tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * EFI entry point.
4 *
5 * Copyright (C) 2013, 2014 Red Hat, Inc.
6 * Author: Mark Salter <msalter@redhat.com>
7 */
8#include <linux/linkage.h>
9#include <asm/assembler.h>
10
11 /*
12 * The entrypoint of a arm64 bare metal image is at offset #0 of the
13 * image, so this is a reasonable default for primary_entry_offset.
14 * Only when the EFI stub is integrated into the core kernel, it is not
15 * guaranteed that the PE/COFF header has been copied to memory too, so
16 * in this case, primary_entry_offset should be overridden by the
17 * linker and point to primary_entry() directly.
18 */
19 .weak primary_entry_offset
20
21SYM_CODE_START(efi_enter_kernel)
22 /*
23 * efi_pe_entry() will have copied the kernel image if necessary and we
24 * end up here with device tree address in x1 and the kernel entry
25 * point stored in x0. Save those values in registers which are
26 * callee preserved.
27 */
28 ldr w2, =primary_entry_offset
29 add x19, x0, x2 // relocated Image entrypoint
30
31 mov x0, x1 // DTB address
32 mov x1, xzr
33 mov x2, xzr
34 mov x3, xzr
35
36 /*
37 * Clean the remainder of this routine to the PoC
38 * so that we can safely disable the MMU and caches.
39 */
40 adr x4, 1f
41 dc civac, x4
42 dsb sy
43
44 /* Turn off Dcache and MMU */
45 mrs x4, CurrentEL
46 cmp x4, #CurrentEL_EL2
47 mrs x4, sctlr_el1
48 b.ne 0f
49 mrs x4, sctlr_el2
500: bic x4, x4, #SCTLR_ELx_M
51 bic x4, x4, #SCTLR_ELx_C
52 b.eq 1f
53 b 2f
54
55 .balign 32
561: pre_disable_mmu_workaround
57 msr sctlr_el2, x4
58 isb
59 br x19 // jump to kernel entrypoint
60
612: pre_disable_mmu_workaround
62 msr sctlr_el1, x4
63 isb
64 br x19 // jump to kernel entrypoint
65
66 .org 1b + 32
67SYM_CODE_END(efi_enter_kernel)