From 8e85ae5318bb47af04c9b2e4d2158ce113e9c991 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Thu, 7 Feb 2019 17:52:57 -0800
Subject: [PATCH] Added getpid system call

---
 src/drivers/nulldrv/main.s | 10 +++++++++-
 src/kernel/scheduler.cpp   | 14 +++++++-------
 src/kernel/syscall.cpp     | 28 +++++++++++++++++++---------
 src/kernel/syscall.h       |  1 +
 4 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/src/drivers/nulldrv/main.s b/src/drivers/nulldrv/main.s
index a0175bd..fdad2b2 100644
--- a/src/drivers/nulldrv/main.s
+++ b/src/drivers/nulldrv/main.s
@@ -1,11 +1,19 @@
 global _start
 _start:
 	xor rbp, rbp	; Sentinel rbp
+
+	mov rax, 5		; GETPID syscall
+	int 0xee
+	mov r12, rax	; save pid to r12
+
+	mov rax, 1		; DEBUG syscall
+	int 0xee
+
 	mov r11, 0		; counter
 	mov rbx, 20		; sleep timeout
 
 .loop:
-	mov rax, 1		; DEBUG syscall
+	mov rax, 2		; MESSAGE syscall
 	;mov rax, 0		; NOOP syscall
 	;syscall
 	int 0xee
diff --git a/src/kernel/scheduler.cpp b/src/kernel/scheduler.cpp
index 0155263..cc1d693 100644
--- a/src/kernel/scheduler.cpp
+++ b/src/kernel/scheduler.cpp
@@ -216,13 +216,11 @@ void scheduler::prune(uint64_t now)
 	while (proc) {
 		bool ready = proc->flags && process_flags::ready;
 		ready |= proc->wake_on_time(now);
-		if (!ready) {
-			proc = proc->next();
-			continue;
-		}
 
 		auto *remove = proc;
 		proc = proc->next();
+		if (!ready) continue;
+
 		m_blocked.remove(remove);
 		m_runlists[remove->priority].push_front(remove);
 	}
@@ -234,15 +232,17 @@ scheduler::schedule(uintptr_t rsp0)
 
 	// TODO: lol a real clock
 	static uint64_t now = 0;
-	prune(++now);
 
 	m_current->rsp = rsp0;
 	m_runlists[m_current->priority].remove(m_current);
 
-	if (m_current->flags && process_flags::ready)
+	if (m_current->flags && process_flags::ready) {
 		m_runlists[m_current->priority].push_back(m_current);
-	else
+	} else {
 		m_blocked.push_back(m_current);
+	}
+
+	prune(++now);
 
 	uint8_t pri = 0;
 	while (m_runlists[pri].empty()) {
diff --git a/src/kernel/syscall.cpp b/src/kernel/syscall.cpp
index bdd65e2..a50d2cc 100644
--- a/src/kernel/syscall.cpp
+++ b/src/kernel/syscall.cpp
@@ -40,20 +40,23 @@ syscall_dispatch(uintptr_t return_rsp, cpu_state &regs)
 	console *cons = console::get();
 	syscall call = static_cast<syscall>(regs.rax);
 
+	auto &s = scheduler::get();
+	auto *p = s.current();
+
 	switch (call) {
 	case syscall::noop:
 		break;
 
 	case syscall::debug:
 		cons->set_color(11);
-		cons->printf("\nReceived DEBUG syscall\n");
+		cons->printf("\nProcess %u: Received DEBUG syscall\n", p->pid);
 		cons->set_color();
 		print_regs(regs);
 		break;
 
 	case syscall::message:
 		cons->set_color(11);
-		cons->printf("\nReceived MESSAGE syscall\n");
+		cons->printf("\nProcess %u: Received MESSAGE syscall\n", p->pid);
 		cons->set_color();
 		break;
 
@@ -64,7 +67,7 @@ syscall_dispatch(uintptr_t return_rsp, cpu_state &regs)
 			auto &s = scheduler::get();
 			auto *p = s.current();
 			p->wait_on_signal(-1ull);
-			cons->printf("\nReceived PAUSE syscall\n");
+			cons->printf("\nProcess %u: Received PAUSE syscall\n", p->pid);
 			return_rsp = s.schedule(return_rsp);
 			cons->set_color();
 		}
@@ -73,16 +76,23 @@ syscall_dispatch(uintptr_t return_rsp, cpu_state &regs)
 	case syscall::sleep:
 		{
 			cons->set_color(11);
-
-			auto &s = scheduler::get();
-			auto *p = s.current();
-			p->wait_on_time(regs.rbx);
-			cons->printf("\nReceived SLEEP syscall\n");
-			return_rsp = s.schedule(return_rsp);
+			cons->printf("\nProcess %u: Received SLEEP syscall\n", p->pid);
+			cons->printf("Sleeping until %lu\n", regs.rbx);
 			cons->set_color();
+
+			p->wait_on_time(regs.rbx);
+			return_rsp = s.schedule(return_rsp);
 		}
 		break;
 
+	case syscall::getpid:
+		cons->set_color(11);
+		cons->printf("\nProcess %u: Received GETPID syscall\n", p->pid);
+		cons->set_color();
+		regs.rax = p->pid;
+		break;
+
+
 	default:
 		cons->set_color(9);
 		cons->printf("\nReceived unknown syscall: %02x\n", call);
diff --git a/src/kernel/syscall.h b/src/kernel/syscall.h
index 12df735..a1f27c5 100644
--- a/src/kernel/syscall.h
+++ b/src/kernel/syscall.h
@@ -11,6 +11,7 @@ enum class syscall : uint64_t
 	message,
 	pause,
 	sleep,
+	getpid,
 
 	last_syscall
 };