--- /dev/null
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * LoongArch specific definitions for NOLIBC
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
+ */
+
+#ifndef _NOLIBC_ARCH_LOONGARCH_H
+#define _NOLIBC_ARCH_LOONGARCH_H
+
+/* Syscalls for LoongArch :
+ * - stack is 16-byte aligned
+ * - syscall number is passed in a7
+ * - arguments are in a0, a1, a2, a3, a4, a5
+ * - the system call is performed by calling "syscall 0"
+ * - syscall return comes in a0
+ * - 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.
+ *
+ * On LoongArch, select() is not implemented so we have to use pselect6().
+ */
+#define __ARCH_WANT_SYS_PSELECT6
+
+#define my_syscall0(num) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0"); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "=r"(_arg1) \
+ : "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall1(num, arg1) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall2(num, arg1, arg2) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_arg2), \
+ "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall3(num, arg1, arg2, arg3) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_arg2), "r"(_arg3), \
+ "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall4(num, arg1, arg2, arg3, arg4) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
+ register long _arg4 __asm__ ("a3") = (long)(arg4); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_arg2), "r"(_arg3), "r"(_arg4), \
+ "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
+ register long _arg4 __asm__ ("a3") = (long)(arg4); \
+ register long _arg5 __asm__ ("a4") = (long)(arg5); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
+ "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
+({ \
+ register long _num __asm__ ("a7") = (num); \
+ register long _arg1 __asm__ ("a0") = (long)(arg1); \
+ register long _arg2 __asm__ ("a1") = (long)(arg2); \
+ register long _arg3 __asm__ ("a2") = (long)(arg3); \
+ register long _arg4 __asm__ ("a3") = (long)(arg4); \
+ register long _arg5 __asm__ ("a4") = (long)(arg5); \
+ register long _arg6 __asm__ ("a5") = (long)(arg6); \
+ \
+ __asm__ volatile ( \
+ "syscall 0\n" \
+ : "+r"(_arg1) \
+ : "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), "r"(_arg6), \
+ "r"(_num) \
+ : "memory", "$t0", "$t1", "$t2", "$t3", \
+ "$t4", "$t5", "$t6", "$t7", "$t8" \
+ ); \
+ _arg1; \
+})
+
+char **environ __attribute__((weak));
+const unsigned long *_auxv __attribute__((weak));
+
+#if __loongarch_grlen == 32
+#define LONGLOG "2"
+#define SZREG "4"
+#define REG_L "ld.w"
+#define LONG_S "st.w"
+#define LONG_ADD "add.w"
+#define LONG_ADDI "addi.w"
+#define LONG_SLL "slli.w"
+#define LONG_BSTRINS "bstrins.w"
+#else // __loongarch_grlen == 64
+#define LONGLOG "3"
+#define SZREG "8"
+#define REG_L "ld.d"
+#define LONG_S "st.d"
+#define LONG_ADD "add.d"
+#define LONG_ADDI "addi.d"
+#define LONG_SLL "slli.d"
+#define LONG_BSTRINS "bstrins.d"
+#endif
+
+/* startup code */
+void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
+{
+ __asm__ volatile (
+ REG_L " $a0, $sp, 0\n" // argc (a0) was in the stack
+ LONG_ADDI " $a1, $sp, "SZREG"\n" // argv (a1) = sp + SZREG
+ LONG_SLL " $a2, $a0, "LONGLOG"\n" // envp (a2) = SZREG*argc ...
+ LONG_ADDI " $a2, $a2, "SZREG"\n" // + SZREG (skip null)
+ LONG_ADD " $a2, $a2, $a1\n" // + argv
+
+ "move $a3, $a2\n" // iterate a3 over envp to find auxv (after NULL)
+ "0:\n" // do {
+ REG_L " $a4, $a3, 0\n" // a4 = *a3;
+ LONG_ADDI " $a3, $a3, "SZREG"\n" // a3 += sizeof(void*);
+ "bne $a4, $zero, 0b\n" // } while (a4);
+ "la.pcrel $a4, _auxv\n" // a4 = &_auxv
+ LONG_S " $a3, $a4, 0\n" // store a3 into _auxv
+
+ "la.pcrel $a3, environ\n" // a3 = &environ
+ LONG_S " $a2, $a3, 0\n" // store envp(a2) into environ
+ LONG_BSTRINS " $sp, $zero, 3, 0\n" // sp must be 16-byte aligned
+ "bl main\n" // main() returns the status code, we'll exit with it.
+ "li.w $a7, 93\n" // NR_exit == 93
+ "syscall 0\n"
+ );
+ __builtin_unreachable();
+}
+
+#endif // _NOLIBC_ARCH_LOONGARCH_H
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