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/*
* Copyright (c) 2020 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*
* Routines for managing virtual address spaces
*/
#include <stdint.h>
#include <kernel_arch_interface.h>
#include <zephyr/spinlock.h>
#include <mmu.h>
#include <zephyr/init.h>
#include <kernel_internal.h>
#include <zephyr/internal/syscall_handler.h>
#include <zephyr/toolchain.h>
#include <zephyr/linker/linker-defs.h>
#include <zephyr/sys/bitarray.h>
#include <zephyr/sys/check.h>
#include <zephyr/sys/math_extras.h>
#include <zephyr/timing/timing.h>
#include <zephyr/logging/log.h>
LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
#ifdef CONFIG_DEMAND_PAGING
#include <zephyr/kernel/mm/demand_paging.h>
#endif /* CONFIG_DEMAND_PAGING */
/*
* General terminology:
* - A page frame is a page-sized physical memory region in RAM. It is a
* container where a data page may be placed. It is always referred to by
* physical address. We have a convention of using uintptr_t for physical
* addresses. We instantiate a struct k_mem_page_frame to store metadata for
* every page frame.
*
* - A data page is a page-sized region of data. It may exist in a page frame,
* or be paged out to some backing store. Its location can always be looked
* up in the CPU's page tables (or equivalent) by virtual address.
* The data type will always be void * or in some cases uint8_t * when we
* want to do pointer arithmetic.
*/
/* Spinlock to protect any globals in this file and serialize page table
* updates in arch code
*/
struct k_spinlock z_mm_lock;
/*
* General page frame management
*/
/* Database of all RAM page frames */
struct k_mem_page_frame k_mem_page_frames[K_MEM_NUM_PAGE_FRAMES];
#if __ASSERT_ON
/* Indicator that k_mem_page_frames has been initialized, many of these APIs do
* not work before POST_KERNEL
*/
static bool page_frames_initialized;
#endif
/* Add colors to page table dumps to indicate mapping type */
#define COLOR_PAGE_FRAMES 1
#if COLOR_PAGE_FRAMES
#define ANSI_DEFAULT "\x1B" "[0m"
#define ANSI_RED "\x1B" "[1;31m"
#define ANSI_GREEN "\x1B" "[1;32m"
#define ANSI_YELLOW "\x1B" "[1;33m"
#define ANSI_BLUE "\x1B" "[1;34m"
#define ANSI_MAGENTA "\x1B" "[1;35m"
#define ANSI_CYAN "\x1B" "[1;36m"
#define ANSI_GREY "\x1B" "[1;90m"
#define COLOR(x) printk(_CONCAT(ANSI_, x))
#else
#define COLOR(x) do { } while (false)
#endif /* COLOR_PAGE_FRAMES */
/* LCOV_EXCL_START */
static void page_frame_dump(struct k_mem_page_frame *pf)
{
if (k_mem_page_frame_is_free(pf)) {
COLOR(GREY);
printk("-");
} else if (k_mem_page_frame_is_reserved(pf)) {
COLOR(CYAN);
printk("R");
} else if (k_mem_page_frame_is_busy(pf)) {
COLOR(MAGENTA);
printk("B");
} else if (k_mem_page_frame_is_pinned(pf)) {
COLOR(YELLOW);
printk("P");
} else if (k_mem_page_frame_is_available(pf)) {
COLOR(GREY);
printk(".");
} else if (k_mem_page_frame_is_mapped(pf)) {
COLOR(DEFAULT);
printk("M");
} else {
COLOR(RED);
printk("?");
}
}
void k_mem_page_frames_dump(void)
{
int column = 0;
__ASSERT(page_frames_initialized, "%s called too early", __func__);
printk("Physical memory from 0x%lx to 0x%lx\n",
K_MEM_PHYS_RAM_START, K_MEM_PHYS_RAM_END);
for (int i = 0; i < K_MEM_NUM_PAGE_FRAMES; i++) {
struct k_mem_page_frame *pf = &k_mem_page_frames[i];
page_frame_dump(pf);
column++;
if (column == 64) {
column = 0;
printk("\n");
}
}
COLOR(DEFAULT);
if (column != 0) {
printk("\n");
}
}
/* LCOV_EXCL_STOP */
#define VIRT_FOREACH(_base, _size, _pos) \
for ((_pos) = (_base); \
(_pos) < ((uint8_t *)(_base) + (_size)); (_pos) += CONFIG_MMU_PAGE_SIZE)
#define PHYS_FOREACH(_base, _size, _pos) \
for ((_pos) = (_base); \
(_pos) < ((uintptr_t)(_base) + (_size)); (_pos) += CONFIG_MMU_PAGE_SIZE)
/*
* Virtual address space management
*
* Call all of these functions with z_mm_lock held.
*
* Overall virtual memory map: When the kernel starts, it resides in
* virtual memory in the region K_MEM_KERNEL_VIRT_START to
* K_MEM_KERNEL_VIRT_END. Unused virtual memory past this, up to the limit
* noted by CONFIG_KERNEL_VM_SIZE may be used for runtime memory mappings.
*
* If CONFIG_ARCH_MAPS_ALL_RAM is set, we do not just map the kernel image,
* but have a mapping for all RAM in place. This is for special architectural
* purposes and does not otherwise affect page frame accounting or flags;
* the only guarantee is that such RAM mapping outside of the Zephyr image
* won't be disturbed by subsequent memory mapping calls.
*
* +--------------+ <- K_MEM_VIRT_RAM_START
* | Undefined VM | <- May contain ancillary regions like x86_64's locore
* +--------------+ <- K_MEM_KERNEL_VIRT_START (often == K_MEM_VIRT_RAM_START)
* | Mapping for |
* | main kernel |
* | image |
* | |
* | |
* +--------------+ <- K_MEM_VM_FREE_START
* | |
* | Unused, |
* | Available VM |
* | |
* |..............| <- mapping_pos (grows downward as more mappings are made)
* | Mapping |
* +--------------+
* | Mapping |
* +--------------+
* | ... |
* +--------------+
* | Mapping |
* +--------------+ <- mappings start here
* | Reserved | <- special purpose virtual page(s) of size K_MEM_VM_RESERVED
* +--------------+ <- K_MEM_VIRT_RAM_END
*/
/* Bitmap of virtual addresses where one bit corresponds to one page.
* This is being used for virt_region_alloc() to figure out which
* region of virtual addresses can be used for memory mapping.
*
* Note that bit #0 is the highest address so that allocation is
* done in reverse from highest address.
*/
SYS_BITARRAY_DEFINE_STATIC(virt_region_bitmap,
CONFIG_KERNEL_VM_SIZE / CONFIG_MMU_PAGE_SIZE);
static bool virt_region_inited;
#define Z_VIRT_REGION_START_ADDR K_MEM_VM_FREE_START
#define Z_VIRT_REGION_END_ADDR (K_MEM_VIRT_RAM_END - K_MEM_VM_RESERVED)
static inline uintptr_t virt_from_bitmap_offset(size_t offset, size_t size)
{
return POINTER_TO_UINT(K_MEM_VIRT_RAM_END)
- (offset * CONFIG_MMU_PAGE_SIZE) - size;
}
static inline size_t virt_to_bitmap_offset(void *vaddr, size_t size)
{
return (POINTER_TO_UINT(K_MEM_VIRT_RAM_END)
- POINTER_TO_UINT(vaddr) - size) / CONFIG_MMU_PAGE_SIZE;
}
static void virt_region_init(void)
{
size_t offset, num_bits;
/* There are regions where we should never map via
* k_mem_map() and k_mem_map_phys_bare(). Mark them as
* already allocated so they will never be used.
*/
if (K_MEM_VM_RESERVED > 0) {
/* Mark reserved region at end of virtual address space */
num_bits = K_MEM_VM_RESERVED / CONFIG_MMU_PAGE_SIZE;
(void)sys_bitarray_set_region(&virt_region_bitmap,
num_bits, 0);
}
/* Mark all bits up to Z_FREE_VM_START as allocated */
num_bits = POINTER_TO_UINT(K_MEM_VM_FREE_START)
- POINTER_TO_UINT(K_MEM_VIRT_RAM_START);
offset = virt_to_bitmap_offset(K_MEM_VIRT_RAM_START, num_bits);
num_bits /= CONFIG_MMU_PAGE_SIZE;
(void)sys_bitarray_set_region(&virt_region_bitmap,
num_bits, offset);
virt_region_inited = true;
}
static void virt_region_free(void *vaddr, size_t size)
{
size_t offset, num_bits;
uint8_t *vaddr_u8 = (uint8_t *)vaddr;
if (unlikely(!virt_region_inited)) {
virt_region_init();
}
#ifndef CONFIG_KERNEL_DIRECT_MAP
/* Without the need to support K_MEM_DIRECT_MAP, the region must be
* able to be represented in the bitmap. So this case is
* simple.
*/
__ASSERT((vaddr_u8 >= Z_VIRT_REGION_START_ADDR)
&& ((vaddr_u8 + size - 1) < Z_VIRT_REGION_END_ADDR),
"invalid virtual address region %p (%zu)", vaddr_u8, size);
if (!((vaddr_u8 >= Z_VIRT_REGION_START_ADDR)
&& ((vaddr_u8 + size - 1) < Z_VIRT_REGION_END_ADDR))) {
return;
}
offset = virt_to_bitmap_offset(vaddr, size);
num_bits = size / CONFIG_MMU_PAGE_SIZE;
(void)sys_bitarray_free(&virt_region_bitmap, num_bits, offset);
#else /* !CONFIG_KERNEL_DIRECT_MAP */
/* With K_MEM_DIRECT_MAP, the region can be outside of the virtual
* memory space, wholly within it, or overlap partially.
* So additional processing is needed to make sure we only
* mark the pages within the bitmap.
*/
if (((vaddr_u8 >= Z_VIRT_REGION_START_ADDR) &&
(vaddr_u8 < Z_VIRT_REGION_END_ADDR)) ||
(((vaddr_u8 + size - 1) >= Z_VIRT_REGION_START_ADDR) &&
((vaddr_u8 + size - 1) < Z_VIRT_REGION_END_ADDR))) {
uint8_t *adjusted_start = MAX(vaddr_u8, Z_VIRT_REGION_START_ADDR);
uint8_t *adjusted_end = MIN(vaddr_u8 + size,
Z_VIRT_REGION_END_ADDR);
size_t adjusted_sz = adjusted_end - adjusted_start;
offset = virt_to_bitmap_offset(adjusted_start, adjusted_sz);
num_bits = adjusted_sz / CONFIG_MMU_PAGE_SIZE;
(void)sys_bitarray_free(&virt_region_bitmap, num_bits, offset);
}
#endif /* !CONFIG_KERNEL_DIRECT_MAP */
}
static void *virt_region_alloc(size_t size, size_t align)
{
uintptr_t dest_addr;
size_t alloc_size;
size_t offset;
size_t num_bits;
int ret;
if (unlikely(!virt_region_inited)) {
virt_region_init();
}
/* Possibly request more pages to ensure we can get an aligned virtual address */
num_bits = (size + align - CONFIG_MMU_PAGE_SIZE) / CONFIG_MMU_PAGE_SIZE;
alloc_size = num_bits * CONFIG_MMU_PAGE_SIZE;
ret = sys_bitarray_alloc(&virt_region_bitmap, num_bits, &offset);
if (ret != 0) {
LOG_ERR("insufficient virtual address space (requested %zu)",
size);
return NULL;
}
/* Remember that bit #0 in bitmap corresponds to the highest
* virtual address. So here we need to go downwards (backwards?)
* to get the starting address of the allocated region.
*/
dest_addr = virt_from_bitmap_offset(offset, alloc_size);
if (alloc_size > size) {
uintptr_t aligned_dest_addr = ROUND_UP(dest_addr, align);
/* Here is the memory organization when trying to get an aligned
* virtual address:
*
* +--------------+ <- K_MEM_VIRT_RAM_START
* | Undefined VM |
* +--------------+ <- K_MEM_KERNEL_VIRT_START (often == K_MEM_VIRT_RAM_START)
* | Mapping for |
* | main kernel |
* | image |
* | |
* | |
* +--------------+ <- K_MEM_VM_FREE_START
* | ... |
* +==============+ <- dest_addr
* | Unused |
* |..............| <- aligned_dest_addr
* | |
* | Aligned |
* | Mapping |
* | |
* |..............| <- aligned_dest_addr + size
* | Unused |
* +==============+ <- offset from K_MEM_VIRT_RAM_END == dest_addr + alloc_size
* | ... |
* +--------------+
* | Mapping |
* +--------------+
* | Reserved |
* +--------------+ <- K_MEM_VIRT_RAM_END
*/
/* Free the two unused regions */
virt_region_free(UINT_TO_POINTER(dest_addr),
aligned_dest_addr - dest_addr);
if (((dest_addr + alloc_size) - (aligned_dest_addr + size)) > 0) {
virt_region_free(UINT_TO_POINTER(aligned_dest_addr + size),
(dest_addr + alloc_size) - (aligned_dest_addr + size));
}
dest_addr = aligned_dest_addr;
}
/* Need to make sure this does not step into kernel memory */
if (dest_addr < POINTER_TO_UINT(Z_VIRT_REGION_START_ADDR)) {
(void)sys_bitarray_free(&virt_region_bitmap, size, offset);
return NULL;
}
return UINT_TO_POINTER(dest_addr);
}
/*
* Free page frames management
*
* Call all of these functions with z_mm_lock held.
*/
/* Linked list of unused and available page frames.
*
* TODO: This is very simple and treats all free page frames as being equal.
* However, there are use-cases to consolidate free pages such that entire
* SRAM banks can be switched off to save power, and so obtaining free pages
* may require a more complex ontology which prefers page frames in RAM banks
* which are still active.
*
* This implies in the future there may be multiple slists managing physical
* pages. Each page frame will still just have one snode link.
*/
static sys_sflist_t free_page_frame_list;
/* Number of unused and available free page frames.
* This information may go stale immediately.
*/
static size_t z_free_page_count;
#define PF_ASSERT(pf, expr, fmt, ...) \
__ASSERT(expr, "page frame 0x%lx: " fmt, k_mem_page_frame_to_phys(pf), \
##__VA_ARGS__)
/* Get an unused page frame. don't care which one, or NULL if there are none */
static struct k_mem_page_frame *free_page_frame_list_get(void)
{
sys_sfnode_t *node;
struct k_mem_page_frame *pf = NULL;
node = sys_sflist_get(&free_page_frame_list);
if (node != NULL) {
z_free_page_count--;
pf = CONTAINER_OF(node, struct k_mem_page_frame, node);
PF_ASSERT(pf, k_mem_page_frame_is_free(pf),
"on free list but not free");
pf->va_and_flags = 0;
}
return pf;
}
/* Release a page frame back into the list of free pages */
static void free_page_frame_list_put(struct k_mem_page_frame *pf)
{
PF_ASSERT(pf, k_mem_page_frame_is_available(pf),
"unavailable page put on free list");
sys_sfnode_init(&pf->node, K_MEM_PAGE_FRAME_FREE);
sys_sflist_append(&free_page_frame_list, &pf->node);
z_free_page_count++;
}
static void free_page_frame_list_init(void)
{
sys_sflist_init(&free_page_frame_list);
}
static void page_frame_free_locked(struct k_mem_page_frame *pf)
{
pf->va_and_flags = 0;
free_page_frame_list_put(pf);
}
/*
* Memory Mapping
*/
/* Called after the frame is mapped in the arch layer, to update our
* local ontology (and do some assertions while we're at it)
*/
static void frame_mapped_set(struct k_mem_page_frame *pf, void *addr)
{
PF_ASSERT(pf, !k_mem_page_frame_is_free(pf),
"attempted to map a page frame on the free list");
PF_ASSERT(pf, !k_mem_page_frame_is_reserved(pf),
"attempted to map a reserved page frame");
/* We do allow multiple mappings for pinned page frames
* since we will never need to reverse map them.
* This is uncommon, use-cases are for things like the
* Zephyr equivalent of VSDOs
*/
PF_ASSERT(pf, !k_mem_page_frame_is_mapped(pf) || k_mem_page_frame_is_pinned(pf),
"non-pinned and already mapped to %p",
k_mem_page_frame_to_virt(pf));
uintptr_t flags_mask = CONFIG_MMU_PAGE_SIZE - 1;
uintptr_t va = (uintptr_t)addr & ~flags_mask;
pf->va_and_flags &= flags_mask;
pf->va_and_flags |= va | K_MEM_PAGE_FRAME_MAPPED;
}
/* LCOV_EXCL_START */
/* Go through page frames to find the physical address mapped
* by a virtual address.
*
* @param[in] virt Virtual Address
* @param[out] phys Physical address mapped to the input virtual address
* if such mapping exists.
*
* @retval 0 if mapping is found and valid
* @retval -EFAULT if virtual address is not mapped
*/
static int virt_to_page_frame(void *virt, uintptr_t *phys)
{
uintptr_t paddr;
struct k_mem_page_frame *pf;
int ret = -EFAULT;
K_MEM_PAGE_FRAME_FOREACH(paddr, pf) {
if (k_mem_page_frame_is_mapped(pf)) {
if (virt == k_mem_page_frame_to_virt(pf)) {
ret = 0;
if (phys != NULL) {
*phys = k_mem_page_frame_to_phys(pf);
}
break;
}
}
}
return ret;
}
/* LCOV_EXCL_STOP */
__weak FUNC_ALIAS(virt_to_page_frame, arch_page_phys_get, int);
#ifdef CONFIG_DEMAND_PAGING
static int page_frame_prepare_locked(struct k_mem_page_frame *pf, bool *dirty_ptr,
bool page_in, uintptr_t *location_ptr);
static inline void do_backing_store_page_in(uintptr_t location);
static inline void do_backing_store_page_out(uintptr_t location);
#endif /* CONFIG_DEMAND_PAGING */
/* Allocate a free page frame, and map it to a specified virtual address
*
* TODO: Add optional support for copy-on-write mappings to a zero page instead
* of allocating, in which case page frames will be allocated lazily as
* the mappings to the zero page get touched. This will avoid expensive
* page-ins as memory is mapped and physical RAM or backing store storage will
* not be used if the mapped memory is unused. The cost is an empty physical
* page of zeroes.
*/
static int map_anon_page(void *addr, uint32_t flags)
{
struct k_mem_page_frame *pf;
uintptr_t phys;
bool lock = (flags & K_MEM_MAP_LOCK) != 0U;
pf = free_page_frame_list_get();
if (pf == NULL) {
#ifdef CONFIG_DEMAND_PAGING
uintptr_t location;
bool dirty;
int ret;
pf = k_mem_paging_eviction_select(&dirty);
__ASSERT(pf != NULL, "failed to get a page frame");
LOG_DBG("evicting %p at 0x%lx",
k_mem_page_frame_to_virt(pf),
k_mem_page_frame_to_phys(pf));
ret = page_frame_prepare_locked(pf, &dirty, false, &location);
if (ret != 0) {
return -ENOMEM;
}
if (dirty) {
do_backing_store_page_out(location);
}
pf->va_and_flags = 0;
#else
return -ENOMEM;
#endif /* CONFIG_DEMAND_PAGING */
}
phys = k_mem_page_frame_to_phys(pf);
arch_mem_map(addr, phys, CONFIG_MMU_PAGE_SIZE, flags);
if (lock) {
k_mem_page_frame_set(pf, K_MEM_PAGE_FRAME_PINNED);
}
frame_mapped_set(pf, addr);
#ifdef CONFIG_DEMAND_PAGING
if (!lock) {
k_mem_paging_eviction_add(pf);
}
#endif
LOG_DBG("memory mapping anon page %p -> 0x%lx", addr, phys);
return 0;
}
void *k_mem_map_phys_guard(uintptr_t phys, size_t size, uint32_t flags, bool is_anon)
{
uint8_t *dst;
size_t total_size;
int ret;
k_spinlock_key_t key;
uint8_t *pos;
bool uninit = (flags & K_MEM_MAP_UNINIT) != 0U;
__ASSERT(!is_anon || (is_anon && page_frames_initialized),
"%s called too early", __func__);
__ASSERT((flags & K_MEM_CACHE_MASK) == 0U,
"%s does not support explicit cache settings", __func__);
if (((flags & K_MEM_PERM_USER) != 0U) &&
((flags & K_MEM_MAP_UNINIT) != 0U)) {
LOG_ERR("user access to anonymous uninitialized pages is forbidden");
return NULL;
}
if ((size % CONFIG_MMU_PAGE_SIZE) != 0U) {
LOG_ERR("unaligned size %zu passed to %s", size, __func__);
return NULL;
}
if (size == 0) {
LOG_ERR("zero sized memory mapping");
return NULL;
}
/* Need extra for the guard pages (before and after) which we
* won't map.
*/
if (size_add_overflow(size, CONFIG_MMU_PAGE_SIZE * 2, &total_size)) {
LOG_ERR("too large size %zu passed to %s", size, __func__);
return NULL;
}
key = k_spin_lock(&z_mm_lock);
dst = virt_region_alloc(total_size, CONFIG_MMU_PAGE_SIZE);
if (dst == NULL) {
/* Address space has no free region */
goto out;
}
/* Unmap both guard pages to make sure accessing them
* will generate fault.
*/
arch_mem_unmap(dst, CONFIG_MMU_PAGE_SIZE);
arch_mem_unmap(dst + CONFIG_MMU_PAGE_SIZE + size,
CONFIG_MMU_PAGE_SIZE);
/* Skip over the "before" guard page in returned address. */
dst += CONFIG_MMU_PAGE_SIZE;
if (is_anon) {
/* Mapping from anonymous memory */
flags |= K_MEM_CACHE_WB;
#ifdef CONFIG_DEMAND_MAPPING
if ((flags & K_MEM_MAP_LOCK) == 0) {
flags |= K_MEM_MAP_UNPAGED;
VIRT_FOREACH(dst, size, pos) {
arch_mem_map(pos,
uninit ? ARCH_UNPAGED_ANON_UNINIT
: ARCH_UNPAGED_ANON_ZERO,
CONFIG_MMU_PAGE_SIZE, flags);
}
LOG_DBG("memory mapping anon pages %p to %p unpaged", dst, pos-1);
/* skip the memset() below */
uninit = true;
} else
#endif
{
VIRT_FOREACH(dst, size, pos) {
ret = map_anon_page(pos, flags);
if (ret != 0) {
/* TODO:
* call k_mem_unmap(dst, pos - dst)
* when implemented in #28990 and
* release any guard virtual page as well.
*/
dst = NULL;
goto out;
}
}
}
} else {
/* Mapping known physical memory.
*
* arch_mem_map() is a void function and does not return
* anything. Arch code usually uses ASSERT() to catch
* mapping errors. Assume this works correctly for now.
*/
arch_mem_map(dst, phys, size, flags);
}
out:
k_spin_unlock(&z_mm_lock, key);
if (dst != NULL && !uninit) {
/* If we later implement mappings to a copy-on-write
* zero page, won't need this step
*/
memset(dst, 0, size);
}
return dst;
}
void k_mem_unmap_phys_guard(void *addr, size_t size, bool is_anon)
{
uintptr_t phys;
uint8_t *pos;
struct k_mem_page_frame *pf;
k_spinlock_key_t key;
size_t total_size;
int ret;
/* Need space for the "before" guard page */
__ASSERT_NO_MSG(POINTER_TO_UINT(addr) >= CONFIG_MMU_PAGE_SIZE);
/* Make sure address range is still valid after accounting
* for two guard pages.
*/
pos = (uint8_t *)addr - CONFIG_MMU_PAGE_SIZE;
k_mem_assert_virtual_region(pos, size + (CONFIG_MMU_PAGE_SIZE * 2));
key = k_spin_lock(&z_mm_lock);
/* Check if both guard pages are unmapped.
* Bail if not, as this is probably a region not mapped
* using k_mem_map().
*/
pos = addr;
ret = arch_page_phys_get(pos - CONFIG_MMU_PAGE_SIZE, NULL);
if (ret == 0) {
__ASSERT(ret == 0,
"%s: cannot find preceding guard page for (%p, %zu)",
__func__, addr, size);
goto out;
}
ret = arch_page_phys_get(pos + size, NULL);
if (ret == 0) {
__ASSERT(ret == 0,
"%s: cannot find succeeding guard page for (%p, %zu)",
__func__, addr, size);
goto out;
}
if (is_anon) {
/* Unmapping anonymous memory */
VIRT_FOREACH(addr, size, pos) {
#ifdef CONFIG_DEMAND_PAGING
enum arch_page_location status;
uintptr_t location;
status = arch_page_location_get(pos, &location);
switch (status) {
case ARCH_PAGE_LOCATION_PAGED_OUT:
/*
* No pf is associated with this mapping.
* Simply get rid of the MMU entry and free
* corresponding backing store.
*/
arch_mem_unmap(pos, CONFIG_MMU_PAGE_SIZE);
k_mem_paging_backing_store_location_free(location);
continue;
case ARCH_PAGE_LOCATION_PAGED_IN:
/*
* The page is in memory but it may not be
* accessible in order to manage tracking
* of the ARCH_DATA_PAGE_ACCESSED flag
* meaning arch_page_phys_get() could fail.
* Still, we know the actual phys address.
*/
phys = location;
ret = 0;
break;
default:
ret = arch_page_phys_get(pos, &phys);
break;
}
#else
ret = arch_page_phys_get(pos, &phys);
#endif
__ASSERT(ret == 0,
"%s: cannot unmap an unmapped address %p",
__func__, pos);
if (ret != 0) {
/* Found an address not mapped. Do not continue. */
goto out;
}
__ASSERT(k_mem_is_page_frame(phys),
"%s: 0x%lx is not a page frame", __func__, phys);
if (!k_mem_is_page_frame(phys)) {
/* Physical address has no corresponding page frame
* description in the page frame array.
* This should not happen. Do not continue.
*/
goto out;
}
/* Grab the corresponding page frame from physical address */
pf = k_mem_phys_to_page_frame(phys);
__ASSERT(k_mem_page_frame_is_mapped(pf),
"%s: 0x%lx is not a mapped page frame", __func__, phys);
if (!k_mem_page_frame_is_mapped(pf)) {
/* Page frame is not marked mapped.
* This should not happen. Do not continue.
*/
goto out;
}
arch_mem_unmap(pos, CONFIG_MMU_PAGE_SIZE);
#ifdef CONFIG_DEMAND_PAGING
if (!k_mem_page_frame_is_pinned(pf)) {
k_mem_paging_eviction_remove(pf);
}
#endif
/* Put the page frame back into free list */
page_frame_free_locked(pf);
}
} else {
/*
* Unmapping previous mapped memory with specific physical address.
*
* Note that we don't have to unmap the guard pages, as they should
* have been unmapped. We just need to unmapped the in-between
* region [addr, (addr + size)).
*/
arch_mem_unmap(addr, size);
}
/* There are guard pages just before and after the mapped
* region. So we also need to free them from the bitmap.
*/
pos = (uint8_t *)addr - CONFIG_MMU_PAGE_SIZE;
total_size = size + (CONFIG_MMU_PAGE_SIZE * 2);
virt_region_free(pos, total_size);
out:
k_spin_unlock(&z_mm_lock, key);
}
int k_mem_update_flags(void *addr, size_t size, uint32_t flags)
{
uintptr_t phys;
k_spinlock_key_t key;
int ret;
k_mem_assert_virtual_region(addr, size);
key = k_spin_lock(&z_mm_lock);
/*
* We can achieve desired result without explicit architecture support
* by unmapping and remapping the same physical memory using new flags.
*/
ret = arch_page_phys_get(addr, &phys);
if (ret < 0) {
goto out;
}
/* TODO: detect and handle paged-out memory as well */
arch_mem_unmap(addr, size);
arch_mem_map(addr, phys, size, flags);
out:
k_spin_unlock(&z_mm_lock, key);
return ret;
}
size_t k_mem_free_get(void)
{
size_t ret;
k_spinlock_key_t key;
__ASSERT(page_frames_initialized, "%s called too early", __func__);
key = k_spin_lock(&z_mm_lock);
#ifdef CONFIG_DEMAND_PAGING
if (z_free_page_count > CONFIG_DEMAND_PAGING_PAGE_FRAMES_RESERVE) {
ret = z_free_page_count - CONFIG_DEMAND_PAGING_PAGE_FRAMES_RESERVE;
} else {
ret = 0;
}
#else
ret = z_free_page_count;
#endif /* CONFIG_DEMAND_PAGING */
k_spin_unlock(&z_mm_lock, key);
return ret * (size_t)CONFIG_MMU_PAGE_SIZE;
}
/* Get the default virtual region alignment, here the default MMU page size
*
* @param[in] phys Physical address of region to be mapped, aligned to MMU_PAGE_SIZE
* @param[in] size Size of region to be mapped, aligned to MMU_PAGE_SIZE
*
* @retval alignment to apply on the virtual address of this region
*/
static size_t virt_region_align(uintptr_t phys, size_t size)
{
ARG_UNUSED(phys);
ARG_UNUSED(size);
return CONFIG_MMU_PAGE_SIZE;
}
__weak FUNC_ALIAS(virt_region_align, arch_virt_region_align, size_t);
/* This may be called from arch early boot code before z_cstart() is invoked.
* Data will be copied and BSS zeroed, but this must not rely on any
* initialization functions being called prior to work correctly.
*/
void k_mem_map_phys_bare(uint8_t **virt_ptr, uintptr_t phys, size_t size, uint32_t flags)
{
uintptr_t aligned_phys, addr_offset;
size_t aligned_size, align_boundary;
k_spinlock_key_t key;
uint8_t *dest_addr;
size_t num_bits;
size_t offset;
#ifndef CONFIG_KERNEL_DIRECT_MAP
__ASSERT(!(flags & K_MEM_DIRECT_MAP), "The direct-map is not enabled");
#endif /* CONFIG_KERNEL_DIRECT_MAP */
addr_offset = k_mem_region_align(&aligned_phys, &aligned_size,
phys, size,
CONFIG_MMU_PAGE_SIZE);
__ASSERT(aligned_size != 0U, "0-length mapping at 0x%lx", aligned_phys);
__ASSERT(aligned_phys < (aligned_phys + (aligned_size - 1)),
"wraparound for physical address 0x%lx (size %zu)",
aligned_phys, aligned_size);
align_boundary = arch_virt_region_align(aligned_phys, aligned_size);
key = k_spin_lock(&z_mm_lock);
if (IS_ENABLED(CONFIG_KERNEL_DIRECT_MAP) &&
(flags & K_MEM_DIRECT_MAP)) {
dest_addr = (uint8_t *)aligned_phys;
/* Mark the region of virtual memory bitmap as used
* if the region overlaps the virtual memory space.
*
* Basically if either end of region is within
* virtual memory space, we need to mark the bits.
*/
if (IN_RANGE(aligned_phys,
(uintptr_t)K_MEM_VIRT_RAM_START,
(uintptr_t)(K_MEM_VIRT_RAM_END - 1)) ||
IN_RANGE(aligned_phys + aligned_size - 1,
(uintptr_t)K_MEM_VIRT_RAM_START,
(uintptr_t)(K_MEM_VIRT_RAM_END - 1))) {
uint8_t *adjusted_start = MAX(dest_addr, K_MEM_VIRT_RAM_START);
uint8_t *adjusted_end = MIN(dest_addr + aligned_size,
K_MEM_VIRT_RAM_END);
size_t adjusted_sz = adjusted_end - adjusted_start;
num_bits = adjusted_sz / CONFIG_MMU_PAGE_SIZE;
offset = virt_to_bitmap_offset(adjusted_start, adjusted_sz);
if (sys_bitarray_test_and_set_region(
&virt_region_bitmap, num_bits, offset, true)) {
goto fail;
}
}
} else {
/* Obtain an appropriately sized chunk of virtual memory */
dest_addr = virt_region_alloc(aligned_size, align_boundary);
if (!dest_addr) {
goto fail;
}
}
/* If this fails there's something amiss with virt_region_get */
__ASSERT((uintptr_t)dest_addr <
((uintptr_t)dest_addr + (size - 1)),
"wraparound for virtual address %p (size %zu)",
dest_addr, size);
LOG_DBG("arch_mem_map(%p, 0x%lx, %zu, %x) offset %lu", dest_addr,
aligned_phys, aligned_size, flags, addr_offset);
arch_mem_map(dest_addr, aligned_phys, aligned_size, flags);
k_spin_unlock(&z_mm_lock, key);
*virt_ptr = dest_addr + addr_offset;
return;
fail:
/* May re-visit this in the future, but for now running out of
* virtual address space or failing the arch_mem_map() call is
* an unrecoverable situation.
*
* Other problems not related to resource exhaustion we leave as
* assertions since they are clearly programming mistakes.
*/
LOG_ERR("memory mapping 0x%lx (size %zu, flags 0x%x) failed",
phys, size, flags);
k_panic();
}
void k_mem_unmap_phys_bare(uint8_t *virt, size_t size)
{
uintptr_t aligned_virt, addr_offset;
size_t aligned_size;
k_spinlock_key_t key;
addr_offset = k_mem_region_align(&aligned_virt, &aligned_size,
POINTER_TO_UINT(virt), size,
CONFIG_MMU_PAGE_SIZE);
__ASSERT(aligned_size != 0U, "0-length mapping at 0x%lx", aligned_virt);
__ASSERT(aligned_virt < (aligned_virt + (aligned_size - 1)),
"wraparound for virtual address 0x%lx (size %zu)",
aligned_virt, aligned_size);
key = k_spin_lock(&z_mm_lock);
LOG_DBG("arch_mem_unmap(0x%lx, %zu) offset %lu",
aligned_virt, aligned_size, addr_offset);
arch_mem_unmap(UINT_TO_POINTER(aligned_virt), aligned_size);
virt_region_free(UINT_TO_POINTER(aligned_virt), aligned_size);
k_spin_unlock(&z_mm_lock, key);
}