From patchwork Sun Oct 7 15:37:31 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brad Smith X-Patchwork-Id: 980190 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=comstyle.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=comstyle.com header.i=@comstyle.com header.b="T/a9oCr/"; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 42SnhX2x8vzB2xQ for ; Mon, 8 Oct 2018 02:38:34 +1100 (AEDT) Received: from localhost ([::1]:42734 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g9B8Y-0003NY-Ny for incoming@patchwork.ozlabs.org; Sun, 07 Oct 2018 11:38:30 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59348) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g9B7s-0003C0-Mx for qemu-devel@nongnu.org; Sun, 07 Oct 2018 11:37:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g9B7r-0004Ff-V6 for qemu-devel@nongnu.org; Sun, 07 Oct 2018 11:37:48 -0400 Received: from speedy.comstyle.com ([2001:470:1d:8c::2]:27889 helo=mail.comstyle.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1g9B7r-0004Bt-N7 for qemu-devel@nongnu.org; Sun, 07 Oct 2018 11:37:47 -0400 Received: from mail.comstyle.com (localhost [127.0.0.1]) by mail.comstyle.com (Postfix) with ESMTP id 920059843A for ; Sun, 7 Oct 2018 11:37:24 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=comstyle.com; h=date:from :to:subject:message-id:mime-version:content-type; s=selector1; bh=pFx6PNxGHmRnRJlT9SzexkvsNgI=; b=T/a9oCr//rlhZ3gS/LaDtPtCIXFj 1qprmhHX24Ivw+eWUmgQoD1MxgFK6BJiyU32ZmZHc3buKhmBssLXZwkdaWWe3wLR JMbCnvZVBsd6aFvUV5gZgM8EPDtdHMk1APrRGy1GFz6UQa8jIssbpCTVnCse40gH dryAXtwqFrRW0vc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=comstyle.com; h=date:from:to :subject:message-id:mime-version:content-type; q=dns; s= selector1; b=PnUtRPx+d9oUCGM8apyXVlP9mWFtirxIh85LKXGbachLjXvzQOJ uXKb3TFW16b6Am4ofYCgziIc4LseO/1EAf3IAvGH1xkIGAbORuAh6Fmg7uUsfuSI a/WHXumu6ij8QMGwtoe87/U7Xr7/xoNJLLOlRDrQHKoWvoiH9PTxP0QI= Received: from humpty.home.comstyle.com (unknown [IPv6:2001:470:c454:100:13af:4407:2bbf:771f]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: brad) by mail.comstyle.com (Postfix) with ESMTPSA id 73E0D98439 for ; Sun, 7 Oct 2018 11:37:24 -0400 (EDT) Date: Sun, 7 Oct 2018 11:37:31 -0400 From: Brad Smith To: qemu-devel@nongnu.org Message-ID: <20181007153731.GA32288@humpty.home.comstyle.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:470:1d:8c::2 Subject: [Qemu-devel] [PATCH] oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Use MAP_STACK in qemu_alloc_stack() on OpenBSD. Added to -current and will be in our soon to be 6.4 release. MAP_STACK Indicate that the mapping is used as a stack. This flag must be used in combination with MAP_ANON and MAP_PRIVATE. Implement MAP_STACK option for mmap(). Synchronous faults (pagefault and syscall) confirm the stack register points at MAP_STACK memory, otherwise SIGSEGV is delivered. sigaltstack() and pthread_attr_setstack() are modified to create a MAP_STACK sub-region which satisfies alignment requirements. Observe that MAP_STACK can only be set/cleared by mmap(), which zeroes the contents of the region -- there is no mprotect() equivalent operation, so there is no MAP_STACK-adding gadget. Signed-off-by: Brad Smith Reviewed-by: Kamil Rytarowski diff --git a/util/oslib-posix.c b/util/oslib-posix.c index fbd0dc8c57..51e9a012c2 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -611,7 +611,11 @@ void *qemu_alloc_stack(size_t *sz) *sz += pagesz; ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE, - MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + MAP_PRIVATE | MAP_ANONYMOUS +#ifdef MAP_STACK + | MAP_STACK +#endif + , -1, 0); if (ptr == MAP_FAILED) { perror("failed to allocate memory for stack"); abort();