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Message-Id: <20200511073151.19043-2-jgross@suse.com>
Date: Mon, 11 May 2020 09:31:50 +0200
From: Juergen Gross <jgross@...e.com>
To: xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
clang-built-linux@...glegroups.com
Cc: Juergen Gross <jgross@...e.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 1/2] xen/xenbus: avoid large structs and arrays on the stack
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 <arnd@...db.de>
Signed-off-by: Juergen Gross <jgross@...e.com>
---
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;
}
--
2.26.1
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