sw/device/lib/virtual_memory.h

/*
 * Copyright 2023 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef SW_DEVICE_LIB_VIRTUAL_MEMORY_H_
#define SW_DEVICE_LIB_VIRTUAL_MEMORY_H_

#include <stdbool.h>
#include <stdint.h>

#define PAGE_SIZE (0x1000)

// Add a page table entry for a megapage, which maps
// a 4MB region in virtual memory.
void machine_map_megapage(void *paddr, void *vaddr, uint32_t *pt);

// Generate 2-level page table entries to cover a specified region.
void machine_map_region(uint32_t paddr, uint32_t vaddr_start,
                        uint32_t vaddr_end, uint32_t *l1pt, uint32_t *l2pt,
                        bool user);

// Trampoline that writes the page table base, exception and interrupt
// delegation, and S-mode trap vector. Afterwards, returns into supervisor mode.
void supervisor_trampoline(uint32_t a0_smode_fn, uint32_t a1_satp,
                           uint32_t a2_medeleg, uint32_t a3_stvec,
                           uint32_t a4_mideleg);

// Trampoline that drops into U-mode, at the given address.
void user_trampoline(uint32_t a0_umode_fn);

#endif  // SW_DEVICE_LIB_VIRTUAL_MEMORY_H_