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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 0x616c6c6f63686472
#define DESCLEN 8
typedef struct Allocation Allocation;
struct Allocation {
uint64_t magic;
uint64_t len;
Allocation *next, *prev;
void *stacktrace[4];
char desc[DESCLEN];
};
Allocation *malloc_last = NULL;
extern uint8_t pbitmap[]; /* linker.ld */
static size_t pbitmap_len; /* in bytes */
static size_t pbitmap_firstfree = 0;
static
bool bitmap_get(long i)
{
assert(i >= 0);
size_t b = i / 8;
uint8_t m = 1 << (i&7);
assert(b < pbitmap_len);
return (pbitmap[b]&m) != 0;
}
static
bool bitmap_set(long i, bool v)
{
assert(i >= 0);
size_t b = i / 8;
uint8_t m = 1 << (i&7);
assert(b < pbitmap_len);
bool prev = (pbitmap[b]&m) != 0;
if (v) pbitmap[b] |= m;
else pbitmap[b] &= ~m;
return prev;
}
static
long toindex(void *p)
{
return ((long)p - (long)pbitmap) / PAGE_SIZE;
}
static
size_t page_amt(size_t bytes)
{
return (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
}
void
mem_init(void *memtop)
{
kprintf("memory %8x -> %8x\n", &_bss_end, memtop);
pbitmap_len = toindex(memtop) / 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 = toindex(addr);
for (size_t i = 0; i * PAGE_SIZE < len; i++) {
if ((first + i) / 8 >= pbitmap_len)
break;
bitmap_set(first + i, true);
}
}
void
mem_debugprint(void)
{
size_t count = 0, bytes = 0, pages = 0;
kprintf("[kern] current allocations:\n");
for (Allocation *iter = malloc_last; iter; iter = iter->prev) {
kprintf(
"%08p %6dB %.8s ",
((void*)iter) + sizeof(Allocation),
iter->len - sizeof(Allocation),
iter->desc
);
for (size_t i = 0; i < 4; i++) {
kprintf(" k/%08x", iter->stacktrace[i]);
}
kprintf("\n");
count++;
bytes += iter->len;
pages += page_amt(iter->len);
}
kprintf(
"%d in total, %d bytes, %d pages = %dB used\n",
count, bytes, pages, pages*PAGE_SIZE
);
}
void
*page_alloc(size_t pages)
{
assert(pages == 1); /* not using that assertion... yet */
/* i do realize how painfully slow this is */
size_t streak = 0;
for (size_t i = pbitmap_firstfree; 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_firstfree = i + streak - 1;
return pbitmap + 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 *addr, size_t pages)
{
assert(addr >= (void*)pbitmap);
size_t first = toindex(addr);
for (size_t i = 0; i < pages; i++) {
if (bitmap_set(first + i, false) == false) {
panic_invalid_state();
}
}
if (pbitmap_firstfree > first) {
pbitmap_firstfree = first;
}
}
void
kmalloc_sanity(const void *addr)
{
assert(addr);
const Allocation *hdr = addr - sizeof(Allocation);
assert(hdr->magic == MALLOC_MAGIC);
if (hdr->next) assert(hdr->next->prev == hdr);
if (hdr->prev) assert(hdr->prev->next == hdr);
}
// TODO better kmalloc
void
*kmalloc(size_t len, const char *desc)
{
Allocation *hdr;
void *addr;
if (KMALLOC_MAX < len) {
panic_invalid_state();
}
len += sizeof(Allocation);
assert(len <= PAGE_SIZE);
hdr = page_alloc(page_amt(len));
hdr->magic = MALLOC_MAGIC;
hdr->len = len;
memset(hdr->desc, ' ', DESCLEN);
if (desc) {
for (int i = 0; i < DESCLEN; i++) {
if (desc[i] == '\0') break;
hdr->desc[i] = desc[i];
}
}
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(Allocation);
#ifndef NDEBUG
memset(addr, 0xCC, len);
#endif
kmalloc_sanity(addr);
return addr;
}
void
kfree(void *ptr)
{
Allocation *hdr;
size_t pages;
if (ptr == NULL) return;
hdr = ptr - sizeof(Allocation);
kmalloc_sanity(ptr);
pages = page_amt(hdr->len);
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;
#ifndef NDEBUG
memset(hdr, 0xC0, pages * PAGE_SIZE);
#endif
page_free(hdr, pages);
}
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