New paging manager and multiboot2 tools

src/Makefile

@@ -5,14 +5,15 @@ LD_SCRIPT := linker.ld
 # Note that BOOT_OBJ do not match boot.S
 # Indeed boot.o generated by boot.S should appear
 # first in the kernel binary (thus it must be linked first, cf the $(EXEC) rule)
-BOOT_OBJ := $(addsuffix .cc,$(basename $(shell find ./boot -name '*.cc' -name '*.S' ! -name "boot.S")))
+BOOT_OBJ := $(addsuffix .o,$(basename $(shell find ./boot -name '*.cc' -o -name '*.S' ! -name "boot.S")))
 DRIVERS_OBJ := $(addsuffix .o,$(basename $(shell find ./drivers -name '*.cc' -o -name '*.S')))
-LIBS_OBJ := $(addsuffix .cc,$(basename $(shell find ./libs -name '*.cc' -o -name '*.S')))
+LIBS_OBJ := $(addsuffix .o,$(basename $(shell find ./libs -name '*.cc' -o -name '*.S')))
 CORE_OBJ := $(addsuffix .o,$(basename $(shell find ./core -name '*.cc' -o -name '*.S')))
 
 all: $(EXEC)
 
 $(EXEC): boot/boot.o $(BOOT_OBJ) $(DRIVERS_OBJ) $(LIBS_OBJ) $(CORE_OBJ) boucane.o
+	echo $(BOOT_OBJ)
 	$(CC) -n -T $(LD_SCRIPT) -nostdlib -o $@ $^
 
 %.o: %.S

src/boot/boot.S

@@ -43,11 +43,11 @@ mb_header_end:
 .section .text
 .code32 # Require since grub do not enable long mode
 
-MB_INFO:
- .int 0xABCDEF # Will contains the Multiboot2 information data structure address
+MB_INFO: # Will contains the Multiboot2 information data structure address
+ .long 0x0
 
 _start:
-mov %ebx,(MB_INFO)
+mov %ebx, (MB_INFO)
 # Zeroing the .bss section
 mov $_bss_start, %eax
 mov $_bss_end, %ebx

src/boot/multiboot2.cc

@@ -0,0 +1,55 @@
+#include "multiboot2.hpp"
+#include "libs/string.hpp"
+#include "libs/stdio.hpp"
+
+u32* mb2_find_tag(u32 *mb2_info_addr, char type){
+    u32 size=(u32)mb2_info_addr[0];
+
+    char *location=((char*)mb2_info_addr)+8; // Goto first tag
+    char *start=(char*)mb2_info_addr;
+
+    while((location-start) < size){
+        // Goto next 64bit align address
+        while(((u64)location&0x7) != 0)
+            location++;
+        // Parse type
+        u32 cur_type=((u32*)location)[0];
+        u32 cur_size=((u32*)location)[1];
+
+        if(cur_type==type){
+            return (u32*)location;
+        }
+        location+=cur_size;
+    }
+
+    return 0;
+}
+
+char mb2_find_bootloader_name(u32* mb2_info_addr, char *return_name){
+    u32* addr=mb2_find_tag(mb2_info_addr,2);
+    if(addr){
+        u32 size=addr[1];
+        memcpy(addr+2, return_name, size);
+        return 1;
+    }
+    return 0;
+}
+char mb2_find_new_rsdp(u32* mb2_info_addr, u64 *return_addr, u32 *return_size){
+    u32* addr=mb2_find_tag(mb2_info_addr,15);
+    if(addr){
+        *return_size=addr[1];
+        *return_addr=(u64)addr+2;
+        return 1;
+    }
+    return 0;   
+}
+
+char mb2_find_old_rsdp(u32* mb2_info_addr, u64 *return_addr, u32 *return_size){
+    u32* addr=mb2_find_tag(mb2_info_addr,14);
+    if(addr){
+        *return_size=addr[1];
+        *return_addr=(u64)addr+2;
+        return 1;
+    }
+    return 0;   
+}

src/boot/multiboot2.hpp

@@ -0,0 +1,8 @@
+#pragma once
+
+#include "core/types.hpp"
+
+u32* mb2_find_tag(u32 *mb2_info_addr, char type);
+char mb2_find_bootloader_name(u32* mb2_info_addr, char *return_name);
+char mb2_find_new_rsdp(u32* mb2_info_addr, u64 *return_addr, u32 *return_size);
+char mb2_find_old_rsdp(u32* mb2_info_addr, u64 *return_addr, u32 *return_size);

src/boucane.cc

@@ -1,10 +1,21 @@
 #include "boucane.hpp"
 #include "core/idt.hpp"
+#include "boot/multiboot2.hpp"
+#include "core/paging.hpp"
+
+extern u32 MB_INFO;
 
 extern "C" void boucane(){
     clear();
-    printk("Booting Boucane v%d.%d.%d",VERSION_MAJOR,VERSION_MINOR, VERSION_PATH);
+    printk("Booting Boucane v%d.%d.%d\n",VERSION_MAJOR,VERSION_MINOR, VERSION_PATH);
     idt_enable_interrupt();
 
+    paging_enable();
+
+    u64 p;
+    u32 size;
+    if(mb2_find_old_rsdp((u32*)MB_INFO,&p,&size)){
+        printk("RSDP Table found!");
+    }
     while(1);
 }

src/core/paging.cc

@@ -0,0 +1,173 @@
+#include "paging.hpp"
+#include "core/types.hpp"
+#include "libs/stdio.hpp"
+#include "libs/string.hpp"
+
+char paging_status[PAGING_MAX_PAGE / 8];
+
+void paging_enable() {
+    // Init status
+    for (int i = 0; i < PAGING_MAX_PAGE / 8; i++) {
+        paging_status[i] = 0;
+    }
+
+    // Allocate paging for the kernel (to not override the source
+    // code during the next paging_allocate_table() calls)
+    paging_allocate_contiguous(PAGING_KERNEL_USED_PAGE);
+
+    // Setting up new kernel address space
+    u64* pml4=paging_allocate_table();
+    for(int i=0;i<PAGING_KERNEL_SPACE_MAX_PAGE;i++){
+        int addr=i*4096;
+        paging_allocate_addr(pml4,addr,addr, PAGING_OPT_P|PAGING_OPT_RW); // Identity map
+    }
+    // Load new pml4
+    asm volatile(
+        "movq %0, %%rax        \n\t"
+        "movq %%rax, %%cr3     \n\t"
+        :: "r" (pml4));
+}
+
+u64 paging_as_phy(u64* pml4_table, u64 virt){
+    u16 pml4=virt>>39&0x1FF;
+    u16 pdp=virt>>30&0x1FF;
+    u16 pd=virt>>21&0x1FF;
+    u16 pt=(virt>>12)&0x1FF;
+    
+    u64* pdp_table=(u64*)PAGE(pml4_table[pml4]);
+    u64* pd_table=(u64*)PAGE(pdp_table[pdp]);
+    u64* pt_table=(u64*)PAGE(pd_table[pd]);
+    return((PAGE(pt_table[pt]))|(virt&0xFFF));
+}
+u64* paging_allocate_contiguous(int npages){
+    int n_contiguous=0;
+    for (int i = 0; i < PAGING_MAX_PAGE / 8; i++) {
+        for (int j = 0; j < 8; j++) {
+            char bit=(paging_status[i]&(0x1<<j))>>j;
+            if(bit!=1){
+                n_contiguous++;
+            }
+            else {
+                n_contiguous=0;
+            }
+            if(n_contiguous==npages){
+                n_contiguous--; // Since we use it now as index, not a counter
+                int start_page=(i*8+j)-n_contiguous;
+                while(n_contiguous>=0){
+                    int cur_page=(i*8+j)-n_contiguous;
+                    paging_status[cur_page/8]|=(0x1<<(cur_page%8)); // Allocate
+                    n_contiguous--;
+                }
+                u64 phy_addr=(4096*start_page);
+                return (u64*) phy_addr;
+            }
+        }   
+    }
+
+    printk("Could not allocate %d contigous pages. Kernel panic!",npages);
+    while(1);
+    return 0;
+}
+
+void paging_deallocate(u64 addr){
+    u64 page_number=PAGE(addr)/4096;
+    char byte=paging_status[page_number/8];
+    paging_status[page_number/8]=byte&(~(1<<(page_number%8)));
+}
+
+void paging_deallocate_pml4(u64* pml4){
+    for(int i=0;i<512;i++){
+        u64* pdp=(u64*)PAGE(pml4[i]);
+        if(pml4[i]==0)
+            continue;
+        for(int j=0;j<512;j++){
+            u64* pd=(u64*)PAGE(pdp[j]);
+            if(pdp[j]==0)
+                continue;
+            for(int k=0;k<512;k++){
+                u64* pt=(u64*)PAGE(pd[k]);
+                if(pd[k]==0)
+                    continue;
+                for(int l=0;l<512;l++){
+                    if(pt[l]==0)
+                        continue;
+                    paging_deallocate_table((u64*)PAGE(pt[l]));
+                }
+                paging_deallocate_table((u64*)PAGE(pd[k]));
+            }
+            paging_deallocate_table((u64*)PAGE(pdp[j]));
+        }
+        paging_deallocate_table((u64*)PAGE(pml4[i]));
+    }
+    paging_deallocate_table((u64*)PAGE((u64)pml4));
+}
+
+void paging_dump(int min, int max) {
+    for (int i = 0; i < PAGING_MAX_PAGE / 8; i++) {
+        if(i>=min && i<=max){
+            printk("Byte %d   ", i);
+            for (int j = 0; j < 8; j++) {
+                char bit = (paging_status[i] & (0x1 << j)) >> j;
+                printk("%d", bit);
+            }
+            print("\n");
+        }
+    }
+}
+
+u64* paging_allocate_table(){
+    u64* table=paging_allocate_contiguous(8);
+    memset(table, 0, 32768); // nb_entries * entry size = 512 * 64
+    return table;
+}
+
+void paging_deallocate_table(u64* table){
+    char *c_table=(char*)PAGE((u64)table);
+    for(u8 i=0;i<8;i++){
+        paging_deallocate((u64)c_table);
+        c_table+=4096;
+    }
+}
+
+void paging_allocate_addr(u64* pml4_table, u64 virt, u64 phy, u16 options){
+    u16 pml4=virt>>39&0x1FF;
+    u16 pdp=virt>>30&0x1FF;
+    u16 pd=virt>>21&0x1FF;
+    u16 pt=virt>>12&0x1FF;
+    options&=0xFFF; // Ensure options are on 12bits
+    
+    // Solve pdp
+    if(pml4_table[pml4] == 0){
+        pml4_table[pml4]=(u64)paging_allocate_table();
+        pml4_table[pml4]|=options;
+        paging_allocate_addr(pml4_table,virt,phy,options);
+        return;
+    }
+    // Solve pd
+    u64* pdp_table=(u64*)PAGE(pml4_table[pml4]);
+    if(pdp_table[pdp] == 0){
+        pdp_table[pdp]=(u64)paging_allocate_table();
+        pdp_table[pdp]|=options;
+        paging_allocate_addr(pml4_table,virt,phy,options);
+        return;
+    }
+    // Solve pt
+    u64* pd_table=(u64*)PAGE(pdp_table[pdp]);
+    if(pd_table[pd] == 0){
+        pd_table[pd]=(u64)paging_allocate_table();
+        pd_table[pd]|=options;
+        paging_allocate_addr(pml4_table,virt,phy,options);
+        return;
+    }
+    // Solve address
+    u64* pt_table=(u64*)PAGE(pd_table[pd]);
+    if(pt_table[pt] == 0){
+        pt_table[pt]=PAGE(phy);
+        pt_table[pt]|=options;
+        return;
+    }
+    
+    printk("Virtual address %x already in use. Kernel panic!",virt);
+    while(1);
+
+}

src/core/paging.hpp

@@ -0,0 +1,66 @@
+#pragma once
+
+#include "core/types.hpp"
+
+#define PAGING_MAX_PAGE (20*512)
+/**
+ * Current number of page (from the beginning of the ram) used by the kernel that
+ * should not be used by the paging allocation mechanism and should not be granted
+ * for allocation
+ */
+#define PAGING_KERNEL_USED_PAGE (2*512)
+/// @brief New number of page reachable at the end of the paging_enable() call
+#define PAGING_KERNEL_SPACE_MAX_PAGE (20*512)
+#define PAGING_ALLOCATE() paging_allocate_contiguous(1)
+#define PAGING_OPT_P 1
+#define PAGING_OPT_RW (1<<1)
+
+/// @brief Get page address that contain addr
+#define PAGE(addr) (addr&(~(0xFFF)))
+
+/**
+ * Setup and enable PAE paging
+ */
+void paging_enable();
+
+/**
+ * Allocate the next available page
+ * and return its physical address
+ */
+u64* paging_allocate_contiguous(int npages);
+
+/**
+ * Deallocate a page located at addr
+ */
+void paging_deallocate(u64 addr);
+
+/**
+ * Dump a specific range of bytes in the paging_status
+ */
+void paging_dump(int min, int max);
+
+/**
+ * Deallocate all the pages linked to a pml4
+ */
+void paging_deallocate_pml4(u64* pml4);
+
+/**
+ * Deallocate all the pages related to a pml4 structure
+ */
+void paging_deallocate_table(u64* table);
+
+/**
+ * Allocate table structure (pml4, pdp etc..)
+ */
+u64* paging_allocate_table();
+
+/**
+ * Map virtual page associated to virt
+ * to the physical page associated with phy
+ */
+void paging_allocate_addr(u64* pml4_table,u64 virt, u64 phy, u16 options);
+
+/**
+ * Get associated physical address
+ */
+u64 paging_as_phy(u64* pml4_table, u64 virt);

src/libs/string.cc

@@ -8,6 +8,13 @@ void memcpy(void* src, void* dst, u32 size){
         *(c_dst+i)=*(c_src+i);
 }
 
+void memset(void *dst, char value, u64 size){
+    char* ptr=(char*)dst;
+    for(u64 i=0;i<size;i++){
+        ptr[i]=value;
+    }
+}
+
 void itoa(u64 i, char *a){
     // Check if lower than 0
     u8 neg=0;

src/libs/string.hpp

@@ -7,6 +7,8 @@
  */
 void memcpy(void *src, void *dst, u32 size);
 
+void memset(void *dst, char value, u64 size);
+
 /**
  * Convert int to char array
  */

tools/bochsrc

@@ -1,2 +1,4 @@
 romimage: file=$BXSHARE/BIOS-bochs-latest, options=fastboot
 vgaromimage: file=$BXSHARE/VGABIOS-lgpl-latest
+
+cpu: count=1, ips=10000000, reset_on_triple_fault=0