/* SPDX-License-Identifier: LGPL-2.1 OR MIT */ /* * x86_64 specific definitions for NOLIBC * Copyright (C) 2017-2022 Willy Tarreau */ #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 */