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Full PMM implementation

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Tom-on
2025-04-04 16:58:54 +02:00
parent 5d7a4d790f
commit 25771de53e
6 changed files with 78 additions and 28 deletions
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kernel/src/pmm.c
+50 -12
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@@ -1,13 +1,15 @@
#include <bootloader.h>
#include <kernel.h>
#include <paging.h>
#include <string.h>
#include <pmm.h>
// Bitmap & helpers
uint32_t* bitmap;
int pmm_ready = 0;
#define SET_BLOCK(_b) bitmap[(_b) / 32] |= (1 << ((_b) % 32))
#define USET_BLOCK(_b) bitmap[(_b) / 32] &= ~(1 << ((_b) % 32))
#define TEST_BLOCK(_b) ((bitmap[(_b) % 32] & (1 << ((_b) % 32))) ? 1 : 0)
#define TEST_BLOCK(_b) ((bitmap[(_b) / 32] & (1 << ((_b) % 32))) ? 1 : 0)
// Status
size_t usedBlocks = 0;
@@ -15,27 +17,63 @@ size_t maxBlocks = 0;
int pmm_init(void) {
size_t totalmem = (bootloader.memLower + bootloader.memUpper) * 1024;
maxBlocks = totalmem / PMM_BS;
maxBlocks = dceil(totalmem, PMM_BS);
size_t bitmapBytes = dceil(maxBlocks, PMM_BPB);
usedBlocks = maxBlocks;
bitmap = NULL;
// # of pagetabs required to map the bitmap
size_t ptcount = dceil(dceil(bitmapBytes, PAGE_SIZE), 1024);
// Find enough space for the bitmap
struct boot_memmap* mmap;
int found = 0;
for (size_t i = 0; i < bootloader.memmapLen; i++) {
mmap = &bootloader.memmap[i];
if (mmap->type != BOOT_MMAP_AVAILABLE ||
mmap->size < maxBlocks / PMM_BPB) continue;
if (mmap->type == BOOT_MMAP_AVAILABLE &&
mmap->size >= maxBlocks / PMM_BPB) {
found = 1;
break;
}
}
if (!found) return 1; // Not enough memory
bitmap = (uint32_t*)mmap->base;
break;
uint32_t pageFrameStart = mmap->base;
pag_registerTempFrame(pageFrameStart);
mmap->base += ptcount * PAGE_SIZE;
uint32_t bitmapStart = KERNEL_HEAP - dceil(bitmapBytes, PAGE_SIZE) * PAGE_SIZE;
uint32_t bitmapStartPhys = mmap->base;
bitmap = (uint32_t*)bitmapStart;
size_t pagecount = dceil(bitmapBytes, PAGE_SIZE);
for (size_t i = 0; i < pagecount; i++) {
// We can't unmap this with pag_umapPage(), it's in a tempFrame
pag_mapPage(bitmapStart + i * PAGE_SIZE, mmap->base + i * PAGE_SIZE, 0);
}
if (bitmap == NULL) return 1;
// Set all blocks as used
memset(bitmap, 1, maxBlocks / PMM_BPB);
memset(bitmap, 0xff, maxBlocks / PMM_BPB);
for (size_t i = 0; i < bootloader.memmapLen; i++) {
mmap = &bootloader.memmap[i];
if (mmap->type == BOOT_MMAP_AVAILABLE) pmm_initRegion(mmap->base, mmap->size);
}
pmm_deinitRegion(bitmapStartPhys, bitmapBytes);
pmm_deinitRegion(pageFrameStart, ptcount * PAGE_SIZE);
debugf(
"[pmm] Physical memory manager initialized.\n"
"\tAvailable memory: %d blocks free (%d bytes)\n"
"\tBitmap at phys(%08x), virt(%08x), %d bytes\n",
maxBlocks - usedBlocks, (maxBlocks - usedBlocks) * PMM_BS,
bitmapStartPhys, bitmapStart, bitmapBytes
);
pmm_ready = 1;
return 0;
}
@@ -45,11 +83,11 @@ int findFreeBlocks(size_t blockCount) {
uint32_t max = maxBlocks / 32;
uint32_t freeCount = 0;
for (size_t i = 0; i < max; i++) {
// We don't have to check, cause it's all reserved
// We don't have to check, cause it's all used
if (bitmap[i] == 0xffffffff) continue;
for (uint8_t j = 0; j < 32; j++) {
if (TEST_BLOCK(i * PMM_BPB + j)) freeCount++;
if (TEST_BLOCK(i * PMM_BPB + j) == 0) freeCount++;
else freeCount = 0;
if (freeCount >= blockCount) return i * PMM_BPB + j;
@@ -78,8 +116,8 @@ void pmm_deinitRegion(size_t base, size_t len) {
uint32_t blockCount = len / PMM_BS;
while (blockCount-- > 0) {
align++;
SET_BLOCK(align); // We can't increment here, because macros -_(._.)_-
align++;
usedBlocks++;
}