[PATCH] fbdev: Fix incorrect unaligned access in little-endian machines

The drawing function cfbfillrect does not work correctly when access is not
unsigned-long aligned.  It manifests as extra lines of pixels that are not
complete drawn.  Reversing the shift operator solves the problem, so I would
presume that this bug would manifest only on little endian machines.  The
function cfbcopyarea may also have this bug.

Aligned access should present no problems.

Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 24 insertions, 36 deletions

diff --git a/drivers/video/cfbcopyarea.c b/drivers/video/cfbcopyarea.c
index cdc71572cf35..74415325b016 100644
--- a/drivers/video/cfbcopyarea.c
+++ b/drivers/video/cfbcopyarea.c
@@ -64,8 +64,8 @@ bitcpy(unsigned long __iomem *dst, int dst_idx, const unsigned long __iomem *src
         int const shift = dst_idx-src_idx;
         int left, right;
 
-        first = ~0UL >> dst_idx;
-        last = ~(~0UL >> ((dst_idx+n) % bits));
+        first = FB_SHIFT_HIGH(~0UL, dst_idx);
+        last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
 
         if (!shift) {
                 // Same alignment for source and dest
@@ -216,8 +216,8 @@ bitcpy_rev(unsigned long __iomem *dst, int dst_idx, const unsigned long __iomem
 
         shift = dst_idx-src_idx;
 
-        first = ~0UL << (bits - 1 - dst_idx);
-        last = ~(~0UL << (bits - 1 - ((dst_idx-n) % bits)));
+        first = FB_SHIFT_LOW(~0UL, bits - 1 - dst_idx);
+        last = ~(FB_SHIFT_LOW(~0UL, bits - 1 - ((dst_idx-n) % bits)));
 
         if (!shift) {
                 // Same alignment for source and dest
diff --git a/drivers/video/cfbfillrect.c b/drivers/video/cfbfillrect.c
index 167d9314e6eb..e5ff62e9cfb8 100644
--- a/drivers/video/cfbfillrect.c
+++ b/drivers/video/cfbfillrect.c
@@ -110,8 +110,8 @@ bitfill_aligned(unsigned long __iomem *dst, int dst_idx, unsigned long pat, unsi
         if (!n)
                 return;
 
-        first = ~0UL >> dst_idx;
-        last = ~(~0UL >> ((dst_idx+n) % bits));
+        first = FB_SHIFT_HIGH(~0UL, dst_idx);
+        last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
 
         if (dst_idx+n <= bits) {
                 // Single word
@@ -167,8 +167,8 @@ bitfill_unaligned(unsigned long __iomem *dst, int dst_idx, unsigned long pat,
         if (!n)
                 return;
 
-        first = ~0UL >> dst_idx;
-        last = ~(~0UL >> ((dst_idx+n) % bits));
+        first = FB_SHIFT_HIGH(~0UL, dst_idx);
+        last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
 
         if (dst_idx+n <= bits) {
                 // Single word
@@ -221,8 +221,8 @@ bitfill_aligned_rev(unsigned long __iomem *dst, int dst_idx, unsigned long pat,
         if (!n)
                 return;
 
-        first = ~0UL >> dst_idx;
-        last = ~(~0UL >> ((dst_idx+n) % bits));
+        first = FB_SHIFT_HIGH(~0UL, dst_idx);
+        last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
 
         if (dst_idx+n <= bits) {
                 // Single word
@@ -290,8 +290,8 @@ bitfill_unaligned_rev(unsigned long __iomem *dst, int dst_idx, unsigned long pat
         if (!n)
                 return;
 
-        first = ~0UL >> dst_idx;
-        last = ~(~0UL >> ((dst_idx+n) % bits));
+        first = FB_SHIFT_HIGH(~0UL, dst_idx);
+        last = ~(FB_SHIFT_HIGH(~0UL, (dst_idx+n) % bits));
 
         if (dst_idx+n <= bits) {
                 // Single word
diff --git a/drivers/video/cfbimgblt.c b/drivers/video/cfbimgblt.c
index 7a01742a82af..910e2338a27e 100644
--- a/drivers/video/cfbimgblt.c
+++ b/drivers/video/cfbimgblt.c
@@ -76,18 +76,6 @@ static u32 cfb_tab32[] = {
 #define FB_WRITEL fb_writel
 #define FB_READL  fb_readl
 
-#if defined (__BIG_ENDIAN)
-#define LEFT_POS(bpp)          (32 - bpp)
-#define SHIFT_HIGH(val, bits)  ((val) >> (bits))
-#define SHIFT_LOW(val, bits)   ((val) << (bits))
-#define BIT_NR(b)              (7 - (b))
-#else
-#define LEFT_POS(bpp)          (0)
-#define SHIFT_HIGH(val, bits)  ((val) << (bits))
-#define SHIFT_LOW(val, bits)   ((val) >> (bits))
-#define BIT_NR(b)              (b)
-#endif
-
 static inline void color_imageblit(const struct fb_image *image, 
                                    struct fb_info *p, u8 __iomem *dst1, 
                                    u32 start_index,
@@ -109,7 +97,7 @@ static inline void color_imageblit(const struct fb_image *image,
                 val = 0;
                 
                 if (start_index) {
-                        u32 start_mask = ~(SHIFT_HIGH(~(u32)0, start_index));
+                        u32 start_mask = ~(FB_SHIFT_HIGH(~(u32)0, start_index));
                         val = FB_READL(dst) & start_mask;
                         shift = start_index;
                 }
@@ -119,20 +107,20 @@ static inline void color_imageblit(const struct fb_image *image,
                                 color = palette[*src];
                         else
                                 color = *src;
-                        color <<= LEFT_POS(bpp);
-                        val |= SHIFT_HIGH(color, shift);
+                        color <<= FB_LEFT_POS(bpp);
+                        val |= FB_SHIFT_HIGH(color, shift);
                         if (shift >= null_bits) {
                                 FB_WRITEL(val, dst++);
         
                                 val = (shift == null_bits) ? 0 : 
-                                        SHIFT_LOW(color, 32 - shift);
+                                        FB_SHIFT_LOW(color, 32 - shift);
                         }
                         shift += bpp;
                         shift &= (32 - 1);
                         src++;
                 }
                 if (shift) {
-                        u32 end_mask = SHIFT_HIGH(~(u32)0, shift);
+                        u32 end_mask = FB_SHIFT_HIGH(~(u32)0, shift);
 
                         FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
                 }
@@ -162,8 +150,8 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
         u32 i, j, l;
         
         dst2 = (u32 __iomem *) dst1;
-        fgcolor <<= LEFT_POS(bpp);
-        bgcolor <<= LEFT_POS(bpp);
+        fgcolor <<= FB_LEFT_POS(bpp);
+        bgcolor <<= FB_LEFT_POS(bpp);
 
         for (i = image->height; i--; ) {
                 shift = val = 0;
@@ -174,21 +162,21 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
 
                 /* write leading bits */
                 if (start_index) {
-                        u32 start_mask = ~(SHIFT_HIGH(~(u32)0, start_index));
+                        u32 start_mask = ~(FB_SHIFT_HIGH(~(u32)0,start_index));
                         val = FB_READL(dst) & start_mask;
                         shift = start_index;
                 }
 
                 while (j--) {
                         l--;
-                        color = (*s & 1 << (BIT_NR(l))) ? fgcolor : bgcolor;
-                        val |= SHIFT_HIGH(color, shift);
+                        color = (*s & 1 << (FB_BIT_NR(l))) ? fgcolor : bgcolor;
+                        val |= FB_SHIFT_HIGH(color, shift);
                         
                         /* Did the bitshift spill bits to the next long? */
                         if (shift >= null_bits) {
                                 FB_WRITEL(val, dst++);
                                 val = (shift == null_bits) ? 0 :
-                                         SHIFT_LOW(color,32 - shift);
+                                        FB_SHIFT_LOW(color,32 - shift);
                         }
                         shift += bpp;
                         shift &= (32 - 1);
@@ -197,7 +185,7 @@ static inline void slow_imageblit(const struct fb_image *image, struct fb_info *
 
                 /* write trailing bits */
                 if (shift) {
-                        u32 end_mask = SHIFT_HIGH(~(u32)0, shift);
+                        u32 end_mask = FB_SHIFT_HIGH(~(u32)0, shift);
 
                         FB_WRITEL((FB_READL(dst) & end_mask) | val, dst);
                 }