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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 <spinlock.h>
#include <mmu.h>
#include <init.h>
#include <kernel_internal.h>
#include <syscall_handler.h>
#include <toolchain.h>
#include <linker/linker-defs.h>
#include <sys/bitarray.h>
#include <timing/timing.h>
#include <logging/log.h>
LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
/*
* 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 z_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 z_page_frame z_page_frames[Z_NUM_PAGE_FRAMES];
#if __ASSERT_ON
/* Indicator that z_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 (0)
#endif
static void page_frame_dump(struct z_page_frame *pf)
{
if (z_page_frame_is_reserved(pf)) {
COLOR(CYAN);
printk("R");
} else if (z_page_frame_is_busy(pf)) {
COLOR(MAGENTA);
printk("B");
} else if (z_page_frame_is_pinned(pf)) {
COLOR(YELLOW);
printk("P");
} else if (z_page_frame_is_available(pf)) {
COLOR(GREY);
printk(".");
} else if (z_page_frame_is_mapped(pf)) {
COLOR(DEFAULT);
printk("M");
} else {
COLOR(RED);
printk("?");
}
}
void z_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",
Z_PHYS_RAM_START, Z_PHYS_RAM_END);
for (int i = 0; i < Z_NUM_PAGE_FRAMES; i++) {
struct z_page_frame *pf = &z_page_frames[i];
page_frame_dump(pf);
column++;
if (column == 64) {
column = 0;
printk("\n");
}
}
COLOR(DEFAULT);
if (column != 0) {
printk("\n");
}
}
#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 Z_KERNEL_VIRT_START to
* Z_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.
*
* +--------------+ <- Z_VIRT_RAM_START
* | Undefined VM | <- May contain ancillary regions like x86_64's locore
* +--------------+ <- Z_KERNEL_VIRT_START (often == Z_VIRT_RAM_START)
* | Mapping for |
* | main kernel |
* | image |
* | |
* | |
* +--------------+ <- Z_FREE_VM_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 Z_VM_RESERVED
* +--------------+ <- Z_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(virt_region_bitmap,
CONFIG_KERNEL_VM_SIZE / CONFIG_MMU_PAGE_SIZE);
static bool virt_region_inited;
#define Z_VIRT_REGION_START_ADDR Z_FREE_VM_START
#define Z_VIRT_REGION_END_ADDR (Z_VIRT_RAM_END - Z_VM_RESERVED)
static inline uintptr_t virt_from_bitmap_offset(size_t offset, size_t size)
{
return POINTER_TO_UINT(Z_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(Z_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 z_phys_map(). Mark them as
* already allocated so they will never be used.
*/
if (Z_VM_RESERVED > 0) {
/* Mark reserved region at end of virtual address space */
num_bits = Z_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(Z_FREE_VM_START)
- POINTER_TO_UINT(Z_VIRT_RAM_START);
offset = virt_to_bitmap_offset(Z_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_alloc(size_t size)
{
uintptr_t dest_addr;
size_t offset;
size_t num_bits;
int ret;
if (unlikely(!virt_region_inited)) {
virt_region_init();
}
num_bits = size / 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, size);
/* 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);
}
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();
}
__ASSERT((vaddr_u8 >= Z_VIRT_REGION_START_ADDR)
&& ((vaddr_u8 + size) < 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) < 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);
}
/*
* 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_slist_t free_page_frame_list;
/* Number of unused and available free page frames */
size_t z_free_page_count;
#define PF_ASSERT(pf, expr, fmt, ...) \
__ASSERT(expr, "page frame 0x%lx: " fmt, z_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 z_page_frame *free_page_frame_list_get(void)
{
sys_snode_t *node;
struct z_page_frame *pf = NULL;
node = sys_slist_get(&free_page_frame_list);
if (node != NULL) {
z_free_page_count--;
pf = CONTAINER_OF(node, struct z_page_frame, node);
PF_ASSERT(pf, z_page_frame_is_available(pf),
"unavailable but somehow on free list");
}
return pf;
}
/* Release a page frame back into the list of free pages */
static void free_page_frame_list_put(struct z_page_frame *pf)
{
PF_ASSERT(pf, z_page_frame_is_available(pf),
"unavailable page put on free list");
sys_slist_append(&free_page_frame_list, &pf->node);
z_free_page_count++;
}
static void free_page_frame_list_init(void)
{
sys_slist_init(&free_page_frame_list);
}
static void page_frame_free_locked(struct z_page_frame *pf)
{
pf->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 z_page_frame *pf, void *addr)
{
PF_ASSERT(pf, !z_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, !z_page_frame_is_mapped(pf) || z_page_frame_is_pinned(pf),
"non-pinned and already mapped to %p", pf->addr);
pf->flags |= Z_PAGE_FRAME_MAPPED;
pf->addr = addr;
}
/* 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 z_page_frame *pf;
int ret = -EFAULT;
Z_PAGE_FRAME_FOREACH(paddr, pf) {
if (z_page_frame_is_mapped(pf)) {
if (virt == pf->addr) {
ret = 0;
*phys = z_page_frame_to_phys(pf);
break;
}
}
}
return ret;
}
__weak FUNC_ALIAS(virt_to_page_frame, arch_page_phys_get, int);
#ifdef CONFIG_DEMAND_PAGING
static int page_frame_prepare_locked(struct z_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 z_page_frame *pf;
uintptr_t phys;
bool lock = (flags & K_MEM_MAP_LOCK) != 0U;
bool uninit = (flags & K_MEM_MAP_UNINIT) != 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", pf->addr,
z_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->flags = 0;
#else
return -ENOMEM;
#endif /* CONFIG_DEMAND_PAGING */
}
phys = z_page_frame_to_phys(pf);
arch_mem_map(addr, phys, CONFIG_MMU_PAGE_SIZE, flags | K_MEM_CACHE_WB);
if (lock) {
pf->flags |= Z_PAGE_FRAME_PINNED;
}
frame_mapped_set(pf, addr);
LOG_DBG("memory mapping anon page %p -> 0x%lx", addr, phys);
if (!uninit) {
/* If we later implement mappings to a copy-on-write
* zero page, won't need this step
*/
memset(addr, 0, CONFIG_MMU_PAGE_SIZE);
}
return 0;
}
void *k_mem_map(size_t size, uint32_t flags)
{
uint8_t *dst;
size_t total_size;
int ret;
k_spinlock_key_t key;
uint8_t *pos;
__ASSERT(!(((flags & K_MEM_PERM_USER) != 0U) &&
((flags & K_MEM_MAP_UNINIT) != 0U)),
"user access to anonymous uninitialized pages is forbidden");
__ASSERT(size % CONFIG_MMU_PAGE_SIZE == 0U,
"unaligned size %zu passed to %s", size, __func__);
__ASSERT(size != 0, "zero sized memory mapping");
__ASSERT(page_frames_initialized, "%s called too early", __func__);
__ASSERT((flags & K_MEM_CACHE_MASK) == 0U,
"%s does not support explicit cache settings", __func__);
key = k_spin_lock(&z_mm_lock);
/* Need extra for the guard pages (before and after) which we
* won't map.
*/
total_size = size + CONFIG_MMU_PAGE_SIZE * 2;
dst = virt_region_alloc(total_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;
VIRT_FOREACH(dst, size, pos) {
ret = map_anon_page(pos, flags);
if (ret != 0) {
/* TODO: call k_mem_unmap(dst, pos - dst) when
* implmented in #28990 and release any guard virtual
* page as well.
*/
dst = NULL;
goto out;
}
}
out:
k_spin_unlock(&z_mm_lock, key);
return dst;
}
void k_mem_unmap(void *addr, size_t size)
{
uintptr_t phys;
uint8_t *pos;
struct z_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;
z_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;
}
VIRT_FOREACH(addr, size, pos) {
ret = arch_page_phys_get(pos, &phys);
__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(z_is_page_frame(phys),
"%s: 0x%lx is not a page frame", __func__, phys);
if (!z_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 = z_phys_to_page_frame(phys);
__ASSERT(z_page_frame_is_mapped(pf),
"%s: 0x%lx is not a mapped page frame", __func__, phys);
if (!z_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);
/* Put the page frame back into free list */
page_frame_free_locked(pf);
}
/* 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);
}
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
k_spin_unlock(&z_mm_lock, key);
return ret * (size_t)CONFIG_MMU_PAGE_SIZE;
}
/* 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 z_phys_map(uint8_t **virt_ptr, uintptr_t phys, size_t size, uint32_t flags)
{
uintptr_t aligned_phys, addr_offset;
size_t aligned_size;
k_spinlock_key_t key;
uint8_t *dest_addr;
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);
key = k_spin_lock(&z_mm_lock);
/* Obtain an appropriately sized chunk of virtual memory */
dest_addr = virt_region_alloc(aligned_size);
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 z_phys_unmap(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);
arch_mem_unmap(UINT_TO_POINTER(aligned_virt), aligned_size);
virt_region_free(virt, size);
k_spin_unlock(&z_mm_lock, key);
}
/*
* Miscellaneous
*/
size_t k_mem_region_align(uintptr_t *aligned_addr, size_t *aligned_size,
uintptr_t addr, size_t size, size_t align)
{
size_t addr_offset;
/* The actual mapped region must be page-aligned. Round down the
* physical address and pad the region size appropriately
*/
*aligned_addr = ROUND_DOWN(addr, align);
addr_offset = addr - *aligned_addr;
*aligned_size = ROUND_UP(size + addr_offset, align);
return addr_offset;
}
#if defined(CONFIG_LINKER_USE_BOOT_SECTION) || defined(CONFIG_LINKER_USE_PINNED_SECTION)
static void mark_linker_section_pinned(void *start_addr, void *end_addr,
bool pin)
{
struct z_page_frame *pf;
uint8_t *addr;
uintptr_t pinned_start = ROUND_DOWN(POINTER_TO_UINT(start_addr),
CONFIG_MMU_PAGE_SIZE);
uintptr_t pinned_end = ROUND_UP(POINTER_TO_UINT(end_addr),
CONFIG_MMU_PAGE_SIZE);
size_t pinned_size = pinned_end - pinned_start;
VIRT_FOREACH(UINT_TO_POINTER(pinned_start), pinned_size, addr)
{
pf = z_phys_to_page_frame(Z_BOOT_VIRT_TO_PHYS(addr));
frame_mapped_set(pf, addr);
if (pin) {
pf->flags |= Z_PAGE_FRAME_PINNED;
} else {
pf->flags &= ~Z_PAGE_FRAME_PINNED;
}
}
}
#endif /* CONFIG_LINKER_USE_BOOT_SECTION) || CONFIG_LINKER_USE_PINNED_SECTION */
void z_mem_manage_init(void)
{
uintptr_t phys;
uint8_t *addr;
struct z_page_frame *pf;
k_spinlock_key_t key = k_spin_lock(&z_mm_lock);
free_page_frame_list_init();
ARG_UNUSED(addr);
#ifdef CONFIG_ARCH_HAS_RESERVED_PAGE_FRAMES
/* If some page frames are unavailable for use as memory, arch
* code will mark Z_PAGE_FRAME_RESERVED in their flags
*/
arch_reserved_pages_update();
#endif /* CONFIG_ARCH_HAS_RESERVED_PAGE_FRAMES */
#ifdef CONFIG_LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT
/* All pages composing the Zephyr image are mapped at boot in a
* predictable way. This can change at runtime.
*/
VIRT_FOREACH(Z_KERNEL_VIRT_START, Z_KERNEL_VIRT_SIZE, addr)
{
pf = z_phys_to_page_frame(Z_BOOT_VIRT_TO_PHYS(addr));
frame_mapped_set(pf, addr);
/* TODO: for now we pin the whole Zephyr image. Demand paging
* currently tested with anonymously-mapped pages which are not
* pinned.
*
* We will need to setup linker regions for a subset of kernel
* code/data pages which are pinned in memory and
* may not be evicted. This will contain critical CPU data
* structures, and any code used to perform page fault
* handling, page-ins, etc.
*/
pf->flags |= Z_PAGE_FRAME_PINNED;
}
#endif /* CONFIG_LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT */
#ifdef CONFIG_LINKER_USE_BOOT_SECTION
/* Pin the boot section to prevent it from being swapped out during
* boot process. Will be un-pinned once boot process completes.
*/
mark_linker_section_pinned(lnkr_boot_start, lnkr_boot_end, true);
#endif
#ifdef CONFIG_LINKER_USE_PINNED_SECTION
/* Pin the page frames correspondng to the pinned symbols */
mark_linker_section_pinned(lnkr_pinned_start, lnkr_pinned_end, true);
#endif
/* Any remaining pages that aren't mapped, reserved, or pinned get
* added to the free pages list
*/
Z_PAGE_FRAME_FOREACH(phys, pf) {
if (z_page_frame_is_available(pf)) {
free_page_frame_list_put(pf);
}
}
LOG_DBG("free page frames: %zu", z_free_page_count);
#ifdef CONFIG_DEMAND_PAGING
#ifdef CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM
z_paging_histogram_init();
#endif
k_mem_paging_backing_store_init();
k_mem_paging_eviction_init();
#endif
#if __ASSERT_ON
page_frames_initialized = true;
#endif
k_spin_unlock(&z_mm_lock, key);
#ifndef CONFIG_LINKER_GENERIC_SECTIONS_PRESENT_AT_BOOT
/* If BSS section is not present in memory at boot,
* it would not have been cleared. This needs to be
* done now since paging mechanism has been initialized
* and the BSS pages can be brought into physical
* memory to be cleared.
*/
z_bss_zero();
#endif
}
void z_mem_manage_boot_finish(void)
{
#ifdef CONFIG_LINKER_USE_BOOT_SECTION
/* At the end of boot process, unpin the boot sections
* as they don't need to be in memory all the time anymore.
*/
mark_linker_section_pinned(lnkr_boot_start, lnkr_boot_end, false);
#endif
}
#ifdef CONFIG_DEMAND_PAGING
#ifdef CONFIG_DEMAND_PAGING_STATS
struct k_mem_paging_stats_t paging_stats;
extern struct k_mem_paging_histogram_t z_paging_histogram_eviction;
extern struct k_mem_paging_histogram_t z_paging_histogram_backing_store_page_in;
extern struct k_mem_paging_histogram_t z_paging_histogram_backing_store_page_out;
#endif
static inline void do_backing_store_page_in(uintptr_t location)
{
#ifdef CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM
uint32_t time_diff;
#ifdef CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS
timing_t time_start, time_end;
time_start = timing_counter_get();
#else
uint32_t time_start;
time_start = k_cycle_get_32();
#endif /* CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS */
#endif /* CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM */
k_mem_paging_backing_store_page_in(location);
#ifdef CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM
#ifdef CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS
time_end = timing_counter_get();
time_diff = (uint32_t)timing_cycles_get(&time_start, &time_end);
#else
time_diff = k_cycle_get_32() - time_start;
#endif /* CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS */
z_paging_histogram_inc(&z_paging_histogram_backing_store_page_in,
time_diff);
#endif /* CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM */
}
static inline void do_backing_store_page_out(uintptr_t location)
{
#ifdef CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM
uint32_t time_diff;
#ifdef CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS
timing_t time_start, time_end;
time_start = timing_counter_get();
#else
uint32_t time_start;
time_start = k_cycle_get_32();
#endif /* CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS */
#endif /* CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM */
k_mem_paging_backing_store_page_out(location);
#ifdef CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM
#ifdef CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS
time_end = timing_counter_get();
time_diff = (uint32_t)timing_cycles_get(&time_start, &time_end);
#else
time_diff = k_cycle_get_32() - time_start;
#endif /* CONFIG_DEMAND_PAGING_STATS_USING_TIMING_FUNCTIONS */
z_paging_histogram_inc(&z_paging_histogram_backing_store_page_out,
time_diff);
#endif /* CONFIG_DEMAND_PAGING_TIMING_HISTOGRAM */
}
/* Current implementation relies on interrupt locking to any prevent page table
* access, which falls over if other CPUs are active. Addressing this is not
* as simple as using spinlocks as regular memory reads/writes constitute
* "access" in this sense.
*
* Current needs for demand paging are on uniprocessor systems.
*/
BUILD_ASSERT(!IS_ENABLED(CONFIG_SMP));
static void virt_region_foreach(void *addr, size_t size,
void (*func)(void *))
{
z_mem_assert_virtual_region(addr, size);
for (size_t offset = 0; offset < size; offset += CONFIG_MMU_PAGE_SIZE) {
func((uint8_t *)addr + offset);
}
}
/*
* Perform some preparatory steps before paging out. The provided page frame
* must be evicted to the backing store immediately after this is called
* with a call to k_mem_paging_backing_store_page_out() if it contains
* a data page.
*
* - Map page frame to scratch area if requested. This always is true if we're
* doing a page fault, but is only set on manual evictions if the page is
* dirty.
* - If mapped:
* - obtain backing store location and populate location parameter
* - Update page tables with location
* - Mark page frame as busy
*
* Returns -ENOMEM if the backing store is full
*/
static int page_frame_prepare_locked(struct z_page_frame *pf, bool *dirty_ptr,
bool page_fault, uintptr_t *location_ptr)
{
uintptr_t phys;
int ret;
bool dirty = *dirty_ptr;
phys = z_page_frame_to_phys(pf);
__ASSERT(!z_page_frame_is_pinned(pf), "page frame 0x%lx is pinned",
phys);
/* If the backing store doesn't have a copy of the page, even if it
* wasn't modified, treat as dirty. This can happen for a few
* reasons:
* 1) Page has never been swapped out before, and the backing store
* wasn't pre-populated with this data page.
* 2) Page was swapped out before, but the page contents were not
* preserved after swapping back in.
* 3) Page contents were preserved when swapped back in, but were later
* evicted from the backing store to make room for other evicted
* pages.
*/
if (z_page_frame_is_mapped(pf)) {
dirty = dirty || !z_page_frame_is_backed(pf);
}
if (dirty || page_fault) {
arch_mem_scratch(phys);
}
if (z_page_frame_is_mapped(pf)) {
ret = k_mem_paging_backing_store_location_get(pf, location_ptr,
page_fault);
if (ret != 0) {
LOG_ERR("out of backing store memory");
return -ENOMEM;
}
arch_mem_page_out(pf->addr, *location_ptr);
} else {