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![Stephen Warren](/assets/img/avatar_default.png)
ARM CPUs can architecturally (speculatively) prefetch completely arbitrary normal memory locations, as defined by the current translation tables. The current MMU configuration for 64-bit Tegras maps an extremely large range of addresses as DRAM, well beyond the actual physical maximum DRAM window, even though U-Boot only needs access to the first 2GB of DRAM; the Tegra port of U-Boot deliberately limits itself to 2GB of RAM since some HW modules on at least some 64-bit Tegra SoCs can only access a 32-bit physical address space. This change reduces the amount of RAM mapped via the MMU to disallow the CPU from ever speculatively accessing RAM that U-Boot will definitely not access. This avoids the possibility of the HW raising SError due to accesses to always-invalid physical addresses. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Tom Warren <twarren@nvidia.com>
36 lines
776 B
C
36 lines
776 B
C
/*
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* (C) Copyright 2014 - 2015 Xilinx, Inc.
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* Michal Simek <michal.simek@xilinx.com>
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* (This file derived from arch/arm/cpu/armv8/zynqmp/cpu.c)
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*
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* Copyright (c) 2015, NVIDIA CORPORATION. All rights reserved.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <asm/system.h>
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#include <asm/armv8/mmu.h>
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static struct mm_region tegra_mem_map[] = {
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{
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.virt = 0x0UL,
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.phys = 0x0UL,
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.size = 0x80000000UL,
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.attrs = PTE_BLOCK_MEMTYPE(MT_DEVICE_NGNRNE) |
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PTE_BLOCK_NON_SHARE |
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PTE_BLOCK_PXN | PTE_BLOCK_UXN
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}, {
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.virt = 0x80000000UL,
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.phys = 0x80000000UL,
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.size = 0x80000000UL,
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.attrs = PTE_BLOCK_MEMTYPE(MT_NORMAL) |
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PTE_BLOCK_INNER_SHARE
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}, {
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/* List terminator */
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0,
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}
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};
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struct mm_region *mem_map = tegra_mem_map;
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