From 15f3911599a8d005edee46247470afe2a7a0b4aa Mon Sep 17 00:00:00 2001
From: Aleksa Vuckovic <aleksa@vuckovic.cc>
Date: Mon, 27 Feb 2023 01:59:33 +0100
Subject: almost done multitasking

---
 kernel/src/scheduler/process.c | 96 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 84 insertions(+), 12 deletions(-)

(limited to 'kernel/src/scheduler/process.c')

diff --git a/kernel/src/scheduler/process.c b/kernel/src/scheduler/process.c
index e85cc11..e7ef7e5 100644
--- a/kernel/src/scheduler/process.c
+++ b/kernel/src/scheduler/process.c
@@ -3,24 +3,27 @@
 #include <heap.h>
 #include <scheduler.h>
 #include <libk/list.h>
+#include <libk/stdio.h>
 #include <process.h>
+#include <timer.h>
+#include <panic.h>
 
 process_t process_queue;
 process_t *curr_process;
 
-void init_process(uint64_t priv_lvl, uint64_t rip, uint64_t rdi, uint64_t rsi,
-		  uint64_t rdx)
+process_t *init_process(uint64_t priv_lvl, uint64_t rip, uint64_t argc,
+			uint64_t *argv)
 {
 	uint32_t stack_size = 32 * 1024;
-	uint64_t rsp = (uint64_t)kalloc(stack_size) + stack_size;
-	regs_t *regs = (regs_t *)(rsp + sizeof(regs_t));
+	uint64_t rsp = (uint64_t)kalloc(stack_size) + stack_size - 8;
+	regs_t *regs = (regs_t *)(rsp - sizeof(regs_t));
 
 	regs->rax = 0;
 	regs->rbx = 0;
 	regs->rcx = 0;
-	regs->rdx = rdx;
-	regs->rdi = rdi;
-	regs->rsi = rsi;
+	regs->rdx = (uint64_t)argv;
+	regs->rdi = rip;
+	regs->rsi = argc;
 	regs->rsp = rsp;
 	regs->rbp = 0;
 	regs->r8 = 0;
@@ -31,7 +34,7 @@ void init_process(uint64_t priv_lvl, uint64_t rip, uint64_t rdi, uint64_t rsi,
 	regs->r13 = 0;
 	regs->r14 = 0;
 	regs->r15 = 0;
-	regs->rip = rip;
+	regs->rip = (uint64_t)process_init_wrapper;
 	regs->rflags = 0;
 	regs->error = 0;
 
@@ -46,15 +49,84 @@ void init_process(uint64_t priv_lvl, uint64_t rip, uint64_t rdi, uint64_t rsi,
 	}
 
 	process_t *new_process = (process_t *)kalloc(sizeof(process_t));
+	new_process->rsp = rsp - sizeof(regs_t);
 	add_to_list(&new_process->list, &process_queue.list,
 		    process_queue.list.next);
+	return new_process;
 }
 
-__attribute__((noreturn)) void context_switch(uint64_t irq_rsp)
+void process_init_wrapper(uint64_t rip, uint64_t argc, uint64_t *argv)
+{
+	void (*f)(uint64_t rdi, ...) = (void (*)(uint64_t rdi, ...))rip;
+	switch (argc) {
+	case 0:
+		(*f)(argv[0]);
+		break;
+	case 1:
+		(*f)(argv[0]);
+		break;
+	case 2:
+		(*f)(argv[0], argv[1]);
+		break;
+	case 3:
+		(*f)(argv[0], argv[1], argv[2]);
+		break;
+	case 4:
+		(*f)(argv[0], argv[1], argv[2], argv[3]);
+		break;
+	case 5:
+		(*f)(argv[0], argv[1], argv[2], argv[3], argv[4]);
+		break;
+	default:
+		(*f)(argv[0], argv[1], argv[2], argv[3], argv[4], argv[5]);
+		break;
+	}
+	kfree(argv);
+	remove_current_process();
+}
+
+__attribute__((noreturn)) void idle_thread()
+{
+	uint64_t x = 0;
+	__asm__ __volatile__("mov %%rsp, %0;" : "=r"(x) : :);
+	printf("current rsp: 0x%x\n", x);
+	printf("idle_thread()\n");
+	for (;;) {
+		printf("1");
+		wait(2000);
+		__asm__ __volatile__("pause; hlt;");
+	}
+}
+
+__attribute__((noreturn)) void idle_thread2()
 {
-	save_context_to_rsp(irq_rsp, curr_process->rsp);
+	printf("idle_thread2()\n");
+	for (;;) {
+		printf("2");
+		wait(1000);
+		__asm__ __volatile__("pause; hlt;");
+	}
+}
 
-	process_t *next_process = scheduler();
+__attribute__((noreturn)) void remove_current_process()
+{
+	free_node(&curr_process->list);
+	kfree(curr_process);
+	curr_process = scheduler();
+	if (curr_process == NULL) {
+		printf("no processes left\n");
+		for (;;) {
+			__asm__ __volatile__("pause; hlt;");
+		}
+	}
+	restore_context_from_rsp(curr_process->rsp);
+}
 
-	restore_context_from_rsp(next_process->rsp);
+__attribute__((noreturn)) void context_switch(uint64_t irq_rsp)
+{
+	printf("irq_rsp: 0x%x\n", irq_rsp);
+	print_regs_from_rsp(irq_rsp);
+	curr_process->rsp = save_context_from_rsp(irq_rsp);
+	curr_process = scheduler();
+	restore_context_from_rsp(curr_process->rsp);
 }
-- 
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