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tools/nolibc: Add support for LoongArch
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Add support for LoongArch (32 and 64 bit) to nolibc.

Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Feiyang Chen authored and Paul E. McKenney committed Mar 20, 2023
1 parent b551cb7 commit 73f12c6
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200 changes: 200 additions & 0 deletions tools/include/nolibc/arch-loongarch.h
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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

/* 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
2 changes: 2 additions & 0 deletions tools/include/nolibc/arch.h
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Expand Up @@ -29,6 +29,8 @@
#include "arch-riscv.h"
#elif defined(__s390x__)
#include "arch-s390.h"
#elif defined(__loongarch__)
#include "arch-loongarch.h"
#endif

#endif /* _NOLIBC_ARCH_H */

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