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Commit ac036f95 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

vga: optimise console scrolling 

Where possible, call memset16(), memmove() or memcpy() instead of using
open-coded loops.  I don't like the calling convention that uses a byte
count instead of a count of u16s, but it's a little late to change that.
Reduces code size of fbcon.o by almost 400 bytes on my laptop build.

[akpm@linux-foundation.org: fix build]
Link: http://lkml.kernel.org/r/20170720184539.31609-9-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox <mawilcox@microsoft.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1caffba9

arch/mips/include/asm/vga.h

+7 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#ifndef _ASM_VGA_H

#define _ASM_VGA_H



#include <linux/string.h>

#include <asm/addrspace.h>

#include <asm/byteorder.h>
@@ -40,9 +41,15 @@ static inline u16 scr_readw(volatile const u16 *addr) 
	return le16_to_cpu(*addr);

}



static inline void scr_memsetw(u16 *s, u16 v, unsigned int count)

{

	memset16(s, cpu_to_le16(v), count / 2);

}



#define scr_memcpyw(d, s, c) memcpy(d, s, c)

#define scr_memmovew(d, s, c) memmove(d, s, c)

#define VT_BUF_HAVE_MEMCPYW

#define VT_BUF_HAVE_MEMMOVEW

#define VT_BUF_HAVE_MEMSETW



#endif /* _ASM_VGA_H */

arch/powerpc/include/asm/vga.h

+8 −0
Original line number Diff line number Diff line
@@ -33,8 +33,16 @@ static inline u16 scr_readw(volatile const u16 *addr) 
	return le16_to_cpu(*addr);

}



#define VT_BUF_HAVE_MEMSETW

static inline void scr_memsetw(u16 *s, u16 v, unsigned int n)

{

	memset16(s, cpu_to_le16(v), n / 2);

}



#define VT_BUF_HAVE_MEMCPYW

#define VT_BUF_HAVE_MEMMOVEW

#define scr_memcpyw	memcpy

#define scr_memmovew	memmove



#endif /* !CONFIG_VGA_CONSOLE && !CONFIG_MDA_CONSOLE */

arch/sparc/include/asm/vga.h

+25 −0
Original line number Diff line number Diff line
@@ -8,9 +8,13 @@ 
#define _LINUX_ASM_VGA_H_



#include <linux/bug.h>

#include <linux/string.h>

#include <asm/types.h>



#define VT_BUF_HAVE_RW

#define VT_BUF_HAVE_MEMSETW

#define VT_BUF_HAVE_MEMCPYW

#define VT_BUF_HAVE_MEMMOVEW



#undef scr_writew

#undef scr_readw
@@ -29,6 +33,27 @@ static inline u16 scr_readw(const u16 *addr) 
	return *addr;

}



static inline void scr_memsetw(u16 *p, u16 v, unsigned int n)

{

	BUG_ON((long) p >= 0);



	memset16(p, cpu_to_le16(v), n / 2);

}



static inline void scr_memcpyw(u16 *d, u16 *s, unsigned int n)

{

	BUG_ON((long) d >= 0);



	memcpy(d, s, n);

}



static inline void scr_memmovew(u16 *d, u16 *s, unsigned int n)

{

	BUG_ON((long) d >= 0);



	memmove(d, s, n);

}



#define VGA_MAP_MEM(x,s) (x)



#endif

include/linux/vt_buffer.h

+13 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#ifndef _LINUX_VT_BUFFER_H_

#define _LINUX_VT_BUFFER_H_



#include <linux/string.h>



#if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_MDA_CONSOLE)

#include <asm/vga.h>
@@ -26,24 +27,33 @@ 
#ifndef VT_BUF_HAVE_MEMSETW

static inline void scr_memsetw(u16 *s, u16 c, unsigned int count)

{

#ifdef VT_BUF_HAVE_RW

	count /= 2;

	while (count--)

		scr_writew(c, s++);

#else

	memset16(s, c, count / 2);

#endif

}

#endif



#ifndef VT_BUF_HAVE_MEMCPYW

static inline void scr_memcpyw(u16 *d, const u16 *s, unsigned int count)

{

#ifdef VT_BUF_HAVE_RW

	count /= 2;

	while (count--)

		scr_writew(scr_readw(s++), d++);

#else

	memcpy(d, s, count);

#endif

}

#endif



#ifndef VT_BUF_HAVE_MEMMOVEW

static inline void scr_memmovew(u16 *d, const u16 *s, unsigned int count)

{

#ifdef VT_BUF_HAVE_RW

	if (d < s)

		scr_memcpyw(d, s, count);

	else {
@@ -53,6 +63,9 @@ static inline void scr_memmovew(u16 *d, const u16 *s, unsigned int count) 
		while (count--)

			scr_writew(scr_readw(--s), --d);

	}

#else

	memmove(d, s, count);

#endif

}

#endif