Working i386 paging and liballoc

kernel/mm/bba.c

@@ -0,0 +1,89 @@
+/*
+Copyright 2025 Kamil Kowalczyk
+
+Redistribution and use in source and binary forms, with or
+without modification, are permitted provided that the following
+conditions are met:
+
+1. Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+“AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#include <libk/types.h>
+#include <libk/bitmap.h>
+#include <libk/string.h>
+#include <libk/util.h>
+#include <libk/compiler.h>
+#include <sync/spinlock.h>
+#include <mm/bba.h>
+#include <config.h>
+
+static struct bba bba;
+static volatile byte_t bba_membuf[BBA_SIZE] aligned(4096);
+static volatile byte_t bba_bm_membuf[BBA_BM_SIZE] aligned(4096);
+
+void bba_init(void) {
+  memset((void *)&bba, 0, sizeof(bba));
+  bba.baseptr = (uptr_t)bba_membuf;
+  bitmap_init(&bba.bm, (byte_t *)bba_bm_membuf, BBA_SIZE / BBA_BLOCK_SIZE);
+  sl_init(&bba.sl, "bba");
+  dbgf("bba_init(): initialized BBA %zu blocks, %zu block size, total=%zu\n",
+      BBA_SIZE / BBA_BLOCK_SIZE, BBA_BLOCK_SIZE, sizeof(bba_membuf));
+}
+
+uptr_t bba_alloc(void) {
+  uptr_t ret = 0;
+
+  sl_lock(&bba.sl);
+
+  for (usize_t i = 0; i < bba.bm.bit_count; i++) {
+    if (!bitmap_test(&bba.bm, i)) {
+      ret = (bba.baseptr + i * BBA_BLOCK_SIZE);
+      bitmap_set(&bba.bm, i);
+      goto done;
+    }
+  }
+
+done:
+  sl_unlock(&bba.sl);
+  return ret;
+}
+
+void bba_free(uptr_t addr) {
+  uptr_t aligned_addr = ALIGN_DOWN(addr, BBA_BLOCK_SIZE);
+
+  if (aligned_addr < bba.baseptr)
+    goto done;
+
+  if (aligned_addr >= bba.baseptr + bba.bm.bit_count * BBA_BLOCK_SIZE)
+    goto done;
+
+  usize_t bit = (usize_t)(aligned_addr - bba.baseptr) / BBA_BLOCK_SIZE;
+
+  sl_lock(&bba.sl);
+  bitmap_clear(&bba.bm, bit);
+  sl_unlock(&bba.sl);
+
+done:
+  return;
+}