From patchwork Mon Sep 5 18:13:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 9315067 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 50E1960760 for ; Mon, 5 Sep 2016 19:04:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4405E289DB for ; Mon, 5 Sep 2016 19:04:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 39137289E2; Mon, 5 Sep 2016 19:04:05 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 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 mail.wl.linuxfoundation.org (Postfix) with ESMTPS id B9D30289DB for ; Mon, 5 Sep 2016 19:04:04 +0000 (UTC) Received: from localhost ([::1]:56429 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgzBb-0002VB-QB for patchwork-qemu-devel@patchwork.kernel.org; Mon, 05 Sep 2016 15:04:03 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38648) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgyQ3-0003Nu-HN for qemu-devel@nongnu.org; Mon, 05 Sep 2016 14:14:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bgyPy-0001AF-Gj for qemu-devel@nongnu.org; Mon, 05 Sep 2016 14:14:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42040) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgyPr-00015z-Oa; Mon, 05 Sep 2016 14:14:43 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6B5CF7F0A0; Mon, 5 Sep 2016 18:14:43 +0000 (UTC) Received: from noname.redhat.com (ovpn-116-62.ams2.redhat.com [10.36.116.62]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u85IDt81020627; Mon, 5 Sep 2016 14:14:42 -0400 From: Kevin Wolf To: qemu-block@nongnu.org Date: Mon, 5 Sep 2016 20:13:49 +0200 Message-Id: <1473099234-10882-38-git-send-email-kwolf@redhat.com> In-Reply-To: <1473099234-10882-1-git-send-email-kwolf@redhat.com> References: <1473099234-10882-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 05 Sep 2016 18:14:43 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 37/42] 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, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Peter Lieven 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. The memory for the guard page is deductated from stack memory so that the usable stack size is effectively reduced by the size of one page. This is equivalent to how the glibc stack allocation routines behave. Signed-off-by: Peter Lieven Reviewed-by: Richard Henderson Acked-by: Paolo Bonzini Signed-off-by: Kevin Wolf --- include/sysemu/os-posix.h | 27 ++++++++++++++++++++++++++ util/oslib-posix.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 75 insertions(+) diff --git a/include/sysemu/os-posix.h b/include/sysemu/os-posix.h index 9c7dfdf..87e60fe 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: size of required stack in bytes + * + * 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 a + * guard page to catch a potential stack overflow. The memory + * for the guard page is deductated from stack memory so that + * the usable stack size is effectively sz bytes minus the size + * of one page. + * + * 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..74dbe1c 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -499,3 +499,51 @@ pid_t qemu_fork(Error **errp) } return pid; } + +static size_t adjust_stack_size(size_t sz, size_t pagesz) +{ +#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); + return sz; +} + +void *qemu_alloc_stack(size_t sz) +{ + void *ptr, *guardpage; + size_t pagesz = getpagesize(); + sz = adjust_stack_size(sz, pagesz); + + ptr = mmap(NULL, sz, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); + if (ptr == MAP_FAILED) { + abort(); + } + +#if defined(HOST_IA64) + /* separate register stack */ + guardpage = ptr + (((sz - pagesz) / 2) & ~pagesz); +#elif defined(HOST_HPPA) + /* stack grows up */ + guardpage = ptr + sz - 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) +{ + size_t pagesz = getpagesize(); + sz = adjust_stack_size(sz, pagesz); + munmap(stack, sz); +}