From 50ae76602cfb1079a3062a18c1767dce525985f0 Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Tue, 19 Nov 2019 04:02:10 +0100 Subject: [PATCH] arm: arm11: allow unaligned memory access 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 Signed-off-by: Heinrich Schuchardt --- arch/arm/cpu/arm11/Makefile | 4 ++++ arch/arm/cpu/arm11/sctlr.S | 25 +++++++++++++++++++++++++ 2 files changed, 29 insertions(+) create mode 100644 arch/arm/cpu/arm11/sctlr.S diff --git a/arch/arm/cpu/arm11/Makefile b/arch/arm/cpu/arm11/Makefile index 5d721fce12..5dfa01ae8d 100644 --- a/arch/arm/cpu/arm11/Makefile +++ b/arch/arm/cpu/arm11/Makefile @@ -4,3 +4,7 @@ # Wolfgang Denk, DENX Software Engineering, wd@denx.de. obj-y = cpu.o + +ifneq ($(CONFIG_SPL_BUILD),y) +obj-$(CONFIG_EFI_LOADER) += sctlr.o +endif diff --git a/arch/arm/cpu/arm11/sctlr.S b/arch/arm/cpu/arm11/sctlr.S new file mode 100644 index 0000000000..74a7fc4a25 --- /dev/null +++ b/arch/arm/cpu/arm11/sctlr.S @@ -0,0 +1,25 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Routines to access the system control register + * + * Copyright (c) 2019 Heinrich Schuchardt + */ + +#include + +/* + * void allow_unaligned(void) - allow unaligned access + * + * This routine sets the enable unaligned data support flag and clears the + * aligned flag in the system control register. + * After calling this routine unaligned access does no longer leads to a + * data abort or undefined behavior but is handled by the CPU. + * For details see the "ARM Architecture Reference Manual" for ARMv6. + */ +ENTRY(allow_unaligned) + mrc p15, 0, r0, c1, c0, 0 @ load system control register + orr r0, r0, #1 << 22 @ set unaligned data support flag + bic r0, r0, #2 @ clear aligned flag + mcr p15, 0, r0, c1, c0, 0 @ write system control register + bx lr @ return +ENDPROC(allow_unaligned)