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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 | /* SPDX-License-Identifier: LGPL-2.1 OR MIT */ /* * x86_64 specific definitions for NOLIBC * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu> */ #ifndef _NOLIBC_ARCH_X86_64_H #define _NOLIBC_ARCH_X86_64_H #include "compiler.h" #include "crt.h" /* Syscalls for x86_64 : * - registers are 64-bit * - syscall number is passed in rax * - arguments are in rdi, rsi, rdx, r10, r8, r9 respectively * - the system call is performed by calling the syscall instruction * - syscall return comes in rax * - rcx and r11 are clobbered, others are preserved. * - the arguments are cast to long and assigned into the target registers * which are then simply passed as registers to the asm code, so that we * don't have to experience issues with register constraints. * - the syscall number is always specified last in order to allow to force * some registers before (gcc refuses a %-register at the last position). * - see also x86-64 ABI section A.2 AMD64 Linux Kernel Conventions, A.2.1 * Calling Conventions. * * Link x86-64 ABI: https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/home * */ #define my_syscall0(num) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall1(num, arg1) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), \ "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall2(num, arg1, arg2) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ register long _arg2 __asm__ ("rsi") = (long)(arg2); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), "r"(_arg2), \ "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall3(num, arg1, arg2, arg3) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ register long _arg2 __asm__ ("rsi") = (long)(arg2); \ register long _arg3 __asm__ ("rdx") = (long)(arg3); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), \ "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall4(num, arg1, arg2, arg3, arg4) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ register long _arg2 __asm__ ("rsi") = (long)(arg2); \ register long _arg3 __asm__ ("rdx") = (long)(arg3); \ register long _arg4 __asm__ ("r10") = (long)(arg4); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \ "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ register long _arg2 __asm__ ("rsi") = (long)(arg2); \ register long _arg3 __asm__ ("rdx") = (long)(arg3); \ register long _arg4 __asm__ ("r10") = (long)(arg4); \ register long _arg5 __asm__ ("r8") = (long)(arg5); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) #define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \ ({ \ long _ret; \ register long _num __asm__ ("rax") = (num); \ register long _arg1 __asm__ ("rdi") = (long)(arg1); \ register long _arg2 __asm__ ("rsi") = (long)(arg2); \ register long _arg3 __asm__ ("rdx") = (long)(arg3); \ register long _arg4 __asm__ ("r10") = (long)(arg4); \ register long _arg5 __asm__ ("r8") = (long)(arg5); \ register long _arg6 __asm__ ("r9") = (long)(arg6); \ \ __asm__ volatile ( \ "syscall\n" \ : "=a"(_ret) \ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \ "r"(_arg6), "0"(_num) \ : "rcx", "r11", "memory", "cc" \ ); \ _ret; \ }) /* startup code */ /* * x86-64 System V ABI mandates: * 1) %rsp must be 16-byte aligned right before the function call. * 2) The deepest stack frame should be zero (the %rbp). * */ void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void) { __asm__ volatile ( "xor %ebp, %ebp\n" /* zero the stack frame */ "mov %rsp, %rdi\n" /* save stack pointer to %rdi, as arg1 of _start_c */ "and $-16, %rsp\n" /* %rsp must be 16-byte aligned before call */ "call _start_c\n" /* transfer to c runtime */ "hlt\n" /* ensure it does not return */ ); __builtin_unreachable(); } #define NOLIBC_ARCH_HAS_MEMMOVE void *memmove(void *dst, const void *src, size_t len); #define NOLIBC_ARCH_HAS_MEMCPY void *memcpy(void *dst, const void *src, size_t len); #define NOLIBC_ARCH_HAS_MEMSET void *memset(void *dst, int c, size_t len); __asm__ ( ".section .text.nolibc_memmove_memcpy\n" ".weak memmove\n" ".weak memcpy\n" "memmove:\n" "memcpy:\n" "movq %rdx, %rcx\n\t" "movq %rdi, %rax\n\t" "movq %rdi, %rdx\n\t" "subq %rsi, %rdx\n\t" "cmpq %rcx, %rdx\n\t" "jb .Lbackward_copy\n\t" "rep movsb\n\t" "retq\n" ".Lbackward_copy:" "leaq -1(%rdi, %rcx, 1), %rdi\n\t" "leaq -1(%rsi, %rcx, 1), %rsi\n\t" "std\n\t" "rep movsb\n\t" "cld\n\t" "retq\n" ".section .text.nolibc_memset\n" ".weak memset\n" "memset:\n" "xchgl %eax, %esi\n\t" "movq %rdx, %rcx\n\t" "pushq %rdi\n\t" "rep stosb\n\t" "popq %rax\n\t" "retq\n" ); #endif /* _NOLIBC_ARCH_X86_64_H */ |