We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.
Hi experts，
In ARMv8, EL1/2/3 can use either their own stack pointer, SP_ELx or SP_EL0.
SP_EL0 can be used in EL0.
why it is safe to use SP_EL0 in EL1/2/3? I think the applications in EL0 may get the data of kernel in EL1 through SP_EL0.
Can anybody explain why? Thank you!
The kernel uses SP_EL0 but it doesn't use the EL0 stack.
As part of the transition between states SP_EL0 is changed to point at the kernel stack (and changed back to point at the thread's stack on return to EL0.)
Thank you very much. But I dont quite understand it.
You mean, both SP_EL0 and SP_EL1 points at the kernel stack when OS is running?
What I understand (I could be wrong) is, when the code is running on the OS kernel (EL1), the SP_EL0 points at the kernel stack and the data push into the stack. Then, a exception occured, the SP_EL0 switches to SP_EL1 that points at a new address(new kernel stack?).
If understood in this way, are there two stacks in EL1?
Please tell me where I got wrong, thanks.