2 files changed, 233 insertions, 0 deletions

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 823ce788b14b..43f014cfb458 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -1,2 +1,3 @@
 obj-y   += grant-table.o features.o events.o
 obj-y   += xenbus/
+obj-$(CONFIG_XEN_XENCOMM)       += xencomm.o
diff --git a/drivers/xen/xencomm.c b/drivers/xen/xencomm.c
new file mode 100644
index 000000000000..797cb4e31f07
--- /dev/null
+++ b/drivers/xen/xencomm.c
@@ -0,0 +1,232 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ * Copyright (C) IBM Corp. 2006
+ *
+ * Authors: Hollis Blanchard <hollisb@us.ibm.com>
+ */
+
+#include <linux/gfp.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <xen/xencomm.h>
+#include <xen/interface/xen.h>
+#ifdef __ia64__
+#include <asm/xen/xencomm.h>    /* for is_kern_addr() */
+#endif
+
+#ifdef HAVE_XEN_PLATFORM_COMPAT_H
+#include <xen/platform-compat.h>
+#endif
+
+static int xencomm_init(struct xencomm_desc *desc,
+                        void *buffer, unsigned long bytes)
+{
+        unsigned long recorded = 0;
+        int i = 0;
+
+        while ((recorded < bytes) && (i < desc->nr_addrs)) {
+                unsigned long vaddr = (unsigned long)buffer + recorded;
+                unsigned long paddr;
+                int offset;
+                int chunksz;
+
+                offset = vaddr % PAGE_SIZE; /* handle partial pages */
+                chunksz = min(PAGE_SIZE - offset, bytes - recorded);
+
+                paddr = xencomm_vtop(vaddr);
+                if (paddr == ~0UL) {
+                        printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
+                               __func__, vaddr);
+                        return -EINVAL;
+                }
+
+                desc->address[i++] = paddr;
+                recorded += chunksz;
+        }
+
+        if (recorded < bytes) {
+                printk(KERN_DEBUG
+                       "%s: could only translate %ld of %ld bytes\n",
+                       __func__, recorded, bytes);
+                return -ENOSPC;
+        }
+
+        /* mark remaining addresses invalid (just for safety) */
+        while (i < desc->nr_addrs)
+                desc->address[i++] = XENCOMM_INVALID;
+
+        desc->magic = XENCOMM_MAGIC;
+
+        return 0;
+}
+
+static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
+                                          void *buffer, unsigned long bytes)
+{
+        struct xencomm_desc *desc;
+        unsigned long buffer_ulong = (unsigned long)buffer;
+        unsigned long start = buffer_ulong & PAGE_MASK;
+        unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
+        unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
+        unsigned long size = sizeof(*desc) +
+                sizeof(desc->address[0]) * nr_addrs;
+
+        /*
+         * slab allocator returns at least sizeof(void*) aligned pointer.
+         * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
+         * cross page boundary.
+         */
+        if (sizeof(*desc) > sizeof(void *)) {
+                unsigned long order = get_order(size);
+                desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
+                                                               order);
+                if (desc == NULL)
+                        return NULL;
+
+                desc->nr_addrs =
+                        ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
+                        sizeof(*desc->address);
+        } else {
+                desc = kmalloc(size, gfp_mask);
+                if (desc == NULL)
+                        return NULL;
+
+                desc->nr_addrs = nr_addrs;
+        }
+        return desc;
+}
+
+void xencomm_free(struct xencomm_handle *desc)
+{
+        if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
+                struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
+                if (sizeof(*desc__) > sizeof(void *)) {
+                        unsigned long size = sizeof(*desc__) +
+                                sizeof(desc__->address[0]) * desc__->nr_addrs;
+                        unsigned long order = get_order(size);
+                        free_pages((unsigned long)__va(desc), order);
+                } else
+                        kfree(__va(desc));
+        }
+}
+
+static int xencomm_create(void *buffer, unsigned long bytes,
+                          struct xencomm_desc **ret, gfp_t gfp_mask)
+{
+        struct xencomm_desc *desc;
+        int rc;
+
+        pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
+
+        if (bytes == 0) {
+                /* don't create a descriptor; Xen recognizes NULL. */
+                BUG_ON(buffer != NULL);
+                *ret = NULL;
+                return 0;
+        }
+
+        BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
+
+        desc = xencomm_alloc(gfp_mask, buffer, bytes);
+        if (!desc) {
+                printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
+                return -ENOMEM;
+        }
+
+        rc = xencomm_init(desc, buffer, bytes);
+        if (rc) {
+                printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
+                xencomm_free((struct xencomm_handle *)__pa(desc));
+                return rc;
+        }
+
+        *ret = desc;
+        return 0;
+}
+
+/* check if memory address is within VMALLOC region  */
+static int is_phys_contiguous(unsigned long addr)
+{
+        if (!is_kernel_addr(addr))
+                return 0;
+
+        return (addr < VMALLOC_START) || (addr >= VMALLOC_END);
+}
+
+static struct xencomm_handle *xencomm_create_inline(void *ptr)
+{
+        unsigned long paddr;
+
+        BUG_ON(!is_phys_contiguous((unsigned long)ptr));
+
+        paddr = (unsigned long)xencomm_pa(ptr);
+        BUG_ON(paddr & XENCOMM_INLINE_FLAG);
+        return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
+}
+
+/* "mini" routine, for stack-based communications: */
+static int xencomm_create_mini(void *buffer,
+        unsigned long bytes, struct xencomm_mini *xc_desc,
+        struct xencomm_desc **ret)
+{
+        int rc = 0;
+        struct xencomm_desc *desc;
+        BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
+
+        desc = (void *)xc_desc;
+
+        desc->nr_addrs = XENCOMM_MINI_ADDRS;
+
+        rc = xencomm_init(desc, buffer, bytes);
+        if (!rc)
+                *ret = desc;
+
+        return rc;
+}
+
+struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
+{
+        int rc;
+        struct xencomm_desc *desc;
+
+        if (is_phys_contiguous((unsigned long)ptr))
+                return xencomm_create_inline(ptr);
+
+        rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
+
+        if (rc || desc == NULL)
+                return NULL;
+
+        return xencomm_pa(desc);
+}
+
+struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
+                        struct xencomm_mini *xc_desc)
+{
+        int rc;
+        struct xencomm_desc *desc = NULL;
+
+        if (is_phys_contiguous((unsigned long)ptr))
+                return xencomm_create_inline(ptr);
+
+        rc = xencomm_create_mini(ptr, bytes, xc_desc,
+                                &desc);
+
+        if (rc)
+                return NULL;
+
+        return xencomm_pa(desc);
+}