CMa4+HS4GJrbuFmWbbadjim6nGfa xlww== X-Gm-Message-State: AKS2vOwp15AmqDO/F8IZ+bVzr/0pkp1mfeY5n14UGodITU5ZmEgJNuFq w3SYA7m1FNSGmbiQYBLsd1iY8dTudmJC X-Received: by 10.28.137.146 with SMTP id l140mr31873776wmd.101.1499280435994; Wed, 05 Jul 2017 11:47:15 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.164.129 with HTTP; Wed, 5 Jul 2017 11:47:15 -0700 (PDT) From: Guy Yur Date: Wed, 5 Jul 2017 21:47:15 +0300 Message-ID: Subject: Re: emulators/qemu-user-static needs MAP_GUARD support To: alc@freebsd.org Cc: freebsd-current , kib@freebsd.org, Sean Bruno Content-Type: text/plain; charset="UTF-8" X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.23 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: Wed, 05 Jul 2017 18:47:18 -0000 Hi Alan, On 1 July 2017 at 23:07, Alan Cox wrote: > > On Sat, Jul 1, 2017 at 2:46 PM, Guy Yur wrote: >> >> Hi, >> >> I tried to run armv6 /bin/sh in a chroot on an >> amd64 host using qemu-arm-static. >> It failed on invalid argument to mmap. >> >> # cp /usr/local/bin/qemu-arm-static /chroots/armv6/root/ >> # chroot /chroots/armv6 /root/qemu-arm-static /bin/sh >> /lib/libedit.so.7: mmap of entire address space failed: Invalid argument >> >> ... snipped >> > > MAP_ANON should not be passed to mmap(2) at the same time as MAP_GUARD. > Passing MAP_FIXED at the same time is okay. > The problem is definitely in qemu user mode mmap emulation code. https://github.com/seanbruno/qemu-bsd-user/blob/bsd-user/bsd-user/mmap.c#L464 qemu adds MAP_FIXED | MAP_ANONYMOUS if MAP_FIXED is not set in flags when the emulated mmap call is done. So rtld-elf passes MAP_GUARD and the kernel receives MAP_GUARD and MAP_ANON and rejects the call. Do you know if the MAP_ANONYMOUS is needed in the call? I am currently using a workaround patch to convert MAP_GUARD to MAP_PRIVATE | MAP_ANON | MAP_NOCORE (like rtld-elf does if OS version doesn't support MAP_GUARD). https://github.com/guyyur/freebsd-ports_patches/blob/master/emulators_qemu-sbruno__MAP_GUARD_workaround.patch With the patch qemu-arm-static is working. I would prefer using a better fix that retains the MAP_GUARD protections. Thanks, Guy