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0aea86a217
This patch add support for various user access functions. These functions use the standard LDR/STR instructions and not the LDRT/STRT variants in order to allow kernel addresses (after set_fs(KERNEL_DS)). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
62 lines
1.4 KiB
ArmAsm
62 lines
1.4 KiB
ArmAsm
/*
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* Copyright (C) 2012 ARM Ltd.
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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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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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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* Copy to user space from a kernel buffer (alignment handled by the hardware)
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*
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* Parameters:
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* x0 - to
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* x1 - from
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* x2 - n
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* Returns:
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* x0 - bytes not copied
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*/
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ENTRY(__copy_to_user)
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add x4, x0, x2 // upper user buffer boundary
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subs x2, x2, #8
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b.mi 2f
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1:
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ldr x3, [x1], #8
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subs x2, x2, #8
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USER(9f, str x3, [x0], #8 )
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b.pl 1b
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2: adds x2, x2, #4
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b.mi 3f
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ldr w3, [x1], #4
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sub x2, x2, #4
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USER(9f, str w3, [x0], #4 )
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3: adds x2, x2, #2
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b.mi 4f
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ldrh w3, [x1], #2
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sub x2, x2, #2
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USER(9f, strh w3, [x0], #2 )
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4: adds x2, x2, #1
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b.mi 5f
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ldrb w3, [x1]
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USER(9f, strb w3, [x0] )
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5: mov x0, #0
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ret
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ENDPROC(__copy_to_user)
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.section .fixup,"ax"
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.align 2
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9: sub x0, x4, x0 // bytes not copied
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ret
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.previous
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