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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
/*
* Syscall MD Layer — RISC-V Register Extraction
*
* Extracts syscall number (a7) and arguments (a0-a5) from the TrapFrame,
* calls the MI dispatcher, and writes the return value back to a0.
*
* Reference: docs/specs/syscall.md §5
*/
#include <lume/syscall.h>
#include <lume/syscall_nr.h>
#include <arch/trapframe.h>
#include <arch/cpu.h>
void syscall_dispatch_md(arch::TrapFrame* tf)
{
uint64 nr = tf->a[7]; /* RISC-V ABI: syscall number in a7 */
uint64 args[6] = {
tf->a[0], tf->a[1], tf->a[2],
tf->a[3], tf->a[4], tf->a[5],
};
/* Enable interrupts so timer and preemption work during syscalls */
arch::cpu::intr_on();
int64 ret = syscall_dispatch(nr, args);
arch::cpu::intr_off();
/* sys_rt_sigreturn restores the entire TrapFrame from the signal
* frame on the user stack. Writing ret into a[0] would clobber
* the restored value, so we must skip the writeback. */
if (nr == static_cast<uint64>(SYS_rt_sigreturn)){
return;
}
tf->a[0] = static_cast<uint64>(ret); /* Return value in a0 */
}
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