fbmem: fix fb_read, fb_write unaligned accesses

fb_{read,write} access the framebuffer using lots of fb_{read,write}l's
but don't check that the file position is aligned which can cause problems
on some architectures which do not support unaligned accesses.

Since the operations are essentially memcpy_{from,to}io, new
fb_memcpy_{from,to}fb macros have been defined and these are used instead.

For Sparc, fb_{read,write} macros use sbus_{read,write}, so this defines
new sbus_memcpy_{from,to}io functions the same as memcpy_{from,to}io but
using sbus_{read,write}b instead of {read,write}b.

Signed-off-by: James Hogan <james@albanarts.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 32 deletions

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index a43442341ddd..0e6aa3d96a42 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -697,9 +697,9 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
         struct inode *inode = file->f_path.dentry->d_inode;
         int fbidx = iminor(inode);
         struct fb_info *info = registered_fb[fbidx];
-        u32 *buffer, *dst;
-        u32 __iomem *src;
-        int c, i, cnt = 0, err = 0;
+        u8 *buffer, *dst;
+        u8 __iomem *src;
+        int c, cnt = 0, err = 0;
         unsigned long total_size;
 
         if (!info || ! info->screen_base)
@@ -730,7 +730,7 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
         if (!buffer)
                 return -ENOMEM;
 
-        src = (u32 __iomem *) (info->screen_base + p);
+        src = (u8 __iomem *) (info->screen_base + p);
 
         if (info->fbops->fb_sync)
                 info->fbops->fb_sync(info);
@@ -738,17 +738,9 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
         while (count) {
                 c  = (count > PAGE_SIZE) ? PAGE_SIZE : count;
                 dst = buffer;
-                for (i = c >> 2; i--; )
-                        *dst++ = fb_readl(src++);
-                if (c & 3) {
-                        u8 *dst8 = (u8 *) dst;
-                        u8 __iomem *src8 = (u8 __iomem *) src;
-
-                        for (i = c & 3; i--;)
-                                *dst8++ = fb_readb(src8++);
-
-                        src = (u32 __iomem *) src8;
-                }
+                fb_memcpy_fromfb(dst, src, c);
+                dst += c;
+                src += c;
 
                 if (copy_to_user(buf, buffer, c)) {
                         err = -EFAULT;
@@ -772,9 +764,9 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
         struct inode *inode = file->f_path.dentry->d_inode;
         int fbidx = iminor(inode);
         struct fb_info *info = registered_fb[fbidx];
-        u32 *buffer, *src;
-        u32 __iomem *dst;
-        int c, i, cnt = 0, err = 0;
+        u8 *buffer, *src;
+        u8 __iomem *dst;
+        int c, cnt = 0, err = 0;
         unsigned long total_size;
 
         if (!info || !info->screen_base)
@@ -811,7 +803,7 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
         if (!buffer)
                 return -ENOMEM;
 
-        dst = (u32 __iomem *) (info->screen_base + p);
+        dst = (u8 __iomem *) (info->screen_base + p);
 
         if (info->fbops->fb_sync)
                 info->fbops->fb_sync(info);
@@ -825,19 +817,9 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
                         break;
                 }
 
-                for (i = c >> 2; i--; )
-                        fb_writel(*src++, dst++);
-
-                if (c & 3) {
-                        u8 *src8 = (u8 *) src;
-                        u8 __iomem *dst8 = (u8 __iomem *) dst;
-
-                        for (i = c & 3; i--; )
-                                fb_writeb(*src8++, dst8++);
-
-                        dst = (u32 __iomem *) dst8;
-                }
-
+                fb_memcpy_tofb(dst, src, c);
+                dst += c;
+                src += c;
                 *ppos += c;
                 buf += c;
                 cnt += c;