Softcode GDT table selectors

scopeInfinity · scopeInfinity · commit accdbce355c0 · 2021-09-05T01:27:30.000+01:00
diff --git a/include/fuzzy/kernel/process/process.h b/include/fuzzy/kernel/process/process.h
@@ -3,7 +3,9 @@
 #include<stddef.h>
 
 #define MAX_PROCESS 10
-#define GDT_TABLE_SIZE MAX_PROCESS*2+3
+// each process will have CS and DS, and kernel
+// CS and DS is already included in GDT standard table.
+#define GDT_TABLE_SIZE ((MAX_PROCESS-1)*2+GDT_STD_SIZE)
 
 typedef char ARGV[PROCESS_MAX_ARGC][PROCESS_MAX_ARG_LEN];
 
diff --git a/include/fuzzy/memmgr/tables/gdt.asm b/include/fuzzy/memmgr/tables/gdt.asm
@@ -0,0 +1,21 @@
+; constants only
+
+; START_ENSURE_SAME_gdt_h
+
+GDT_STD_SELECTOR_NULL       EQU     0
+GDT_STD_SELECTOR_KERNEL_CS  EQU     1
+GDT_STD_SELECTOR_KERNEL_DS  EQU     2
+GDT_STD_SELECTOR_ABS16_CS   EQU     3
+GDT_STD_SELECTOR_ABS16_DS   EQU     4
+GDT_STD_SELECTOR_ABS32_DS   EQU     6
+GDT_STD_SIZE                EQU     5 ; FIX
+
+GDT_STD_SIZEOF_ENTRY        EQU     8
+; END_ENSURE_SAME_gdt_h
+
+GDT_NULL_CS     EQU   (GDT_STD_SELECTOR_NULL*GDT_STD_SIZEOF_ENTRY)
+GDT_KERNEL_CS   EQU   (GDT_STD_SELECTOR_KERNEL_CS*GDT_STD_SIZEOF_ENTRY)
+GDT_KERNEL_DS   EQU   (GDT_STD_SELECTOR_KERNEL_DS*GDT_STD_SIZEOF_ENTRY)
+GDT_ABS16_CS    EQU   (GDT_STD_SELECTOR_ABS16_CS*GDT_STD_SIZEOF_ENTRY)
+GDT_ABS16_DS    EQU   (GDT_STD_SELECTOR_ABS16_DS*GDT_STD_SIZEOF_ENTRY)
+GDT_ABS32_DS    EQU   (GDT_STD_SELECTOR_ABS32_DS*GDT_STD_SIZEOF_ENTRY)
diff --git a/include/fuzzy/memmgr/tables/gdt.h b/include/fuzzy/memmgr/tables/gdt.h
@@ -3,6 +3,18 @@
 // Min GDT_TABLE_SIZE:    5
 // Max GDT_TABLE_SIZE: 8192
 
+// START_ENSURE_SAME_gdt_asm
+#define GDT_STD_SELECTOR_NULL      0
+#define GDT_STD_SELECTOR_KERNEL_CS 1
+#define GDT_STD_SELECTOR_KERNEL_DS 2
+#define GDT_STD_SELECTOR_ABS16_CS  3
+#define GDT_STD_SELECTOR_ABS16_DS  4
+#define GDT_STD_SELECTOR_ABS32_DS  6
+#define GDT_STD_SIZE 5 // FIX
+// Entries on and after GDT_STD_SIZE are reserved for applications
+// and are in CS, DS order for each app.
+// END_ENSURE_SAME_gdt_asm
+
 #pragma pack(push, 1)
 struct GDTReference {
     unsigned short size;
@@ -18,6 +30,8 @@ struct GDTEntry {
 };
 #pragma pack(pop)
 
+#define GDT_KERNEL_CS (GDT_STD_SELECTOR_KERNEL_CS*sizeof(struct GDTEntry))
+
 int get_gdt_baseaddress(struct GDTEntry gdt_table[], unsigned int table_size, int entry_id);
 
 void populate_gdt_entry(struct GDTEntry *entry,
diff --git a/src/bootloader/Makefile.mk b/src/bootloader/Makefile.mk
@@ -20,7 +20,7 @@ $(bt_stage1): $(SRC_BOOTLOADER)/stage1.asm $(SRC_BOOTLOADER)/constants.asm $(SRC
 
 $(bt_stage2).elf: $(SRC_BOOTLOADER)/stage2.asm $(SRC_BOOTLOADER)/stage2.c $(INCLUDE_DIR)/memmgr/tables/gdt.h $(SRC_MEMMGR)/tables/gdt.c $(SRC_BOOTLOADER)/io.asm $(SRC_BOOTLOADER)/constants.asm $(BUILD_LIB_UTILS)/libutils_16 $(BUILD_DRIVERS)/display/libtm_bios $(BUILD_DRIVERS)/disk/libdisk_16
 	mkdir -p $$(dirname $(bt_stage2))
-	nasm -o $(BUILD_BOOTLOADER)/stage2_asm.o -f elf32 -i $(SRC_BOOTLOADER)/ $(SRC_BOOTLOADER)/stage2.asm
+	$(NASM) -o $(BUILD_BOOTLOADER)/stage2_asm.o -i $(SRC_BOOTLOADER)/ $(SRC_BOOTLOADER)/stage2.asm
 	$(CC) -m16 -fno-pie -c -Isrc \
 	    -Iinclude \
 		-D SECTOR_START_SHARED_LIBRARY=$(SECTOR_START_SHARED_LIBRARY) \
diff --git a/src/bootloader/stage2.asm b/src/bootloader/stage2.asm
@@ -1,6 +1,7 @@
 ; Fuzzy Bootloader Stage 2
 %include "constants.asm"
 %include "io.asm"
+%include "fuzzy/memmgr/tables/gdt.asm"
 
 [BITS 16]
 
@@ -38,7 +39,7 @@ global call_int_0x15
 
         ; __TEST_INJECT_BT2__: mov eax, 0x198A65C3
         ; __TEST_INJECT_BT2__: HLT
-        jmp 0x08:0x0000     ; address of smart kernel init
+        jmp GDT_KERNEL_CS:0x0000     ; address of smart kernel init
 
     label_exit:
         HLT
diff --git a/src/bootloader/stage2.c b/src/bootloader/stage2.c
@@ -1,3 +1,4 @@
+#include <fuzzy/memmgr/tables/gdt.h>
 #include <fuzzy/memmgr/layout.h>
 
 #include <lib/utils/color.h>
@@ -8,8 +9,7 @@
 
 #include "memmgr/tables/gdt.c"
 
-#define GDT_TABLE_SIZE 5
-struct GDTEntry gdt_table[GDT_TABLE_SIZE];
+struct GDTEntry gdt_table[GDT_STD_SIZE];
 struct GDTReference gdtr;
 
 char DIGIT_TO_HEX[] = "0123456789ABCDEF";
@@ -87,7 +87,7 @@ void entry_stage() {
     load_static_library();
     load_kernel();
 
-    populate_gdt_table(&gdtr, gdt_table, GDT_TABLE_SIZE, 0);
+    populate_gdt_table(&gdtr, gdt_table, GDT_STD_SIZE, 0);
 
     // Enter_protected_mode never returns.
     print_log("Loading GDT Table and entering protected mode");
diff --git a/src/drivers/disk/disk.c b/src/drivers/disk/disk.c
@@ -1,4 +1,6 @@
 // written for protected mode
+#include <fuzzy/kernel/process/process.h>
+
 #include <lib/utils/logging.h>
 #include <fuzzy/real_mode/client.h>
 
@@ -29,5 +31,10 @@ int load_sectors(unsigned int full_address,
     unsigned int status = eax >> 8;
     print_info("[load_sectors] [dev %x]:%x -> mem:%x, cnt: %d; err: %x",
         drive, lba, full_address, count, status);
+    if(status == 0) {
+        // no error copy from temporary address to dst address.
+        // TODO: redefine GDT table order.
+        // kernel_memncpy_absolute(int dst_ds, char *dst_address, int src_ds, char *src_address, size_t size);
+    }
     return status;
 }
diff --git a/src/drivers/display/Makefile.mk b/src/drivers/display/Makefile.mk
@@ -2,11 +2,11 @@ $(BUILD_DRIVERS)/display/libtm_bios: $(SRC_DRIVERS)/display/text_mode_bios.c $(S
 	# 16 bit mode
 	mkdir -p $(BUILD_DRIVERS)/display/
 	$(CC) -m16 -fno-pie -c -Isrc -o $(BUILD_DRIVERS)/display/text_mode_bios_c.o $(SRC_DRIVERS)/display/text_mode_bios.c
-	nasm -o $(SRC_DRIVERS)/display/text_mode_bios_asm.o -f elf32 $(SRC_DRIVERS)/display/text_mode_bios.asm
-	ar rc 	$@ $(BUILD_DRIVERS)/display/text_mode_bios_c.o $(SRC_DRIVERS)/display/text_mode_bios_asm.o
+	$(NASM) -o $(BUILD_DRIVERS)/display/text_mode_bios_asm.o $(SRC_DRIVERS)/display/text_mode_bios.asm
+	ar rc 	$@ $(BUILD_DRIVERS)/display/text_mode_bios_c.o $(BUILD_DRIVERS)/display/text_mode_bios_asm.o
 
 $(BUILD_DRIVERS)/display/libtm_vga: $(SRC_DRIVERS)/display/text_mode_vga.c $(SRC_DRIVERS)/display/text_mode_vga.asm $(SRC_DRIVERS)/display/text_mode.h
 	mkdir -p $(BUILD_DRIVERS)/display/
 	$(CC) -m32 -fno-pie -c -Isrc -o $(BUILD_DRIVERS)/display/text_mode_vga_c.o $(SRC_DRIVERS)/display/text_mode_vga.c
-	nasm -o $(SRC_DRIVERS)/display/text_mode_vga_asm.o -f elf32 $(SRC_DRIVERS)/display/text_mode_vga.asm
-	ar rc $@ $(BUILD_DRIVERS)/display/text_mode_vga_c.o $(SRC_DRIVERS)/display/text_mode_vga_asm.o
+	$(NASM) -o $(BUILD_DRIVERS)/display/text_mode_vga_asm.o $(SRC_DRIVERS)/display/text_mode_vga.asm
+	ar rc $@ $(BUILD_DRIVERS)/display/text_mode_vga_c.o $(BUILD_DRIVERS)/display/text_mode_vga_asm.o
diff --git a/src/drivers/display/text_mode_vga.asm b/src/drivers/display/text_mode_vga.asm
@@ -1,3 +1,5 @@
+%include "fuzzy/memmgr/tables/gdt.asm"
+
 [BITS 32]
 
 global _low_put_char
@@ -14,12 +16,12 @@ global _low_flush
         ; push edi
 
         push ds
-        mov eax, 0x20
+        mov eax, GDT_ABS16_DS
         mov ds, eax                 ; Absolute memory address
 
         mov ebx,[ebp + 0x10]        ; (ROW_WIDTH*y+x)
         shl ebx, 1
-        add ebx,0xb8000
+        add ebx, 0xb8000
         mov al, [ebp + 0x8]         ; (char)
         mov ah, [ebp + 0xc]         ; (color)
         mov [ebx], ax
@@ -39,7 +41,7 @@ global _low_flush
         ; push esi
         ; push edi
         push ds
-        mov eax, 0x20
+        mov eax, GDT_ABS16_DS
         mov ds, eax                 ; Absolute memory address
 
         ; Copy char+colors in Row Order Format
@@ -71,7 +73,7 @@ global _low_flush
         push esi
         push edi
         push es
-        mov eax, 0x20
+        mov eax, GDT_ABS16_DS
         mov es, eax                 ; Absolute memory address
 
         mov esi, [ebp + 0x8]    ; (buffer)
diff --git a/src/kernel/core.asm b/src/kernel/core.asm
@@ -1,4 +1,5 @@
 %include "fuzzy/memmgr/layout.asm"
+%include "fuzzy/memmgr/tables/gdt.asm"
 
 [BITS 32]
 
@@ -9,7 +10,7 @@ global kernel_core_entry_asm
 [SECTION .text]
         ; protected mode real entry point.
         CLI
-        mov ax, 0x10
+        mov ax, GDT_KERNEL_DS
         mov es, ax
         mov ss, ax
         mov ds, ax
diff --git a/src/kernel/interrupts/exceptions.asm b/src/kernel/interrupts/exceptions.asm
@@ -1,3 +1,5 @@
+%include "fuzzy/memmgr/tables/gdt.asm"
+
 [BITS 32]
 
 extern interrupt_handler_0x00_0x1F_exception
@@ -47,7 +49,7 @@ global _interrupt_handler_0x1F_exception
         xor eax, eax
         mov eax, ss    ; execution ss (current also)
         push eax
-        mov eax, 0x10  ; kernel ds
+        mov eax, GDT_KERNEL_DS  ; kernel ds
         mov ds, eax
         mov eax, %1
         push eax
diff --git a/src/kernel/interrupts/interrupts.asm b/src/kernel/interrupts/interrupts.asm
@@ -1,4 +1,5 @@
 %include "fuzzy/memmgr/layout.asm"
+%include "fuzzy/memmgr/tables/gdt.asm"
 
 [BITS 32]
 
@@ -49,7 +50,7 @@ KERNEL_STACK_MARKER_NOTNEW EQU 0x10000000
         ; HANDLE_SS_START
         ; if ss is not already in kernel mode than create kernel stack
         ; and save ongoing stack.
-        mov ax, 0x10
+        mov ax, GDT_KERNEL_DS
         push ebx
         mov bx, ss
         cmp bx, ax
@@ -79,7 +80,7 @@ KERNEL_STACK_MARKER_NOTNEW EQU 0x10000000
 
         ; Let's move to kernel mode and move interrupt arguments as function argument
         ; es: will updated in next section, and will be es==ds
-        mov ax, 0x10
+        mov ax, GDT_KERNEL_DS
         mov ds, ax
         mov fs, ax
         mov gs, ax
diff --git a/src/kernel/interrupts/interrupts.c b/src/kernel/interrupts/interrupts.c
@@ -2,6 +2,7 @@
 #include <fuzzy/kernel/interrupts/interrupts.h>
 #include <fuzzy/kernel/interrupts/timer.h>
 #include <fuzzy/memmgr/layout.h>
+#include <fuzzy/memmgr/tables/gdt.h>
 
 #include <lib/utils/logging.h>
 
@@ -49,7 +50,7 @@ void populate_idt_entry_32bit(int id,
     ) {
     populate_idt_entry(
         id,
-        0x08,  // kernel code segment selector
+        GDT_KERNEL_CS,
         address,
         1,
         dpl,
diff --git a/src/kernel/interrupts/timer.asm b/src/kernel/interrupts/timer.asm
@@ -1,4 +1,5 @@
 %include "fuzzy/memmgr/layout.asm"
+%include "fuzzy/memmgr/tables/gdt.asm"
 
 [BITS 32]
 
@@ -28,7 +29,7 @@ global create_infant_process_irq0_stack
 
         ; new stack and segment area
         mov esp, STACKINIT_KERNEL_EVENT
-        mov eax, 0x10
+        mov eax, GDT_KERNEL_DS
         mov ss, eax
         mov ds, eax
         mov es, eax
diff --git a/src/kernel/process/allocation.c b/src/kernel/process/allocation.c
@@ -18,52 +18,54 @@
 
 int get_idt_cs_entry(int process_id) {
     if(process_id == PID_KERNEL) {
-        return 1;
+        return GDT_STD_SELECTOR_KERNEL_CS;
     }
-    return (process_id<<1)+3;
+    // Assumes kernel PID is 0
+    return ((process_id-1)<<1)+GDT_STD_SIZE;
 }
 
 int get_idt_ds_entry(int process_id) {
      if(process_id == PID_KERNEL) {
-        return 2;
+        return GDT_STD_SELECTOR_KERNEL_DS;
     }
-   return (process_id<<1)+4;
+    // Assumes kernel PID is 0
+    return ((process_id-1)<<1)+GDT_STD_SIZE+1;
 }
 
 int get_gdt_number_from_entry_id(int id) {
     return id*sizeof(struct GDTEntry);
 }
 
 int get_idt_reverse_pid_lookup_cs(int cs) {
-    if(cs%sizeof(struct GDTEntry)!=0) {
-        PANIC(cs, "get_idt_reverse_pid_lookup(cs) called with cs%8!=0.");
+    const int entry_size = sizeof(struct GDTEntry);
+    if(cs%entry_size!=0) {
+        PANIC(cs, "get_idt_reverse_pid_lookup_cs(cs) called with cs%8!=0.");
     }
-    int segment_id = cs/sizeof(struct GDTEntry);
-    if(segment_id<=0) {
-        PANIC(cs, "get_idt_reverse_pid_lookup(cs) called with segment_id<=0.");
-    }
-    int cs_index = (segment_id-1)/2;
-    if(cs_index==0) {
+    int selector = cs/entry_size;
+    if(selector == GDT_STD_SELECTOR_KERNEL_CS) {
         return PID_KERNEL;
     }
-    // cs_index == 1 is absolute segment gdt entry
-    return cs_index-1;
+    if(selector >= GDT_STD_SIZE && (selector-GDT_STD_SIZE)%2==0) {
+        int pid = (selector-GDT_STD_SIZE)/2 + 1;
+        return pid;
+    }
+    PANIC(cs, "get_idt_reverse_pid_lookup_cs(cs) is not valid app CS");
 }
 
 int get_idt_reverse_pid_lookup_ds(int ds) {
-    if(ds%sizeof(struct GDTEntry)!=0) {
-        PANIC(ds, "get_idt_reverse_pid_lookup(ds) called with ds%8!=0.");
+    const int entry_size = sizeof(struct GDTEntry);
+    if(ds%entry_size!=0) {
+        PANIC(ds, "get_idt_reverse_pid_lookup_ds(ds) called with ds%8!=0.");
     }
-    int segment_id = ds/sizeof(struct GDTEntry);
-    if(segment_id<0) {
-        PANIC(ds, "get_idt_reverse_pid_lookup(ds) called with segment_id<2.");
-    }
-    int ds_index = segment_id/2-1;
-    if(ds_index==0) {
+    int selector = ds/entry_size;
+    if(selector == GDT_STD_SELECTOR_KERNEL_DS) {
         return PID_KERNEL;
     }
-    // ds_index == 1 is absolute segment gdt entry
-    return ds_index-1;
+    if(selector >= GDT_STD_SIZE && (selector-GDT_STD_SIZE)%2==1) {
+        int pid = (selector-GDT_STD_SIZE)/2 + 1;
+        return pid;
+    }
+    PANIC(ds, "get_idt_reverse_pid_lookup_ds(ds) is not valid app DS");
 }
 
 // operations
diff --git a/src/memmgr/tables/gdt.c b/src/memmgr/tables/gdt.c
@@ -45,32 +45,40 @@ void populate_gdt_table(
 
     // NULL selector
     populate_gdt_entry(
-        &gdt_table[0],
+        &gdt_table[GDT_STD_SELECTOR_NULL],
         0,0,0,0);
     // Kernel Code Segment Selector
     populate_gdt_entry(
-        &gdt_table[1],
+        &gdt_table[GDT_STD_SELECTOR_KERNEL_CS],
         MEMORY_KERNEL_LOCATION, MEMORY_KERNEL_LOCATION+MEMORY_KERNEL_SIZE-1,
         0b0100,  // 32-bit protected mode
         0x9a);
     // Kernel Data Segment Selector
     populate_gdt_entry(
-        &gdt_table[2],
+        &gdt_table[GDT_STD_SELECTOR_KERNEL_DS],
         MEMORY_KERNEL_LOCATION, MEMORY_KERNEL_LOCATION+MEMORY_KERNEL_SIZE-1,
         0b0100,  // 32-bit protected mode
         0x92);
     // Absolute Code Segment Selector
     populate_gdt_entry(
-        &gdt_table[3],
+        &gdt_table[GDT_STD_SELECTOR_ABS16_CS],
         0, 0xfffff,
         0b0000,  // 16-bit protected mode
         0x9a);
     // Absolute Data Segment Selector
     populate_gdt_entry(
-        &gdt_table[4],
+        &gdt_table[GDT_STD_SELECTOR_ABS16_DS],
         0, 0xfffff,
         0b0000,  // 16-bit protected mode
         0x92);
+    // NOT USING &gdt_table[5] for now.
+    // Absolute Data Segment Selector
+    // populate_gdt_entry(
+    //     &gdt_table[GDT_STD_SELECTOR_ABS32_DS],
+    //     0, 0xffffffff,
+    //     0b0100,  // 32-bit protected mode
+    //     0x92);
+    // Ensure GDT_STD_SIZE = last sector entry+1
 
     gdtr->base_address = ds_fix+(int)gdt_table;
     gdtr->size = (entries_count*sizeof(struct GDTEntry));
diff --git a/src/real_mode/Makefile.mk b/src/real_mode/Makefile.mk
diff --git a/src/real_mode/client.asm b/src/real_mode/client.asm
diff --git a/src/real_mode/static_library.asm b/src/real_mode/static_library.asm
