Implement user process

Enterprise 2023-09-09 08:51:25 views: null

Article directory

Preface

The blog records the operation of the experiment in Chapter 11 of "Restore the Truth of the Operating System"~

Experimental environment: ubuntu18.04+VMware, Bochs download and install

Experiment content:

  1. Define and initialize TSS.
  2. Implement user processes.

prerequisite knowledge

Introduction to TSS

TSS, Task State Segment, task status segment. It is a way for the processor to natively support multitasking in hardware, which means that the processor originally wanted operating system developers to use this structure to implement multitasking.

TSS is a fixed-format data structure used to store the environment of a task.

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The operation of Linux TSS is to load TSS(TR) once ~

Task switching methods used by modern operating systems

  • When an interrupt occurs in user mode (privilege level 3), the processor will get the values ​​of SS0 and ESP0 fields from the TSS of the current task.
  • Only one TSS is created per CPU, and all tasks executing on each CPU share one TSS.
  • After a TR loads a TSS, the TR register will always point to that TSS, and the TSS will never be reloaded.
  • When the process is switched, it is only necessary to update SS0 and ESP0 in the TSS to the segment address and stack pointer of the kernel stack of the new task.
  • Linux's operation on TSS is to load the TSS to TR once, and then modify the content of the same TSS continuously, without repeated loading.
  • Task switching in Linux does not use call and jmp instructions, which avoids the inefficiency of task switching.

user process

Flowchart for creating and executing processes

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Reference from: "Operating System - Truth Restoration" 11. User Process

Experimental operation

experiment one

Reviseglobal.h

Create a new one tss.c( tss.hPlace it in the newly created userprog directory. This directory stores code files related to the user process)

[Note]: tss.h refers to the path of thread

Reviseinit.c

makefile

BUILD_DIR = ./build
ENTRY_POINT = 0xc0001500
AS = nasm
CC = gcc
LD = ld
LIB = -I lib/ -I lib/kernel/ -I lib/user/ -I kernel/ -I device/ 
ASFLAGS = -f elf
CFLAGS = -Wall -m32 -fno-stack-protector $(LIB) -c -fno-builtin -W -Wstrict-prototypes -Wmissing-prototypes
LDFLAGS =  -m elf_i386 -Ttext $(ENTRY_POINT) -e main -Map $(BUILD_DIR)/kernel.map
OBJS = $(BUILD_DIR)/main.o $(BUILD_DIR)/init.o $(BUILD_DIR)/interrupt.o \
      $(BUILD_DIR)/timer.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/print.o $(BUILD_DIR)/switch.o \
      $(BUILD_DIR)/debug.o $(BUILD_DIR)/string.o $(BUILD_DIR)/memory.o \
      $(BUILD_DIR)/bitmap.o $(BUILD_DIR)/thread.o $(BUILD_DIR)/list.o \
      $(BUILD_DIR)/sync.o $(BUILD_DIR)/console.o $(BUILD_DIR)/keyboard.o \
      $(BUILD_DIR)/ioqueue.o $(BUILD_DIR)/tss.o
      
##############     c代码编译     ###############
$(BUILD_DIR)/main.o: kernel/main.c lib/kernel/print.h \
        lib/stdint.h kernel/init.h lib/string.h kernel/memory.h \
        thread/thread.h kernel/interrupt.h device/console.h \
        device/keyboard.h device/ioqueue.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/init.o: kernel/init.c kernel/init.h lib/kernel/print.h \
        lib/stdint.h kernel/interrupt.h device/timer.h kernel/memory.h \
        thread/thread.h device/console.h device/keyboard.h userprog/tss.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/interrupt.o: kernel/interrupt.c kernel/interrupt.h \
        lib/stdint.h kernel/global.h lib/kernel/io.h lib/kernel/print.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/timer.o: device/timer.c device/timer.h lib/kernel/io.h lib/kernel/print.h \
        kernel/interrupt.h thread/thread.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/debug.o: kernel/debug.c kernel/debug.h \
        lib/kernel/print.h lib/stdint.h kernel/interrupt.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/string.o: lib/string.c lib/string.h \
	kernel/debug.h kernel/global.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/memory.o: kernel/memory.c kernel/memory.h \
	lib/stdint.h lib/kernel/bitmap.h kernel/debug.h lib/string.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/bitmap.o: lib/kernel/bitmap.c lib/kernel/bitmap.h kernel/global.h \
	lib/string.h kernel/interrupt.h lib/kernel/print.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/thread.o: thread/thread.c thread/thread.h \
	lib/stdint.h lib/string.h kernel/global.h kernel/memory.h \
	kernel/debug.h kernel/interrupt.h lib/kernel/print.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/list.o: lib/kernel/list.c lib/kernel/list.h \
	kernel/interrupt.h lib/stdint.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/sync.o: thread/sync.c thread/sync.h \
	lib/stdint.h thread/thread.h kernel/debug.h kernel/interrupt.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/console.o: device/console.c device/console.h \
	lib/kernel/print.h thread/sync.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/keyboard.o: device/keyboard.c device/keyboard.h \
	lib/kernel/print.h lib/kernel/io.h kernel/interrupt.h \
	kernel/global.h lib/stdint.h device/ioqueue.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/ioqueue.o: device/ioqueue.c device/ioqueue.h \
	kernel/interrupt.h kernel/global.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/tss.o: userprog/tss.c userprog/tss.h \
	kernel/global.h thread/thread.h lib/kernel/print.h
	$(CC) $(CFLAGS) $< -o $@
	
##############    汇编代码编译    ###############
$(BUILD_DIR)/kernel.o: kernel/kernel.S
	$(AS) $(ASFLAGS) $< -o $@

$(BUILD_DIR)/print.o: lib/kernel/print.S
	$(AS) $(ASFLAGS) $< -o $@

$(BUILD_DIR)/switch.o: thread/switch.S
	$(AS) $(ASFLAGS) $< -o $@

##############    链接所有目标文件    #############
$(BUILD_DIR)/kernel.bin: $(OBJS)
	$(LD) $(LDFLAGS) $^ -o $@

.PHONY : mk_dir hd clean all

mk_dir:
	if [ ! -d $(BUILD_DIR) ]; then mkdir $(BUILD_DIR); fi

hd:
	dd if=$(BUILD_DIR)/kernel.bin \
           of=/home/cooiboi/bochs/boot/hd60M.img \
           bs=512 count=200 seek=9 conv=notrunc

clean:
	cd $(BUILD_DIR) && rm -f  ./*

build: $(BUILD_DIR)/kernel.bin

all: mk_dir build hd

Insert image description here
Insert image description here

Experiment 2

Modify thread.h, thread.c, global.h, memory.c, memory.h, thread.c, thread.h.

write process.c,process.h

makefile

BUILD_DIR = ./build
ENTRY_POINT = 0xc0001500
AS = nasm
CC = gcc
LD = ld
LIB = -I lib/ -I lib/kernel/ -I lib/user/ -I kernel/ -I device/ 
ASFLAGS = -f elf
CFLAGS = -Wall -m32 -fno-stack-protector $(LIB) -c -fno-builtin -W -Wstrict-prototypes -Wmissing-prototypes
LDFLAGS =  -m elf_i386 -Ttext $(ENTRY_POINT) -e main -Map $(BUILD_DIR)/kernel.map
OBJS = $(BUILD_DIR)/main.o $(BUILD_DIR)/init.o $(BUILD_DIR)/interrupt.o \
      $(BUILD_DIR)/timer.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/print.o $(BUILD_DIR)/switch.o \
      $(BUILD_DIR)/debug.o $(BUILD_DIR)/string.o $(BUILD_DIR)/memory.o \
      $(BUILD_DIR)/bitmap.o $(BUILD_DIR)/thread.o $(BUILD_DIR)/list.o \
      $(BUILD_DIR)/sync.o $(BUILD_DIR)/console.o $(BUILD_DIR)/keyboard.o \
      $(BUILD_DIR)/ioqueue.o $(BUILD_DIR)/tss.o $(BUILD_DIR)/process.o
      
##############     c代码编译     ###############
$(BUILD_DIR)/main.o: kernel/main.c lib/kernel/print.h \
        lib/stdint.h kernel/init.h lib/string.h kernel/memory.h \
        thread/thread.h kernel/interrupt.h device/console.h \
        device/keyboard.h device/ioqueue.h userprog/process.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/init.o: kernel/init.c kernel/init.h lib/kernel/print.h \
        lib/stdint.h kernel/interrupt.h device/timer.h kernel/memory.h \
        thread/thread.h device/console.h device/keyboard.h userprog/tss.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/interrupt.o: kernel/interrupt.c kernel/interrupt.h \
        lib/stdint.h kernel/global.h lib/kernel/io.h lib/kernel/print.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/timer.o: device/timer.c device/timer.h lib/kernel/io.h lib/kernel/print.h \
        kernel/interrupt.h thread/thread.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@

$(BUILD_DIR)/debug.o: kernel/debug.c kernel/debug.h \
        lib/kernel/print.h lib/stdint.h kernel/interrupt.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/string.o: lib/string.c lib/string.h \
	kernel/debug.h kernel/global.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/memory.o: kernel/memory.c kernel/memory.h \
	lib/stdint.h lib/kernel/bitmap.h kernel/debug.h lib/string.h \
	thread/sync.h thread/thread.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/bitmap.o: lib/kernel/bitmap.c lib/kernel/bitmap.h kernel/global.h \
	lib/string.h kernel/interrupt.h lib/kernel/print.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/thread.o: thread/thread.c thread/thread.h \
	lib/stdint.h lib/string.h kernel/global.h kernel/memory.h \
	kernel/debug.h kernel/interrupt.h lib/kernel/print.h \
	userprog/process.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/list.o: lib/kernel/list.c lib/kernel/list.h \
	kernel/interrupt.h lib/stdint.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/sync.o: thread/sync.c thread/sync.h \
	lib/stdint.h thread/thread.h kernel/debug.h kernel/interrupt.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/console.o: device/console.c device/console.h \
	lib/kernel/print.h thread/sync.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/keyboard.o: device/keyboard.c device/keyboard.h \
	lib/kernel/print.h lib/kernel/io.h kernel/interrupt.h \
	kernel/global.h lib/stdint.h device/ioqueue.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/ioqueue.o: device/ioqueue.c device/ioqueue.h \
	kernel/interrupt.h kernel/global.h kernel/debug.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/tss.o: userprog/tss.c userprog/tss.h \
	kernel/global.h thread/thread.h lib/kernel/print.h
	$(CC) $(CFLAGS) $< -o $@
	
$(BUILD_DIR)/process.o: userprog/process.c userprog/process.h \
	lib/string.h kernel/global.h kernel/memory.h lib/kernel/print.h \
	thread/thread.h kernel/interrupt.h kernel/debug.h device/console.h
	$(CC) $(CFLAGS) $< -o $@
	
##############    汇编代码编译    ###############
$(BUILD_DIR)/kernel.o: kernel/kernel.S
	$(AS) $(ASFLAGS) $< -o $@

$(BUILD_DIR)/print.o: lib/kernel/print.S
	$(AS) $(ASFLAGS) $< -o $@

$(BUILD_DIR)/switch.o: thread/switch.S
	$(AS) $(ASFLAGS) $< -o $@

##############    链接所有目标文件    #############
$(BUILD_DIR)/kernel.bin: $(OBJS)
	$(LD) $(LDFLAGS) $^ -o $@

.PHONY : mk_dir hd clean all

mk_dir:
	if [ ! -d $(BUILD_DIR) ]; then mkdir $(BUILD_DIR); fi

hd:
	dd if=$(BUILD_DIR)/kernel.bin \
           of=/home/cooiboi/bochs/boot/hd60M.img \
           bs=512 count=200 seek=9 conv=notrunc

clean:
	cd $(BUILD_DIR) && rm -f  ./*

build: $(BUILD_DIR)/kernel.bin

all: mk_dir build hd


sudo bin/bochs -f boot/bochsrc.disk

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