[amd64] Get memory map/GRUB info from loader

conf/make/amd64.mk

@@ -17,7 +17,8 @@ OBJS+=$(O)/arch/amd64/kernel.o \
 	  $(O)/arch/amd64/mm/map.o \
 	  $(O)/arch/amd64/hw/timer.o \
 	  $(O)/arch/amd64/acpi/tables.o \
-	  $(O)/arch/amd64/acpi/hpet.o
+	  $(O)/arch/amd64/acpi/hpet.o \
+	  $(O)/arch/amd64/mm/phys.o
 kernel_OBJS=$(O)/arch/amd64/entry.o \
 			$(OBJS)
 kernel_LINKER=$(S)/arch/amd64/link.ld

include/arch/amd64/loader/data.h

@@ -0,0 +1,8 @@
+#pragma once
+#include <stdint.h>
+
+struct amd64_loader_data {
+    uint32_t multiboot_info_ptr;
+    // Just in case
+    uint8_t checksum;
+} __attribute__((packed));

include/arch/amd64/mm/phys.h

@@ -0,0 +1,5 @@
+#pragma once
+#include "arch/amd64/loader/multiboot.h"
+#include <sys/types.h>
+
+void amd64_phys_memory_map(const multiboot_memory_map_t *mmap, size_t length);

src/arch/amd64/entry.S

@@ -1,4 +1,6 @@
 .section .text
+// Args:
+// %rdi - Address of loader's information struct
 .global _start
 _start:
     cli

src/arch/amd64/kernel.c

@@ -1,23 +1,53 @@
 #include "sys/mm.h"
 #include "sys/debug.h"
+#include "sys/panic.h"
 #include "arch/amd64/hw/gdt.h"
 #include "arch/amd64/hw/pic8259.h"
 #include "arch/amd64/hw/ints.h"
 #include "arch/amd64/hw/timer.h"
+#include "arch/amd64/loader/data.h"
+#include "arch/amd64/loader/multiboot.h"
+#include "arch/amd64/mm/phys.h"
 #include "arch/amd64/acpi/tables.h"
 
 // TODO: move to some util header
 #define __wfe() asm volatile ("sti; hlt")
 
-void kernel_main(void) {
+static struct amd64_loader_data *loader_data = 0;
+static multiboot_info_t *multiboot_info;
+
+static uint8_t amd64_loader_data_checksum(const struct amd64_loader_data *ld) {
+    uint8_t chk = 0;
+    for (size_t i = 0; i < sizeof(struct amd64_loader_data); ++i) {
+        chk += ((uint8_t *) ld)[i];
+    }
+    return chk;
+}
+
+static void amd64_loader_data_process(void) {
+    // Virtualize pointer locations, as the loader has passed their
+    // physical locations
+    multiboot_info = (multiboot_info_t *) MM_VIRTUALIZE(loader_data->multiboot_info_ptr);
+}
+
+void kernel_main(uintptr_t loader_info_phys_ptr) {
     kdebug("Booting\n");
 
 #if defined(KERNEL_TEST_MODE)
     kdebug("Kernel testing mode enabled\n");
 #endif
 
+    // Obtain boot information from loader
+    loader_data = (struct amd64_loader_data *) MM_VIRTUALIZE(loader_info_phys_ptr);
+    if (amd64_loader_data_checksum(loader_data)) {
+        panic("Loader data checksum is invalid\n");
+    }
+    // Process loader data
+    amd64_loader_data_process();
+
     // Memory management
     amd64_mm_init();
+    amd64_phys_memory_map((multiboot_memory_map_t *) MM_VIRTUALIZE(multiboot_info->mmap_addr), multiboot_info->mmap_length);
     amd64_gdt_init();
     pic8259_init();
     acpi_tables_init();

src/arch/amd64/loader/boot.S

@@ -88,6 +88,7 @@ long_entry:
     mov %ax, %ss
 
 .code64
+    leaq loader_data(%rip), %rdi
     movq 4(%rsp), %rax
     jmp *%rax
 .code32

src/arch/amd64/loader/loader.c

@@ -1,11 +1,13 @@
 #include "arch/amd64/loader/multiboot.h"
 #include "arch/amd64/loader/util.h"
+#include "arch/amd64/loader/data.h"
 #include "elf.h"
 
 #define KERNEL_VIRT_BASE        0xFFFFFF0000000000
 
 extern void long_entry(uint64_t v);
 
+struct amd64_loader_data loader_data;
 uint64_t pml4[512] __attribute__((aligned(0x1000)));
 static uint64_t loader_pdpt[512] __attribute__((aligned(0x1000)));
 static uint64_t kernel_pdpt[512] __attribute__((aligned(0x1000)));
@@ -85,6 +87,9 @@ void loader_main(uint32_t magic, struct multiboot_info *mb_info) {
         panic("Invalid bootloader magic");
     }
 
+    // Setup loader_data
+    loader_data.multiboot_info_ptr = (uint64_t) mb_info;
+
     struct multiboot_mod_list *mod_list = (struct multiboot_mod_list *) mb_info->mods_addr;
 
     if (mb_info->mods_count != 1) {
@@ -109,5 +114,13 @@ void loader_main(uint32_t magic, struct multiboot_info *mb_info) {
     paging_init();
 
     uint64_t entry = elf_load(mod_list[0].mod_start);
+
+    // Calculate checksum for loader_data
+    uint8_t checksum = 0;
+    for (size_t i = 0; i < sizeof(struct amd64_loader_data) - sizeof(uint8_t); ++i) {
+        checksum += ((uint8_t *) &loader_data)[i];
+    }
+    loader_data.checksum = -checksum;
+
     long_entry(entry);
 }

src/arch/amd64/mm/phys.c

@@ -0,0 +1,20 @@
+#include "arch/amd64/mm/phys.h"
+#include "sys/debug.h"
+
+void amd64_phys_memory_map(const multiboot_memory_map_t *mmap, size_t length) {
+    static const char *mmap_region_strings[6] = {
+        "Unknown", "Available", "Used", "ACPI", "Reserved", "Defective"
+    };
+    kdebug("Memory map @ %p\n", mmap);
+    uintptr_t curr_item = (uintptr_t) mmap;
+    uintptr_t mmap_end = length + curr_item;
+
+    while (curr_item < mmap_end) {
+        const multiboot_memory_map_t *entry = (const multiboot_memory_map_t *) (curr_item);
+        size_t type_index = (entry->type >= (sizeof(mmap_region_strings) / sizeof(mmap_region_strings[0]))) ? 0 : entry->type;
+
+        kdebug("%p - %p: %s\n", entry->addr, entry->addr + entry->size, mmap_region_strings[type_index]);
+
+        curr_item += entry->size + sizeof(uint32_t);
+    }
+}