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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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57f4959bad
'User Access Override' is a new ARMv8.2 feature which allows the
unprivileged load and store instructions to be overridden to behave in
the normal way.
This patch converts {get,put}_user() and friends to use ldtr*/sttr*
instructions - so that they can only access EL0 memory, then enables
UAO when fs==KERNEL_DS so that these functions can access kernel memory.
This allows user space's read/write permissions to be checked against the
page tables, instead of testing addr<USER_DS, then using the kernel's
read/write permissions.
Signed-off-by: James Morse <james.morse@arm.com>
[catalin.marinas@arm.com: move uao_thread_switch() above dsb()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
84 lines
1.9 KiB
ArmAsm
84 lines
1.9 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/alternative.h>
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#include <asm/assembler.h>
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#include <asm/cache.h>
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#include <asm/cpufeature.h>
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#include <asm/sysreg.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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.macro ldrb1 ptr, regB, val
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ldrb \ptr, [\regB], \val
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.endm
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.macro strb1 ptr, regB, val
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uao_user_alternative 9998f, strb, sttrb, \ptr, \regB, \val
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.endm
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.macro ldrh1 ptr, regB, val
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ldrh \ptr, [\regB], \val
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.endm
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.macro strh1 ptr, regB, val
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uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val
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.endm
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.macro ldr1 ptr, regB, val
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ldr \ptr, [\regB], \val
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.endm
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.macro str1 ptr, regB, val
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uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val
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.endm
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.macro ldp1 ptr, regB, regC, val
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ldp \ptr, \regB, [\regC], \val
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.endm
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.macro stp1 ptr, regB, regC, val
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uao_stp 9998f, \ptr, \regB, \regC, \val
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.endm
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end .req x5
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ENTRY(__copy_to_user)
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ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
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CONFIG_ARM64_PAN)
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add end, x0, x2
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#include "copy_template.S"
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ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
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CONFIG_ARM64_PAN)
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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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9998: sub x0, end, dst // bytes not copied
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ret
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.previous
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