From patchwork Mon May 11 07:31:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 11539843 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 002AA913 for ; Mon, 11 May 2020 07:33:00 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 D99E52075E for ; Mon, 11 May 2020 07:33:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D99E52075E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jY2v1-0004M4-1u; Mon, 11 May 2020 07:32:07 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jY2uz-0004Le-KL for xen-devel@lists.xenproject.org; Mon, 11 May 2020 07:32:05 +0000 X-Inumbo-ID: 7d0814a6-9359-11ea-9887-bc764e2007e4 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 7d0814a6-9359-11ea-9887-bc764e2007e4; Mon, 11 May 2020 07:31:55 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id D0575AC5B; Mon, 11 May 2020 07:31:56 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH 1/2] xen/xenbus: avoid large structs and arrays on the stack Date: Mon, 11 May 2020 09:31:50 +0200 Message-Id: <20200511073151.19043-2-jgross@suse.com> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200511073151.19043-1-jgross@suse.com> References: <20200511073151.19043-1-jgross@suse.com> MIME-Version: 1.0 X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini , Arnd Bergmann Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" xenbus_map_ring_valloc() and its sub-functions are putting quite large structs and arrays on the stack. This is problematic at runtime, but might also result in build failures (e.g. with clang due to the option -Werror,-Wframe-larger-than=... used). Fix that by moving most of the data from the stack into a dynamically allocated struct. Performance is no issue here, as xenbus_map_ring_valloc() is used only when adding a new PV device to a backend driver. While at it move some duplicated code from pv/hvm specific mapping functions to the single caller. Reported-by: Arnd Bergmann Signed-off-by: Juergen Gross --- drivers/xen/xenbus/xenbus_client.c | 127 +++++++++++++++-------------- 1 file changed, 66 insertions(+), 61 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c index 040d2a43e8e3..d8e5c5e4fa67 100644 --- a/drivers/xen/xenbus/xenbus_client.c +++ b/drivers/xen/xenbus/xenbus_client.c @@ -69,11 +69,27 @@ struct xenbus_map_node { unsigned int nr_handles; }; +struct map_ring_valloc { + struct xenbus_map_node *node; + + /* Why do we need two arrays? See comment of __xenbus_map_ring */ + union { + unsigned long addrs[XENBUS_MAX_RING_GRANTS]; + pte_t *ptes[XENBUS_MAX_RING_GRANTS]; + }; + phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS]; + + struct gnttab_map_grant_ref map[XENBUS_MAX_RING_GRANTS]; + struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS]; + + unsigned int idx; /* HVM only. */ +}; + static DEFINE_SPINLOCK(xenbus_valloc_lock); static LIST_HEAD(xenbus_valloc_pages); struct xenbus_ring_ops { - int (*map)(struct xenbus_device *dev, + int (*map)(struct xenbus_device *dev, struct map_ring_valloc *info, grant_ref_t *gnt_refs, unsigned int nr_grefs, void **vaddr); int (*unmap)(struct xenbus_device *dev, void *vaddr); @@ -449,12 +465,32 @@ int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs, unsigned int nr_grefs, void **vaddr) { int err; + struct map_ring_valloc *info; + + *vaddr = NULL; + + if (nr_grefs > XENBUS_MAX_RING_GRANTS) + return -EINVAL; + + info = kzalloc(sizeof(*info), GFP_KERNEL); + if (!info) + return -ENOMEM; + + info->node = kzalloc(sizeof(*info->node), GFP_KERNEL); + if (!info->node) { + err = -ENOMEM; + goto out; + } + + err = ring_ops->map(dev, info, gnt_refs, nr_grefs, vaddr); - err = ring_ops->map(dev, gnt_refs, nr_grefs, vaddr); /* Some hypervisors are buggy and can return 1. */ if (err > 0) err = GNTST_general_error; + out: + kfree(info->node); + kfree(info); return err; } EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc); @@ -466,12 +502,10 @@ static int __xenbus_map_ring(struct xenbus_device *dev, grant_ref_t *gnt_refs, unsigned int nr_grefs, grant_handle_t *handles, - phys_addr_t *addrs, + struct map_ring_valloc *info, unsigned int flags, bool *leaked) { - struct gnttab_map_grant_ref map[XENBUS_MAX_RING_GRANTS]; - struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS]; int i, j; int err = GNTST_okay; @@ -479,23 +513,22 @@ static int __xenbus_map_ring(struct xenbus_device *dev, return -EINVAL; for (i = 0; i < nr_grefs; i++) { - memset(&map[i], 0, sizeof(map[i])); - gnttab_set_map_op(&map[i], addrs[i], flags, gnt_refs[i], - dev->otherend_id); + gnttab_set_map_op(&info->map[i], info->phys_addrs[i], flags, + gnt_refs[i], dev->otherend_id); handles[i] = INVALID_GRANT_HANDLE; } - gnttab_batch_map(map, i); + gnttab_batch_map(info->map, i); for (i = 0; i < nr_grefs; i++) { - if (map[i].status != GNTST_okay) { - err = map[i].status; - xenbus_dev_fatal(dev, map[i].status, + if (info->map[i].status != GNTST_okay) { + err = info->map[i].status; + xenbus_dev_fatal(dev, info->map[i].status, "mapping in shared page %d from domain %d", gnt_refs[i], dev->otherend_id); goto fail; } else - handles[i] = map[i].handle; + handles[i] = info->map[i].handle; } return GNTST_okay; @@ -503,19 +536,19 @@ static int __xenbus_map_ring(struct xenbus_device *dev, fail: for (i = j = 0; i < nr_grefs; i++) { if (handles[i] != INVALID_GRANT_HANDLE) { - memset(&unmap[j], 0, sizeof(unmap[j])); - gnttab_set_unmap_op(&unmap[j], (phys_addr_t)addrs[i], + gnttab_set_unmap_op(&info->unmap[j], + info->phys_addrs[i], GNTMAP_host_map, handles[i]); j++; } } - if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, j)) + if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, info->unmap, j)) BUG(); *leaked = false; for (i = 0; i < j; i++) { - if (unmap[i].status != GNTST_okay) { + if (info->unmap[i].status != GNTST_okay) { *leaked = true; break; } @@ -566,21 +599,12 @@ static int xenbus_unmap_ring(struct xenbus_device *dev, grant_handle_t *handles, return err; } -struct map_ring_valloc_hvm -{ - unsigned int idx; - - /* Why do we need two arrays? See comment of __xenbus_map_ring */ - phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS]; - unsigned long addrs[XENBUS_MAX_RING_GRANTS]; -}; - static void xenbus_map_ring_setup_grant_hvm(unsigned long gfn, unsigned int goffset, unsigned int len, void *data) { - struct map_ring_valloc_hvm *info = data; + struct map_ring_valloc *info = data; unsigned long vaddr = (unsigned long)gfn_to_virt(gfn); info->phys_addrs[info->idx] = vaddr; @@ -590,38 +614,27 @@ static void xenbus_map_ring_setup_grant_hvm(unsigned long gfn, } static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev, + struct map_ring_valloc *info, grant_ref_t *gnt_ref, unsigned int nr_grefs, void **vaddr) { - struct xenbus_map_node *node; + struct xenbus_map_node *node = info->node; int err; void *addr; bool leaked = false; - struct map_ring_valloc_hvm info = { - .idx = 0, - }; unsigned int nr_pages = XENBUS_PAGES(nr_grefs); - if (nr_grefs > XENBUS_MAX_RING_GRANTS) - return -EINVAL; - - *vaddr = NULL; - - node = kzalloc(sizeof(*node), GFP_KERNEL); - if (!node) - return -ENOMEM; - err = alloc_xenballooned_pages(nr_pages, node->hvm.pages); if (err) goto out_err; gnttab_foreach_grant(node->hvm.pages, nr_grefs, xenbus_map_ring_setup_grant_hvm, - &info); + info); err = __xenbus_map_ring(dev, gnt_ref, nr_grefs, node->handles, - info.phys_addrs, GNTMAP_host_map, &leaked); + info, GNTMAP_host_map, &leaked); node->nr_handles = nr_grefs; if (err) @@ -641,11 +654,13 @@ static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev, spin_unlock(&xenbus_valloc_lock); *vaddr = addr; + info->node = NULL; + return 0; out_xenbus_unmap_ring: if (!leaked) - xenbus_unmap_ring(dev, node->handles, nr_grefs, info.addrs); + xenbus_unmap_ring(dev, node->handles, nr_grefs, info->addrs); else pr_alert("leaking %p size %u page(s)", addr, nr_pages); @@ -653,7 +668,6 @@ static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev, if (!leaked) free_xenballooned_pages(nr_pages, node->hvm.pages); out_err: - kfree(node); return err; } @@ -677,39 +691,29 @@ EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree); #ifdef CONFIG_XEN_PV static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev, + struct map_ring_valloc *info, grant_ref_t *gnt_refs, unsigned int nr_grefs, void **vaddr) { - struct xenbus_map_node *node; + struct xenbus_map_node *node = info->node; struct vm_struct *area; - pte_t *ptes[XENBUS_MAX_RING_GRANTS]; - phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS]; int err = GNTST_okay; int i; bool leaked; - *vaddr = NULL; - - if (nr_grefs > XENBUS_MAX_RING_GRANTS) - return -EINVAL; - - node = kzalloc(sizeof(*node), GFP_KERNEL); - if (!node) - return -ENOMEM; - - area = alloc_vm_area(XEN_PAGE_SIZE * nr_grefs, ptes); + area = alloc_vm_area(XEN_PAGE_SIZE * nr_grefs, info->ptes); if (!area) { kfree(node); return -ENOMEM; } for (i = 0; i < nr_grefs; i++) - phys_addrs[i] = arbitrary_virt_to_machine(ptes[i]).maddr; + info->phys_addrs[i] = + arbitrary_virt_to_machine(info->ptes[i]).maddr; err = __xenbus_map_ring(dev, gnt_refs, nr_grefs, node->handles, - phys_addrs, - GNTMAP_host_map | GNTMAP_contains_pte, + info, GNTMAP_host_map | GNTMAP_contains_pte, &leaked); if (err) goto failed; @@ -722,6 +726,8 @@ static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev, spin_unlock(&xenbus_valloc_lock); *vaddr = area->addr; + info->node = NULL; + return 0; failed: @@ -730,7 +736,6 @@ static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev, else pr_alert("leaking VM area %p size %u page(s)", area, nr_grefs); - kfree(node); return err; }