PM / Hibernate: Implement compat_ioctl for /dev/snapshot

This allows uswsusp built for i386 to run on an x86_64 kernel (tested
with Debian package version 1.0+20110509-2).

References: http://bugs.debian.org/502816
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 64 insertions, 0 deletions

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 78bdb4404aab..6b1ab7a88522 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -21,6 +21,7 @@
 #include <linux/swapops.h>
 #include <linux/pm.h>
 #include <linux/fs.h>
+#include <linux/compat.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
@@ -380,6 +381,66 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
         return error;
 }
 
+#ifdef CONFIG_COMPAT
+
+struct compat_resume_swap_area {
+        compat_loff_t offset;
+        u32 dev;
+} __packed;
+
+static long
+snapshot_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        BUILD_BUG_ON(sizeof(loff_t) != sizeof(compat_loff_t));
+
+        switch (cmd) {
+        case SNAPSHOT_GET_IMAGE_SIZE:
+        case SNAPSHOT_AVAIL_SWAP_SIZE:
+        case SNAPSHOT_ALLOC_SWAP_PAGE: {
+                compat_loff_t __user *uoffset = compat_ptr(arg);
+                loff_t offset;
+                mm_segment_t old_fs;
+                int err;
+
+                old_fs = get_fs();
+                set_fs(KERNEL_DS);
+                err = snapshot_ioctl(file, cmd, (unsigned long) &offset);
+                set_fs(old_fs);
+                if (!err && put_user(offset, uoffset))
+                        err = -EFAULT;
+                return err;
+        }
+
+        case SNAPSHOT_CREATE_IMAGE:
+                return snapshot_ioctl(file, cmd,
+                                      (unsigned long) compat_ptr(arg));
+
+        case SNAPSHOT_SET_SWAP_AREA: {
+                struct compat_resume_swap_area __user *u_swap_area =
+                        compat_ptr(arg);
+                struct resume_swap_area swap_area;
+                mm_segment_t old_fs;
+                int err;
+
+                err = get_user(swap_area.offset, &u_swap_area->offset);
+                err |= get_user(swap_area.dev, &u_swap_area->dev);
+                if (err)
+                        return -EFAULT;
+                old_fs = get_fs();
+                set_fs(KERNEL_DS);
+                err = snapshot_ioctl(file, SNAPSHOT_SET_SWAP_AREA,
+                                     (unsigned long) &swap_area);
+                set_fs(old_fs);
+                return err;
+        }
+
+        default:
+                return snapshot_ioctl(file, cmd, arg);
+        }
+}
+
+#endif /* CONFIG_COMPAT */
+
 static const struct file_operations snapshot_fops = {
         .open = snapshot_open,
         .release = snapshot_release,
@@ -387,6 +448,9 @@ static const struct file_operations snapshot_fops = {
         .write = snapshot_write,
         .llseek = no_llseek,
         .unlocked_ioctl = snapshot_ioctl,
+#ifdef CONFIG_COMPAT
+        .compat_ioctl = snapshot_compat_ioctl,
+#endif
 };
 
 static struct miscdevice snapshot_device = {