1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * AMD Memory Encryption Support
5 * Copyright (C) 2016 Advanced Micro Devices, Inc.
7 * Author: Tom Lendacky <thomas.lendacky@amd.com>
10 #include <linux/linkage.h>
11 #include <linux/pgtable.h>
13 #include <asm/processor-flags.h>
14 #include <asm/msr-index.h>
15 #include <asm/nospec-branch.h>
19 SYM_FUNC_START(sme_encrypt_execute)
23 * RDI - virtual address for the encrypted mapping
24 * RSI - virtual address for the decrypted mapping
25 * RDX - length to encrypt
26 * RCX - virtual address of the encryption workarea, including:
27 * - stack page (PAGE_SIZE)
28 * - encryption routine page (PAGE_SIZE)
29 * - intermediate copy buffer (PMD_PAGE_SIZE)
30 * R8 - physcial address of the pagetables to use for encryption
34 movq %rsp, %rbp /* RBP now has original stack pointer */
36 /* Set up a one page stack in the non-encrypted memory area */
37 movq %rcx, %rax /* Workarea stack page */
38 leaq PAGE_SIZE(%rax), %rsp /* Set new stack pointer */
39 addq $PAGE_SIZE, %rax /* Workarea encryption routine */
42 movq %rdi, %r10 /* Encrypted area */
43 movq %rsi, %r11 /* Decrypted area */
44 movq %rdx, %r12 /* Area length */
46 /* Copy encryption routine into the workarea */
47 movq %rax, %rdi /* Workarea encryption routine */
48 leaq __enc_copy(%rip), %rsi /* Encryption routine */
49 movq $(.L__enc_copy_end - __enc_copy), %rcx /* Encryption routine length */
52 /* Setup registers for call */
53 movq %r10, %rdi /* Encrypted area */
54 movq %r11, %rsi /* Decrypted area */
55 movq %r8, %rdx /* Pagetables used for encryption */
56 movq %r12, %rcx /* Area length */
57 movq %rax, %r8 /* Workarea encryption routine */
58 addq $PAGE_SIZE, %r8 /* Workarea intermediate copy buffer */
60 ANNOTATE_RETPOLINE_SAFE
61 call *%rax /* Call the encryption routine */
65 movq %rbp, %rsp /* Restore original stack pointer */
69 SYM_FUNC_END(sme_encrypt_execute)
71 SYM_FUNC_START(__enc_copy)
73 * Routine used to encrypt memory in place.
74 * This routine must be run outside of the kernel proper since
75 * the kernel will be encrypted during the process. So this
76 * routine is defined here and then copied to an area outside
77 * of the kernel where it will remain and run decrypted
80 * On entry the registers must be:
81 * RDI - virtual address for the encrypted mapping
82 * RSI - virtual address for the decrypted mapping
83 * RDX - address of the pagetables to use for encryption
84 * RCX - length of area
85 * R8 - intermediate copy buffer
87 * RAX - points to this routine
89 * The area will be encrypted by copying from the non-encrypted
90 * memory space to an intermediate buffer and then copying from the
91 * intermediate buffer back to the encrypted memory space. The physical
92 * addresses of the two mappings are the same which results in the area
93 * being encrypted "in place".
95 /* Enable the new page tables */
98 /* Flush any global TLBs */
100 andq $~X86_CR4_PGE, %rdx
102 orq $X86_CR4_PGE, %rdx
108 movq %rcx, %r9 /* Save area length */
109 movq %rdi, %r10 /* Save encrypted area address */
110 movq %rsi, %r11 /* Save decrypted area address */
112 /* Set the PAT register PA5 entry to write-protect */
113 movl $MSR_IA32_CR_PAT, %ecx
115 mov %rdx, %r15 /* Save original PAT value */
116 andl $0xffff00ff, %edx /* Clear PA5 */
117 orl $0x00000500, %edx /* Set PA5 to WP */
120 wbinvd /* Invalidate any cache entries */
122 /* Copy/encrypt up to 2MB at a time */
123 movq $PMD_PAGE_SIZE, %r12
130 movq %r11, %rsi /* Source - decrypted area */
131 movq %r8, %rdi /* Dest - intermediate copy buffer */
135 movq %r8, %rsi /* Source - intermediate copy buffer */
136 movq %r10, %rdi /* Dest - encrypted area */
142 subq %r12, %r9 /* Kernel length decrement */
143 jnz 1b /* Kernel length not zero? */
145 /* Restore PAT register */
146 movl $MSR_IA32_CR_PAT, %ecx
148 mov %r15, %rdx /* Restore original PAT value */
156 SYM_FUNC_END(__enc_copy)