From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52285C43461 for ; Fri, 11 Sep 2020 14:48:18 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A1741223BD for ; Fri, 11 Sep 2020 14:48:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="wRuHjmDo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1741223BD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42574 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kGkLY-0004bs-Jq for qemu-devel@archiver.kernel.org; Fri, 11 Sep 2020 10:48:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59936) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kGkKR-0003lJ-1A for qemu-devel@nongnu.org; Fri, 11 Sep 2020 10:47:07 -0400 Received: from mail-wr1-x444.google.com ([2a00:1450:4864:20::444]:44519) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kGkKO-00075X-LE for qemu-devel@nongnu.org; Fri, 11 Sep 2020 10:47:06 -0400 Received: by mail-wr1-x444.google.com with SMTP id s12so11731066wrw.11 for ; Fri, 11 Sep 2020 07:47:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version:content-transfer-encoding; bh=Ea76MJ47jAYiA6wXyZ/DEkVFDAARxGqrNURaYM66h3g=; b=wRuHjmDobcDXeA8JOzGC+xNdm1AD5UbmLcZWr84Uotlyz7nuHhYXlya+Rw0B0+wjTs U1meiHKQGWmyPj0vQBI8hKzC5XdeS8YBNAzh6NVQvt75IxpmpKIpuA6Xus0jSeSp36y0 oVDtdzxtKD6wmunOdobDEKdE+H4+423boUBkIs07NETE48qnmYqjRM8S2T5fKziBAtsR H9Se5gEydyP3zqz96ZBhsYh/2Je+8WPPp40Cek/faGCXxoX+qOv6SLf+lZo+ILZHUM6E joBQX063z96ZLTaB6GGmklxqWkDQKhwRZDi4fb8se88SiZkMIbxvY8t9JKcuEdTzoQl2 hHZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version:content-transfer-encoding; bh=Ea76MJ47jAYiA6wXyZ/DEkVFDAARxGqrNURaYM66h3g=; b=Oc0ODDoKzAomMLDilH2lEnO68K5jJBLBvgdy5y+GonNygcam6LXPi7CKLfQJT7xQ5Y T35pvNaO2IsndG0iy76K6Ntav6kw4kC7p5MuOG/+vvEQFOC6mhYMKU3I6Z4JITzS+sLg Zjsczc+PHhERjG2OhrG9FDIKLuaLCNHhDs/mx9dj31P37I15sOKF+gjx/wLjbkDrUYt/ DqEtdhb2rFLYteER6NfEUnEVu27+OZ6H09l5SV6IhEdQ2OQGMGX2wyK5gQi9U7zp/Mqv OuMPpWRp7DePCFiHLRwrhanNB4sXvvyunXZngnGihuLEV47OWMIx4572Nrfeidjylclq GIPg== X-Gm-Message-State: AOAM5322J+m4ONijeCtarIr6Xr8LVAKUiWpOciHSmVZmvY8y4/XMNzNn Q154TfqoUdktFDFtKtfevwBMvQ== X-Google-Smtp-Source: ABdhPJzpESWA5nu4VwgbB25PZDeK7AEiy/hQqMsuSYff6mFpduI7zQePo8xab/P/jCu1nYV4XiOp3g== X-Received: by 2002:adf:f585:: with SMTP id f5mr2565615wro.64.1599835622297; Fri, 11 Sep 2020 07:47:02 -0700 (PDT) Received: from zen.linaroharston ([51.148.130.216]) by smtp.gmail.com with ESMTPSA id m3sm5021599wrs.83.2020.09.11.07.47.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Sep 2020 07:47:01 -0700 (PDT) Received: from zen (localhost [127.0.0.1]) by zen.linaroharston (Postfix) with ESMTP id 6DC491FF7E; Fri, 11 Sep 2020 15:47:00 +0100 (BST) References: <159970958159.31371.12301700684467003959.malonedeb@wampee.canonical.com> <92de5ee0-629a-640a-d547-8c2d650742f2@vivier.eu> <87tuw4odwk.fsf@linaro.org> <87r1r8odph.fsf@linaro.org> <87o8mco7el.fsf@linaro.org> User-agent: mu4e 1.5.5; emacs 28.0.50 From: Alex =?utf-8?Q?Benn=C3=A9e?= To: Bug 1895080 <1895080@bugs.launchpad.net> Subject: Re: [Bug 1895080] [NEW] pgb_reserved_va: Assertion `addr == test' failed In-reply-to: Date: Fri, 11 Sep 2020 15:47:00 +0100 Message-ID: <87k0x0nzff.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=2a00:1450:4864:20::444; envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x444.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hansni Bu <1895080@bugs.launchpad.net> writes: >> > No, it's not set by CentOS-7.5. >> > Does it mean that we just cannot run the ELF in such a case? I've tried >> > many times, the assert always fails. Maybe, we can blame CentOS-7.5. >> >> The trouble is without MAP_FIXED_NOREPLACE we are at the mercy of the >> host kernel to allow the address request to be honoured. A plain >> MAP_FIXED won't do as it can clober existing mappings. In theory a >> suitable hole has been identified but sometimes the kernel makes a >> decision to offset the suggested mapping for it's own reasons. >> > > MAP_FIXED_NOREPLACE is quite a new feature. > > >> > BTW: with the option "-p 65536", the case runs successfully. >> >> Hmm interesting. I wonder if we are seeing a fail due to mmap_min_addr? >> What does: >> >> /proc/sys/vm/mmap_min_addr >> >> give you on the system? >> > > It gives me 4096. And guest_base has this value. Maybe that's the strange > point. mmap_min_addr give us 0x1000. While we are requesting this address, > the kernel gives us 0x10000. Yeah the meaning of mmap_min_addr should be exactly that which is odd why the kernel doesn't honour the request. That said it seems to be a user tweakable knob so you could just up it. >> >> You can manually set the reserved_va and the base address using -R and >> -B although that is more of a developer work around. I think moving the >> assert to the condition above would be an improvement just because it >> tells us what the requested base address was and what the kernel decided >> to give us. >> > > Setting guest_base with -B to 0x10000 works. Tried some -R values, no luc= k. > Agree to print a more hintful message. OK - one other test you try is running inside a chroot which *does not* have visibility of /proc. That will cause it to fall back to the old probing technique of trying multiple mmap operations to find the hole. I suspect that works because the attempt to map 0x1000 would fail the check. The reason we default to probing /proc/self/map now is that brute force technique falls over when trying to probe for a hole on 64 bit systems, especially when built with stack protection/clang debug instrumentation. In the meantime I'll spin up a patch to improve the failure mode. > > >> >> > >> > On Fri, Sep 11, 2020 at 5:50 PM Alex Benn=C3=A9e <1895080@bugs.launchp= ad.net> >> > wrote: >> > >> >> Alex Benn=C3=A9e writes: >> >> >> >> > Laurent Vivier writes: >> >> > >> >> >> >> >>> Then trying qemu-riscv32 with a simple ELF, I get: >> >> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D= =3D test' >> >> failed. >> >> >>> >> >> >>> strace shows that: >> >> >>> mmap(0x1000, 4294963200, PROT_NONE, >> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> >> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `ad= dr >> =3D=3D >> >> test' failed. >> >> >>> ) =3D 103 >> >> >>> >> >> >>> The source code is in the function pgb_reserved_va (linux- >> >> >>> user/elfload.c). I think mmap cannot guarantee that the returned >> >> pointer >> >> >>> (test) equals to the parameter of addr. So is this a bug to assert >> >> (addr >> >> >>> =3D=3D test)? >> >> >> >> >> > I'm assuming CentOS 7.5 actually has a definition for >> >> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for - >> >> > otherwise we are in the position of hoping the kernel honours what = we >> >> > asked for. >> >> >> >> Doh re-reading I see it's not set in the strace output. Maybe we shou= ld >> >> promote the assert case to the failure leg so we have: >> >> >> >> if (addr =3D=3D MAP_FAILED || addr !=3D test) { >> >> error_report(...) >> >> } >> >> >> >> so we at least fail with a user friendly error rather than an abort? >> >> >> >> -- >> >> Alex Benn=C3=A9e >> >> >> >> -- >> >> You received this bug notification because you are subscribed to the = bug >> >> report. >> >> https://bugs.launchpad.net/bugs/1895080 >> >> >> >> Title: >> >> pgb_reserved_va: Assertion `addr =3D=3D test' failed >> >> >> >> Status in QEMU: >> >> New >> >> >> >> Bug description: >> >> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu he= ad >> >> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux- >> >> user. >> >> >> >> Firstly, compile fails: >> >> Compiling C object >> libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o >> >> ../qemu.git/linux-user/strace.c:1210:18: error: =E2=80=98FALLOC_FL_= KEEP_SIZE=E2=80=99 >> >> undeclared here (not in a function) >> >> FLAG_GENERIC(FALLOC_FL_KEEP_SIZE), >> >> >> >> I have to add below include to linux-user/strace.c >> >> diff --git a/linux-user/strace.c b/linux-user/strace.c >> >> index 11fea14fba..22e51d4a8a 100644 >> >> --- a/linux-user/strace.c >> >> +++ b/linux-user/strace.c >> >> @@ -7,6 +7,7 @@ >> >> #include >> >> #include >> >> #include >> >> +#include >> >> #include >> >> #include >> >> #include >> >> >> >> Then trying qemu-riscv32 with a simple ELF, I get: >> >> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D = test' >> >> failed. >> >> >> >> strace shows that: >> >> mmap(0x1000, 4294963200, PROT_NONE, >> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> >> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `ad= dr >> =3D=3D >> >> test' failed. >> >> ) =3D 103 >> >> >> >> The source code is in the function pgb_reserved_va (linux- >> >> user/elfload.c). I think mmap cannot guarantee that the returned >> >> pointer (test) equals to the parameter of addr. So is this a bug to >> >> assert (addr =3D=3D test)? >> >> >> >> Attached configure script and test ELF file. >> >> >> >> Thanks. >> >> >> >> To manage notifications about this bug go to: >> >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions >> >> >> >> >> -- >> Alex Benn=C3=A9e >> >> -- >> You received this bug notification because you are subscribed to the bug >> report. >> https://bugs.launchpad.net/bugs/1895080 >> >> Title: >> pgb_reserved_va: Assertion `addr =3D=3D test' failed >> >> Status in QEMU: >> New >> >> Bug description: >> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head >> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux- >> user. >> >> Firstly, compile fails: >> Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c= .o >> ../qemu.git/linux-user/strace.c:1210:18: error: =E2=80=98FALLOC_FL_KEE= P_SIZE=E2=80=99 >> undeclared here (not in a function) >> FLAG_GENERIC(FALLOC_FL_KEEP_SIZE), >> >> I have to add below include to linux-user/strace.c >> diff --git a/linux-user/strace.c b/linux-user/strace.c >> index 11fea14fba..22e51d4a8a 100644 >> --- a/linux-user/strace.c >> +++ b/linux-user/strace.c >> @@ -7,6 +7,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> >> Then trying qemu-riscv32 with a simple ELF, I get: >> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D tes= t' >> failed. >> >> strace shows that: >> mmap(0x1000, 4294963200, PROT_NONE, >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr = =3D=3D >> test' failed. >> ) =3D 103 >> >> The source code is in the function pgb_reserved_va (linux- >> user/elfload.c). I think mmap cannot guarantee that the returned >> pointer (test) equals to the parameter of addr. So is this a bug to >> assert (addr =3D=3D test)? >> >> Attached configure script and test ELF file. >> >> Thanks. >> >> To manage notifications about this bug go to: >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions >> --=20 Alex Benn=C3=A9e From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C5D1DC43461 for ; Fri, 11 Sep 2020 14:56:35 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0C09B22273 for ; Fri, 11 Sep 2020 14:56:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0C09B22273 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:38478 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kGkTa-0006qk-8M for qemu-devel@archiver.kernel.org; Fri, 11 Sep 2020 10:56:34 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34498) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kGkSp-0006Ow-ER for qemu-devel@nongnu.org; Fri, 11 Sep 2020 10:55:47 -0400 Received: from indium.canonical.com ([91.189.90.7]:37854) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1kGkSm-0008Uu-QD for qemu-devel@nongnu.org; Fri, 11 Sep 2020 10:55:47 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1kGkSk-0007AX-AU for ; Fri, 11 Sep 2020 14:55:42 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 4DC582E80DB for ; Fri, 11 Sep 2020 14:55:42 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Fri, 11 Sep 2020 14:47:00 -0000 From: =?utf-8?q?Alex_Benn=C3=A9e?= <1895080@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=New; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: linux-user X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: ajbennee hansni laurent-vivier X-Launchpad-Bug-Reporter: Hansni Bu (hansni) X-Launchpad-Bug-Modifier: =?utf-8?q?Alex_Benn=C3=A9e_=28ajbennee=29?= References: <159970958159.31371.12301700684467003959.malonedeb@wampee.canonical.com> <92de5ee0-629a-640a-d547-8c2d650742f2@vivier.eu> <87tuw4odwk.fsf@linaro.org> <87r1r8odph.fsf@linaro.org> <87o8mco7el.fsf@linaro.org> Message-ID: <87k0x0nzff.fsf@linaro.org> Subject: Re: [Bug 1895080] [NEW] pgb_reserved_va: Assertion `addr == test' failed X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="83bdf6c8a3a5f87722c8927e54838522f3e57504"; Instance="production" X-Launchpad-Hash: f2ec6b3ce5049dba468cf99f5ab36f87587d2ea4 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/11 02:05:39 X-ACL-Warn: Detected OS = Linux 3.11 and newer [fuzzy] X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1895080 <1895080@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20200911144700.SGbVjJSh0crxKXzrBXBsOwxhPWCCCyCPx5Xtv2I6OZ0@z> Hansni Bu <1895080@bugs.launchpad.net> writes: >> > No, it's not set by CentOS-7.5. >> > Does it mean that we just cannot run the ELF in such a case? I've tried >> > many times, the assert always fails. Maybe, we can blame CentOS-7.5. >> >> The trouble is without MAP_FIXED_NOREPLACE we are at the mercy of the >> host kernel to allow the address request to be honoured. A plain >> MAP_FIXED won't do as it can clober existing mappings. In theory a >> suitable hole has been identified but sometimes the kernel makes a >> decision to offset the suggested mapping for it's own reasons. >> > > MAP_FIXED_NOREPLACE is quite a new feature. > > >> > BTW: with the option "-p 65536", the case runs successfully. >> >> Hmm interesting. I wonder if we are seeing a fail due to mmap_min_addr? >> What does: >> >> /proc/sys/vm/mmap_min_addr >> >> give you on the system? >> > > It gives me 4096. And guest_base has this value. Maybe that's the strange > point. mmap_min_addr give us 0x1000. While we are requesting this address, > the kernel gives us 0x10000. Yeah the meaning of mmap_min_addr should be exactly that which is odd why the kernel doesn't honour the request. That said it seems to be a user tweakable knob so you could just up it. >> >> You can manually set the reserved_va and the base address using -R and >> -B although that is more of a developer work around. I think moving the >> assert to the condition above would be an improvement just because it >> tells us what the requested base address was and what the kernel decided >> to give us. >> > > Setting guest_base with -B to 0x10000 works. Tried some -R values, no luc= k. > Agree to print a more hintful message. OK - one other test you try is running inside a chroot which *does not* have visibility of /proc. That will cause it to fall back to the old probing technique of trying multiple mmap operations to find the hole. I suspect that works because the attempt to map 0x1000 would fail the check. The reason we default to probing /proc/self/map now is that brute force technique falls over when trying to probe for a hole on 64 bit systems, especially when built with stack protection/clang debug instrumentation. In the meantime I'll spin up a patch to improve the failure mode. > > >> >> > >> > On Fri, Sep 11, 2020 at 5:50 PM Alex Benn=C3=A9e <1895080@bugs.launchp= ad.net> >> > wrote: >> > >> >> Alex Benn=C3=A9e writes: >> >> >> >> > Laurent Vivier writes: >> >> > >> >> >> >> >>> Then trying qemu-riscv32 with a simple ELF, I get: >> >> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D= =3D test' >> >> failed. >> >> >>> >> >> >>> strace shows that: >> >> >>> mmap(0x1000, 4294963200, PROT_NONE, >> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> >> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `ad= dr >> =3D=3D >> >> test' failed. >> >> >>> ) =3D 103 >> >> >>> >> >> >>> The source code is in the function pgb_reserved_va (linux- >> >> >>> user/elfload.c). I think mmap cannot guarantee that the returned >> >> pointer >> >> >>> (test) equals to the parameter of addr. So is this a bug to assert >> >> (addr >> >> >>> =3D=3D test)? >> >> >> >> >> > I'm assuming CentOS 7.5 actually has a definition for >> >> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for - >> >> > otherwise we are in the position of hoping the kernel honours what = we >> >> > asked for. >> >> >> >> Doh re-reading I see it's not set in the strace output. Maybe we shou= ld >> >> promote the assert case to the failure leg so we have: >> >> >> >> if (addr =3D=3D MAP_FAILED || addr !=3D test) { >> >> error_report(...) >> >> } >> >> >> >> so we at least fail with a user friendly error rather than an abort? >> >> >> >> -- >> >> Alex Benn=C3=A9e >> >> >> >> -- >> >> You received this bug notification because you are subscribed to the = bug >> >> report. >> >> https://bugs.launchpad.net/bugs/1895080 >> >> >> >> Title: >> >> pgb_reserved_va: Assertion `addr =3D=3D test' failed >> >> >> >> Status in QEMU: >> >> New >> >> >> >> Bug description: >> >> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu he= ad >> >> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux- >> >> user. >> >> >> >> Firstly, compile fails: >> >> Compiling C object >> libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o >> >> ../qemu.git/linux-user/strace.c:1210:18: error: =E2=80=98FALLOC_FL_= KEEP_SIZE=E2=80=99 >> >> undeclared here (not in a function) >> >> FLAG_GENERIC(FALLOC_FL_KEEP_SIZE), >> >> >> >> I have to add below include to linux-user/strace.c >> >> diff --git a/linux-user/strace.c b/linux-user/strace.c >> >> index 11fea14fba..22e51d4a8a 100644 >> >> --- a/linux-user/strace.c >> >> +++ b/linux-user/strace.c >> >> @@ -7,6 +7,7 @@ >> >> #include >> >> #include >> >> #include >> >> +#include >> >> #include >> >> #include >> >> #include >> >> >> >> Then trying qemu-riscv32 with a simple ELF, I get: >> >> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D = test' >> >> failed. >> >> >> >> strace shows that: >> >> mmap(0x1000, 4294963200, PROT_NONE, >> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> >> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `ad= dr >> =3D=3D >> >> test' failed. >> >> ) =3D 103 >> >> >> >> The source code is in the function pgb_reserved_va (linux- >> >> user/elfload.c). I think mmap cannot guarantee that the returned >> >> pointer (test) equals to the parameter of addr. So is this a bug to >> >> assert (addr =3D=3D test)? >> >> >> >> Attached configure script and test ELF file. >> >> >> >> Thanks. >> >> >> >> To manage notifications about this bug go to: >> >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions >> >> >> >> >> -- >> Alex Benn=C3=A9e >> >> -- >> You received this bug notification because you are subscribed to the bug >> report. >> https://bugs.launchpad.net/bugs/1895080 >> >> Title: >> pgb_reserved_va: Assertion `addr =3D=3D test' failed >> >> Status in QEMU: >> New >> >> Bug description: >> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head >> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux- >> user. >> >> Firstly, compile fails: >> Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c= .o >> ../qemu.git/linux-user/strace.c:1210:18: error: =E2=80=98FALLOC_FL_KEE= P_SIZE=E2=80=99 >> undeclared here (not in a function) >> FLAG_GENERIC(FALLOC_FL_KEEP_SIZE), >> >> I have to add below include to linux-user/strace.c >> diff --git a/linux-user/strace.c b/linux-user/strace.c >> index 11fea14fba..22e51d4a8a 100644 >> --- a/linux-user/strace.c >> +++ b/linux-user/strace.c >> @@ -7,6 +7,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> >> Then trying qemu-riscv32 with a simple ELF, I get: >> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D tes= t' >> failed. >> >> strace shows that: >> mmap(0x1000, 4294963200, PROT_NONE, >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) =3D 0x10000 >> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr = =3D=3D >> test' failed. >> ) =3D 103 >> >> The source code is in the function pgb_reserved_va (linux- >> user/elfload.c). I think mmap cannot guarantee that the returned >> pointer (test) equals to the parameter of addr. So is this a bug to >> assert (addr =3D=3D test)? >> >> Attached configure script and test ELF file. >> >> Thanks. >> >> To manage notifications about this bug go to: >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions >> -- = Alex Benn=C3=A9e -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1895080 Title: pgb_reserved_va: Assertion `addr =3D=3D test' failed Status in QEMU: New Bug description: This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux- user. Firstly, compile fails: Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o ../qemu.git/linux-user/strace.c:1210:18: error: =E2=80=98FALLOC_FL_KEEP_S= IZE=E2=80=99 undeclared here (not in a function) FLAG_GENERIC(FALLOC_FL_KEEP_SIZE), I have to add below include to linux-user/strace.c diff --git a/linux-user/strace.c b/linux-user/strace.c index 11fea14fba..22e51d4a8a 100644 --- a/linux-user/strace.c +++ b/linux-user/strace.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include Then trying qemu-riscv32 with a simple ELF, I get: linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D test' = failed. strace shows that: mmap(0x1000, 4294963200, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESER= VE, -1, 0) =3D 0x10000 write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: ../qemu.= git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr =3D=3D test= ' failed. ) =3D 103 The source code is in the function pgb_reserved_va (linux- user/elfload.c). I think mmap cannot guarantee that the returned pointer (test) equals to the parameter of addr. So is this a bug to assert (addr =3D=3D test)? Attached configure script and test ELF file. Thanks. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions