diff options
Diffstat (limited to 'src/cpu/x86/64bit/entry64.inc')
| -rw-r--r-- | src/cpu/x86/64bit/entry64.inc | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/cpu/x86/64bit/entry64.inc b/src/cpu/x86/64bit/entry64.inc new file mode 100644 index 0000000000..f726fab506 --- /dev/null +++ b/src/cpu/x86/64bit/entry64.inc @@ -0,0 +1,62 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (c) 2019 Patrick Rudolph <siro@das-labor.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +/* + * For starting coreboot in long mode. + * + * For reference see "AMD64 ArchitectureProgrammer's Manual Volume 2", + * Document 24593-Rev. 3.31-July 2019 Chapter 5.3 + * + * Clobbers: eax, ecx, edx + */ + +#if defined(__x86_64__) + .code32 +#if (CONFIG_ARCH_X86_64_PGTBL_LOC & 0xfff) > 0 +#error pagetables must be 4KiB aligned! +#endif + +#include <cpu/x86/msr.h> +#include <arch/rom_segs.h> + +setup_longmode: + /* Get page table address */ + movl $(CONFIG_ARCH_X86_64_PGTBL_LOC), %eax + + /* load identity mapped page tables */ + movl %eax, %cr3 + + /* enable PAE */ + movl %cr4, %eax + btsl $5, %eax + movl %eax, %cr4 + + /* enable long mode */ + movl $(IA32_EFER), %ecx + rdmsr + btsl $8, %eax + wrmsr + + /* enable paging */ + movl %cr0, %eax + btsl $31, %eax + movl %eax, %cr0 + + /* use long jump to switch to 64-bit code segment */ + ljmp $ROM_CODE_SEG64, $__longmode_start +.code64 +__longmode_start: + +#endif |