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#include <kernel/arch/generic.h>
#include <kernel/malloc.h>
#include <kernel/panic.h>
#include <kernel/util.h>
#include <shared/mem.h>
#include <stdbool.h>
#include <stdint.h>
#define MALLOC_MAGIC 0xA770C666
struct malloc_hdr {
uint32_t magic;
uint32_t page_amt;
struct malloc_hdr *next, *prev;
void *stacktrace[4];
};
struct malloc_hdr *malloc_last = NULL;
extern uint8_t pbitmap[], pbitmap_start[]; /* linker.ld */
static size_t pbitmap_len;
static size_t pbitmap_searchstart = 0;
static size_t pbitmap_taken = 0;
static bool bitmap_get(size_t i) {
size_t b = i / 8;
assert(b < pbitmap_len);
return 0 < (pbitmap[b] & (1 << (i&7)));
}
static void bitmap_set(size_t i, bool v) {
size_t b = i / 8;
uint8_t m = 1 << (i&7);
assert(b < pbitmap_len);
if ((pbitmap[b] & m) ^ v) {
/* value changes */
if (v) pbitmap_taken++;
else pbitmap_taken--;
}
if (v) pbitmap[b] |= m;
else pbitmap[b] &= ~m;
}
void mem_init(void *memtop) {
kprintf("memory %8x -> %8x\n", &_bss_end, memtop);
size_t pageamt = ((uintptr_t)memtop - (uintptr_t)pbitmap_start) / PAGE_SIZE;
pbitmap_len = pageamt / 8;
memset(pbitmap, 0, pbitmap_len);
mem_reserve(pbitmap, pbitmap_len);
}
void mem_reserve(void *addr, size_t len) {
kprintf("reserved %8x -> %8x\n", addr, addr + len);
/* align to the previous page */
size_t off = (uintptr_t)addr & PAGE_MASK;
addr -= off;
len += off;
size_t first = ((uintptr_t)addr - (uintptr_t)pbitmap_start) / PAGE_SIZE;
for (size_t i = 0; i * PAGE_SIZE < len; i++) {
if (first + i >= pbitmap_len) break;
if (bitmap_get(first + i))
panic_invalid_state();
bitmap_set(first + i, true);
}
}
void mem_debugprint(void) {
size_t total = 0;
kprintf("current kmallocs:\n");
kprintf("addr pages\n");
for (struct malloc_hdr *iter = malloc_last; iter; iter = iter->prev) {
kprintf("%08x %05x", iter, iter->page_amt);
for (size_t i = 0; i < 4; i++)
kprintf(" k/%08x", iter->stacktrace[i]);
kprintf("\n peek 0x%x\n", *(uint32_t*)(&iter[1]));
total++;
}
kprintf(" total 0x%x\n", total);
kprintf("pbitmap usage %u/%u\n", pbitmap_taken, pbitmap_len * 8);
}
void *page_alloc(size_t pages) {
/* i do realize how painfully slow this is */
size_t streak = 0;
for (size_t i = pbitmap_searchstart; i < pbitmap_len * 8; i++) {
if (bitmap_get(i)) {
streak = 0;
continue;
}
if (++streak >= pages) {
/* found hole big enough for this allocation */
i = i + 1 - streak;
for (size_t j = 0; j < streak; j++)
bitmap_set(i + j, true);
pbitmap_searchstart = i + streak - 1;
return pbitmap_start + i * PAGE_SIZE;
}
}
kprintf("we ran out of memory :(\ngoodbye.\n");
panic_unimplemented();
}
void *page_zalloc(size_t pages) {
void *p = page_alloc(pages);
memset(p, 0, pages * PAGE_SIZE);
return p;
}
// frees `pages` consecutive pages starting from *first
void page_free(void *first_addr, size_t pages) {
assert(first_addr >= (void*)pbitmap_start);
size_t first = ((uintptr_t)first_addr - (uintptr_t)pbitmap_start) / PAGE_SIZE;
if (pbitmap_searchstart > first)
pbitmap_searchstart = first;
for (size_t i = 0; i < pages; i++) {
assert(bitmap_get(first + i));
bitmap_set(first + i, false);
}
}
void kmalloc_sanity(const void *addr) {
assert(addr);
const struct malloc_hdr *hdr = addr - sizeof(struct malloc_hdr);
assert(hdr->magic == MALLOC_MAGIC);
if (hdr->next) assert(hdr->next->prev == hdr);
if (hdr->prev) assert(hdr->prev->next == hdr);
}
void *kmalloc(size_t len) {
// TODO better kmalloc
struct malloc_hdr *hdr;
void *addr;
uint32_t pages;
len += sizeof(struct malloc_hdr);
pages = len / PAGE_SIZE + 1;
hdr = page_alloc(pages);
hdr->magic = MALLOC_MAGIC;
hdr->page_amt = pages;
hdr->next = NULL;
hdr->prev = malloc_last;
if (hdr->prev) {
assert(!hdr->prev->next);
hdr->prev->next = hdr;
}
for (size_t i = 0; i < 4; i++)
hdr->stacktrace[i] = debug_caller(i);
malloc_last = hdr;
addr = (void*)hdr + sizeof(struct malloc_hdr);
kmalloc_sanity(addr);
return addr;
}
void kfree(void *ptr) {
struct malloc_hdr *hdr;
if (ptr == NULL) return;
hdr = ptr - sizeof(struct malloc_hdr);
kmalloc_sanity(ptr);
hdr->magic = ~MALLOC_MAGIC; // (hopefully) detect double frees
if (hdr->next)
hdr->next->prev = hdr->prev;
if (hdr->prev)
hdr->prev->next = hdr->next;
if (malloc_last == hdr)
malloc_last = hdr->prev;
page_free(hdr, hdr->page_amt);
}
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