From 9dbf8131d6aaff1617ef2bc7ebf54838f808688d Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Thu, 6 Aug 2020 20:02:44 +0200
Subject: Fixed messed up registers

---
 apps/init.c                |  2 +-
 src/drivers/interrupts.asm | 14 ++++++++++++++
 src/features/load.c        |  8 ++++++++
 src/features/proc.c        | 27 +++++++++++----------------
 src/features/syscall.c     |  4 +++-
 src/inc/load.h             |  6 ++++++
 src/inc/proc.h             |  1 -
 7 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/apps/init.c b/apps/init.c
index 859ffe8..1c7540c 100644
--- a/apps/init.c
+++ b/apps/init.c
@@ -43,7 +43,7 @@ void serial_print(const char *data)
 void main()
 {
 	serial_print("Init loaded\n");
-	__asm__ volatile("int $0x80");
+	/* __asm__ volatile("int $0x80"); */
 	while (1) {
 		__asm__ volatile("hlt");
 	};
diff --git a/src/drivers/interrupts.asm b/src/drivers/interrupts.asm
index 8f8afbb..59c323c 100644
--- a/src/drivers/interrupts.asm
+++ b/src/drivers/interrupts.asm
@@ -37,6 +37,13 @@ irq_common_stub:
 	push fs
 	push gs
 
+	mov ax, 0x10
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	cld
+
 	push esp
 	call irq_handler
 	add esp, 4
@@ -113,6 +120,13 @@ isr_common_stub:
 	push fs
 	push gs
 
+	mov ax, 0x10
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	cld
+
 	push esp
 	call isr_handler
 	add esp, 4
diff --git a/src/features/load.c b/src/features/load.c
index bc56235..36548bb 100644
--- a/src/features/load.c
+++ b/src/features/load.c
@@ -2,6 +2,7 @@
 
 #include <def.h>
 #include <fs.h>
+#include <load.h>
 #include <mem.h>
 #include <print.h>
 #include <proc.h>
@@ -14,4 +15,11 @@ void bin_load(char *path, struct proc *proc)
 	proc->regs.ebp = (u32)stack;
 	proc->regs.esp = (u32)stack;
 	proc->regs.eip = (u32)data;
+
+	proc->regs.ds = GDT_DATA_OFFSET;
+	proc->regs.es = GDT_DATA_OFFSET;
+	proc->regs.fs = GDT_DATA_OFFSET;
+	proc->regs.gs = GDT_DATA_OFFSET;
+	proc->regs.cs = GDT_CODE_OFFSET;
+	proc->regs.eflags = EFLAGS_ALWAYS | EFLAGS_INTERRUPTS;
 }
diff --git a/src/features/proc.c b/src/features/proc.c
index 0378183..594e9ec 100644
--- a/src/features/proc.c
+++ b/src/features/proc.c
@@ -15,12 +15,14 @@ struct proc *last;
 
 void scheduler(struct regs *regs)
 {
-	printf("%d", current->pid);
-	memcpy(&current->regs, regs, sizeof(struct regs));
+	if (current) {
+		printf("%d", current->pid);
+		memcpy(&current->regs, regs, sizeof(struct regs));
+	}
 
 	timer_handler();
 
-	if (current->next)
+	if (current && current->next)
 		current = current->next;
 	else
 		current = root;
@@ -38,6 +40,7 @@ void proc_print()
 {
 	struct proc *proc = root;
 
+	printf("\n");
 	while (proc) {
 		printf("Process %d [%s]\n", proc->pid,
 		       proc->state == PROC_RUNNING ? "running" : "sleeping");
@@ -60,6 +63,8 @@ void proc_attach(struct proc *proc)
 
 struct proc *proc_make()
 {
+	/* if (current) */
+	/* 	current->state = PROC_ASLEEP; */
 	struct proc *proc = malloc(sizeof(*proc));
 	proc->pid = pid++;
 	proc->state = PROC_RUNNING;
@@ -69,24 +74,14 @@ struct proc *proc_make()
 	return proc;
 }
 
-void proc_jump(struct proc *proc)
-{
-	void (*entry)();
-	*(void **)(&entry) = (u32 *)proc->regs.eip;
-	__asm__ volatile("movl %%eax, %%ebp" ::"a"(proc->regs.ebp));
-	__asm__ volatile("movl %%eax, %%esp" ::"a"(proc->regs.esp));
-	current = proc;
-	sti();
-	entry();
-}
-
 void proc_init()
 {
 	cli();
 	irq_install_handler(0, scheduler);
 
-	current = root = proc_make();
+	root = proc_make();
 	bin_load("/init", root);
 	proc_print();
-	proc_jump(root);
+	sti();
+	hlt();
 }
diff --git a/src/features/syscall.c b/src/features/syscall.c
index ebfff59..2279429 100644
--- a/src/features/syscall.c
+++ b/src/features/syscall.c
@@ -1,5 +1,6 @@
 // MIT License, Copyright (c) 2020 Marvin Borner
 
+#include <cpu.h>
 #include <interrupts.h>
 #include <load.h>
 #include <print.h>
@@ -11,7 +12,8 @@ void syscall_handler(struct regs *r)
 
 	struct proc *a = proc_make();
 	bin_load("/a", a);
-	proc_jump(a);
+	sti();
+	hlt();
 }
 
 void syscall_init()
diff --git a/src/inc/load.h b/src/inc/load.h
index 60fecf9..697248e 100644
--- a/src/inc/load.h
+++ b/src/inc/load.h
@@ -5,6 +5,12 @@
 
 #include <proc.h>
 
+#define EFLAGS_ALWAYS 0x2 // Always one
+#define EFLAGS_INTERRUPTS 0x200 // Enable interrupts
+
+#define GDT_DATA_OFFSET 0x10 // Data segment offset in GDT
+#define GDT_CODE_OFFSET 0x8 // Code segment offset in GDT
+
 void bin_load(char *path, struct proc *proc);
 
 #endif
diff --git a/src/inc/proc.h b/src/inc/proc.h
index bc3d115..dc8b9e9 100644
--- a/src/inc/proc.h
+++ b/src/inc/proc.h
@@ -17,7 +17,6 @@ struct proc {
 };
 
 void proc_init();
-void proc_jump(struct proc *proc);
 struct proc *proc_make();
 
 #endif
-- 
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