Multiboot/Grub progress

12 files changed, 216 insertions, 62 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index e51469d..8296e02 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -5,6 +5,7 @@ COBJS = entry_asm.o \
 	multiboot.o \
 	drivers/interrupts.o \
 	drivers/interrupts_asm.o \
+	drivers/gdt.o \
 	drivers/cpu.o \
 	drivers/serial.o \
 	drivers/pci.o \
diff --git a/kernel/drivers/cpu.c b/kernel/drivers/cpu.c
index 2c86008..5d53bef 100644
--- a/kernel/drivers/cpu.c
+++ b/kernel/drivers/cpu.c
@@ -91,21 +91,6 @@ void fpu_restore(void)
 	__asm__ volatile("fxrstor (%0)" ::"r"(fpu_state));
 }
 
-void tss_set_stack(u32 ss, u32 esp)
-{
-	UNUSED(ss);
-	UNUSED(esp);
-	return;
-	/* assert(tss_entry && ss && esp); */
-	/* struct { */
-	/* 	u32 prev; */
-	/* 	u32 esp0; */
-	/* 	u32 ss0; */
-	/* } *tss = (void *)tss_entry; */
-	/* tss->esp0 = esp; */
-	/* tss->ss0 = ss; */
-}
-
 CLEAR static struct cpuid cpuid(u32 code)
 {
 	u32 a, b, c, d;
diff --git a/kernel/drivers/gdt.c b/kernel/drivers/gdt.c
new file mode 100644
index 0000000..73db111
--- /dev/null
+++ b/kernel/drivers/gdt.c
@@ -0,0 +1,96 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <assert.h>
+#include <def.h>
+#include <gdt.h>
+#include <mem.h>
+
+static struct gdt_entry gdt[6] = { 0 };
+static struct tss_entry tss = { 0 };
+
+PROTECTED static struct gdt_ptr gp = { 0 };
+
+CLEAR static void gdt_set_gate(u32 num, u32 base, u32 limit, u8 access, u8 gran)
+{
+	// Set descriptor base address
+	gdt[num].base_low = (u16)(base & 0xffff);
+	gdt[num].base_middle = (u8)((base >> 16) & 0xff);
+	gdt[num].base_high = (u8)((base >> 24) & 0xff);
+	gdt[num].limit_low = (u16)(limit & 0xffff);
+
+	// Set granularity and access flags
+	gdt[num].granularity = (u8)((limit >> 16) & 0x0f);
+	gdt[num].granularity |= (gran & 0xf0);
+	gdt[num].access = access;
+}
+
+CLEAR static void tss_write(u32 num, u16 ss0, u32 esp0)
+{
+	u32 base = (u32)&tss;
+	u32 limit = base + sizeof(tss);
+
+	gdt_set_gate(num, base, limit, 0xe9, 0x00);
+
+	memset(&tss, 0, sizeof(tss));
+
+	tss.ss0 = ss0;
+	tss.esp0 = esp0;
+	tss.cs = 0x0b;
+	tss.ss = tss.ds = tss.es = tss.fs = tss.gs = 0x13;
+}
+
+CLEAR static void tss_flush(void)
+{
+	__asm__ volatile("ltr %0" ::"r"((u16)0x2b));
+}
+
+CLEAR static void gdt_flush(void)
+{
+	__asm__ volatile("lgdt %0" ::"m"(gp) : "memory");
+}
+
+void tss_set_stack(u32 ss, u32 esp)
+{
+	assert(ss && esp);
+	tss.esp0 = esp;
+	tss.ss0 = ss;
+}
+
+CLEAR void gdt_install(void)
+{
+	// Set GDT pointer and limit
+	gp.limit = (sizeof(struct gdt_entry) * 6) - 1;
+	gp.base = &gdt;
+
+	// NULL descriptor
+	gdt_set_gate(0, 0, 0, 0, 0);
+
+	// Code segment
+	gdt_set_gate(1, 0, 0xffffffff, 0x9a, 0xcf);
+
+	// Data segment
+	gdt_set_gate(2, 0, 0xffffffff, 0x92, 0xcf);
+
+	// User mode code segment
+	gdt_set_gate(3, 0, 0xffffffff, 0xfa, 0xcf);
+
+	// User mode data segment
+	gdt_set_gate(4, 0, 0xffffffff, 0xf2, 0xcf);
+
+	// Write TSS
+	tss_write(5, GDT_SUPER_DATA_OFFSET, STACK_START);
+
+	// Remove old GDT and install the new changes!
+	gdt_flush();
+	tss_flush();
+
+	__asm__ volatile("mov %%ax, %%ds\n"
+			 "mov %%ax, %%es\n"
+			 "mov %%ax, %%fs\n"
+			 "mov %%ax, %%gs\n"
+			 "mov %%ax, %%ss\n" ::"a"(GDT_SUPER_DATA_OFFSET)
+			 : "memory");
+
+	__asm__ volatile("ljmpl $" STRINGIFY(GDT_SUPER_CODE_OFFSET) ", $code\n"
+								    "code:\n");
+}
diff --git a/kernel/features/mm.c b/kernel/features/mm.c
index 39a6316..9dd425e 100644
--- a/kernel/features/mm.c
+++ b/kernel/features/mm.c
@@ -8,6 +8,7 @@
 #include <fb.h>
 #include <mem.h>
 #include <mm.h>
+#include <multiboot.h>
 #include <print.h>
 #include <rand.h>
 
@@ -133,7 +134,12 @@ static void physical_page_set_free(u32 address)
 	memory[page / 8] &= ~(1 << (page % 8));
 }
 
-static void physical_set_used(struct memory_range range)
+CLEAR void physical_set_total(u32 total)
+{
+	memory_total = total;
+}
+
+void physical_set_used(struct memory_range range)
 {
 	assert(PAGE_ALIGNED(range.base) && PAGE_ALIGNED(range.size));
 
@@ -146,7 +152,7 @@ static void physical_set_used(struct memory_range range)
 	}
 }
 
-static void physical_set_free(struct memory_range range)
+void physical_set_free(struct memory_range range)
 {
 	assert(PAGE_ALIGNED(range.base) && PAGE_ALIGNED(range.size));
 
@@ -721,29 +727,7 @@ void memory_user_hook(void)
 
 CLEAR void memory_install(void)
 {
-	struct mem_info *mem_info = NULL;
-	struct vid_info *vid_info = NULL;
-
-	for (struct mmap_boot *p = mem_info->start; (u32)(p - mem_info->start) < mem_info->size;
-	     p++) {
-		if (p->hbase || !p->acpi || !p->type)
-			continue;
-
-		u32 size = p->lsize;
-		if (p->hsize)
-			size = U32_MAX - p->lbase;
-
-		/* printf("Memory region: %x-%x\n", p->lbase, p->lbase + size); */
-		if (p->type == MEMORY_AVAILABLE) {
-			physical_set_free(memory_range_around(p->lbase, size));
-			memory_total += size;
-		} else if (p->type == MEMORY_DEFECT) {
-			printf("Defect memory at 0x%x-0x%x!\n", p->lbase, p->lbase + size);
-			physical_set_used(memory_range_around(p->lbase, size));
-		} else {
-			physical_set_used(memory_range_around(p->lbase, size));
-		}
-	}
+	multiboot_mmap();
 
 	for (u32 i = 0; i < PAGE_KERNEL_COUNT; i++) {
 		union page_dir_entry *dir_entry = &kernel_dir.entries[i];
@@ -757,7 +741,7 @@ CLEAR void memory_install(void)
 	printf("Detected memory: %dKiB (%dMiB)\n", memory_total >> 10, memory_total >> 20);
 
 	// Set first MiB 'used' (bootloader(s), VESA tables, memory maps, ...)
-	physical_set_used(memory_range(0, 0x00100000));
+	//physical_set_used(memory_range(0, 0x00100000));
 
 	// Map kernel
 	memory_map_identity(&kernel_dir, kernel_ro_memory_range(), MEMORY_READONLY);
@@ -772,13 +756,10 @@ CLEAR void memory_install(void)
 	memory_map_identity(&kernel_dir, memory_range(STACK_START, PAGE_SIZE), MEMORY_READONLY);
 
 	// Map framebuffer
-	memory_map_identity(&kernel_dir, memory_range_around((u32)vid_info->vbe, 0x1000),
-			    MEMORY_NONE);
+	/* memory_map_identity(&kernel_dir, memory_range_around((u32)vid_info->vbe, 0x1000), */
+	/* 		    MEMORY_NONE); */
 	/* fb_map_buffer(virtual_kernel_dir(), vid_info); */
 
-	// Map TSS
-	//memory_map_identity(&kernel_dir, memory_range_around(boot->tss, 0x1000), MEMORY_NONE);
-
 	// Unmap NULL byte/page
 	struct memory_range zero = memory_range(0, PAGE_SIZE);
 	virtual_free(&kernel_dir, zero);
diff --git a/kernel/features/proc.c b/kernel/features/proc.c
index 70f2efc..6812c72 100644
--- a/kernel/features/proc.c
+++ b/kernel/features/proc.c
@@ -5,6 +5,7 @@
 #include <cpu.h>
 #include <errno.h>
 #include <fs.h>
+#include <gdt.h>
 #include <load.h>
 #include <mem.h>
 #include <mm.h>
diff --git a/kernel/inc/cpu.h b/kernel/inc/cpu.h
index 3d29e4f..7ac6074 100644
--- a/kernel/inc/cpu.h
+++ b/kernel/inc/cpu.h
@@ -32,8 +32,6 @@ void cr3_set(u32 cr3);
 u32 cr4_get(void);
 void cr4_set(u32 cr4);
 
-void tss_set_stack(u32 ss, u32 esp);
-
 void clac(void);
 void stac(void);
 
diff --git a/kernel/inc/gdt.h b/kernel/inc/gdt.h
new file mode 100644
index 0000000..06388a9
--- /dev/null
+++ b/kernel/inc/gdt.h
@@ -0,0 +1,60 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#ifndef GDT_H
+#define GDT_H
+
+#include <def.h>
+
+#define GDT_SUPER_CODE_OFFSET 0x08 // Super (kernel) code segment offset in GDT
+#define GDT_SUPER_DATA_OFFSET 0x10 // Super (kernel) data segment offset in GDT
+#define GDT_USER_CODE_OFFSET 0x1b // User code segment offset in GDT (with ring3 mask)
+#define GDT_USER_DATA_OFFSET 0x23 // User data segment offset in GDT (with ring3 mask)
+
+struct gdt_entry {
+	u16 limit_low;
+	u16 base_low;
+	u8 base_middle;
+	u8 access;
+	u8 granularity;
+	u8 base_high;
+} PACKED;
+
+struct gdt_ptr {
+	u16 limit;
+	void *base;
+} PACKED;
+
+struct tss_entry {
+	u32 prev_tss;
+	u32 esp0;
+	u32 ss0;
+	u32 esp1;
+	u32 ss1;
+	u32 esp2;
+	u32 ss2;
+	u32 cr3;
+	u32 eip;
+	u32 eflags;
+	u32 eax;
+	u32 ecx;
+	u32 edx;
+	u32 ebx;
+	u32 esp;
+	u32 ebp;
+	u32 esi;
+	u32 edi;
+	u32 es;
+	u32 cs;
+	u32 ss;
+	u32 ds;
+	u32 fs;
+	u32 gs;
+	u32 ldt;
+	u16 trap;
+	u16 iomap_base;
+} PACKED;
+
+void gdt_install(void);
+void tss_set_stack(u32 ss, u32 esp);
+
+#endif
diff --git a/kernel/inc/mm.h b/kernel/inc/mm.h
index 1652695..a33d9d1 100644
--- a/kernel/inc/mm.h
+++ b/kernel/inc/mm.h
@@ -27,6 +27,9 @@ void page_fault_handler(struct regs *r) NONNULL;
 
 struct memory_range physical_alloc(u32 size);
 void physical_free(struct memory_range range);
+void physical_set_used(struct memory_range range);
+void physical_set_free(struct memory_range range);
+void physical_set_total(u32 total);
 
 /**
  * Virtual
diff --git a/kernel/inc/multiboot.h b/kernel/inc/multiboot.h
index f9851fb..839ade7 100644
--- a/kernel/inc/multiboot.h
+++ b/kernel/inc/multiboot.h
@@ -104,9 +104,11 @@ struct multiboot_info {
 };
 
 struct multiboot_mmap_entry {
-	u32 size;
-	u64 addr;
-	u64 len;
+	u32 struct_size;
+	u32 addr;
+	u32 addr_high;
+	u32 len;
+	u32 len_high;
 	u32 type;
 } PACKED;
 
@@ -119,6 +121,7 @@ struct multiboot_mod_list {
 	u32 pad;
 };
 
+void multiboot_mmap(void);
 void multiboot_init(u32 magic, u32 addr);
 
 #endif
diff --git a/kernel/inc/proc.h b/kernel/inc/proc.h
index 877e53e..e74286c 100644
--- a/kernel/inc/proc.h
+++ b/kernel/inc/proc.h
@@ -15,11 +15,6 @@
 #define EFLAGS_ALWAYS 0x2 // Always one
 #define EFLAGS_INTERRUPTS 0x200 // Enable interrupts
 
-#define GDT_SUPER_CODE_OFFSET 0x08 // Super (kernel) code segment offset in GDT
-#define GDT_SUPER_DATA_OFFSET 0x10 // Super (kernel) data segment offset in GDT
-#define GDT_USER_CODE_OFFSET 0x1b // User code segment offset in GDT (with ring3 mask)
-#define GDT_USER_DATA_OFFSET 0x23 // User data segment offset in GDT (with ring3 mask)
-
 #define RING(regs) ((regs->cs) & 3)
 
 enum proc_priv { PROC_PRIV_NONE, PROC_PRIV_ROOT, PROC_PRIV_KERNEL };
diff --git a/kernel/main.c b/kernel/main.c
index e0e544b..37dd2da 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -3,6 +3,7 @@
 #include <boot.h>
 #include <cpu.h>
 #include <fs.h>
+#include <gdt.h>
 #include <ide.h>
 #include <interrupts.h>
 #include <io.h>
@@ -26,11 +27,11 @@ int kernel_main(u32 magic, u32 addr)
 	// Serial connection
 	serial_install();
 	serial_print("\nKernel was compiled at " __TIME__ " on " __DATE__ "\n");
-	serial_print("Serial connected. LOOPING!\n");
+	serial_print("Serial connected!\n");
+
+	gdt_install();
 
 	multiboot_init(magic, addr);
-	while (1)
-		;
 
 	memory_install();
 	memory_switch_dir(virtual_kernel_dir());
diff --git a/kernel/multiboot.c b/kernel/multiboot.c
index eafe4c5..a9a0c75 100644
--- a/kernel/multiboot.c
+++ b/kernel/multiboot.c
@@ -2,16 +2,46 @@
 
 #include <assert.h>
 #include <def.h>
+#include <mm.h>
 #include <multiboot.h>
 
-static struct multiboot_info *info = NULL;
+PROTECTED static struct multiboot_info *info = NULL;
 
-void multiboot_init(u32 magic, u32 addr)
+CLEAR void multiboot_init(u32 magic, u32 addr)
 {
 	assert(magic == MULTIBOOT_MAGIC);
 	info = (void *)addr;
 
 	if (info->flags & MULTIBOOT_INFO_CMDLINE) {
-		printf("CMDLINE: '%s'\n", info->cmdline);
+		// TODO: Do something useful with grub cmdline?
+		/* printf("CMDLINE: '%s'\n", info->cmdline); */
 	}
 }
+
+CLEAR void multiboot_mmap(void)
+{
+	assert(info->flags & MULTIBOOT_INFO_MEMORY);
+
+	struct multiboot_mmap_entry *mmap = (void *)info->mmap_addr;
+	u32 length = info->mmap_length;
+	u32 count = length / sizeof(*mmap);
+
+	u32 total = 0;
+
+	for (u32 i = 0; i < count; i++) {
+		/* printf("Memory region 0x%x-0x%x\n", mmap->addr, mmap->addr + mmap->len); */
+		if (mmap->type == MULTIBOOT_MEMORY_AVAILABLE) {
+			total += mmap->len;
+			physical_set_free(memory_range_around(mmap->addr, mmap->len));
+		} else if (mmap->type == MULTIBOOT_MEMORY_BADRAM) {
+			printf("Defect memory at 0x%x-0x%x\n", mmap->addr, mmap->addr + mmap->len);
+			physical_set_used(memory_range_around(mmap->addr, mmap->len));
+		} else {
+			physical_set_used(memory_range_around(mmap->addr, mmap->len));
+		}
+
+		mmap++;
+	}
+
+	physical_set_total(total);
+}