scheduling usermode processes & code refactoring

17 files changed, 166 insertions, 173 deletions

diff --git a/Makefile b/Makefile
index 4d63ac4..4bbe5dc 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ WNO += -Wno-error=infinite-recursion
 
 CFLAGS = $(W) $(WNO) -fno-omit-frame-pointer -mcmodel=large
 CFLAGS += -mgeneral-regs-only # disables SIMD instructions
-CFLAGS += -MD -O3 -ffreestanding -nostdlib
+CFLAGS += -MD -O3 -ffreestanding -nostdlib -std=gnu89
 CFLAGS += -fno-common -fno-stack-protector
 CFLAGS += -fno-pie -no-pie -fno-pic
 CFLAGS += -g -fsanitize=undefined
diff --git a/kernel/include/apic.h b/kernel/include/apic.h
index 0025e53..991fc10 100644
--- a/kernel/include/apic.h
+++ b/kernel/include/apic.h
@@ -5,6 +5,11 @@
 #include <atomic.h>
 
 uint8_t curr_cpu_apic_id(void);
+void clear_apic_errors(void);
+void wait_for_delivery(void);
+void select_ap(uint32_t apic_id);
+void send_init_ipi(uint32_t apic_id);
+void send_sipi(uint32_t apic_id);
 void init_ap_cpus(void);
 
 extern mutex_t cnt_lock;
diff --git a/kernel/include/containter_of.h b/kernel/include/containter_of.h
index 9cadd91..9672988 100644
--- a/kernel/include/containter_of.h
+++ b/kernel/include/containter_of.h
@@ -5,7 +5,6 @@
 #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
 #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
 #define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
-#define typeof_member(T, m) typeof(((T *)0)->m)
 
 /**
  * container_of - cast a member of a structure out to the containing structure
@@ -23,23 +22,4 @@
 		((type *)(__mptr - offsetof(type, member)));              \
 	})
 
-/**
- * container_of_safe - cast a member of a structure out to the containing structure
- * @ptr:	the pointer to the member.
- * @type:	the type of the container struct this is embedded in.
- * @member:	the name of the member within the struct.
- *
- * If IS_ERR_OR_NULL(ptr), ptr is returned unchanged.
- */
-#define container_of_safe(ptr, type, member)                                   \
-	({                                                                     \
-		void *__mptr = (void *)(ptr);                                  \
-		static_assert(__same_type(*(ptr), ((type *)0)->member) ||      \
-				      __same_type(*(ptr), void),               \
-			      "pointer type mismatch in container_of_safe()"); \
-		IS_ERR_OR_NULL(__mptr) ?                                       \
-			ERR_CAST(__mptr) :                                     \
-			((type *)(__mptr - offsetof(type, member)));           \
-	})
-
 #endif
diff --git a/kernel/include/madt.h b/kernel/include/madt.h
index 571f92a..b824b38 100644
--- a/kernel/include/madt.h
+++ b/kernel/include/madt.h
@@ -50,6 +50,11 @@ struct MADT_lapic_addr {
 	uint64_t phys_addr;
 } __attribute__((packed));
 
+void madt_parse_cpu(uint64_t *addr);
+void madt_parse_ioapic(uint64_t *addr);
+void madt_parse_int(uint64_t *addr);
+void madt_parse_lapic_nmi(uint64_t *addr);
+void madt_parse_lapic_addr_ovr(uint64_t *addr);
 void parse_madt(void);
 
 #endif
diff --git a/kernel/include/process.h b/kernel/include/process.h
index 14107c2..abbcd08 100644
--- a/kernel/include/process.h
+++ b/kernel/include/process.h
@@ -20,7 +20,6 @@ process_t *init_process(uint64_t priv_lvl, uint64_t rip, uint64_t argc,
 			uint64_t *argv);
 void process_init_wrapper(uint64_t rip, uint64_t argc, uint64_t *argv);
 __attribute__((noreturn)) void idle_thread(void);
-__attribute__((noreturn)) void idle_thread2(void);
 __attribute__((noreturn)) void remove_current_process(void);
 __attribute__((noreturn)) void context_switch(uint64_t irq_rsp);
 
diff --git a/kernel/include/regs.h b/kernel/include/regs.h
index 67795ae..81ddbe3 100644
--- a/kernel/include/regs.h
+++ b/kernel/include/regs.h
@@ -23,8 +23,8 @@
 #define RIP_OFF 0x88
 #define CS_OFF 0x90
 #define RFLAGS_OFF 0x98
-#define RSP_OFF 0x100
-#define SS_OFF 0x108
+#define RSP_OFF 0xA0
+#define SS_OFF 0xA8
 
 struct regs_t {
 	uint64_t r15;
diff --git a/kernel/include/userspace.h b/kernel/include/userspace.h
index e03695d..ebd483e 100644
--- a/kernel/include/userspace.h
+++ b/kernel/include/userspace.h
@@ -1,7 +1,7 @@
 #ifndef USERSPACE_H
 #define USERSPACE_H
 
+void init_userspace(void);
 void begin_userspace(void);
-void jump_userspace(void);
 
 #endif
diff --git a/kernel/src/apic/apic.c b/kernel/src/apic/apic.c
index ad3ccec..0316b5c 100644
--- a/kernel/src/apic/apic.c
+++ b/kernel/src/apic/apic.c
@@ -22,84 +22,88 @@ uint8_t curr_cpu_apic_id()
 			 0xFF);
 }
 
+void clear_apic_errors()
+{
+	*((__volatile__ uint32_t *)(lapic_addr + 0x280)) = 0;
+}
+
+void wait_for_delivery()
+{
+	do {
+		__asm__ __volatile__("pause" : : : "memory");
+	} while (*((__volatile__ uint32_t *)(uint64_t)(lapic_addr + 0x300)) &
+		 (1 << 12));
+}
+
+void select_ap(uint32_t apic_id)
+{
+	*((__volatile__ uint32_t *)(lapic_addr + 0x310)) =
+		(*((__volatile__ uint32_t *)(lapic_addr + 0x310)) &
+		 0x00ffffff) |
+		apic_id;
+}
+
+void send_init_ipi(uint32_t apic_id)
+{
+	clear_apic_errors();
+	select_ap(apic_id);
+
+	/* trigger INIT IPI */
+	*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
+		(*((__volatile__ uint32_t *)(lapic_addr + 0x300)) &
+		 0xfff00000) |
+		0x00C500;
+
+	wait_for_delivery();
+	select_ap(apic_id);
+
+	/* deassert */
+	*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
+		(*((__volatile__ uint32_t *)(lapic_addr + 0x300)) &
+		 0xfff00000) |
+		0x008500;
+
+	wait_for_delivery();
+}
+
+void send_sipi(uint32_t apic_id)
+{
+	clear_apic_errors();
+	select_ap(apic_id);
+
+	/* trigger STARTUP IPI for 0800:0000 */
+	*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
+		(*((__volatile__ uint32_t *)(lapic_addr + 0x300)) &
+		 0xfff0f800) |
+		0x000608;
+
+	/* wait 200 usec */
+	wait(1);
+	wait_for_delivery();
+}
+
 void init_ap_cpus()
 {
-	uint8_t bspid = curr_cpu_apic_id();
+	uint8_t bspid;
+	size_t i;
+	size_t j;
 
 	init_mutex(&cnt_lock);
 	map_addr(lapic_addr, lapic_addr, FLAG_PRESENT);
 
-	size_t i;
-	size_t j;
+	bspid = curr_cpu_apic_id();
+
 	for (i = 0; i < numcores; i++) {
 		/* do not start BSP, that's already running this code */
 		if (cpu_apic_ids[i] == bspid)
 			continue;
 
-		/* send INIT IPI */
-
-		/* clear APIC errors */
-		*((__volatile__ uint32_t *)(lapic_addr + 0x280)) = 0;
-		/* select AP */
-		*((__volatile__ uint32_t *)(lapic_addr + 0x310)) =
-			(*((__volatile__ uint32_t *)(lapic_addr + 0x310)) &
-			 0x00ffffff) |
-			((uint32_t)cpu_apic_ids[i] << 24);
-		/* trigger INIT IPI */
-		*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
-			(*((__volatile__ uint32_t *)(lapic_addr + 0x300)) &
-			 0xfff00000) |
-			0x00C500;
-		/* wait for delivery */
-		do {
-			__asm__ __volatile__("pause" : : : "memory");
-		} while (*((__volatile__ uint32_t *)(uint64_t)(lapic_addr +
-							       0x300)) &
-			 (1 << 12));
-		/* select AP */
-		*((__volatile__ uint32_t *)(lapic_addr + 0x310)) =
-			(*((__volatile__ uint32_t *)(lapic_addr + 0x310)) &
-			 0x00ffffff) |
-			((uint32_t)cpu_apic_ids[i] << 24);
-		/* deassert */
-		*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
-			(*((__volatile__ uint32_t *)(lapic_addr + 0x300)) &
-			 0xfff00000) |
-			0x008500;
-		/* wait for delivery */
-		do {
-			__asm__ __volatile__("pause" : : : "memory");
-		} while (*((__volatile__ uint32_t *)(uint64_t)(lapic_addr +
-							       0x300)) &
-			 (1 << 12));
-		/* wait 10 msec */
-		wait(10);
+		send_init_ipi((uint32_t)cpu_apic_ids[i] << 24);
 
-		/* send STARTUP IPI (twice) */
+		wait(10);
 
 		for (j = 0; j < 2; j++) {
-			/* clear APIC errors */
-			*((__volatile__ uint32_t *)(lapic_addr + 0x280)) = 0;
-			/* select AP */
-			*((__volatile__ uint32_t *)(lapic_addr + 0x310)) =
-				(*((__volatile__ uint32_t *)(lapic_addr +
-							     0x310)) &
-				 0x00ffffff) |
-				((uint32_t)cpu_apic_ids[i] << 24);
-			/* trigger STARTUP IPI for 0800:0000 */
-			*((__volatile__ uint32_t *)(lapic_addr + 0x300)) =
-				(*((__volatile__ uint32_t *)(lapic_addr +
-							     0x300)) &
-				 0xfff0f800) |
-				0x000608;
-			/* wait 200 usec */
-			wait(1);
-			/* wait for delivery */
-			do {
-				__asm__ __volatile__("pause" : : : "memory");
-			} while (*((__volatile__ uint32_t
-					    *)(uint64_t)(lapic_addr + 0x300)) &
-				 (1 << 12));
+			send_sipi((uint32_t)cpu_apic_ids[i] << 24);
 		}
 	}
 
diff --git a/kernel/src/apic/ioapic.c b/kernel/src/apic/ioapic.c
index 7fe005b..1e20486 100644
--- a/kernel/src/apic/ioapic.c
+++ b/kernel/src/apic/ioapic.c
@@ -30,14 +30,16 @@ void ioapic_set_irq(uint8_t irq, uint64_t apic_id, uint8_t vector)
 {
 	const uint32_t low_index = (uint32_t)0x10 + irq * 2;
 	const uint32_t high_index = (uint32_t)0x10 + irq * 2 + 1;
+	uint32_t high;
+	uint32_t low;
 
-	uint32_t high = ioapic_read((uint8_t)high_index);
+	high = ioapic_read((uint8_t)high_index);
 	/* set APIC ID */
 	high &= (uint32_t)~0xff000000;
 	high |= (uint32_t)apic_id << 24;
 	ioapic_write((uint8_t)high_index, high);
 
-	uint32_t low = ioapic_read((uint8_t)low_index);
+	low = ioapic_read((uint8_t)low_index);
 
 	/* unmask the IRQ */
 	low &= (uint32_t) ~(1 << 16);
@@ -57,10 +59,12 @@ void ioapic_set_irq(uint8_t irq, uint64_t apic_id, uint8_t vector)
 
 void apic_remap_interrupts()
 {
+	uint8_t bspid;
+
 	map_addr(ioapic_addr, ioapic_addr, FLAG_PRESENT);
 	map_addr(lapic_addr, lapic_addr, FLAG_PRESENT);
 
-	uint8_t bspid = curr_cpu_apic_id();
+	bspid = curr_cpu_apic_id();
 
 	/* irq is 2 because of gsi remap */
 	ioapic_set_irq(0x2, bspid, 0x20); /* timer */
diff --git a/kernel/src/apic/madt.c b/kernel/src/apic/madt.c
index 2ddf90f..d45b1cb 100644
--- a/kernel/src/apic/madt.c
+++ b/kernel/src/apic/madt.c
@@ -66,25 +66,28 @@ void madt_parse_lapic_addr_ovr(uint64_t *addr)
 void parse_madt()
 {
 	uint64_t *madt_addr = find_sys_table_addr("APIC");
+	struct MADT *madt;
+	size_t curr_size;
+	uint8_t type;
+	uint8_t len;
 
 	if (madt_addr == NULL) {
 		printf("MADT NOT FOUND\n");
 		return;
 	}
 
-	struct MADT *madt = (struct MADT *)kalloc(sizeof(struct MADT));
+	madt = (struct MADT *)kalloc(sizeof(struct MADT));
 	memcpy(madt, madt_addr, sizeof(struct MADT));
 	lapic_addr = madt->lapic_addr;
 
-	size_t curr_size;
 	for (curr_size = sizeof(struct MADT); curr_size < madt->h.Length;) {
 		struct MADT_type_header *m = (struct MADT_type_header *)kalloc(
 			sizeof(struct MADT_type_header));
 		memcpy(m,
 		       (uint64_t *)((uint64_t)madt_addr + (uint64_t)curr_size),
 		       sizeof(struct MADT_type_header));
-		uint8_t type = m->type;
-		uint8_t len = m->len;
+		type = m->type;
+		len = m->len;
 		kfree(m);
 
 		switch (type) {
diff --git a/kernel/src/apic/rsdp.c b/kernel/src/apic/rsdp.c
index 6a1505f..fa16816 100644
--- a/kernel/src/apic/rsdp.c
+++ b/kernel/src/apic/rsdp.c
@@ -6,14 +6,17 @@
 
 uint64_t *find_rsdp()
 {
-	map_addr(0x0, 0x0, FLAG_PRESENT);
 	const char *rsdp_cs = "RSD PTR ";
 	uint64_t i;
 	size_t j;
+	char *x;
+	uint8_t ind;
+
+	map_addr(0x0, 0x0, FLAG_PRESENT);
 
 	for (i = 0x10; i < 0x100000; i += 0x10) {
-		char *x = (char *)i;
-		uint8_t ind = 1;
+		x = (char *)i;
+		ind = 1;
 		for (j = 0; j < strlen(rsdp_cs); j++) {
 			if (rsdp_cs[j] != x[j]) {
 				ind = 0;
@@ -30,33 +33,35 @@ uint64_t *find_rsdp()
 void list_sys_tables(void)
 {
 	uint64_t *rsdp = find_rsdp();
+	struct RSDP_descriptor *rsdp_desc;
+	struct ACPI_header *rsdt;
+	uint32_t entries;
+	size_t i;
+	size_t j;
+	uint32_t na_addr;
+	uint32_t addr;
+	struct ACPI_header *t;
 
 	if (rsdp == NULL) {
 		printf("RSDP NOT FOUND\n");
 		return;
 	}
 
-	struct RSDP_descriptor *rsdp_desc = (struct RSDP_descriptor *)rsdp;
+	rsdp_desc = (struct RSDP_descriptor *)rsdp;
 	map_addr(rsdp_desc->RsdtAddress, rsdp_desc->RsdtAddress, FLAG_PRESENT);
 
-	struct ACPI_header *rsdt =
-		(struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
+	rsdt = (struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
 	memcpy(rsdt, (uint64_t *)(uint64_t)rsdp_desc->RsdtAddress,
 	       sizeof(struct ACPI_header));
 
-	uint32_t entries =
-		(rsdt->Length - (uint32_t)sizeof(struct ACPI_header)) / 4;
-	size_t i;
-	size_t j;
+	entries = (rsdt->Length - (uint32_t)sizeof(struct ACPI_header)) / 4;
 	for (i = 0; i < entries; i++) {
-		uint32_t na_addr = (uint32_t)rsdp_desc->RsdtAddress +
-				   (uint32_t)sizeof(struct ACPI_header) +
-				   (uint32_t)i * 4;
-		uint32_t addr;
+		na_addr = (uint32_t)rsdp_desc->RsdtAddress +
+			  (uint32_t)sizeof(struct ACPI_header) +
+			  (uint32_t)i * 4;
 		memcpy(&addr, (uint64_t *)(uint64_t)na_addr, 4);
 
-		struct ACPI_header *t = (struct ACPI_header *)kalloc(
-			sizeof(struct ACPI_header));
+		t = (struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
 		memcpy(t, (uint64_t *)(uint64_t)addr,
 		       sizeof(struct ACPI_header));
 
@@ -75,38 +80,40 @@ void list_sys_tables(void)
 uint64_t *find_sys_table_addr(const char *signature)
 {
 	uint64_t *rsdp = find_rsdp();
+	struct RSDP_descriptor *rsdp_desc;
+	struct ACPI_header *rsdt;
+	uint32_t entries;
+	size_t i;
+	size_t j;
+	uint32_t addr;
+	struct ACPI_header *t;
+	uint8_t ind = 1;
 
 	if (rsdp == NULL) {
 		printf("RSDP NOT FOUND\n");
 		return NULL;
 	}
 
-	struct RSDP_descriptor *rsdp_desc = (struct RSDP_descriptor *)rsdp;
+	rsdp_desc = (struct RSDP_descriptor *)rsdp;
 	map_addr(rsdp_desc->RsdtAddress, rsdp_desc->RsdtAddress, FLAG_PRESENT);
 
-	struct ACPI_header *rsdt =
-		(struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
+	rsdt = (struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
 	memcpy(rsdt, (uint64_t *)(uint64_t)rsdp_desc->RsdtAddress,
 	       sizeof(struct ACPI_header));
 
-	uint32_t entries =
-		(rsdt->Length - (uint32_t)sizeof(struct ACPI_header)) / 4;
+	entries = (rsdt->Length - (uint32_t)sizeof(struct ACPI_header)) / 4;
 
-	size_t i;
-	size_t j;
 	for (i = 0; i < entries; i++) {
 		uint32_t na_addr = (uint32_t)rsdp_desc->RsdtAddress +
 				   (uint32_t)sizeof(struct ACPI_header) +
 				   (uint32_t)i * 4;
-		uint32_t addr;
 		memcpy(&addr, (uint64_t *)(uint64_t)na_addr, 4);
 
-		struct ACPI_header *t = (struct ACPI_header *)kalloc(
-			sizeof(struct ACPI_header));
+		t = (struct ACPI_header *)kalloc(sizeof(struct ACPI_header));
 		memcpy(t, (uint64_t *)(uint64_t)addr,
 		       sizeof(struct ACPI_header));
 
-		int ind = 1;
+		ind = 1;
 		for (j = 0; j < 4; j++) {
 			if (t->Signature[j] != signature[j])
 				ind = 0;
diff --git a/kernel/src/boot/multiboot2.c b/kernel/src/boot/multiboot2.c
index 180277d..2b613b0 100644
--- a/kernel/src/boot/multiboot2.c
+++ b/kernel/src/boot/multiboot2.c
@@ -30,10 +30,11 @@ void init_fb(mb2_tag_fb *tag_fb)
 
 void init_mmap(mb2_tag_mmap *tag_mmap)
 {
+	size_t i;
+
 	INIT_LIST(mmap.list)
 
 	/* get data and store it into list */
-	size_t i;
 	for (i = sizeof(mb2_tag_mmap); i < tag_mmap->size;
 	     i += sizeof(mb2_tag_mmap_entry)) {
 		mmap_t *curr_mmap_entry = (mmap_t *)kalloc(sizeof(mmap_t));
@@ -45,9 +46,9 @@ void init_mmap(mb2_tag_mmap *tag_mmap)
 
 void init_module(mb2_tag_module *tag_module)
 {
+	uint32_t name_size;
 	/* name is utf-8 encoded string! */
-	uint32_t name_size =
-		tag_module->size - sizeof(tag_module) + sizeof(char *);
+	name_size = tag_module->size - sizeof(tag_module) + sizeof(char *);
 	tag_module->name = (char *)kalloc(name_size);
 	memcpy(tag_module->name, tag_module + tag_module->size - name_size,
 	       name_size);
@@ -56,19 +57,19 @@ void init_module(mb2_tag_module *tag_module)
 
 void read_mb2(mb2_tag_header *multiboot_bootinfo, uint32_t multiboot_magic)
 {
+	/* we will store framebuffer information here */
+	static mb2_tag_fb *tag_fb;
+	static mb2_tag_mmap *tag_mmap;
+	mb2_tag_header *tag_header;
+
 	if (multiboot_magic != MB2_MAGIC) {
 		/* not loaded by multiboot2 bootloader */
 		__asm__ __volatile__("hlt;");
 	}
 
-	/* we will store framebuffer information here */
-	static mb2_tag_fb *tag_fb;
-	static mb2_tag_mmap *tag_mmap;
-
 	/* skip first 8 bytes (total_size + reserved) */
-	mb2_tag_header *tag_header =
-		(mb2_tag_header *)((uint64_t)multiboot_bootinfo + 8 +
-				   KERNEL_VMA);
+	tag_header = (mb2_tag_header *)((uint64_t)multiboot_bootinfo + 8 +
+					KERNEL_VMA);
 
 	while (tag_header->type != MB2_TAG_END) {
 		/* process tag_type */
diff --git a/kernel/src/check/panic.c b/kernel/src/check/panic.c
index 277ee37..60084b4 100644
--- a/kernel/src/check/panic.c
+++ b/kernel/src/check/panic.c
@@ -6,10 +6,11 @@
 
 __attribute__((noreturn)) void panic(uint64_t rsp, const char *s, ...)
 {
+	va_list list;
+
 	set_color(&main_fb, RED, BLACK);
 	printf("KERNEL PANIC\n");
 	/*	set_color(&main_fb, WHITE, BLACK); */
-	va_list list;
 	va_start(list, s);
 	vprintf(s, list);
 	va_end(list);
diff --git a/kernel/src/main.c b/kernel/src/main.c
index d5e2492..f9d1b8f 100644
--- a/kernel/src/main.c
+++ b/kernel/src/main.c
@@ -51,12 +51,10 @@ int kernel_main(mb2_tag_header *multiboot_bootinfo, uint32_t multiboot_magic)
 	parse_madt();
 	apic_remap_interrupts();
 	enable_interrupts();
+	init_userspace();
 
 	init_scheduler();
 
-	/* init_ap_cpus(); */
-	/* jump_userspace(); */
-
 	for (;;) {
 		__asm__ __volatile__("pause; hlt;");
 	}
diff --git a/kernel/src/scheduler/process.c b/kernel/src/scheduler/process.c
index e057df0..0b383bf 100644
--- a/kernel/src/scheduler/process.c
+++ b/kernel/src/scheduler/process.c
@@ -35,7 +35,7 @@ process_t *init_process(uint64_t priv_lvl, uint64_t rip, uint64_t argc,
 	regs->r14 = 0;
 	regs->r15 = 0;
 	regs->rip = (uint64_t)process_init_wrapper;
-	regs->rflags = 0;
+	regs->rflags = 0x202;
 	regs->error = 0;
 
 	if (priv_lvl == 0) {
@@ -87,20 +87,7 @@ void process_init_wrapper(uint64_t rip, uint64_t argc, uint64_t *argv)
 
 __attribute__((noreturn)) void idle_thread()
 {
-	printf("idle_thread()\n");
 	for (;;) {
-		printf("1");
-		wait(2000);
-		__asm__ __volatile__("pause; hlt;");
-	}
-}
-
-__attribute__((noreturn)) void idle_thread2()
-{
-	printf("idle_thread2()\n");
-	for (;;) {
-		printf("2");
-		wait(1000);
 		__asm__ __volatile__("pause; hlt;");
 	}
 }
@@ -111,10 +98,7 @@ __attribute__((noreturn)) void remove_current_process()
 	kfree(curr_process);
 	curr_process = scheduler();
 	if (curr_process == NULL) {
-		printf("no processes left\n");
-		for (;;) {
-			__asm__ __volatile__("pause; hlt;");
-		}
+		panic(0, "no processes left\n");
 	}
 	restore_context_from_rsp(curr_process->rsp);
 }
diff --git a/kernel/src/scheduler/scheduler.c b/kernel/src/scheduler/scheduler.c
index 91e5ddd..28e2cae 100644
--- a/kernel/src/scheduler/scheduler.c
+++ b/kernel/src/scheduler/scheduler.c
@@ -7,19 +7,27 @@
 #include <libk/stdio.h>
 #include <panic.h>
 #include <regs.h>
+#include <userspace.h>
+#include <apic.h>
 
 mutex_t scheduler_lock;
 uint32_t sched_init = 0;
 
 __attribute__((noreturn)) void init_scheduler()
 {
+	uint32_t argc;
+	uint64_t *argv;
+
 	INIT_LIST(process_queue.list);
 	init_mutex(&scheduler_lock);
-	uint64_t argc = 6;
-	uint64_t *argv = (uint64_t *)kalloc(sizeof(uint64_t) * 6);
-	memset(argv, 0, sizeof(uint64_t) * 6);
-	init_process(0, (uint64_t)idle_thread2, argc, argv);
-	curr_process = init_process(0, (uint64_t)idle_thread, argc, argv);
+
+	argc = 1;
+	argv = (uint64_t *)kalloc(argc * sizeof(uint64_t));
+	memset(argv, 0, sizeof(uint64_t) * argc);
+	init_process(0, (uint64_t)idle_thread, argc, argv);
+	curr_process = init_process(0, (uint64_t)init_ap_cpus, argc, argv);
+	init_process(3, (uint64_t)begin_userspace, argc, argv);
+
 	sched_init = 1;
 	restore_context_from_rsp(curr_process->rsp);
 }
diff --git a/kernel/src/sys/userspace_asm.S b/kernel/src/sys/userspace_asm.S
index 1bb19a3..ca5a0ba 100644
--- a/kernel/src/sys/userspace_asm.S
+++ b/kernel/src/sys/userspace_asm.S
@@ -1,19 +1,13 @@
 .text
 
-.extern begin_userspace
-.extern syscall_handler
-
 .set IA32_EFER, 0xc0000080
 .set STAR_MSR, 0xc0000081
 .set LSTAR_MSR, 0xc0000082
 
-.global jump_userspace
-jump_userspace:
-	mov $0x1b, %ax
-	mov %ax, %ds
-	mov %ax, %es
-	mov %ax, %fs
-	mov %ax, %gs
+.global init_userspace
+init_userspace:
+	push %rbp
+	mov %rsp, %rbp
 
 	mov $LSTAR_MSR, %rcx
 	movabs $__syscall, %rax
@@ -30,6 +24,6 @@ jump_userspace:
 	mov $0x00130008, %edx
 	wrmsr
 
-	movabs $begin_userspace, %rcx
-	mov $0x202, %r11
-	sysretq
+	mov %rbp, %rsp
+	pop %rbp
+	ret