1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * AMD Memory Encryption Support 4 * 5 * Copyright (C) 2016 Advanced Micro Devices, Inc. 6 * 7 * Author: Tom Lendacky <thomas.lendacky@amd.com> 8 */ 9 10 #include <linux/linkage.h> 11 #include <linux/pgtable.h> 12 #include <asm/page.h> 13 #include <asm/processor-flags.h> 14 #include <asm/msr-index.h> 15 #include <asm/nospec-branch.h> 16 17 .text 18 .code64 19 SYM_FUNC_START(sme_encrypt_execute) 20 21 /* 22 * Entry parameters: 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 31 */ 32 33 push %rbp 34 movq %rsp, %rbp /* RBP now has original stack pointer */ 35 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 */ 40 41 push %r12 42 movq %rdi, %r10 /* Encrypted area */ 43 movq %rsi, %r11 /* Decrypted area */ 44 movq %rdx, %r12 /* Area length */ 45 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 */ 50 rep movsb 51 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 */ 59 60 ANNOTATE_RETPOLINE_SAFE 61 call *%rax /* Call the encryption routine */ 62 63 pop %r12 64 65 movq %rbp, %rsp /* Restore original stack pointer */ 66 pop %rbp 67 68 /* Offset to __x86_return_thunk would be wrong here */ 69 ANNOTATE_UNRET_SAFE 70 ret 71 int3 72 SYM_FUNC_END(sme_encrypt_execute) 73 74 SYM_FUNC_START(__enc_copy) 75 /* 76 * Routine used to encrypt memory in place. 77 * This routine must be run outside of the kernel proper since 78 * the kernel will be encrypted during the process. So this 79 * routine is defined here and then copied to an area outside 80 * of the kernel where it will remain and run decrypted 81 * during execution. 82 * 83 * On entry the registers must be: 84 * RDI - virtual address for the encrypted mapping 85 * RSI - virtual address for the decrypted mapping 86 * RDX - address of the pagetables to use for encryption 87 * RCX - length of area 88 * R8 - intermediate copy buffer 89 * 90 * RAX - points to this routine 91 * 92 * The area will be encrypted by copying from the non-encrypted 93 * memory space to an intermediate buffer and then copying from the 94 * intermediate buffer back to the encrypted memory space. The physical 95 * addresses of the two mappings are the same which results in the area 96 * being encrypted "in place". 97 */ 98 /* Enable the new page tables */ 99 mov %rdx, %cr3 100 101 /* Flush any global TLBs */ 102 mov %cr4, %rdx 103 andq $~X86_CR4_PGE, %rdx 104 mov %rdx, %cr4 105 orq $X86_CR4_PGE, %rdx 106 mov %rdx, %cr4 107 108 push %r15 109 push %r12 110 111 movq %rcx, %r9 /* Save area length */ 112 movq %rdi, %r10 /* Save encrypted area address */ 113 movq %rsi, %r11 /* Save decrypted area address */ 114 115 /* Set the PAT register PA5 entry to write-protect */ 116 movl $MSR_IA32_CR_PAT, %ecx 117 rdmsr 118 mov %rdx, %r15 /* Save original PAT value */ 119 andl $0xffff00ff, %edx /* Clear PA5 */ 120 orl $0x00000500, %edx /* Set PA5 to WP */ 121 wrmsr 122 123 wbinvd /* Invalidate any cache entries */ 124 125 /* Copy/encrypt up to 2MB at a time */ 126 movq $PMD_PAGE_SIZE, %r12 127 1: 128 cmpq %r12, %r9 129 jnb 2f 130 movq %r9, %r12 131 132 2: 133 movq %r11, %rsi /* Source - decrypted area */ 134 movq %r8, %rdi /* Dest - intermediate copy buffer */ 135 movq %r12, %rcx 136 rep movsb 137 138 movq %r8, %rsi /* Source - intermediate copy buffer */ 139 movq %r10, %rdi /* Dest - encrypted area */ 140 movq %r12, %rcx 141 rep movsb 142 143 addq %r12, %r11 144 addq %r12, %r10 145 subq %r12, %r9 /* Kernel length decrement */ 146 jnz 1b /* Kernel length not zero? */ 147 148 /* Restore PAT register */ 149 movl $MSR_IA32_CR_PAT, %ecx 150 rdmsr 151 mov %r15, %rdx /* Restore original PAT value */ 152 wrmsr 153 154 pop %r12 155 pop %r15 156 157 /* Offset to __x86_return_thunk would be wrong here */ 158 ANNOTATE_UNRET_SAFE 159 ret 160 int3 161 .L__enc_copy_end: 162 SYM_FUNC_END(__enc_copy) 163