Kernel-User space switching 1.0

Makefile

@@ -1,8 +1,8 @@
-FILES = ./build/kernel.asm.o ./build/kernel.o ./build/idt/idt.asm.o ./build/idt/idt.o ./build/memory/memory.o ./build/io/io.asm.o ./build/memory/heap/heap.o ./build/memory/heap/kheap.o ./build/memory/paging/paging.o ./build/memory/paging/paging.asm.o ./build/disk/disk.o ./build/string/string.o ./build/fs/pparser.o ./build/disk/streamer.o ./build/fs/file.o ./build/fs/fat/fat16.o ./build/gdt/gdt.o ./build/gdt/gdt.asm.o ./build/task/tss.asm.o ./build/task/task.o
+FILES = ./build/kernel.asm.o ./build/kernel.o ./build/idt/idt.asm.o ./build/idt/idt.o ./build/memory/memory.o ./build/io/io.asm.o ./build/memory/heap/heap.o ./build/memory/heap/kheap.o ./build/memory/paging/paging.o ./build/memory/paging/paging.asm.o ./build/disk/disk.o ./build/string/string.o ./build/fs/pparser.o ./build/disk/streamer.o ./build/fs/file.o ./build/fs/fat/fat16.o ./build/gdt/gdt.o ./build/gdt/gdt.asm.o ./build/task/tss.asm.o ./build/task/task.o ./build/task/process.o ./build/task/task.asm.o ./build/isr80h/isr80h.o ./build/isr80h/misc.o ./build/isr80h/io.o
 INCLUDES = -I./src
 FLAGS = -g -ffreestanding -falign-jumps -falign-functions -falign-lables -falign-loops -fstrength-reduce -fomit-frame-pointer -finline-functions -Wno-unused-function -fno-builtin -Werror -Wno-cpp -Wno-unused-parameter -nostdlib -nostartfiles -nodefaultlibs -Wall -O0 -Iinc
 
-all: ./bin/boot.bin ./bin/kernel.bin
+all: ./bin/boot.bin ./bin/kernel.bin user_programs
 	rm -rf ./bin/os.bin
 	dd if=./bin/boot.bin >> ./bin/os.bin
 	dd if=./bin/kernel.bin >> ./bin/os.bin
@@ -15,6 +15,7 @@ all: ./bin/boot.bin ./bin/kernel.bin
 
 	# copy a file over
 	sudo cp ./hello.txt /mnt/d
+	sudo cp ./programs/blank/blank.bin /mnt/d
 	sudo unmount /mnt/d
 
 ./bin/kernel.bin: $(FILES)
@@ -84,7 +85,28 @@ all: ./bin/boot.bin ./bin/kernel.bin
 ./build/task/task.o: ./src/task/task.c
 	i686-elf-gcc $(INCLUDES) -I./src/task $(FLAGS) -std=gnu99 -c ./src/task/task.c -o ./build/task/task.o
 
-clean:
+./build/task/process.o: ./src/task/process.c
+	i686-elf-gcc $(INCLUDES) -I./src/task $(FLAGS) -std=gnu99 -c ./src/task/process.c -o ./build/task/process.o
+
+./build/task/task.asm.o: ./src/task/task.asm
+	nasm -f elf -g ./src/task/task.asm -o ./build/task/task.asm.o
+
+./build/isr80h/isr80h.o: ./src/isr80h/isr80h.c
+	i686-elf-gcc $(INCLUDES) -I./src/isr80h $(FLAGS) -std=gnu99 -c ./src/isr80h/isr80h.c -o ./build/isr80h/isr80h.o
+
+./build/isr80h/misc.o: ./src/isr80h/misc.c
+	i686-elf-gcc $(INCLUDES) -I./src/isr80h $(FLAGS) -std=gnu99 -c ./src/isr80h/misc.c -o ./build/isr80h/misc.o
+
+./build/isr80h/io.o: ./src/isr80h/io.c
+	i686-elf-gcc $(INCLUDES) -I./src/isr80h $(FLAGS) -std=gnu99 -c ./src/isr80h/io.c -o ./build/isr80h/io.o
+
+user_programs:
+	cd ./programs/blank && $(MAKE) all
+
+user_programs_clean:
+	cd ./programs/blank && $(MAKE) clean
+
+clean: user_programs_clean
 	rm -rf ./bin/boot.bin
 	rm -rf ./bin/kernel.bin
 	rm -rf ./bin/os.bin

build/isr80h/to_keep

@@ -0,0 +1 @@
+as

programs/blank/blank.asm

@@ -0,0 +1,19 @@
+%%if 0
+    creating the first program where it will jump in to itself
+%%endif
+[BITS 32]
+
+section .asm
+
+global _start
+
+_start:
+    push message
+    mov eax, 1 ; command print
+    int 0x80
+    add esp, 4
+
+    jmp $
+
+section .data
+message: db 'This is from user space', 0

programs/blank/build/Makefile

@@ -0,0 +1,6 @@
+all:
+	nasm -f elf ./blank.asm -o ./build/blank.o
+	i686-elf-gcc -g -T ./linker.ld -o ./blank.bin -ffreestanding -O0 -nostdlib -fpic -g ./build/blank.o
+
+clean:
+	rm -rf ./build/blank.o

programs/blank/linker.ld

@@ -0,0 +1,46 @@
+/*
+    Here we are specifing the sections that which section is doing which part
+    and so on.
+
+    Here in SECTIONS '. = 1M' means (1024x1024=100000 (in hex))
+    So we are telling that after the boot go to this location where the
+    kernel.bin is saved and start running from that part.
+
+    Here we are aligning everything properly as we are now coding in C.
+    During assmebly we need not wrry for the alignment but for both 
+    asm and C we need to align otherwise code not work properly.
+
+    So we added times 512 at the end of kernel.asm and here.
+*/
+
+ENTRY(_start)
+OUTPUT_FORMAT(binary)
+SECTIONS
+{
+    . = 0x400000;
+    .text : ALIGN(4096)
+    {
+        *(.text)
+    }
+
+    .asm : ALIGN(4096)
+    {
+        *(.asm)
+    }
+
+    .rodata : ALIGN(4096)
+    {
+        *(.rodata)
+    }
+
+    .data : ALIGN(4096)
+    {
+        *(.data)
+    }
+
+    .bss : ALIGN(4096)
+    {
+        *(COMMON)
+        *(.bss)
+    }
+}

src/boot/boot.asm

@@ -1,4 +1,4 @@
-/*
+%%if 0
     First we need to specify the origin so that Os knows the offset needed for the data
     Ideally the origin should be 0x0000 and then the system should jump to the 
     designated location in the case of this system is 0x7c00.
@@ -18,9 +18,9 @@
     are not enough to fill 510 bytes then it will pad it with 0's.
 
     Now then providing the boot signature which is 0x55AA, but we are writing here 0xAA55 due to endianess.
-*/
+%%endif
 
-/*
+%%if 0
     Use Makefile1 for build
 
     Now to run this in the system using qemu we will first create a binary file '.bin'.
@@ -34,9 +34,9 @@
 
     Now to run on qemu use this cmd
         cmd - 'qemu-system-x86_64 -hda ./boot.bin'
-*/
+%%endif
 
-/*
+%%if 0
 ORG 0x7c00
 BITS 16
 
@@ -50,10 +50,10 @@ start:
 
 times 510-($ - $$) db 0
 dw 0xAA55
-*/
+%%endif
 
 
-/*
+%%if 0
     Use Makefile1 for build
 
     To print custom message on the booting screen we will use the below code.
@@ -87,10 +87,10 @@ message: db 'Hello World!', 0
 times 510-($ - $$) db 0
 dw 0xAA55
 
-*/
+%%endif
 
 
-/*
+%%if 0
     Use Makefile1 for build
 
     Ideally we place our start point 0x0000 and we jump from that to the desired location.
@@ -148,10 +148,10 @@ message: db 'Hello World!', 0
 
 times 510-($ - $$) db 0
 dw 0xAA55
-*/
+%%endif
 
 
-/*
+%%if 0
     Use Makefile1 for build
 
     This section we will write and call custom interrupts for Real Mode. 
@@ -231,11 +231,11 @@ message: db 'Hello World!', 0
 
 times 510-($ - $$) db 0
 dw 0xAA55
-*/
+%%endif
 
 
 
-/*
+%%if 0
     Use Makefile1 for build
 
     Removing the unnecessary things from the code like interrupts and able to read the message.txt
@@ -305,10 +305,10 @@ times 510-($ - $$) db 0
 dw 0xAA55
 
 buffer:
-*/
+%%endif
 
 
-/*
+%%if 0
     For here use Makefile2 and earlier use Makefile1
 
     To start the processor in the protected mode after the real mode.
@@ -410,10 +410,10 @@ load32:
 
 times 510-($ - $$) db 0
 dw 0xAA55
-*/
+%%endif
 
 
-/*
+%%if 0
     From here use Makefile and earlier use Makefile1
 
     Now we are creating another file called kernel.asm so we are using this
@@ -554,14 +554,14 @@ ata_lba_read:
 
 times 510-($ - $$) db 0
 dw 0xAA55
-*/
+%%endif
 
-/*
+%%if 0
     From here use Makefile and earlier use Makefile1
 
     In this we are adding FAT16 system to our booting 
     part so that kernel knows how to read the files.
-*/
+%%endif
 ORG 0x7c00
 BITS 16
 

src/config.h

@@ -30,4 +30,9 @@
 #define USER_DATA_SEGMENT 0x23
 #define USER_CODE_SEGMEnt 0x1b
 
+#define PEACHOS_MAX_PROGRAM_ALLOCATIONS 1024
+#define PEACHOS_MAX_PROCESSES 12
+
+#define PEACHOS_MAX_ISR80H_COMMANDS 1024
+
 #endif

src/gdt/gdt.h

@@ -20,7 +20,7 @@ struct gdt{
     uint8_t access;
     uint8_t high_flags;
     uint8_t base_24_31_bits;
-};
+} __attribute__((packed));
 
 /*
     create another sturcture which will use the gdt struct

src/idt/idt.asm

@@ -6,12 +6,14 @@ section .asm
 
 extern int21g_handler
 extern no_interrupt_handler
+extern isr80h_handler
 
 global int21h
 global idt_load
 global no_interrupt
 global enable_interrupts
 global disable_interrupts
+global isr80h_wrapper
 
 enable_interrupts:
     sti
@@ -31,19 +33,49 @@ idt_load:
     ret
 
 int21h:
-    cli
     pushad
     call int21h_handler
     popad
-    sti
     iret
 
 ; we write this interrupt bcoz we dont want the kernel to do anything else if keyboard 
 ; interrupt occurs otherwise it will loop in bios mode continously
 no_interrupt:
-    cli
     pushad
     call no_interrupt_handler
     popad
-    sti
-    iret
+    iret
+
+; calling kernel from the userspace
+; selecting 0x80 as interrupt to give control to kernel from userspace
+isr80h_wrapper:
+    ; interrupt frame start
+    ; already pushed to us by the processor upon entry to this interrupt
+    ; uint32_t ip;
+    ; uint32_t cs;
+    ; uint32_t flags
+    ; uint32_t sp;
+    ; uint32_t ss;
+    ; pushes the general purpose regs to the stack
+    pushad
+
+    ; interrupt frame end
+
+    ; push the stack pointer so that we are pointing to
+    ; the interrupt frame
+    push esp
+
+    ; EAX holds our cmd lets push it to the stack for isr80h_handler
+    push eax
+    call isr80h_handler
+    mov dword[tmp_res], eax
+    add esp, 8
+
+    ; restore general purpose regs for user land
+    popad
+    mov eax, [tmp_res]
+    iretd
+
+section .data
+; inside here is stored the return result from isr80h_handler
+tmp_res dd 0