source: mainline/boot/arch/arm64/src/relocate.c

Last change on this file was 84176f3, checked in by Jakub Jermář <jakub@…>, 6 years ago

arm64: Add support for the architecture

This changeset adds basic support to run HelenOS on AArch64, targeting
the QEMU virt platform.

Boot:

  • Boot relies on the EDK II firmware, GRUB2 for EFI and the HelenOS bootloader (UEFI application). EDK II loads GRUB2 from a CD, GRUB2 loads the HelenOS bootloader (via UEFI) which loads OS components.
  • UEFI applications use the PE/COFF format and must be relocatable. The first problem is solved by manually having the PE/COFF headers and tables written in assembler. The relocatable requirement is addressed by compiling the code with -fpic and having the bootloader relocate itself at its startup.

Kernel:

  • Kernel code for AArch64 consists mostly of stubbing out various architecture-specific hooks: virtual memory management, interrupt and exception handling, context switching (including FPU lazy switching), support for virtual timer, atomic sequences and barriers, cache and TLB maintenance, thread and process initialization.
  • The patch adds a kernel driver for GICv2 (interrupt controller).
  • The PL011 kernel driver is extended to allow userspace to take ownership of the console.
  • The current code is not able to dynamically obtain information about available devices on the underlying machine. The port instead implements a machine-func interface similar to the one implemented by arm32. It defines a machine for the QEMU AArch64 virt platform. The configuration (device addresses and IRQ numbers) is then baked into the machine definition.

User space:

  • Uspace code for AArch64 similarly mostly implements architecture-specific hooks: context saving/restoring, syscall support, TLS support.

The patchset allows to boot the system but user interaction with the OS
is not yet possible.
  • Property mode set to 100644
File size: 2.8 KB
Line 
1/*
2 * Copyright (c) 2019 Petr Pavlu
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup boot_arm64
30 * @{
31 */
32/** @file
33 * @brief Image self-relocation support.
34 */
35
36#include <arch/relocate.h>
37#include <printf.h>
38
39/** Self-relocate the bootloader.
40 *
41 * Note: This code is responsible for self-relocating the bootloader when it is
42 * started. As such, it is required that it is written in a way that it itself
43 * does not need any dynamic relocation.
44 */
45efi_status_t self_relocate(uintptr_t base, const elf_dyn_t *dyn)
46{
47 const elf_rela_t *rela = NULL;
48 uint64_t relasz = 0;
49 uint64_t relaent = 0;
50
51 /* Parse the dynamic array. */
52 while (dyn->d_tag != DT_NULL) {
53 switch (dyn->d_tag) {
54 case DT_RELA:
55 rela = (const elf_rela_t *) (base + dyn->d_un.d_ptr);
56 break;
57 case DT_RELASZ:
58 relasz = dyn->d_un.d_val;
59 break;
60 case DT_RELAENT:
61 relaent = dyn->d_un.d_val;
62 break;
63 }
64 dyn++;
65 }
66
67 /* Validate obtained information. */
68 if (rela == NULL)
69 return EFI_SUCCESS;
70 if (relaent == 0 || relasz % relaent != 0)
71 return EFI_UNSUPPORTED;
72
73 /* Process relocations in the image. */
74 while (relasz > 0) {
75 switch (ELF_R_TYPE(rela->r_info)) {
76 case R_AARCH64_RELATIVE:
77 *(uint64_t *) (base + rela->r_offset) =
78 base + rela->r_addend;
79 break;
80 default:
81 return EFI_UNSUPPORTED;
82 }
83
84 rela = (const elf_rela_t *) ((const char *) rela + relaent);
85 relasz -= relaent;
86 }
87 return EFI_SUCCESS;
88}
89
90/** @}
91 */
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