a1f98849fd
This allows for optional alternative implementations of __copy_to_user and __clear_user, with a possible runtime fallback to the standard version when the alternative provides no gain over that standard version. This is done by making the standard __copy_to_user into a weak alias for the symbol __copy_to_user_std. Same thing for __clear_user. Those two functions are particularly good candidates to have alternative implementations for, since they rely on the STRT instruction which has lower performances than STM instructions on some CPU cores such as the ARM1176 and Marvell Feroceon. Signed-off-by: Nicolas Pitre <nico@marvell.com>
105 lines
2.0 KiB
ArmAsm
105 lines
2.0 KiB
ArmAsm
/*
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* linux/arch/arm/lib/copy_to_user.S
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*
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* Author: Nicolas Pitre
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* Created: Sep 29, 2005
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* Copyright: MontaVista Software, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* Prototype:
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*
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* size_t __copy_to_user(void *to, const void *from, size_t n)
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*
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* Purpose:
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*
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* copy a block to user memory from kernel memory
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*
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* Params:
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*
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* to = user memory
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* from = kernel memory
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* n = number of bytes to copy
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*
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* Return value:
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*
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* Number of bytes NOT copied.
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*/
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.macro ldr1w ptr reg abort
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ldr \reg, [\ptr], #4
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.endm
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.macro ldr4w ptr reg1 reg2 reg3 reg4 abort
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ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4}
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.endm
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.macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
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ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8}
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.endm
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.macro ldr1b ptr reg cond=al abort
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ldr\cond\()b \reg, [\ptr], #1
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.endm
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.macro str1w ptr reg abort
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100: strt \reg, [\ptr], #4
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.section __ex_table, "a"
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.long 100b, \abort
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.previous
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.endm
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.macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
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str1w \ptr, \reg1, \abort
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str1w \ptr, \reg2, \abort
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str1w \ptr, \reg3, \abort
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str1w \ptr, \reg4, \abort
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str1w \ptr, \reg5, \abort
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str1w \ptr, \reg6, \abort
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str1w \ptr, \reg7, \abort
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str1w \ptr, \reg8, \abort
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.endm
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.macro str1b ptr reg cond=al abort
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100: str\cond\()bt \reg, [\ptr], #1
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.section __ex_table, "a"
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.long 100b, \abort
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.previous
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.endm
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.macro enter reg1 reg2
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mov r3, #0
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stmdb sp!, {r0, r2, r3, \reg1, \reg2}
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.endm
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.macro exit reg1 reg2
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add sp, sp, #8
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ldmfd sp!, {r0, \reg1, \reg2}
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.endm
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.text
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ENTRY(__copy_to_user_std)
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WEAK(__copy_to_user)
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#include "copy_template.S"
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ENDPROC(__copy_to_user)
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.section .fixup,"ax"
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.align 0
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copy_abort_preamble
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ldmfd sp!, {r1, r2, r3}
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sub r0, r0, r1
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rsb r0, r0, r2
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copy_abort_end
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.previous
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