From patchwork Mon Sep 26 11:44:27 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Lieven X-Patchwork-Id: 675127 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3sjMzz4QMdz9sBR for ; Mon, 26 Sep 2016 22:03:11 +1000 (AEST) Received: from localhost ([::1]:43824 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1boUcn-00070w-Ou for incoming@patchwork.ozlabs.org; Mon, 26 Sep 2016 08:03:09 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44876) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1boULW-00083h-Gk for qemu-devel@nongnu.org; Mon, 26 Sep 2016 07:45:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1boULQ-0002u5-HW for qemu-devel@nongnu.org; Mon, 26 Sep 2016 07:45:17 -0400 Received: from mx01.kamp.de ([82.141.2.16]:60591) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1boULQ-0002tk-7K for qemu-devel@nongnu.org; Mon, 26 Sep 2016 07:45:12 -0400 Received: (qmail 18177 invoked by uid 89); 26 Sep 2016 11:44:39 -0000 Received: from [195.62.97.28] by client-16-kamp (envelope-from , uid 89) with qmail-scanner-2010/03/19-MF (clamdscan: 0.99.2/22254. avast: 1.2.2/16092600. spamassassin: 3.4.1. 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Processed in 0.382914 secs); 26 Sep 2016 11:44:39 -0000 Received: from smtp.kamp.de (HELO submission.kamp.de) ([195.62.97.28]) by mx01.kamp.de with ESMTPS (DHE-RSA-AES256-GCM-SHA384 encrypted); 26 Sep 2016 11:44:35 -0000 X-GL_Whitelist: yes Received: (qmail 8277 invoked from network); 26 Sep 2016 11:44:34 -0000 Received: from lieven-pc.kamp-intra.net (HELO lieven-pc) (relay@kamp.de@::ffff:172.21.12.60) by submission.kamp.de with ESMTPS (DHE-RSA-AES256-GCM-SHA384 encrypted) ESMTPA; 26 Sep 2016 11:44:34 -0000 Received: by lieven-pc (Postfix, from userid 1000) id A0EA5200D5; Mon, 26 Sep 2016 13:44:34 +0200 (CEST) From: Peter Lieven To: qemu-devel@nongnu.org Date: Mon, 26 Sep 2016 13:44:27 +0200 Message-Id: <1474890272-22952-2-git-send-email-pl@kamp.de> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1474890272-22952-1-git-send-email-pl@kamp.de> References: <1474890272-22952-1-git-send-email-pl@kamp.de> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 82.141.2.16 Subject: [Qemu-devel] [PATCH V8 1/6] oslib-posix: add helpers for stack alloc and free 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: , Cc: kwolf@redhat.com, peter.maydell@linaro.org, mst@redhat.com, armbru@redhat.com, Peter Lieven , dgilbert@redhat.com, mreitz@redhat.com, pbonzini@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" the allocated stack will be adjusted to the minimum supported stack size by the OS and rounded up to be a multiple of the system pagesize. Additionally an architecture dependent guard page is added to the stack to catch stack overflows. Signed-off-by: Peter Lieven --- include/sysemu/os-posix.h | 27 +++++++++++++++++++++++++++ util/oslib-posix.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 70 insertions(+) diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index 9c7dfdf..4a0f493 100644 --- a/include/sysemu/os-posix.h +++ b/include/sysemu/os-posix.h @@ -60,4 +60,31 @@ int qemu_utimens(const char *path, const qemu_timespec *times); bool is_daemonized(void); +/** + * qemu_alloc_stack: + * @sz: pointer to a size_t holding the requested stack size + * + * Allocate memory that can be used as a stack, for instance for + * coroutines. If the memory cannot be allocated, this function + * will abort (like g_malloc()). This function also inserts an + * additional guard page to catch a potential stack overflow. + * Note that the useable stack memory can be greater than the + * requested stack size due to alignment and minimal stack size + * restrictions. In this case the value of sz is adjusted. + * + * The allocated stack must be freed with qemu_free_stack(). + * + * Returns: pointer to (the lowest address of) the stack memory. + */ +void *qemu_alloc_stack(size_t *sz); + +/** + * qemu_free_stack: + * @stack: stack to free + * @sz: size of stack in bytes + * + * Free a stack allocated via qemu_alloc_stack(). + */ +void qemu_free_stack(void *stack, size_t sz); + #endif diff --git a/util/oslib-posix.c b/util/oslib-posix.c index f2d4e9e..7d053b8 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -499,3 +499,46 @@ pid_t qemu_fork(Error **errp) } return pid; } + +void *qemu_alloc_stack(size_t *sz) +{ + void *ptr, *guardpage; + size_t pagesz = getpagesize(); + size_t allocsz; +#ifdef _SC_THREAD_STACK_MIN + /* avoid stacks smaller than _SC_THREAD_STACK_MIN */ + long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN); + *sz = MAX(MAX(min_stack_sz, 0), *sz); +#endif + /* adjust stack size to a multiple of the page size */ + *sz = ROUND_UP(*sz, pagesz); + /* allocate one extra page for the guard page */ + allocsz = *sz + getpagesize(); + + ptr = mmap(NULL, allocsz, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + abort(); + } + +#if defined(HOST_IA64) + /* separate register stack */ + guardpage = ptr + (((allocsz - pagesz) / 2) & ~pagesz); +#elif defined(HOST_HPPA) + /* stack grows up */ + guardpage = ptr + allocsz - pagesz; +#else + /* stack grows down */ + guardpage = ptr; +#endif + if (mprotect(guardpage, pagesz, PROT_NONE) != 0) { + abort(); + } + + return ptr; +} + +void qemu_free_stack(void *stack, size_t sz) +{ + munmap(stack, sz + getpagesize()); +}