From 7e8a831e1fa1fb98d2486f0c262c2609c176abab Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Fri, 25 Jun 2021 21:57:30 +0200
Subject: malloc stub + processes

well, there's only one process, but shh
---
 kernel/main.c | 11 +++++++----
 kernel/mem.c  | 19 +++++++++++++++++++
 kernel/mem.h  |  7 +++++++
 kernel/proc.c | 21 +++++++++++++++++++++
 kernel/proc.h | 13 +++++++++++++
 5 files changed, 67 insertions(+), 4 deletions(-)
 create mode 100644 kernel/mem.c
 create mode 100644 kernel/mem.h
 create mode 100644 kernel/proc.c
 create mode 100644 kernel/proc.h

(limited to 'kernel')

diff --git a/kernel/main.c b/kernel/main.c
index 458558a..5c2c5e8 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -1,9 +1,9 @@
 #include <kernel/gdt.h>
+#include <kernel/mem.h>
+#include <kernel/proc.h>
 #include <kernel/tty.h>
 #include <platform/sysenter.h>
 
-extern void stack_top;
-
 void r3_test();
 
 void kmain()
@@ -11,9 +11,12 @@ void kmain()
 	tty_clear();
 	gdt_init();
 	sysenter_setup();
+	mem_init();
 
-	tty_const("jumping to ring3...");
-	sysexit(r3_test, &stack_top);
+	tty_const("creating process...");
+	struct process *proc = process_new(r3_test);
+	tty_const("switching...");
+	process_switch(proc);
 }
 
 void r3_test() {
diff --git a/kernel/mem.c b/kernel/mem.c
new file mode 100644
index 0000000..8fcaf26
--- /dev/null
+++ b/kernel/mem.c
@@ -0,0 +1,19 @@
+#include <kernel/mem.h>
+
+extern void *_kernel_end;
+static void *highest;
+
+void mem_init() {
+	highest = &_kernel_end;
+}
+
+// should always succeed, there are no error checks anywhere
+void *malloc(size_t size) {
+	void *block = highest;
+	highest += size;
+	return block;
+}
+
+void free(void *ptr) {
+	// not implemented
+}
diff --git a/kernel/mem.h b/kernel/mem.h
new file mode 100644
index 0000000..f779997
--- /dev/null
+++ b/kernel/mem.h
@@ -0,0 +1,7 @@
+#pragma once
+#include <stddef.h>
+
+void mem_init();
+
+void *malloc(size_t size);
+void free(void *ptr);
diff --git a/kernel/proc.c b/kernel/proc.c
new file mode 100644
index 0000000..1178952
--- /dev/null
+++ b/kernel/proc.c
@@ -0,0 +1,21 @@
+#include <kernel/mem.h>
+#include <kernel/proc.h>
+#include <platform/sysenter.h>
+
+struct process *process_current;
+
+struct process *process_new(void *eip) {
+	struct process *proc;
+	proc = malloc(sizeof(struct process));
+
+	// should allocate an actual page. TODO
+	proc->stack_top = proc->esp = malloc(4096);
+	proc->eip = eip;
+
+	return proc;
+}
+
+void process_switch(struct process *proc) {
+	process_current = proc;
+	sysexit(proc->eip, proc->esp);
+}
diff --git a/kernel/proc.h b/kernel/proc.h
new file mode 100644
index 0000000..976b275
--- /dev/null
+++ b/kernel/proc.h
@@ -0,0 +1,13 @@
+#pragma once
+
+struct process {
+	void *stack_top;
+	void *esp;
+
+	void *eip;
+};
+
+extern struct process *process_current;
+
+struct process *process_new(void *eip);
+void process_switch(struct process *proc);
-- 
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