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d47a774680
The UEFI spec mandates that unaligned memory access should be enabled if supported by the CPU architecture. This patch implements the function unaligned_access() to set the enable unaligned data support flag and to clear the aligned flag in the system control register (SCTLR). It is called when UEFI related commands like bootefi are invoked. Reported-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com> Tested-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com> Tested-by: Guillaume Gardet <Guillaume.Gardet@arm.com> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
26 lines
844 B
ArmAsm
26 lines
844 B
ArmAsm
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Routines to access the system control register
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*
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* Copyright (c) 2019 Heinrich Schuchardt
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*/
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#include <linux/linkage.h>
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/*
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* void allow_unaligned(void) - allow unaligned access
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*
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* This routine sets the enable unaligned data support flag and clears the
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* aligned flag in the system control register.
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* After calling this routine unaligned access does no longer leads to a
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* data abort or undefined behavior but is handled by the CPU.
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* For details see the "ARM Architecture Reference Manual" for ARMv6.
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*/
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ENTRY(allow_unaligned)
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mrc p15, 0, r0, c1, c0, 0 @ load system control register
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orr r0, r0, #1 << 22 @ set unaligned data support flag
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bic r0, r0, #2 @ clear aligned flag
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mcr p15, 0, r0, c1, c0, 0 @ write system control register
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bx lr @ return
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ENDPROC(allow_unaligned)
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