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/* SPDX-License-Identifier: GPL-3.0-or-later */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
/**
* @file ipc.c
* Interprocess communication syscall implementations.
*/
#include <apos/uapi.h>
#include <apos/tcb.h>
/**
* IPC server notification syscall handler.
*
* @param callback Address of server callback.
* @return \ref OK and \c 0.
*/
SYSCALL_DEFINE1(ipc_server)(sys_arg_t callback)
{
cur_tcb()->callback = callback;
return SYS_RET1(OK);
}
/**
* Actual IPC syscall handler.
*
* @param pid Process to request RPC to.
* @param d0 IPC argument 0.
* @param d1 IPC argument 1.
* @param d2 IPC argument 2.
* @param d3 IPC argument 3.
* @param fwd Whether to forward.
* @return
*/
static struct sys_ret do_ipc(sys_arg_t pid,
sys_arg_t d0,
sys_arg_t d1,
sys_arg_t d2,
sys_arg_t d3,
bool fwd)
{
struct tcb *t = cur_tcb();
struct tcb *r = get_tcb(pid);
if (!r)
return SYS_RET1(ERR_INVAL);
r = get_rproc(r);
if (!r->callback)
return SYS_RET1(ERR_NOINIT);
/** \todo place data on rpc stack and clone into virtual memory */
set_return(t, r->callback);
if (!fwd)
t->eid = t->pid;
t->pid = r->rid;
return SYS_RET6(OK, t->eid, d0, d1, d2, d3);
}
/**
* IPC request syscall handler.
*
* @param pid Process to request RPC to.
* @param d0 IPC argument 0.
* @param d1 IPC argument 1.
* @param d2 IPC argument 2.
* @param d3 IPC argument 3.
* @return When succesful: OK, thread id of the caller and the arguments as-is.
*/
SYSCALL_DEFINE5(ipc_req)(sys_arg_t pid,
sys_arg_t d0, sys_arg_t d1, sys_arg_t d2, sys_arg_t d3)
{
return do_ipc(pid, d0, d1, d2, d3, false);
}
/**
* IPC forwarding syscall handler.
*
* @param pid Process to request RPC to.
* @param d0 IPC argument 0.
* @param d1 IPC argument 1.
* @param d2 IPC argument 2.
* @param d3 IPC argument 3.
* @return
*/
SYSCALL_DEFINE5(ipc_fwd)(sys_arg_t pid,
sys_arg_t d0, sys_arg_t d1, sys_arg_t d2, sys_arg_t d3)
{
return do_ipc(pid, d0, d1, d2, d3, true);
}
/**
* IPC response syscall handler.
*
* @param d0 IPC return value 0.
* @param d1 IPC return value 1.
* @param d2 IPC return value 2.
* @param d3 IPC return value 3.
* @return \c d0 and \c d1.
*/
SYSCALL_DEFINE4(ipc_resp)(sys_arg_t d0, sys_arg_t d1, sys_arg_t d2,
sys_arg_t d3)
{
struct tcb *t = cur_tcb();
/* something like return_from_callback(t, r) */
return SYS_RET6(OK, t->tid, d0, d1, d2, d3);
}
/**
* Notify syscall handler.
*
* \todo Implement.
*
* @param tid Thread ID to notify.
* @param swap Whether to swap immediately if possible.
* @return \ref OK and 0.
*/
SYSCALL_DEFINE2(ipc_notify)(sys_arg_t tid, sys_arg_t swap){
/** \todo masquerade as kernel call, set from to 0 and set us as
* notify type, no arguments as that would require too much state
* handling for my liking. Instead, a server and a client have to agree
* on some rpc API, and ipc_notify is just used to asynchronously inform
* the client that it should check the status of its async operations.
* Arguably slower than directly telling the client which operation was
* finished, but this would require the kernel to keep track of a notify
* stack. While not impossible, probably too complex. */
/* Something like
*
* struct tcb *t = get_tcb(tid);
* if (t->notify_state == NOTIFY_QUEUED)
* return;
*
* if (t->notify_state == NOTIFY_RUNNING) {
* t->notify = NOTIFY_QUEUED;
* return;
* }
*
* t->notify_state = NOTIFY_QUEUED;
* if (swap)
* do_swap(); // clears t->notify when swapped to
* // if already running in base state, interrupt,
* otherwise wait for return from rpc. If not running,
* just queue the interrupt.
*/
return SYS_RET1(OK);
}
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