| /* 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 |
| |
| /* The struct returned by the stat() syscall, equivalent to stat64(). The |
| * syscall returns 116 bytes and stops in the middle of __unused. |
| */ |
| struct sys_stat_struct { |
| unsigned long st_dev; |
| unsigned long st_ino; |
| unsigned long st_nlink; |
| unsigned int st_mode; |
| unsigned int st_uid; |
| |
| unsigned int st_gid; |
| unsigned int __pad0; |
| unsigned long st_rdev; |
| long st_size; |
| long st_blksize; |
| |
| long st_blocks; |
| unsigned long st_atime; |
| unsigned long st_atime_nsec; |
| unsigned long st_mtime; |
| |
| unsigned long st_mtime_nsec; |
| unsigned long st_ctime; |
| unsigned long st_ctime_nsec; |
| long __unused[3]; |
| }; |
| |
| /* 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; \ |
| }) |
| |
| char **environ __attribute__((weak)); |
| const unsigned long *_auxv __attribute__((weak)); |
| |
| #define __ARCH_SUPPORTS_STACK_PROTECTOR |
| |
| /* 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("omit-frame-pointer"))) _start(void) |
| { |
| __asm__ volatile ( |
| #ifdef NOLIBC_STACKPROTECTOR |
| "call __stack_chk_init\n" // initialize stack protector |
| #endif |
| "pop %rdi\n" // argc (first arg, %rdi) |
| "mov %rsp, %rsi\n" // argv[] (second arg, %rsi) |
| "lea 8(%rsi,%rdi,8),%rdx\n" // then a NULL then envp (third arg, %rdx) |
| "mov %rdx, environ\n" // save environ |
| "xor %ebp, %ebp\n" // zero the stack frame |
| "mov %rdx, %rax\n" // search for auxv (follows NULL after last env) |
| "0:\n" |
| "add $8, %rax\n" // search for auxv using rax, it follows the |
| "cmp -8(%rax), %rbp\n" // ... NULL after last env (rbp is zero here) |
| "jnz 0b\n" |
| "mov %rax, _auxv\n" // save it into _auxv |
| "and $-16, %rsp\n" // x86 ABI : esp must be 16-byte aligned before call |
| "call main\n" // main() returns the status code, we'll exit with it. |
| "mov %eax, %edi\n" // retrieve exit code (32 bit) |
| "mov $60, %eax\n" // NR_exit == 60 |
| "syscall\n" // really exit |
| "hlt\n" // ensure it does not return |
| ); |
| __builtin_unreachable(); |
| } |
| |
| #endif // _NOLIBC_ARCH_X86_64_H |
