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/* 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
#include "compiler.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 _NOLIBC_SYSCALL_CLOBBERLIST \
"memory", "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$t8"
#define my_syscall0(num) \
({ \
register long _num __asm__ ("a7") = (num); \
register long _arg1 __asm__ ("a0"); \
\
__asm__ volatile ( \
"syscall 0\n" \
: "=r"(_arg1) \
: "r"(_num) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_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("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
"bl __stack_chk_init\n" /* initialize stack protector */
#endif
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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