Re: [PATCH] fbmem: Fix fb_read, fb_write unaligned accesses.
From: Florian Tobias Schandinat
Date: Mon Sep 20 2010 - 15:27:32 EST
James Hogan schrieb:
Apologies for corrupted patch. I'll try again.
Comments? I'd also appreciate if somebody familiar with sbus on sparc
could check this patch is sane since I know virtually nothing about sbus
and am not in a position to compile for sparc, let alone test on it:
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@xxxxxxxxxxxxx>
Looks correct and is an improvement.
I think it wouldn't be bad in terms of performance if we could avoid the double
copy operation altogether but it might be overkill to add an
fb_memcpy_{toio_from_user,fromio_to_user} just for that. But that's something
that could be done in a later patch if anyone considers it worth the effort (I
think most users just mmap the framebuffer anyway).
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@xxxxxx>
---
arch/sparc/include/asm/io_32.h | 31 +++++++++++++++++++++++++++
arch/sparc/include/asm/io_64.h | 31 +++++++++++++++++++++++++++
drivers/video/fbmem.c | 46 ++++++++++++---------------------------
include/linux/fb.h | 6 +++++
4 files changed, 82 insertions(+), 32 deletions(-)
diff --git a/arch/sparc/include/asm/io_32.h b/arch/sparc/include/asm/io_32.h
index 2889574..c2ced21 100644
--- a/arch/sparc/include/asm/io_32.h
+++ b/arch/sparc/include/asm/io_32.h
@@ -208,6 +208,21 @@ _memset_io(volatile void __iomem *dst, int c, __kernel_size_t n)
#define memset_io(d,c,sz) _memset_io(d,c,sz)
static inline void
+_sbus_memcpy_fromio(void *dst, const volatile void __iomem *src,
+ __kernel_size_t n)
+{
+ char *d = dst;
+
+ while (n--) {
+ char tmp = sbus_readb(src);
+ *d++ = tmp;
+ src++;
+ }
+}
+
+#define sbus_memcpy_fromio(d, s, sz) _sbus_memcpy_fromio(d, s, sz)
+
+static inline void
_memcpy_fromio(void *dst, const volatile void __iomem *src, __kernel_size_t n)
{
char *d = dst;
@@ -222,6 +237,22 @@ _memcpy_fromio(void *dst, const volatile void __iomem *src, __kernel_size_t n)
#define memcpy_fromio(d,s,sz) _memcpy_fromio(d,s,sz)
static inline void
+_sbus_memcpy_toio(volatile void __iomem *dst, const void *src,
+ __kernel_size_t n)
+{
+ const char *s = src;
+ volatile void __iomem *d = dst;
+
+ while (n--) {
+ char tmp = *s++;
+ sbus_writeb(tmp, d);
+ d++;
+ }
+}
+
+#define sbus_memcpy_toio(d, s, sz) _sbus_memcpy_toio(d, s, sz)
+
+static inline void
_memcpy_toio(volatile void __iomem *dst, const void *src, __kernel_size_t n)
{
const char *s = src;
diff --git a/arch/sparc/include/asm/io_64.h b/arch/sparc/include/asm/io_64.h
index 9517d06..9c89654 100644
--- a/arch/sparc/include/asm/io_64.h
+++ b/arch/sparc/include/asm/io_64.h
@@ -419,6 +419,21 @@ _memset_io(volatile void __iomem *dst, int c, __kernel_size_t n)
#define memset_io(d,c,sz) _memset_io(d,c,sz)
static inline void
+_sbus_memcpy_fromio(void *dst, const volatile void __iomem *src,
+ __kernel_size_t n)
+{
+ char *d = dst;
+
+ while (n--) {
+ char tmp = sbus_readb(src);
+ *d++ = tmp;
+ src++;
+ }
+}
+
+#define sbus_memcpy_fromio(d, s, sz) _sbus_memcpy_fromio(d, s, sz)
+
+static inline void
_memcpy_fromio(void *dst, const volatile void __iomem *src, __kernel_size_t n)
{
char *d = dst;
@@ -433,6 +448,22 @@ _memcpy_fromio(void *dst, const volatile void __iomem *src, __kernel_size_t n)
#define memcpy_fromio(d,s,sz) _memcpy_fromio(d,s,sz)
static inline void
+_sbus_memcpy_toio(volatile void __iomem *dst, const void *src,
+ __kernel_size_t n)
+{
+ const char *s = src;
+ volatile void __iomem *d = dst;
+
+ while (n--) {
+ char tmp = *s++;
+ sbus_writeb(tmp, d);
+ d++;
+ }
+}
+
+#define sbus_memcpy_toio(d, s, sz) _sbus_memcpy_toio(d, s, sz)
+
+static inline void
_memcpy_toio(volatile void __iomem *dst, const void *src, __kernel_size_t n)
{
const char *s = src;
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index b066475..925f25d 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;
diff --git a/include/linux/fb.h b/include/linux/fb.h
index f0268de..7fca3dc 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -931,6 +931,8 @@ static inline struct apertures_struct *alloc_apertures(unsigned int max_num) {
#define fb_writel sbus_writel
#define fb_writeq sbus_writeq
#define fb_memset sbus_memset_io
+#define fb_memcpy_fromfb sbus_memcpy_fromio
+#define fb_memcpy_tofb sbus_memcpy_toio
#elif defined(__i386__) || defined(__alpha__) || defined(__x86_64__) || defined(__hppa__) || defined(__sh__) || defined(__powerpc__) || defined(__avr32__) || defined(__bfin__)
@@ -943,6 +945,8 @@ static inline struct apertures_struct *alloc_apertures(unsigned int max_num) {
#define fb_writel __raw_writel
#define fb_writeq __raw_writeq
#define fb_memset memset_io
+#define fb_memcpy_fromfb memcpy_fromio
+#define fb_memcpy_tofb memcpy_toio
#else
@@ -955,6 +959,8 @@ static inline struct apertures_struct *alloc_apertures(unsigned int max_num) {
#define fb_writel(b,addr) (*(volatile u32 *) (addr) = (b))
#define fb_writeq(b,addr) (*(volatile u64 *) (addr) = (b))
#define fb_memset memset
+#define fb_memcpy_fromfb memcpy
+#define fb_memcpy_tofb memcpy
#endif
--
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