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linux/drivers/video/cfbcopyarea.c
Mikulas Patocka 00a9d699bc framebuffer: fix cfb_copyarea 
The function cfb_copyarea is buggy when the copy operation is not aligned on
long boundary (4 bytes on 32-bit machines, 8 bytes on 64-bit machines).

How to reproduce:
- use x86-64 machine
- use a framebuffer driver without acceleration (for example uvesafb)
- set the framebuffer to 8-bit depth
	(for example fbset -a 1024x768-60 -depth 8)
- load a font with character width that is not a multiple of 8 pixels
	note: the console-tools package cannot load a font that has
	width different from 8 pixels. You need to install the packages
	"kbd" and "console-terminus" and use the program "setfont" to
	set font width (for example: setfont Uni2-Terminus20x10)
- move some text left and right on the bash command line and you get a
	screen corruption

To expose more bugs, put this line to the end of uvesafb_init_info:
info->flags |= FBINFO_HWACCEL_COPYAREA | FBINFO_READS_FAST;
- Now framebuffer console will use cfb_copyarea for console scrolling.
You get a screen corruption when console is scrolled.

This patch is a rewrite of cfb_copyarea. It fixes the bugs, with this
patch, console scrolling in 8-bit depth with a font width that is not a
multiple of 8 pixels works fine.

The cfb_copyarea code was very buggy and it looks like it was written
and never tried with non-8-pixel font.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
2014-02-11 15:01:04 +02:00

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/*
* Generic function for frame buffer with packed pixels of any depth.
*
* Copyright (C) 1999-2005 James Simmons <jsimmons@www.infradead.org>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive for
* more details.
*
* NOTES:
*
* This is for cfb packed pixels. Iplan and such are incorporated in the
* drivers that need them.
*
* FIXME
*
* Also need to add code to deal with cards endians that are different than
* the native cpu endians. I also need to deal with MSB position in the word.
*
* The two functions or copying forward and backward could be split up like
* the ones for filling, i.e. in aligned and unaligned versions. This would
* help moving some redundant computations and branches out of the loop, too.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/fb.h>
#include <asm/types.h>
#include <asm/io.h>
#include "fb_draw.h"
#if BITS_PER_LONG == 32
# define FB_WRITEL fb_writel
# define FB_READL fb_readl
#else
# define FB_WRITEL fb_writeq
# define FB_READL fb_readq
#endif
/*
* Generic bitwise copy algorithm
*/
static void
bitcpy(struct fb_info *p, unsigned long __iomem *dst, unsigned dst_idx,
const unsigned long __iomem *src, unsigned src_idx, int bits,
unsigned n, u32 bswapmask)
{
unsigned long first, last;
int const shift = dst_idx-src_idx;
#if 0
/*
* If you suspect bug in this function, compare it with this simple
* memmove implementation.
*/
fb_memmove((char *)dst + ((dst_idx & (bits - 1))) / 8,
(char *)src + ((src_idx & (bits - 1))) / 8, n / 8);
return;
#endif
first = fb_shifted_pixels_mask_long(p, dst_idx, bswapmask);
last = ~fb_shifted_pixels_mask_long(p, (dst_idx+n) % bits, bswapmask);
if (!shift) {
// Same alignment for source and dest
if (dst_idx+n <= bits) {
// Single word
if (last)
first &= last;
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), first), dst);
} else {
// Multiple destination words
// Leading bits
if (first != ~0UL) {
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), first), dst);
dst++;
src++;
n -= bits - dst_idx;
}
// Main chunk
n /= bits;
while (n >= 8) {
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
FB_WRITEL(FB_READL(src++), dst++);
n -= 8;
}
while (n--)
FB_WRITEL(FB_READL(src++), dst++);
// Trailing bits
if (last)
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), last), dst);
}
} else {
/* Different alignment for source and dest */
unsigned long d0, d1;
int m;
int const left = shift & (bits - 1);
int const right = -shift & (bits - 1);
if (dst_idx+n <= bits) {
// Single destination word
if (last)
first &= last;
d0 = FB_READL(src);
d0 = fb_rev_pixels_in_long(d0, bswapmask);
if (shift > 0) {
// Single source word
d0 <<= left;
} else if (src_idx+n <= bits) {
// Single source word
d0 >>= right;
} else {
// 2 source words
d1 = FB_READL(src + 1);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 >> right | d1 << left;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), first), dst);
} else {
// Multiple destination words
/** We must always remember the last value read, because in case
SRC and DST overlap bitwise (e.g. when moving just one pixel in
1bpp), we always collect one full long for DST and that might
overlap with the current long from SRC. We store this value in
'd0'. */
d0 = FB_READL(src++);
d0 = fb_rev_pixels_in_long(d0, bswapmask);
// Leading bits
if (shift > 0) {
// Single source word
d1 = d0;
d0 <<= left;
n -= bits - dst_idx;
} else {
// 2 source words
d1 = FB_READL(src++);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 >> right | d1 << left;
n -= bits - dst_idx;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), first), dst);
d0 = d1;
dst++;
// Main chunk
m = n % bits;
n /= bits;
while ((n >= 4) && !bswapmask) {
d1 = FB_READL(src++);
FB_WRITEL(d0 >> right | d1 << left, dst++);
d0 = d1;
d1 = FB_READL(src++);
FB_WRITEL(d0 >> right | d1 << left, dst++);
d0 = d1;
d1 = FB_READL(src++);
FB_WRITEL(d0 >> right | d1 << left, dst++);
d0 = d1;
d1 = FB_READL(src++);
FB_WRITEL(d0 >> right | d1 << left, dst++);
d0 = d1;
n -= 4;
}
while (n--) {
d1 = FB_READL(src++);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 >> right | d1 << left;
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(d0, dst++);
d0 = d1;
}
// Trailing bits
if (m) {
if (m <= bits - right) {
// Single source word
d0 >>= right;
} else {
// 2 source words
d1 = FB_READL(src);
d1 = fb_rev_pixels_in_long(d1,
bswapmask);
d0 = d0 >> right | d1 << left;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), last), dst);
}
}
}
}
/*
* Generic bitwise copy algorithm, operating backward
*/
static void
bitcpy_rev(struct fb_info *p, unsigned long __iomem *dst, unsigned dst_idx,
const unsigned long __iomem *src, unsigned src_idx, int bits,
unsigned n, u32 bswapmask)
{
unsigned long first, last;
int shift;
#if 0
/*
* If you suspect bug in this function, compare it with this simple
* memmove implementation.
*/
fb_memmove((char *)dst + ((dst_idx & (bits - 1))) / 8,
(char *)src + ((src_idx & (bits - 1))) / 8, n / 8);
return;
#endif
dst += (dst_idx + n - 1) / bits;
src += (src_idx + n - 1) / bits;
dst_idx = (dst_idx + n - 1) % bits;
src_idx = (src_idx + n - 1) % bits;
shift = dst_idx-src_idx;
first = ~fb_shifted_pixels_mask_long(p, (dst_idx + 1) % bits, bswapmask);
last = fb_shifted_pixels_mask_long(p, (bits + dst_idx + 1 - n) % bits, bswapmask);
if (!shift) {
// Same alignment for source and dest
if ((unsigned long)dst_idx+1 >= n) {
// Single word
if (first)
last &= first;
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), last), dst);
} else {
// Multiple destination words
// Leading bits
if (first) {
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), first), dst);
dst--;
src--;
n -= dst_idx+1;
}
// Main chunk
n /= bits;
while (n >= 8) {
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
FB_WRITEL(FB_READL(src--), dst--);
n -= 8;
}
while (n--)
FB_WRITEL(FB_READL(src--), dst--);
// Trailing bits
if (last != -1UL)
FB_WRITEL( comp( FB_READL(src), FB_READL(dst), last), dst);
}
} else {
// Different alignment for source and dest
unsigned long d0, d1;
int m;
int const left = shift & (bits-1);
int const right = -shift & (bits-1);
if ((unsigned long)dst_idx+1 >= n) {
// Single destination word
if (first)
last &= first;
d0 = FB_READL(src);
if (shift < 0) {
// Single source word
d0 >>= right;
} else if (1+(unsigned long)src_idx >= n) {
// Single source word
d0 <<= left;
} else {
// 2 source words
d1 = FB_READL(src - 1);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 << left | d1 >> right;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), last), dst);
} else {
// Multiple destination words
/** We must always remember the last value read, because in case
SRC and DST overlap bitwise (e.g. when moving just one pixel in
1bpp), we always collect one full long for DST and that might
overlap with the current long from SRC. We store this value in
'd0'. */
d0 = FB_READL(src--);
d0 = fb_rev_pixels_in_long(d0, bswapmask);
// Leading bits
if (shift < 0) {
// Single source word
d1 = d0;
d0 >>= right;
} else {
// 2 source words
d1 = FB_READL(src--);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 << left | d1 >> right;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), first), dst);
d0 = d1;
dst--;
n -= dst_idx+1;
// Main chunk
m = n % bits;
n /= bits;
while ((n >= 4) && !bswapmask) {
d1 = FB_READL(src--);
FB_WRITEL(d0 << left | d1 >> right, dst--);
d0 = d1;
d1 = FB_READL(src--);
FB_WRITEL(d0 << left | d1 >> right, dst--);
d0 = d1;
d1 = FB_READL(src--);
FB_WRITEL(d0 << left | d1 >> right, dst--);
d0 = d1;
d1 = FB_READL(src--);
FB_WRITEL(d0 << left | d1 >> right, dst--);
d0 = d1;
n -= 4;
}
while (n--) {
d1 = FB_READL(src--);
d1 = fb_rev_pixels_in_long(d1, bswapmask);
d0 = d0 << left | d1 >> right;
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(d0, dst--);
d0 = d1;
}
// Trailing bits
if (m) {
if (m <= bits - left) {
// Single source word
d0 <<= left;
} else {
// 2 source words
d1 = FB_READL(src);
d1 = fb_rev_pixels_in_long(d1,
bswapmask);
d0 = d0 << left | d1 >> right;
}
d0 = fb_rev_pixels_in_long(d0, bswapmask);
FB_WRITEL(comp(d0, FB_READL(dst), last), dst);
}
}
}
}
void cfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
{
u32 dx = area->dx, dy = area->dy, sx = area->sx, sy = area->sy;
u32 height = area->height, width = area->width;
unsigned long const bits_per_line = p->fix.line_length*8u;
unsigned long __iomem *base = NULL;
int bits = BITS_PER_LONG, bytes = bits >> 3;
unsigned dst_idx = 0, src_idx = 0, rev_copy = 0;
u32 bswapmask = fb_compute_bswapmask(p);
if (p->state != FBINFO_STATE_RUNNING)
return;
/* if the beginning of the target area might overlap with the end of
the source area, be have to copy the area reverse. */
if ((dy == sy && dx > sx) || (dy > sy)) {
dy += height;
sy += height;
rev_copy = 1;
}
// split the base of the framebuffer into a long-aligned address and the
// index of the first bit
base = (unsigned long __iomem *)((unsigned long)p->screen_base & ~(bytes-1));
dst_idx = src_idx = 8*((unsigned long)p->screen_base & (bytes-1));
// add offset of source and target area
dst_idx += dy*bits_per_line + dx*p->var.bits_per_pixel;
src_idx += sy*bits_per_line + sx*p->var.bits_per_pixel;
if (p->fbops->fb_sync)
p->fbops->fb_sync(p);
if (rev_copy) {
while (height--) {
dst_idx -= bits_per_line;
src_idx -= bits_per_line;
bitcpy_rev(p, base + (dst_idx / bits), dst_idx % bits,
base + (src_idx / bits), src_idx % bits, bits,
width*p->var.bits_per_pixel, bswapmask);
}
} else {
while (height--) {
bitcpy(p, base + (dst_idx / bits), dst_idx % bits,
base + (src_idx / bits), src_idx % bits, bits,
width*p->var.bits_per_pixel, bswapmask);
dst_idx += bits_per_line;
src_idx += bits_per_line;
}
}
}
EXPORT_SYMBOL(cfb_copyarea);
MODULE_AUTHOR("James Simmons <jsimmons@users.sf.net>");
MODULE_DESCRIPTION("Generic software accelerated copyarea");
MODULE_LICENSE("GPL");
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