/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
* Alpha specific definitions for NOLIBC
* Copyright (C) 2025 Thomas Weißschuh <linux@weissschuh.net>
*/
#ifndef _NOLIBC_ARCH_ALPHA_H
#define _NOLIBC_ARCH_ALPHA_H
#include "compiler.h"
#include "crt.h"
/*
* Syscalls for Alpha:
* - registers are 64-bit
* - syscall number is passed in $0/v0
* - the system call is performed by calling callsys
* - syscall return comes in $0/v0, error flag in $19/a3
* - arguments are passed in $16/a0 to $21/a5
* - GCC does not support symbol register names
*/
#define _NOLIBC_SYSCALL_CLOBBERLIST \
"$1", "$2", "$3", "$4", "$5", "$6", "$7", "$8", \
"$22", "$23", "$24", "$25", "$27", "$28", "memory", "cc"
#define __nolibc_syscall0(num) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _err __asm__ ("$19"); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "=r"(_err) \
: \
: _NOLIBC_SYSCALL_CLOBBERLIST, \
"$16", "$17", "$18", "$20", "$21" \
); \
_err ? -_num : _num; \
})
#define __nolibc_syscall1(num, arg1) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _err __asm__ ("$19"); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "=r"(_err) \
: "r"(_arg1) \
: _NOLIBC_SYSCALL_CLOBBERLIST, "$17", "$18", "$20", "$21" \
); \
_err ? -_num : _num; \
})
#define __nolibc_syscall2(num, arg1, arg2) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _err __asm__ ("$19"); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
register long _arg2 __asm__ ("$17") = (long)(arg2); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "=r"(_err) \
: "r"(_arg1), "r"(_arg2) \
: _NOLIBC_SYSCALL_CLOBBERLIST, "$18", "$20", "$21" \
); \
_err ? -_num : _num; \
})
#define __nolibc_syscall3(num, arg1, arg2, arg3) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _err __asm__ ("$19"); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
register long _arg2 __asm__ ("$17") = (long)(arg2); \
register long _arg3 __asm__ ("$18") = (long)(arg3); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "=r"(_err) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3) \
: _NOLIBC_SYSCALL_CLOBBERLIST, "$20", "$21" \
); \
_err ? -_num : _num; \
})
#define __nolibc_syscall4(num, arg1, arg2, arg3, arg4) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
register long _arg2 __asm__ ("$17") = (long)(arg2); \
register long _arg3 __asm__ ("$18") = (long)(arg3); \
register long _arg4 __asm__ ("$19") = (long)(arg4); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "+r"(_arg4) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3) \
: _NOLIBC_SYSCALL_CLOBBERLIST, "$20", "$21" \
); \
_arg4 ? -_num : _num; \
})
#define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
register long _arg2 __asm__ ("$17") = (long)(arg2); \
register long _arg3 __asm__ ("$18") = (long)(arg3); \
register long _arg4 __asm__ ("$19") = (long)(arg4); \
register long _arg5 __asm__ ("$20") = (long)(arg5); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "+r"(_arg4) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg5) \
: _NOLIBC_SYSCALL_CLOBBERLIST, "$21" \
); \
_arg4 ? -_num : _num; \
})
#define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
({ \
register long _num __asm__ ("$0") = (num); \
register long _arg1 __asm__ ("$16") = (long)(arg1); \
register long _arg2 __asm__ ("$17") = (long)(arg2); \
register long _arg3 __asm__ ("$18") = (long)(arg3); \
register long _arg4 __asm__ ("$19") = (long)(arg4); \
register long _arg5 __asm__ ("$20") = (long)(arg5); \
register long _arg6 __asm__ ("$21") = (long)(arg6); \
\
__asm__ volatile ( \
"callsys" \
: "+r"(_num), "+r"(_arg4) \
: "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg5), \
"r"(_arg6) \
: _NOLIBC_SYSCALL_CLOBBERLIST \
); \
_arg4 ? -_num : _num; \
})
/* startup code */
void __attribute__((weak, noreturn)) __nolibc_entrypoint __nolibc_no_stack_protector
_start(void)
{
__asm__ volatile (
"br $gp, 0f\n" /* setup $gp, so that 'lda' works */
"0: ldgp $gp, 0($gp)\n"
"lda $27, _start_c\n" /* setup current function address for _start_c */
"mov $sp, $16\n" /* save argc pointer to $16, as arg1 of _start_c */
"br _start_c\n" /* transfer to c runtime */
);
__nolibc_entrypoint_epilogue();
}
#endif /* _NOLIBC_ARCH_ALPHA_H */
