[Xen-devel] [PATCH] xen: avoid link error on ARM

[Arnd Bergmann <arnd@xxxxxxxx>]

Building the privcmd code as a loadable module on ARM, we get
a link error due to the private cache management functions:

ERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined!

Move the code into a new file that is built along with privcmd.o
but is always built-in, even when the latter is a loadable module.

xen_remap_vma_range() may not be the best name here, if someone
comes up with a better one, let me know.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 drivers/xen/Makefile  |  3 +++
 drivers/xen/mm.c      | 41 +++++++++++++++++++++++++++++++++++++++++
 drivers/xen/privcmd.c | 30 +-----------------------------
 include/xen/xen-ops.h |  3 +++
 4 files changed, 48 insertions(+), 29 deletions(-)
 create mode 100644 drivers/xen/mm.c

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index ad3844d9f876..7124f9e749b4 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -29,6 +29,9 @@ obj-$(CONFIG_SWIOTLB_XEN)             += swiotlb-xen.o
 obj-$(CONFIG_XEN_MCE_LOG)              += mcelog.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)       += xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)              += xen-privcmd.o
+ifdef CONFIG_XEN_PRIVCMD
+obj-y                                  += mm.o
+endif
 obj-$(CONFIG_XEN_STUB)                 += xen-stub.o
 obj-$(CONFIG_XEN_ACPI_HOTPLUG_MEMORY)  += xen-acpi-memhotplug.o
 obj-$(CONFIG_XEN_ACPI_HOTPLUG_CPU)     += xen-acpi-cpuhotplug.o
diff --git a/drivers/xen/mm.c b/drivers/xen/mm.c
new file mode 100644
index 000000000000..8ad0d4900588
--- /dev/null
+++ b/drivers/xen/mm.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Architecture independent helper functions for memory management
+ *
+ * Written by Paul Durrant <paul.durrant@xxxxxxxxxx>
+ */
+#include <linux/mm.h>
+#include <linux/export.h>
+
+struct remap_pfn {
+       struct mm_struct *mm;
+       struct page **pages;
+       pgprot_t prot;
+       unsigned long i;
+};
+
+static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
+                       void *data)
+{
+       struct remap_pfn *r = data;
+       struct page *page = r->pages[r->i];
+       pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
+
+       set_pte_at(r->mm, addr, ptep, pte);
+       r->i++;
+
+       return 0;
+}
+
+/* Used by the privcmd module, but has to be built-in on ARM */
+int xen_remap_vma_range(struct vm_area_struct *vma, unsigned long addr, 
unsigned long len)
+{
+       struct remap_pfn r = {
+               .mm = vma->vm_mm,
+               .pages = vma->vm_private_data,
+               .prot = vma->vm_page_prot,
+       };
+
+       return apply_to_page_range(vma->vm_mm, addr, len, remap_pfn_fn, &r);
+}
+EXPORT_SYMBOL_GPL(xen_remap_vma_range);
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index b24ddac1604b..290b6aca7e1d 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -723,26 +723,6 @@ static long privcmd_ioctl_restrict(struct file *file, void 
__user *udata)
        return 0;
 }
 
-struct remap_pfn {
-       struct mm_struct *mm;
-       struct page **pages;
-       pgprot_t prot;
-       unsigned long i;
-};
-
-static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
-                       void *data)
-{
-       struct remap_pfn *r = data;
-       struct page *page = r->pages[r->i];
-       pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
-
-       set_pte_at(r->mm, addr, ptep, pte);
-       r->i++;
-
-       return 0;
-}
-
 static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
 {
        struct privcmd_data *data = file->private_data;
@@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, 
void __user *udata)
                goto out;
 
        if (xen_feature(XENFEAT_auto_translated_physmap)) {
-               struct remap_pfn r = {
-                       .mm = vma->vm_mm,
-                       .pages = vma->vm_private_data,
-                       .prot = vma->vm_page_prot,
-               };
-
-               rc = apply_to_page_range(r.mm, kdata.addr,
-                                        kdata.num << PAGE_SHIFT,
-                                        remap_pfn_fn, &r);
+               rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << 
PAGE_SHIFT);
        } else {
                unsigned int domid =
                        (xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 4969817124a8..98b30c1613b2 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -109,6 +109,9 @@ static inline int xen_xlate_unmap_gfn_range(struct 
vm_area_struct *vma,
 }
 #endif
 
+int xen_remap_vma_range(struct vm_area_struct *vma, unsigned long addr,
+                       unsigned long len);
+
 /*
  * xen_remap_domain_gfn_array() - map an array of foreign frames by gfn
  * @vma:     VMA to map the pages into
-- 
2.20.0


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