wip: separate allocators into a kernel one and a user one

src/memory/virt/page.c

@@ -0,0 +1,92 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "assert.h"
+#include "kprintf.h"
+#include "memory.h"
+#include "process.h"
+#include "string.h"
+#include "utils.h"
+
+static int16_t find_next_block(size_t nb_pages, uint16_t *pd_index_ptr,
+                               uint32_t **page_table_ptr)
+{
+	for (*pd_index_ptr = 1; *pd_index_ptr < 768; (*pd_index_ptr)++) {
+		if (current_pd[(*pd_index_ptr)] == 0x02) {
+			if (add_page_table(*pd_index_ptr) < 0)
+				return -2;
+		}
+		*page_table_ptr =
+		    (uint32_t *)GET_PAGE_ADDR(0, *pd_index_ptr + PT_START);
+		for (uint16_t i = 0; i + nb_pages - 1 < PT_SIZE; i++) {
+			uint16_t j;
+			for (j = 0; (*page_table_ptr)[i + j] >> 12 == i + j &&
+			            j < nb_pages;
+			     j++)
+				;
+			if (j == nb_pages)
+				return i;
+			i += j;
+		}
+	}
+	return -1;
+}
+
+void *valloc_pages(size_t size, void **phys_addr)
+{
+	const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
+	uint16_t pd_index;
+	uint32_t *page_table;
+	const int16_t index = find_next_block(nb_pages, &pd_index, &page_table);
+
+	if (index < 0) {
+		kprintf(KERN_CRIT "%d: Not enough pages (max: %d)\n", index,
+		        PT_SIZE);
+		return NULL;
+	}
+	for (size_t i = index; i - (size_t)index < nb_pages; i++) {
+		void *frame = alloc_frame();
+		if (!frame) {
+			for (size_t j = index; j < i; j++)
+				free_frame((void *)(page_table[j] & PAGE_MASK));
+			return NULL;
+		}
+		if (phys_addr)
+			*phys_addr = frame;
+		page_table[i] = ((uint32_t)frame & PAGE_MASK) | INIT_FLAGS;
+	}
+	return (void *)GET_PAGE_ADDR(pd_index, index);
+}
+
+int vfree_pages(void *page_ptr, size_t size)
+{
+	const uint32_t page_addr = (uint32_t)page_ptr;
+	const uint32_t nb_pages = CEIL(size, PAGE_SIZE);
+	const uint32_t page_index = page_addr / PAGE_SIZE;
+	const uint32_t pd_index = page_index / PD_SIZE;
+	const uint32_t pt_index = page_index % PD_SIZE;
+
+	if ((uint32_t)pd_index > 0x300) {
+		kprintf(KERN_WARNING "Address out of range\n");
+		return -1;
+	} else if (page_addr % PAGE_SIZE) {
+		kprintf(KERN_WARNING "Invalid address\n");
+		return -1;
+	} else if (pt_index + nb_pages > PT_SIZE) {
+		kprintf(KERN_WARNING "Invalid number of frames\n");
+		return -1;
+	}
+	uint32_t *page_table =
+	    (uint32_t *)GET_PAGE_ADDR(0, PT_START + pd_index);
+	for (uint16_t i = pt_index; i < pt_index + nb_pages; i++) {
+		if (page_table[i] >> 12 == i) {
+			kprintf(KERN_WARNING "Page already free\n");
+			return -2;
+		}
+		free_frame((void *)(page_table[i] & PAGE_MASK));
+		page_table[i] = i << 12;
+	}
+
+	return 0;
+}