Honestly, I am really confused with this particular virtual memory related concept.
Q1) When a page fault occurs, does the processor first finishes the execution of the current instruction and then moves the IP register contents (address of next instruction) to the stack? Or, it aborts current instruction being executed and moves the contents of instruction pointer register to stack?
Q2) If the second case is true, then how does it resume the instruction which was aborted because when if it resumes, the stack contains the instruction pointer value which is nothing but the address of the next instruction. So it will never resume the instruction where the page fault occurred.
What I think
I think the second case sounds wrong. The confusion occurred while i was reading Operating System Principles by Silbershatz and Galvin. In that they have written
when a page fault occurs, we will have to bring in the desired page, correct page table and restart the instruction.
But the instruction pointer always points to the address of the next instruction so it means, according to what this book is trying to convey, we are decrementing the value of IP just to restart the execution of the instruction where the page fault occurred?
In the Intel System Programming guide, chapter 6.5, it says
A page fault is classified as a fault (no surprises there), so when a page fault happened you're in the state "before it ever happened" - well not really, because you're in the fault handler (so EIP and ESP are definitely different, also CR2 contains the address), but when you return it'll be the state before the ever happened, only with changes made by the handler (so, put there page there, or kill the process)