include/zephyr/kernel/internal/mm.h

/*
 * Copyright (c) 2020 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#ifndef ZEPHYR_INCLUDE_KERNEL_INTERNAL_MM_H
#define ZEPHYR_INCLUDE_KERNEL_INTERNAL_MM_H

#include <zephyr/sys/util.h>
#include <zephyr/toolchain.h>

/**
 * @defgroup kernel_mm_internal_apis Kernel Memory Management Internal APIs
 * @ingroup internal_api
 * @{
 */

/*
 * This is the offset to subtract from a virtual address mapped in the
 * kernel's permanent mapping of RAM, to obtain its physical address.
 *
 *     virt_addr = phys_addr + Z_MEM_VM_OFFSET
 *
 * This only works for virtual addresses within the interval
 * [CONFIG_KERNEL_VM_BASE, CONFIG_KERNEL_VM_BASE + (CONFIG_SRAM_SIZE * 1024)).
 *
 * These macros are intended for assembly, linker code, and static initializers.
 * Use with care.
 *
 * Note that when demand paging is active, these will only work with page
 * frames that are pinned to their virtual mapping at boot.
 *
 * TODO: This will likely need to move to an arch API or need additional
 * constraints defined.
 */
#ifdef CONFIG_MMU
#define Z_MEM_VM_OFFSET	((CONFIG_KERNEL_VM_BASE + CONFIG_KERNEL_VM_OFFSET) - \
			 (CONFIG_SRAM_BASE_ADDRESS + CONFIG_SRAM_OFFSET))
#else
#define Z_MEM_VM_OFFSET	0
#endif /* CONFIG_MMU */

#define Z_MEM_PHYS_ADDR(virt)	((virt) - Z_MEM_VM_OFFSET)
#define Z_MEM_VIRT_ADDR(phys)	((phys) + Z_MEM_VM_OFFSET)

#if Z_MEM_VM_OFFSET != 0
#define Z_VM_KERNEL 1
#ifdef CONFIG_XIP
#error "XIP and a virtual memory kernel are not allowed"
#endif
#endif

#ifndef _ASMLANGUAGE
#include <stdint.h>
#include <stddef.h>
#include <inttypes.h>
#include <zephyr/sys/__assert.h>
#include <zephyr/sys/mem_manage.h>

/* Just like Z_MEM_PHYS_ADDR() but with type safety and assertions */
static inline uintptr_t z_mem_phys_addr(void *virt)
{
	uintptr_t addr = (uintptr_t)virt;

#if defined(CONFIG_KERNEL_VM_USE_CUSTOM_MEM_RANGE_CHECK)
	__ASSERT(sys_mm_is_virt_addr_in_range(virt),
		 "address %p not in permanent mappings", virt);
#elif defined(CONFIG_MMU)
	__ASSERT(
#if CONFIG_KERNEL_VM_BASE != 0
		 (addr >= CONFIG_KERNEL_VM_BASE) &&
#endif /* CONFIG_KERNEL_VM_BASE != 0 */
#if (CONFIG_KERNEL_VM_BASE + CONFIG_KERNEL_VM_SIZE) != 0
		 (addr < (CONFIG_KERNEL_VM_BASE +
			  (CONFIG_KERNEL_VM_SIZE))),
#else
		 false,
#endif /* CONFIG_KERNEL_VM_BASE + CONFIG_KERNEL_VM_SIZE != 0 */
		 "address %p not in permanent mappings", virt);
#else
	/* Should be identity-mapped */
	__ASSERT(
#if CONFIG_SRAM_BASE_ADDRESS != 0
		 (addr >= CONFIG_SRAM_BASE_ADDRESS) &&
#endif /* CONFIG_SRAM_BASE_ADDRESS != 0 */
#if (CONFIG_SRAM_BASE_ADDRESS + (CONFIG_SRAM_SIZE * 1024UL)) != 0
		 (addr < (CONFIG_SRAM_BASE_ADDRESS +
			  (CONFIG_SRAM_SIZE * 1024UL))),
#else
		 false,
#endif /* (CONFIG_SRAM_BASE_ADDRESS + (CONFIG_SRAM_SIZE * 1024UL)) != 0 */
		 "physical address 0x%lx not in RAM",
		 (unsigned long)addr);
#endif /* CONFIG_MMU */

	/* TODO add assertion that this page is pinned to boot mapping,
	 * the above checks won't be sufficient with demand paging
	 */

	return Z_MEM_PHYS_ADDR(addr);
}

/* Just like Z_MEM_VIRT_ADDR() but with type safety and assertions */
static inline void *z_mem_virt_addr(uintptr_t phys)
{
#if defined(CONFIG_KERNEL_VM_USE_CUSTOM_MEM_RANGE_CHECK)
	__ASSERT(sys_mm_is_phys_addr_in_range(phys),
		"physical address 0x%lx not in RAM", (unsigned long)phys);
#else
	__ASSERT(
#if CONFIG_SRAM_BASE_ADDRESS != 0
		 (phys >= CONFIG_SRAM_BASE_ADDRESS) &&
#endif /* CONFIG_SRAM_BASE_ADDRESS != 0 */
#if (CONFIG_SRAM_BASE_ADDRESS + (CONFIG_SRAM_SIZE * 1024UL)) != 0
		 (phys < (CONFIG_SRAM_BASE_ADDRESS +
			  (CONFIG_SRAM_SIZE * 1024UL))),
#else
		 false,
#endif /* (CONFIG_SRAM_BASE_ADDRESS + (CONFIG_SRAM_SIZE * 1024UL)) != 0 */
		 "physical address 0x%lx not in RAM", (unsigned long)phys);
#endif /* CONFIG_KERNEL_VM_USE_CUSTOM_MEM_RANGE_CHECK */

	/* TODO add assertion that this page frame is pinned to boot mapping,
	 * the above check won't be sufficient with demand paging
	 */

	return (void *)Z_MEM_VIRT_ADDR(phys);
}

#ifdef __cplusplus
extern "C" {
#endif

/**
 * Map a physical memory region into the kernel's virtual address space
 *
 * This function is intended for mapping memory-mapped I/O regions into
 * the virtual address space. Given a physical address and a size, return a
 * linear address representing the base of where the physical region is mapped
 * in the virtual address space for the Zephyr kernel.
 *
 * This function alters the active page tables in the area reserved
 * for the kernel. This function will choose the virtual address
 * and return it to the caller.
 *
 * Portable code should never assume that phys_addr and linear_addr will
 * be equal.
 *
 * Caching and access properties are controlled by the 'flags' parameter.
 * Unused bits in 'flags' are reserved for future expansion.
 * A caching mode must be selected. By default, the region is read-only
 * with user access and code execution forbidden. This policy is changed
 * by passing K_MEM_CACHE_* and K_MEM_PERM_* macros into the 'flags' parameter.
 *
 * If there is insufficient virtual address space for the mapping this will
 * generate a kernel panic.
 *
 * This API is only available if CONFIG_MMU is enabled.
 *
 * It is highly discouraged to use this function to map system RAM page
 * frames. It may conflict with anonymous memory mappings and demand paging
 * and produce undefined behavior.  Do not use this for RAM unless you know
 * exactly what you are doing. If you need a chunk of memory, use k_mem_map().
 * If you need a contiguous buffer of physical memory, statically declare it
 * and pin it at build time, it will be mapped when the system boots.
 *
 * This API is part of infrastructure still under development and may
 * change.
 *
 * @param[out] virt Output virtual address storage location
 * @param[in]  phys Physical address base of the memory region
 * @param[in]  size Size of the memory region
 * @param[in]  flags Caching mode and access flags, see K_MAP_* macros
 */
void z_phys_map(uint8_t **virt_ptr, uintptr_t phys, size_t size,
		uint32_t flags);

/**
 * Unmap a virtual memory region from kernel's virtual address space.
 *
 * This function is intended to be used by drivers and early boot routines
 * where temporary memory mappings need to be made. This allows these
 * memory mappings to be discarded once they are no longer needed.
 *
 * This function alters the active page tables in the area reserved
 * for the kernel.
 *
 * This will align the input parameters to page boundaries so that
 * this can be used with the virtual address as returned by
 * z_phys_map().
 *
 * This API is only available if CONFIG_MMU is enabled.
 *
 * It is highly discouraged to use this function to unmap memory mappings.
 * It may conflict with anonymous memory mappings and demand paging and
 * produce undefined behavior. Do not use this unless you know exactly
 * what you are doing.
 *
 * This API is part of infrastructure still under development and may
 * change.
 *
 * @param virt Starting address of the virtual address region to be unmapped.
 * @param size Size of the virtual address region
 */
void z_phys_unmap(uint8_t *virt, size_t size);

#ifdef __cplusplus
}
#endif

/** @} */

#endif /* !_ASMLANGUAGE */
#endif /* ZEPHYR_INCLUDE_KERNEL_INTERNAL_MM_H */