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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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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>
51 lines
1.3 KiB
ArmAsm
51 lines
1.3 KiB
ArmAsm
/*
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* Based on arch/arm/lib/strncpy_from_user.S
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*
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* Copyright (C) 1995-2000 Russell King
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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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#include <asm/errno.h>
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.text
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.align 5
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/*
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* Copy a string from user space to kernel space.
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* x0 = dst, x1 = src, x2 = byte length
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* returns the number of characters copied (strlen of copied string),
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* -EFAULT on exception, or "len" if we fill the whole buffer
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*/
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ENTRY(__strncpy_from_user)
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mov x4, x1
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1: subs x2, x2, #1
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bmi 2f
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USER(9f, ldrb w3, [x1], #1 )
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strb w3, [x0], #1
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cbnz w3, 1b
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sub x1, x1, #1 // take NUL character out of count
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2: sub x0, x1, x4
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ret
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ENDPROC(__strncpy_from_user)
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.section .fixup,"ax"
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.align 0
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9: strb wzr, [x0] // null terminate
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mov x0, #-EFAULT
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ret
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.previous
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