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+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * i386 specific definitions for NOLIBC
+ * Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
+ */
+
+#ifndef _NOLIBC_ARCH_I386_H
+#define _NOLIBC_ARCH_I386_H
+
+#include "compiler.h"
+#include "crt.h"
+
+/* Syscalls for i386 :
+ * - mostly similar to x86_64
+ * - registers are 32-bit
+ * - syscall number is passed in eax
+ * - arguments are in ebx, ecx, edx, esi, edi, ebp respectively
+ * - all registers are preserved (except eax of course)
+ * - the system call is performed by calling int $0x80
+ * - syscall return comes in eax
+ * - 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).
+ *
+ * Also, i386 supports the old_select syscall if newselect is not available
+ */
+#define __ARCH_WANT_SYS_OLD_SELECT
+
+#define my_syscall0(num) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall1(num, arg1) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ register long _arg1 __asm__ ("ebx") = (long)(arg1); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "r"(_arg1), \
+ "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall2(num, arg1, arg2) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ register long _arg1 __asm__ ("ebx") = (long)(arg1); \
+ register long _arg2 __asm__ ("ecx") = (long)(arg2); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "r"(_arg1), "r"(_arg2), \
+ "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall3(num, arg1, arg2, arg3) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ register long _arg1 __asm__ ("ebx") = (long)(arg1); \
+ register long _arg2 __asm__ ("ecx") = (long)(arg2); \
+ register long _arg3 __asm__ ("edx") = (long)(arg3); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "r"(_arg1), "r"(_arg2), "r"(_arg3), \
+ "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall4(num, arg1, arg2, arg3, arg4) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ register long _arg1 __asm__ ("ebx") = (long)(arg1); \
+ register long _arg2 __asm__ ("ecx") = (long)(arg2); \
+ register long _arg3 __asm__ ("edx") = (long)(arg3); \
+ register long _arg4 __asm__ ("esi") = (long)(arg4); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
+ "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
+({ \
+ long _ret; \
+ register long _num __asm__ ("eax") = (num); \
+ register long _arg1 __asm__ ("ebx") = (long)(arg1); \
+ register long _arg2 __asm__ ("ecx") = (long)(arg2); \
+ register long _arg3 __asm__ ("edx") = (long)(arg3); \
+ register long _arg4 __asm__ ("esi") = (long)(arg4); \
+ register long _arg5 __asm__ ("edi") = (long)(arg5); \
+ \
+ __asm__ volatile ( \
+ "int $0x80\n" \
+ : "=a" (_ret) \
+ : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
+ "0"(_num) \
+ : "memory", "cc" \
+ ); \
+ _ret; \
+})
+
+#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
+({ \
+ long _eax = (long)(num); \
+ long _arg6 = (long)(arg6); /* Always in memory */ \
+ __asm__ volatile ( \
+ "pushl %[_arg6]\n\t" \
+ "pushl %%ebp\n\t" \
+ "movl 4(%%esp),%%ebp\n\t" \
+ "int $0x80\n\t" \
+ "popl %%ebp\n\t" \
+ "addl $4,%%esp\n\t" \
+ : "+a"(_eax) /* %eax */ \
+ : "b"(arg1), /* %ebx */ \
+ "c"(arg2), /* %ecx */ \
+ "d"(arg3), /* %edx */ \
+ "S"(arg4), /* %esi */ \
+ "D"(arg5), /* %edi */ \
+ [_arg6]"m"(_arg6) /* memory */ \
+ : "memory", "cc" \
+ ); \
+ _eax; \
+})
+
+/* startup code */
+/*
+ * i386 System V ABI mandates:
+ * 1) last pushed argument must be 16-byte aligned.
+ * 2) The deepest stack frame should be set to zero
+ *
+ */
+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 %esp, %eax\n" /* save stack pointer to %eax, as arg1 of _start_c */
+ "add $12, %esp\n" /* avoid over-estimating after the 'and' & 'sub' below */
+ "and $-16, %esp\n" /* the %esp must be 16-byte aligned on 'call' */
+ "sub $12, %esp\n" /* sub 12 to keep it aligned after the push %eax */
+ "push %eax\n" /* push arg1 on stack to support plain stack modes too */
+ "call _start_c\n" /* transfer to c runtime */
+ "hlt\n" /* ensure it does not return */
+ );
+ __builtin_unreachable();
+}
+
+#endif /* _NOLIBC_ARCH_I386_H */