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#include "lib.h"
#include "panic.h"
#include <stdint.h>
#include <stddef.h>
#include <memory.h>
#include <string.h>
#define MEMORY_INTERNAL
#include <memory/virtalloc.h>
struct addr_node {
uintptr_t start;
uintptr_t end;
struct addr_node *next;
struct addr_node *prev;
uint8_t is_alloc; // if node is storing allocated data
uint8_t is_used; // if node is in use by virtalloc
};
#define BSS_NODES 64
static struct addr_node bootstrap_nodes[BSS_NODES];
static struct addr_node *alloc_nodes = NULL;
static size_t free_node_start = 0;
static size_t alloc_node_count = 0;
static size_t used_node_count = 0;
static bool is_allocating = false;
static struct addr_node *start_node = NULL;
static struct addr_node *get_node_idx(int idx) {
if (idx < BSS_NODES) {
return &bootstrap_nodes[idx];
} else {
return &alloc_nodes[idx - BSS_NODES];
}
}
static struct addr_node *get_node(void) {
size_t count = BSS_NODES + alloc_node_count;
if (!is_allocating && used_node_count + 16 >= count) {
is_allocating = true;
int new_alloc = alloc_node_count * 2;
if (new_alloc < 8)
new_alloc = 8;
int allocated = new_alloc - alloc_node_count;
int old = new_alloc - allocated;
alloc_nodes = krealloc(alloc_nodes, sizeof(struct addr_node) * new_alloc);
memset(alloc_nodes + old, 0, sizeof(struct addr_node) + allocated);;
alloc_node_count = new_alloc;
is_allocating = false;
count = BSS_NODES + alloc_node_count;
}
size_t idx = free_node_start;
for (; idx < count; idx++) {
struct addr_node *node = get_node_idx(idx);
if (!node->is_used) {
used_node_count++;
return node;
}
}
panic("could not get virtaddr node");
}
static void free_node(struct addr_node *node) {
node->is_used = false;
used_node_count--;
}
void virtaddr_init(void) {
struct addr_node init = {
.start = 0x400000, // third page table
.end = 0x1000000000000, // 48bit memory address max
.next = NULL,
.prev = NULL,
.is_alloc = false,
.is_used = true,
};
memset(bootstrap_nodes, 0, sizeof(bootstrap_nodes));
bootstrap_nodes[0] = init;
start_node = &bootstrap_nodes[0];
}
void *virtaddr_alloc(int n_pages) {
if (n_pages < 1)
return NULL;
long n_length = n_pages * PAGE_SIZE;
struct addr_node *node = start_node;
for (; node != NULL ; node = node->next) {
if (node->is_alloc)
continue;
long length = node->end - node->start;
if (length >= n_length) {
struct addr_node *new = get_node();
if (node->prev != NULL) {
node->prev->next = new;
}
new->next = node;
node->prev = new;
new->start = node->start;
new->end = new->start + n_length;
node->start = new->end;
new->is_alloc = true;
new->is_used = true;
new->next = node;
return (void *) new->start;
}
}
return NULL;
}
static void merge_back(struct addr_node *node) {
while(node->prev && !node->is_alloc) {
struct addr_node *temp = node->prev;
node->start = node->prev->start;
node->prev = node->prev->prev;
free_node(temp);
}
if (node->prev == NULL) {
start_node = node;
}
}
static void merge_forward(struct addr_node *node) {
while(node->next && !node->is_alloc) {
struct addr_node *temp = node->next;
node->end = node->next->end;
node->next = node->next->next;
free_node(temp);
}
}
long virtaddr_free(void *virtaddr) {
uintptr_t virt = (uintptr_t) virtaddr;
if (virt % PAGE_SIZE)
return -1; // not page aligned, we did not give this out!!!
struct addr_node *node = start_node;
for (; node != NULL; node = node->next) {
if (node->start == virt) {
int length = node->end - node->start;
int pages = length / PAGE_SIZE;
merge_back(node);
merge_forward(node);
return pages;
}
}
return -1;
}
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