dotraplinkage void __kprobes
do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
struct vm_area_struct *vma;
struct task_struct *tsk;
unsigned long address;
struct mm_struct *mm;
int write;
int fault;
tsk = current; //擷取目前程序
mm = tsk->mm; //擷取目前程序的位址空間
address = read_cr2(); //讀取CR2寄存器擷取觸發異常的通路位址
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vma = find_vma(mm, address);//試圖尋找到一個離address最近的vma，vma包含address或在address之後
if (unlikely(!vma)) {
bad_area(regs, error_code, address);
return;
}
if (likely(vma->vm_start <= address))
goto good_area;
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
bad_area(regs, error_code, address);//不是堆棧區域，則用bad_area()來處理
return;
}
if (error_code & PF_USER) {//必須處于使用者空間
if (unlikely(address + 65536 + 32 * sizeof(unsigned long) < regs->sp)) {
bad_area(regs, error_code, address);
return;
}
}
if (unlikely(expand_stack(vma, address))) {//堆棧擴充不成功同樣由bad_area()處理
bad_area(regs, error_code, address);
return;
}
good_area:
write = error_code & PF_WRITE;
if (unlikely(access_error(error_code, write, vma))) {
bad_area_access_error(regs, error_code, address);
return;
}
fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0);
if (unlikely(fault & VM_FAULT_ERROR)) {
mm_fault_error(regs, error_code, address, fault);
return;
}
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, 0,
regs, address);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, 0,
regs, address);
}
check_v8086_mode(regs, address, tsk);
up_read(&mm->mmap_sem);
}