Commit fadab094 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
Browse files

[ARM] 2948/1: new preemption safe copy_{to|from}_user implementation 



Patch from Nicolas Pitre

This patch provides a preemption safe implementation of copy_to_user
and copy_from_user based on the copy template also used for memcpy.
It is enabled unconditionally when CONFIG_PREEMPT=y.  Otherwise if the
configured architecture is not ARMv3 then it is enabled as well as it
gives better performances at least on StrongARM and XScale cores.  If
ARMv3 is not too affected or if it doesn't matter too much then
uaccess.S could be removed altogether.

Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 75494230

arch/arm/lib/Makefile

+14 −2
Original line number Diff line number Diff line
@@ -9,13 +9,25 @@ lib-y := backtrace.o changebit.o csumipv6.o csumpartial.o \ 
		   copy_page.o delay.o findbit.o memchr.o memcpy.o    \

		   memmove.o memset.o memzero.o setbit.o              \

		   strncpy_from_user.o strnlen_user.o                 \

		   strchr.o strrchr.o testchangebit.o                 \

		   testclearbit.o testsetbit.o uaccess.o              \

		   strchr.o strrchr.o                                 \

		   testchangebit.o testclearbit.o testsetbit.o        \

		   getuser.o putuser.o clear_user.o                   \

		   ashldi3.o ashrdi3.o lshrdi3.o muldi3.o             \

		   ucmpdi2.o lib1funcs.o div64.o sha1.o               \

		   io-readsb.o io-writesb.o io-readsl.o io-writesl.o



# the code in uaccess.S is not preemption safe and

# probably faster on ARMv3 only

ifeq ($CONFIG_PREEMPT,y)

  lib-y	+= copy_from_user.o copy_to_user.o

else

ifneq ($(CONFIG_CPU_32v3),y)

  lib-y	+= copy_from_user.o copy_to_user.o

else

  lib-y	+= uaccess.o

endif

endif



ifeq ($(CONFIG_CPU_32v3),y)

  lib-y	+= io-readsw-armv3.o io-writesw-armv3.o

else

arch/arm/lib/copy_from_user.S

0 → 100644
+101 −0
Original line number Diff line number Diff line 
/*

 *  linux/arch/arm/lib/copy_from_user.S

 *

 *  Author:	Nicolas Pitre

 *  Created:	Sep 29, 2005

 *  Copyright:	MontaVista Software, Inc.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License version 2 as

 *  published by the Free Software Foundation.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * Prototype:

 *

 *	size_t __arch_copy_from_user(void *to, const void *from, size_t n)

 *

 * Purpose:

 *

 *	copy a block to kernel memory from user memory

 *

 * Params:

 *

 *	to = kernel memory

 *	from = user memory

 *	n = number of bytes to copy

 *

 * Return value:

 *

 *	Number of bytes NOT copied.

 */



	.macro ldr1w ptr reg abort

100:	ldrt \reg, [\ptr], #4

	.section __ex_table, "a"

	.long 100b, \abort

	.previous

	.endm



	.macro ldr4w ptr reg1 reg2 reg3 reg4 abort

	ldr1w \ptr, \reg1, \abort

	ldr1w \ptr, \reg2, \abort

	ldr1w \ptr, \reg3, \abort

	ldr1w \ptr, \reg4, \abort

	.endm



	.macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort

	ldr4w \ptr, \reg1, \reg2, \reg3, \reg4, \abort

	ldr4w \ptr, \reg5, \reg6, \reg7, \reg8, \abort

	.endm



	.macro ldr1b ptr reg cond=al abort

100:	ldr\cond\()bt \reg, [\ptr], #1

	.section __ex_table, "a"

	.long 100b, \abort

	.previous

	.endm



	.macro str1w ptr reg abort

	str \reg, [\ptr], #4

	.endm



	.macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort

	stmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8}

	.endm



	.macro str1b ptr reg cond=al abort

	str\cond\()b \reg, [\ptr], #1

	.endm



	.macro enter reg1 reg2

	mov	r3, #0

	stmdb	sp!, {r0, r2, r3, \reg1, \reg2}

	.endm



	.macro exit reg1 reg2

	add	sp, sp, #8

	ldmfd	sp!, {r0, \reg1, \reg2}

	.endm



	.text



ENTRY(__arch_copy_from_user)



#include "copy_template.S"



	.section .fixup,"ax"

	.align 0

	copy_abort_preamble

	ldmfd	sp!, {r1, r2}

	sub	r3, r0, r1

	rsb	r1, r3, r2

	str	r1, [sp]

	bl	__memzero

	ldr	r0, [sp], #4

	copy_abort_end

	.previous

arch/arm/lib/copy_to_user.S

0 → 100644
+101 −0
Original line number Diff line number Diff line 
/*

 *  linux/arch/arm/lib/copy_to_user.S

 *

 *  Author:	Nicolas Pitre

 *  Created:	Sep 29, 2005

 *  Copyright:	MontaVista Software, Inc.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License version 2 as

 *  published by the Free Software Foundation.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * Prototype:

 *

 *	size_t __arch_copy_to_user(void *to, const void *from, size_t n)

 *

 * Purpose:

 *

 *	copy a block to user memory from kernel memory

 *

 * Params:

 *

 *	to = user memory

 *	from = kernel memory

 *	n = number of bytes to copy

 *

 * Return value:

 *

 *	Number of bytes NOT copied.

 */



	.macro ldr1w ptr reg abort

	ldr \reg, [\ptr], #4

	.endm



	.macro ldr4w ptr reg1 reg2 reg3 reg4 abort

	ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4}

	.endm



	.macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort

	ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8}

	.endm



	.macro ldr1b ptr reg cond=al abort

	ldr\cond\()b \reg, [\ptr], #1

	.endm



	.macro str1w ptr reg abort

100:	strt \reg, [\ptr], #4

	.section __ex_table, "a"

	.long 100b, \abort

	.previous

	.endm



	.macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort

	str1w \ptr, \reg1, \abort

	str1w \ptr, \reg2, \abort

	str1w \ptr, \reg3, \abort

	str1w \ptr, \reg4, \abort

	str1w \ptr, \reg5, \abort

	str1w \ptr, \reg6, \abort

	str1w \ptr, \reg7, \abort

	str1w \ptr, \reg8, \abort

	.endm



	.macro str1b ptr reg cond=al abort

100:	str\cond\()bt \reg, [\ptr], #1

	.section __ex_table, "a"

	.long 100b, \abort

	.previous

	.endm



	.macro enter reg1 reg2

	mov	r3, #0

	stmdb	sp!, {r0, r2, r3, \reg1, \reg2}

	.endm



	.macro exit reg1 reg2

	add	sp, sp, #8

	ldmfd	sp!, {r0, \reg1, \reg2}

	.endm



	.text



ENTRY(__arch_copy_to_user)



#include "copy_template.S"



	.section .fixup,"ax"

	.align 0

	copy_abort_preamble

	ldmfd	sp!, {r1, r2, r3}

	sub	r0, r0, r1

	rsb	r0, r0, r2

	copy_abort_end

	.previous

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