diff options
Diffstat (limited to 'arch/x86/mm/mem_encrypt_boot.S')
| -rw-r--r-- | arch/x86/mm/mem_encrypt_boot.S | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S new file mode 100644 index 000000000000..730e6d541df1 --- /dev/null +++ b/arch/x86/mm/mem_encrypt_boot.S @@ -0,0 +1,149 @@ +/* + * AMD Memory Encryption Support + * + * Copyright (C) 2016 Advanced Micro Devices, Inc. + * + * Author: Tom Lendacky <thomas.lendacky@amd.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <asm/pgtable.h> +#include <asm/page.h> +#include <asm/processor-flags.h> +#include <asm/msr-index.h> + + .text + .code64 +ENTRY(sme_encrypt_execute) + + /* + * Entry parameters: + * RDI - virtual address for the encrypted kernel mapping + * RSI - virtual address for the decrypted kernel mapping + * RDX - length of kernel + * RCX - virtual address of the encryption workarea, including: + * - stack page (PAGE_SIZE) + * - encryption routine page (PAGE_SIZE) + * - intermediate copy buffer (PMD_PAGE_SIZE) + * R8 - physcial address of the pagetables to use for encryption + */ + + push %rbp + movq %rsp, %rbp /* RBP now has original stack pointer */ + + /* Set up a one page stack in the non-encrypted memory area */ + movq %rcx, %rax /* Workarea stack page */ + leaq PAGE_SIZE(%rax), %rsp /* Set new stack pointer */ + addq $PAGE_SIZE, %rax /* Workarea encryption routine */ + + push %r12 + movq %rdi, %r10 /* Encrypted kernel */ + movq %rsi, %r11 /* Decrypted kernel */ + movq %rdx, %r12 /* Kernel length */ + + /* Copy encryption routine into the workarea */ + movq %rax, %rdi /* Workarea encryption routine */ + leaq __enc_copy(%rip), %rsi /* Encryption routine */ + movq $(.L__enc_copy_end - __enc_copy), %rcx /* Encryption routine length */ + rep movsb + + /* Setup registers for call */ + movq %r10, %rdi /* Encrypted kernel */ + movq %r11, %rsi /* Decrypted kernel */ + movq %r8, %rdx /* Pagetables used for encryption */ + movq %r12, %rcx /* Kernel length */ + movq %rax, %r8 /* Workarea encryption routine */ + addq $PAGE_SIZE, %r8 /* Workarea intermediate copy buffer */ + + call *%rax /* Call the encryption routine */ + + pop %r12 + + movq %rbp, %rsp /* Restore original stack pointer */ + pop %rbp + + ret +ENDPROC(sme_encrypt_execute) + +ENTRY(__enc_copy) +/* + * Routine used to encrypt kernel. + * This routine must be run outside of the kernel proper since + * the kernel will be encrypted during the process. So this + * routine is defined here and then copied to an area outside + * of the kernel where it will remain and run decrypted + * during execution. + * + * On entry the registers must be: + * RDI - virtual address for the encrypted kernel mapping + * RSI - virtual address for the decrypted kernel mapping + * RDX - address of the pagetables to use for encryption + * RCX - length of kernel + * R8 - intermediate copy buffer + * + * RAX - points to this routine + * + * The kernel will be encrypted by copying from the non-encrypted + * kernel space to an intermediate buffer and then copying from the + * intermediate buffer back to the encrypted kernel space. The physical + * addresses of the two kernel space mappings are the same which + * results in the kernel being encrypted "in place". + */ + /* Enable the new page tables */ + mov %rdx, %cr3 + + /* Flush any global TLBs */ + mov %cr4, %rdx + andq $~X86_CR4_PGE, %rdx + mov %rdx, %cr4 + orq $X86_CR4_PGE, %rdx + mov %rdx, %cr4 + + /* Set the PAT register PA5 entry to write-protect */ + push %rcx + movl $MSR_IA32_CR_PAT, %ecx + rdmsr + push %rdx /* Save original PAT value */ + andl $0xffff00ff, %edx /* Clear PA5 */ + orl $0x00000500, %edx /* Set PA5 to WP */ + wrmsr + pop %rdx /* RDX contains original PAT value */ + pop %rcx + + movq %rcx, %r9 /* Save kernel length */ + movq %rdi, %r10 /* Save encrypted kernel address */ + movq %rsi, %r11 /* Save decrypted kernel address */ + + wbinvd /* Invalidate any cache entries */ + + /* Copy/encrypt 2MB at a time */ +1: + movq %r11, %rsi /* Source - decrypted kernel */ + movq %r8, %rdi /* Dest - intermediate copy buffer */ + movq $PMD_PAGE_SIZE, %rcx /* 2MB length */ + rep movsb + + movq %r8, %rsi /* Source - intermediate copy buffer */ + movq %r10, %rdi /* Dest - encrypted kernel */ + movq $PMD_PAGE_SIZE, %rcx /* 2MB length */ + rep movsb + + addq $PMD_PAGE_SIZE, %r11 + addq $PMD_PAGE_SIZE, %r10 + subq $PMD_PAGE_SIZE, %r9 /* Kernel length decrement */ + jnz 1b /* Kernel length not zero? */ + + /* Restore PAT register */ + push %rdx /* Save original PAT value */ + movl $MSR_IA32_CR_PAT, %ecx + rdmsr + pop %rdx /* Restore original PAT value */ + wrmsr + + ret +.L__enc_copy_end: +ENDPROC(__enc_copy) |