Node / public / precursor-lxmfchat.git / files / xous-core / kernel / src / arch / riscv / syscall.rs

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// SPDX-FileCopyrightText: 2020 Sean Cross <sean@xobs.io>

// SPDX-License-Identifier: Apache-2.0

use riscv::register::{sepc, sstatus};

use crate::services::Thread;

extern "C" {

fn _xous_resume_context(regs: *const usize) -> !;

}

pub fn invoke(thread: &mut Thread, supervisor: bool, pc: usize, sp: usize, ret_addr: usize, args: &[usize]) {

set_supervisor(supervisor);

thread.registers[0] = ret_addr;

thread.registers[1] = sp;

assert!(args.len() <= 8, "too many arguments to invoke()");

for (idx, arg) in args.iter().enumerate() {

thread.registers[9 + idx] = *arg;

}

thread.sepc = pc;

}

fn set_supervisor(supervisor: bool) {

if supervisor {

unsafe { sstatus::set_spp(sstatus::SPP::Supervisor) };

} else {

unsafe { sstatus::set_spp(sstatus::SPP::User) };

}

}

pub fn resume(supervisor: bool, thread: &Thread) -> ! {

sepc::write(thread.sepc);

// Return to the appropriate CPU mode

set_supervisor(supervisor);

#[cfg(feature = "debug-print")]

println!(

"Switching to PID {}, SP: {:08x}, PC: {:08x}",

crate::arch::current_pid(),

thread.registers[1],

thread.sepc,

);

unsafe { _xous_resume_context(thread.registers.as_ptr()) };

}