158 lines
8.1 KiB
C
158 lines
8.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* RISCV (32 and 64) specific definitions for NOLIBC
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* Copyright (C) 2017-2022 Willy Tarreau <w@1wt.eu>
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*/
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#ifndef _NOLIBC_ARCH_RISCV_H
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#define _NOLIBC_ARCH_RISCV_H
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#include "compiler.h"
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#include "crt.h"
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/* Syscalls for RISCV :
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* - stack is 16-byte aligned
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* - syscall number is passed in a7
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* - arguments are in a0, a1, a2, a3, a4, a5
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* - the system call is performed by calling ecall
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* - syscall return comes in a0
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* - the arguments are cast to long and assigned into the target
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* registers which are then simply passed as registers to the asm code,
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* so that we don't have to experience issues with register constraints.
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*/
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#define my_syscall0(num) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0"); \
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\
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__asm__ volatile ( \
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"ecall\n\t" \
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: "=r"(_arg1) \
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: "r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall1(num, arg1) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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\
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__asm__ volatile ( \
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"ecall\n" \
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: "+r"(_arg1) \
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: "r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall2(num, arg1, arg2) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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\
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__asm__ volatile ( \
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"ecall\n" \
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: "+r"(_arg1) \
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: "r"(_arg2), \
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"r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall3(num, arg1, arg2, arg3) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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\
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__asm__ volatile ( \
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"ecall\n\t" \
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: "+r"(_arg1) \
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: "r"(_arg2), "r"(_arg3), \
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"r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall4(num, arg1, arg2, arg3, arg4) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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\
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__asm__ volatile ( \
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"ecall\n" \
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: "+r"(_arg1) \
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: "r"(_arg2), "r"(_arg3), "r"(_arg4), \
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"r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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register long _arg5 __asm__ ("a4") = (long)(arg5); \
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\
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__asm__ volatile ( \
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"ecall\n" \
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: "+r"(_arg1) \
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: "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
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"r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
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({ \
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register long _num __asm__ ("a7") = (num); \
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register long _arg1 __asm__ ("a0") = (long)(arg1); \
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register long _arg2 __asm__ ("a1") = (long)(arg2); \
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register long _arg3 __asm__ ("a2") = (long)(arg3); \
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register long _arg4 __asm__ ("a3") = (long)(arg4); \
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register long _arg5 __asm__ ("a4") = (long)(arg5); \
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register long _arg6 __asm__ ("a5") = (long)(arg6); \
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\
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__asm__ volatile ( \
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"ecall\n" \
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: "+r"(_arg1) \
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: "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), "r"(_arg6), \
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"r"(_num) \
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: "memory", "cc" \
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); \
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_arg1; \
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})
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/* startup code */
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void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
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{
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__asm__ volatile (
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".option push\n"
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".option norelax\n"
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"lla gp, __global_pointer$\n"
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".option pop\n"
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"mv a0, sp\n" /* save stack pointer to a0, as arg1 of _start_c */
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"andi sp, a0, -16\n" /* sp must be 16-byte aligned */
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"call _start_c\n" /* transfer to c runtime */
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);
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__builtin_unreachable();
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}
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#endif /* _NOLIBC_ARCH_RISCV_H */
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