Abstract: A computer system has a microprocessor that can execute in a non-privileged user mode and a privileged kernel mode. A user virtual address space is used when the microprocessor is in the user mode, and a kernel virtual address space is used when the microprocessor is in the kernel mode. Each of the address spaces has the same range of virtual addresses that is designated for shared components. The user virtual address space is mapped to an offset position within the kernel address space. When a user process calls a kernel function with a pointer argument, the pointer is biased before being dereferenced to account for the offset of the user address space within the kernel address space. This allows for sharing of position-dependent code, while still allowing the kernel to access the entire user address space.

Abstract: The invention described herein works in conjunction with a processor having an address translation cache that is updated by referencing a page table directory and a plurality of associated page tables referenced by the page table directory. The page table directory and a single page table are configured to generate a memory fault whenever the processor attempts to update its address translation cache. In response to such a memory fault, a memory fault handler temporarily loads a single page table entry with the needed address translation. In addition, the memory fault handler initializes the page table directory so that it references the single page table entry that has been loaded. Control is then returned from the memory fault handler, and the processor obtains the address translation. In response to a subsequent memory fault, the memory fault handler invalidates the previously loaded entry, and loads whatever address translation is currently needed by the processor.

Abstract: The invention includes a computer system having a processor that executes program instructions in privileged and non-privileged execution modes. A user stack is used when the processor is executing in the non-privileged execution mode. A kernel memory stack is used when the processor is executing in the privileged execution mode. The kernel memory stack can grow and shrink dynamically as it is used by its associated thread, through the use of allocate-on-demand memory. A stack overflow handler is executed from within the kernel to resolve allocate-on-demand faults. The stack handler uses only fixed-size memory stacks.