Function rustsbi::enter_privileged

pub unsafe fn enter_privileged(mhartid: usize, opaque: usize) -> !

Enter lower privilege from M code with given SBI parameters.

Before calling this function, you must write target start address into mepc register, and write target privilege into mstatus register. Platform binarys should call this function on all harts to enter lower privilege levels after the initialization process is finished.

After this function is called, the stack pointer register sp is swapped with mscratch, and a mret is called to return to mepc address with target privilege.

Unsafety

This function implictly returns to the program address with the address from mepc register. Caller must ensure that the value in mepc is a valid program address. Caller should also ensure that mstatus.MPP register bits contain valid target privilege level.

Example

unsafe {
    mepc::write(_s_mode_start as usize);
    mstatus::set_mpp(MPP::Supervisor);
    enter_privileged(mhartid::read(), dtb_pa);
}