diff --git a/src/Makefile b/src/Makefile index 0dee4ff..f5f9c83 100644 --- a/src/Makefile +++ b/src/Makefile @@ -1,5 +1,5 @@ EXEC := bringelle -CC := gcc -c -m32 -fno-pie -fno-builtin +CC := gcc -c -m32 -fno-pie -fno-builtin -fno-stack-protector UTILS_SRC := $(wildcard utils/*.c) @@ -16,14 +16,19 @@ bringelle.o: bringelle.c $(CC) $^ utils.o: $(UTILS_SRC) - $(CC) $^ -o $@ + for src in $^ ;\ + do \ + obj=$$(basename $${src} ".c")".o" ;\ + $(CC) $${src} -o utils/$${obj} ;\ + done + ld -melf_i386 -relocatable utils/*.o -o utils.o boot.o: ./boot/boot.S as --32 -o $@ $^ -mx86-used-note=no clean: + find ./ -name "*.o" -delete - rm $(EXEC) - - rm ./*.o .PHONY: clean diff --git a/src/boot/boot.S b/src/boot/boot.S index 746f858..e3830eb 100644 --- a/src/boot/boot.S +++ b/src/boot/boot.S @@ -1,4 +1,5 @@ .extern bringelle +.extern gdt_memcpy .globl _start .text @@ -23,5 +24,28 @@ mb_header: .long MB_ENTRY_ADDR _start: - call bringelle + +# Copy GDT into memory then load its register +call gdt_memcpy +lgdtl (GDTR) + +# Update all segments register +# with the new GDT offset +movw $0x10, %ax +movw %ax, %ds +movw %ax, %es +movw %ax, %fs +movw %ax, %gs + +# Update code segment +ljmp $0x08, $cs_new +cs_new: + +# Update stack segment +movw $0x18, %ax +movw %ax, %ss +movl $0x20000,%esp + +# Start kernel main function +call bringelle diff --git a/src/utils/gdt.c b/src/utils/gdt.c new file mode 100644 index 0000000..85c4a09 --- /dev/null +++ b/src/utils/gdt.c @@ -0,0 +1,52 @@ +#include "gdt.h" +#include "print.h" +#include "mem.h" + +struct GDT_REGISTER GDTR = { 0, 0 }; + +void gdt_memcpy(){ + GDTR.limit=8*4; // Each entry is 8 bytes and 4 entries + GDTR.base=0x800; + + GDT_ENTRY cs_desc; + cs_desc.base=0; + cs_desc.limit=0xFFFFF; + cs_desc.flags=GDT_SZ|GDT_GR; + cs_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_EXEC|GDT_RW; + + GDT_ENTRY ds_desc; + ds_desc.base=0; + ds_desc.limit=0xFFFFF; + ds_desc.flags=GDT_SZ|GDT_GR; + ds_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_RW; + + GDT_ENTRY ss_desc; + ss_desc.base=0; + ss_desc.limit=0; + ss_desc.flags=GDT_SZ|GDT_GR; + ss_desc.access=GDT_PR|GDT_PRVL_0|GDT_S|GDT_RW|GDT_DC; + + // Write GDT descriptors into memory + gdt_write_entry((GDT_ENTRY){0,0,0,0},GDTR.base); // First one must be null + gdt_write_entry(cs_desc, GDTR.base+8); // Each entry is 64 bits (8 bytes) + gdt_write_entry(ds_desc, GDTR.base+8*2); + gdt_write_entry(ss_desc, GDTR.base+8*3); +} + +void gdt_write_entry(GDT_ENTRY entry, u32 addr){ + int descriptor[2]; + + // First row of the descriptor + descriptor[0]=(entry.limit & 0xFFFF)|(entry.base << 16); + + // Format second row of the descriptor + u16 base=(entry.base >> 16) & 0xFF; + u16 access=entry.access & 0xFF; + u16 limit=(entry.limit >> 16) & 0xF; // Remember: limits it is on 20 bits so 4 last bits + u8 flags=entry.flags & 0xF; + u8 base2=entry.base >> 24; // Take the last 8 bits + descriptor[1]=base|access<<8|limit<<16|flags<<20|base2<<24; + + // Copy descriptor into memory + memcpy(descriptor,(void*)addr,8); +} diff --git a/src/utils/gdt.h b/src/utils/gdt.h new file mode 100644 index 0000000..85a75aa --- /dev/null +++ b/src/utils/gdt.h @@ -0,0 +1,44 @@ +#ifndef GDT_H +#define GDT_H + +#include "types.h" + +// Access byte +#define GDT_AC 1 // Access bit +#define GDT_RW 1 << 1 // Read/Write bit +#define GDT_DC 1 << 2 // Direction bit/Conforming bit +#define GDT_EXEC 1 << 3 // Executable bit +#define GDT_S 1 << 4 // Descriptor type +#define GDT_PRVL_0 0 // Privilege (from 0 to 3) +#define GDT_PRVL_1 1 << 5 +#define GDT_PRVL_2 2 << 5 +#define GDT_PRVL_3 3 << 5 +#define GDT_PR 1 << 7 // Present Bit + +// Flags +#define GDT_SZ 1 << 2 // Size bit +#define GDT_GR 1 << 3 // Granularity bit + +typedef struct GDT_ENTRY { + u32 base; + u32 limit; + u8 flags; + u8 access; +} GDT_ENTRY; + +struct GDT_REGISTER { + u16 limit; + u32 base; +} __attribute__((packed)); + +/** + * Copy GDT in memory + */ +void gdt_memcpy(); + +/** + * Write a GDT entry at address addr + */ +void gdt_write_entry(GDT_ENTRY entry, u32 addr); + +#endif diff --git a/src/utils/mem.c b/src/utils/mem.c new file mode 100644 index 0000000..4cefd6d --- /dev/null +++ b/src/utils/mem.c @@ -0,0 +1,8 @@ +#include "mem.h" + +void memcpy(void *src, void *dst, int size){ + u8 *char_src=(u8 *)src; + u8 *char_dst=(u8 *)dst; + for(int i=0;i= MAX_COL){ - col=0; - line+=1; - if(line>=MAX_LINE){ - line=MAX_LINE-1; + VS.col+=1; + if(VS.col>= MAX_COL){ + VS.col=0; + VS.line+=1; + if(VS.line>=MAX_LINE){ + VS.line=MAX_LINE-1; scrollup(); } } @@ -39,13 +51,13 @@ void clear(){ } void scrollup(){ - // Move line up + // Move VS.line up for(char i=1;i<=MAX_LINE;i++){ for(char j=0;j<=MAX_COL;j++) - video[j*2+MAX_COL*(i-1)*2]=video[j*2+MAX_COL*i*2]; + VS.mem[j*2+MAX_COL*(i-1)*2]=VS.mem[j*2+MAX_COL*i*2]; } - // Clear last line + // Clear last VS.line for(char i=0;i<=MAX_COL;i++){ - video[col*2+MAX_COL*(MAX_LINE-1)*2]='\0'; + VS.mem[i*2+MAX_COL*(MAX_LINE-1)*2]='\0'; } } diff --git a/src/utils/print.h b/src/utils/print.h index fb1badd..d04fed2 100644 --- a/src/utils/print.h +++ b/src/utils/print.h @@ -1,6 +1,15 @@ #ifndef PRINT_H #define PRINT_H +#include "types.h" + +typedef enum VIDEO_COLORS { + BLACK=0, BLUE=1, GREEN=2,CYAN=3, RED=4,PURPLE=5,BROWN=6,GRAY=7, + DARK_GRAY=8,LIGHT_BLUE=9,LIGHT_GREEN=10,LIGHT_CYAN=11,LIGHT_RED=12,LIGHT_PURPLE=13,YELLOW=14,WHITE=15 + +} VIDEO_COLORS; + +typedef struct VIDEO_STATE VIDEO_STATE; /** * Print char