Module usermode 

User-mode entry point for x86_64

Provides enter_usermode() which pushes the iretq frame and transitions the CPU from Ring 0 to Ring 3. Also provides map_user_page() for creating user-accessible page table entries through the bootloader’s physical memory mapping.

enter_usermode_returnable() is a variant that saves the boot context (callee-saved registers, RSP, CR3) so that sys_exit can restore it and effectively “return” to the caller, allowing sequential user-mode program execution during bootstrap.

Structs

ForkChildRegs

All GPRs needed to resume a forked child in user mode.

Functions

boot_return_to_kernel^⚠

Restore the boot context saved by enter_usermode_returnable and return to the bootstrap code.

enter_forked_child_returnable^⚠

Enter user mode for a forked child, restoring ALL GPRs from regs.

enter_usermode^⚠

Enter user mode for the first time via iretq.

enter_usermode_returnable^⚠

Enter user mode with the ability to return when the process exits.

has_boot_return_context

Check whether a boot return context is available.

try_enter_usermode

Attempt to enter user mode with the embedded init binary.