| Andre Przywara | 8c6d92d | 2021-05-14 16:13:28 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2021, ARM Limited. All rights reserved. |
| 3 | * |
| 4 | * SPDX-License-Identifier: BSD-3-Clause |
| 5 | * |
| 6 | * The traditional arm64 Linux kernel load address is 512KiB from the |
| 7 | * beginning of DRAM, caused by this having been the default value of the |
| 8 | * kernel's CONFIG_TEXT_OFFSET Kconfig value. |
| 9 | * However kernel version 5.8 changed the default offset (into a 2MB page) |
| 10 | * to 0, so TF-A's default assumption is no longer true. Fortunately the |
| 11 | * kernel got more relaxed about this offset at the same time, so it |
| 12 | * tolerates the wrong offset, but issues a warning: |
| 13 | * [Firmware Bug]: Kernel image misaligned at boot, please fix your bootloader! |
| 14 | * |
| 15 | * We cannot easily change the load address offset in TF-A to be 2MiB, because |
| 16 | * this would break older kernels - and they are not as forgiving in this |
| 17 | * respect. |
| 18 | * |
| 19 | * But we can allow users to load the kernel at the right offset, and |
| 20 | * offer this trampoline here to transition to this new load address. |
| 21 | * Any older kernels, or newer kernels misloaded, will overwrite this code |
| 22 | * here, so it does no harm in this case. |
| 23 | */ |
| 24 | |
| 25 | #include <asm_macros.S> |
| 26 | #include <common/bl_common.ld.h> |
| 27 | |
| 28 | .text |
| 29 | .global _tramp_start |
| 30 | |
| 31 | _tramp_start: |
| 32 | adr x4, _tramp_start |
| 33 | orr x4, x4, #0x1fffff |
| 34 | add x4, x4, #1 /* align up to 2MB */ |
| 35 | br x4 |