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🆕 do_execve函数，跳转至应用层

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This commit is contained in:
fslongjin
2022-02-13 22:41:35 +08:00
parent 781a105d2f
commit 0757e7a3cd
8 changed files with 178 additions and 93 deletions
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119
kernel/process/process.c
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@ -26,7 +26,38 @@ void __switch_to(struct process_control_block *prev, struct process_control_bloc
__asm__ __volatile__("movq %0, %%fs \n\t" ::"a"(next->thread->fs));
__asm__ __volatile__("movq %0, %%gs \n\t" ::"a"(next->thread->gs));
}
/**
* @brief 这是一个用户态的程序
*
*/
void user_level_function()
{
kinfo("Program (user_level_function) is runing...");
while(1);
}
/**
* @brief 使当前进程去执行新的代码
*
* @param regs 当前进程的寄存器
* @return ul 错误码
*/
ul do_execve(struct pt_regs *regs)
{
// 选择这两个寄存器是对应了sysexit指令的需要
regs->rdx = 0x800000; // rip 应用层程序的入口地址 这里的地址选择没有特殊要求，只要是未使用的内存区域即可。
regs->rcx = 0xa00000; // rsp 应用层程序的栈顶地址
regs->rax = 1;
regs->ds = 0;
regs->es = 0;
kdebug("do_execve is running...");
// 将程序代码拷贝到对应的内存中
memcpy((void *)0x800000, user_level_function, 1024);
return 0;
}
/**
@ -38,6 +69,21 @@ void __switch_to(struct process_control_block *prev, struct process_control_bloc
ul initial_kernel_thread(ul arg)
{
kinfo("initial proc running...\targ:%#018lx", arg);
struct pt_regs *regs;
current_pcb->thread->rip = (ul)ret_from_system_call;
current_pcb->thread->rsp = (ul)current_pcb + STACK_SIZE - sizeof(struct pt_regs);
regs = (struct pt_regs *)current_pcb->thread->rsp;
// 将返回用户层的代码压入堆栈，向rdx传入regs的地址，然后jmp到do_execve这个系统调用api的处理函数 这里的设计思路和switch_proc类似
__asm__ __volatile__("movq %1, %%rsp \n\t"
"pushq %2 \n\t"
"jmp do_execve \n\t" ::"D"(regs),
"m"(current_pcb->thread->rsp), "m"(current_pcb->thread->rip)
: "memory");
return 1;
}
@ -62,35 +108,33 @@ ul do_exit(ul code)
*/
extern void kernel_thread_func(void);
__asm__ (
"kernel_thread_func: \n\t"
" popq %r15 \n\t"
" popq %r14 \n\t"
" popq %r13 \n\t"
" popq %r12 \n\t"
" popq %r11 \n\t"
" popq %r10 \n\t"
" popq %r9 \n\t"
" popq %r8 \n\t"
" popq %rbx \n\t"
" popq %rcx \n\t"
" popq %rdx \n\t"
" popq %rsi \n\t"
" popq %rdi \n\t"
" popq %rbp \n\t"
" popq %rax \n\t"
" movq %rax, %ds \n\t"
" popq %rax \n\t"
" movq %rax, %es \n\t"
" popq %rax \n\t"
" addq $0x38, %rsp \n\t"
/////////////////////////////////
" movq %rdx, %rdi \n\t"
" callq *%rbx \n\t"
" movq %rax, %rdi \n\t"
" callq do_exit \n\t"
);
__asm__(
"kernel_thread_func: \n\t"
" popq %r15 \n\t"
" popq %r14 \n\t"
" popq %r13 \n\t"
" popq %r12 \n\t"
" popq %r11 \n\t"
" popq %r10 \n\t"
" popq %r9 \n\t"
" popq %r8 \n\t"
" popq %rbx \n\t"
" popq %rcx \n\t"
" popq %rdx \n\t"
" popq %rsi \n\t"
" popq %rdi \n\t"
" popq %rbp \n\t"
" popq %rax \n\t"
" movq %rax, %ds \n\t"
" popq %rax \n\t"
" movq %rax, %es \n\t"
" popq %rax \n\t"
" addq $0x38, %rsp \n\t"
/////////////////////////////////
" movq %rdx, %rdi \n\t"
" callq *%rbx \n\t"
" movq %rax, %rdi \n\t"
" callq do_exit \n\t");
/**
* @brief 初始化内核进程
@ -116,7 +160,6 @@ int kernel_thread(unsigned long (*fn)(unsigned long), unsigned long arg, unsigne
regs.cs = KERNEL_CS;
regs.ss = KERNEL_DS;
// 置位中断使能标志位
regs.rflags = (1 << 9);
@ -129,7 +172,6 @@ int kernel_thread(unsigned long (*fn)(unsigned long), unsigned long arg, unsigne
void process_init()
{
initial_mm.pgd = (pml4t_t *)global_CR3;
initial_mm.code_addr_start = memory_management_struct.kernel_code_start;
@ -146,23 +188,24 @@ void process_init()
initial_mm.stack_start = _stack_start;
// 向MSR寄存器组中的 IA32_SYSENTER_CS寄存器写入内核的代码段的地址
wrmsr(0x174, KERNEL_CS);
// 初始化进程和tss
set_TSS64(initial_thread.rbp, initial_tss[0].rsp1, initial_tss[0].rsp2, initial_tss[0].ist1, initial_tss[0].ist2, initial_tss[0].ist3, initial_tss[0].ist4, initial_tss[0].ist5, initial_tss[0].ist6, initial_tss[0].ist7);
initial_tss[0].rsp0 = initial_thread.rbp;
// 初始化进程的循环链表
list_init(&initial_proc_union.pcb.list);
kernel_thread(initial_kernel_thread, 10, CLONE_FS | CLONE_FILES | CLONE_SIGNAL); // 初始化内核进程
initial_proc_union.pcb.state = PROC_RUNNING;
// 获取新的进程的pcb
struct process_control_block *p = container_of(list_next(&current_pcb->list), struct process_control_block, list);
// 切换到新的内核线程
// 切换到新的内核线程
switch_proc(current_pcb, p);
}
@ -180,14 +223,11 @@ unsigned long do_fork(struct pt_regs *regs, unsigned long clone_flags, unsigned
{
struct process_control_block *tsk = NULL;
// 获取一个物理页并在这个物理页内初始化pcb
struct Page *pp = alloc_pages(ZONE_NORMAL, 1, PAGE_PGT_MAPPED | PAGE_ACTIVE | PAGE_KERNEL);
tsk = (struct process_control_block *)phys_2_virt(pp->addr_phys);
memset(tsk, 0, sizeof(*tsk));
// 将当前进程的pcb复制到新的pcb内
@ -198,7 +238,6 @@ unsigned long do_fork(struct pt_regs *regs, unsigned long clone_flags, unsigned
list_add(&initial_proc_union.pcb.list, &tsk->list);
++(tsk->pid);
tsk->state = PROC_UNINTERRUPTIBLE;
@ -214,9 +253,9 @@ unsigned long do_fork(struct pt_regs *regs, unsigned long clone_flags, unsigned
thd->rip = regs->rip;
thd->rsp = (ul)tsk + STACK_SIZE - sizeof(struct pt_regs);
// 若进程不是内核层的进程，则跳转到ret from intr
// 若进程不是内核层的进程，则跳转到ret from system call
if (!(tsk->flags & PF_KTHREAD))
thd->rip = regs->rip = (ul)ret_from_intr;
thd->rip = regs->rip = (ul)ret_from_system_call;
tsk->state = PROC_RUNNING;