Finally we got usermode working again, It took awhile but we got it done. A few things we did in this commit:
- Simplified GDT entry initialization in gdt.c for kernel and user segments.
- Fixed TSS structure for task switching.
- Implemented cr2 handling in a page fault.
- Enhanced user stack setup in usermode.c to return the correct RSP.
- Improved syscall implementation in syscall.c, including new syscall numbers.
- Updated syscall entry to correctly handle context switching and argument passing.
- Refactored init.c to demonstrate file operations using syscalls.
- Added new syscalls for file operations in syscalls.h.
- Modified VFS to handle leading slashes in paths correctly.
Signed-off-by: kaguya <vpshinomiya@protonmail.com>