Move headers to include/

2026-03-18 11:48:33 +01:00
parent a1e8aacd01
commit f7735eb3a4
45 changed files with 89 additions and 88 deletions
--- a/src/mem/pmm.c
+++ b/src/mem/pmm.c
@@ -0,0 +1,132 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Physical memory manager from freelist
+ * @license GPL-3.0-only
+ */
+
+/*
+pmm - Physical Memory Manager
+will manage 4kb pages physically
+it will probably need to get some info from Limine,
+to see which pages are used by kernel/bootloader/mmio/fb etc.
+*/
+
+#include <mem/paging.h>
+#include <limine.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <kernel.h>
+#include <mem/utils.h>
+#include <mem/pmm.h>
+
+/*
+First we'll have to discover the physical memory layout,
+and for that we can use a Limine request.
+*/
+
+struct limine_memmap_entry* biggest_entry;
+
+/*
+ * pmm_find_biggest_usable_region - Finding the biggest free memory region
+ * @memmap: Limine memory map
+ * @hhdm:   Limine HHDM offset
+ *
+ * This function uses the memory map provided by the bootloader
+ * to find the single biggest free memory region we can use.
+ */
+static void pmm_find_biggest_usable_region(struct limine_memmap_response* memmap, struct limine_hhdm_response* hhdm)
+{
+    // Max length of a usable memory region
+    uint64_t length_max = 0;
+    uint64_t offset = hhdm->offset;
+
+    DEBUG("Usable Memory:");
+    for (size_t i=0; i<memmap->entry_count; i++) {
+        struct limine_memmap_entry* entry = memmap->entries[i];
+
+        if (entry->type == LIMINE_MEMMAP_USABLE) {
+            DEBUG("0x%p-0x%p mapped at 0x%p-0x%p", entry->base, entry->base+entry->length,
+                        entry->base+offset, entry->base+entry->length+offset);
+            if (entry->length > length_max)
+            {
+                length_max = entry->length;
+                biggest_entry = entry;
+            }
+        }
+    }
+
+    DEBUG("Biggest usable memory region:");
+    DEBUG("0x%p-0x%p mapped at 0x%p-0x%p", biggest_entry->base, biggest_entry->base + biggest_entry->length,
+            biggest_entry->base+offset, biggest_entry->base+biggest_entry->length+offset);
+}
+
+// Offset from Higher Half Direct Map
+uint64_t hhdm_off;
+
+static uintptr_t g_freelist = 0;
+
+/*
+ * pmm_alloc - Allocate a physical page
+ *
+ * This function allocates a single physical page (frame)
+ * 
+ * Return:
+ * <addr> - Address for the allocated page
+ */
+uintptr_t pmm_alloc()
+{
+    if (!g_freelist) {
+		panic(NULL, "PMM is out of memory!");		
+	}
+    uintptr_t addr = g_freelist;
+    g_freelist = *(uintptr_t*) PHYS_TO_VIRT(g_freelist);
+    return addr;
+}
+
+/*
+ * pmm_free - Frees a memory page
+ * @addr: Address to the page
+ */
+void pmm_free(uintptr_t addr)
+{
+    *(uintptr_t*) PHYS_TO_VIRT(addr) = g_freelist;
+    g_freelist = addr;
+}
+
+/*
+ * pmm_init_freelist - PMM freelist initialization
+ *
+ * This function marks the biggest memory region as
+ * free, so we can use it in pmm_alloc.
+ */
+static void pmm_init_freelist()
+{
+    // We simply call pmm_free() on each page that is marked USABLE
+    // in our big memory region.
+    uint64_t base = ALIGN_UP(biggest_entry->base, PAGE_SIZE);
+    uint64_t end = ALIGN_DOWN(biggest_entry->base + biggest_entry->length, PAGE_SIZE);
+
+    uint64_t page_count=0;
+    for (uint64_t addr = base; addr < end; addr += PAGE_SIZE) {
+        pmm_free(addr);
+        page_count++;
+    }
+    DEBUG("%u frames in freelist, available for use (%u bytes)", page_count, page_count*PAGE_SIZE);
+}
+
+/*
+ * pmm_init - Physical memory manager initialization
+ * @boot_ctx: Boot context structure
+ *
+ * This function prepares the PMM for use.
+ * The PMM works with a freelist.
+ */
+void pmm_init(struct boot_context boot_ctx)
+{
+    hhdm_off = boot_ctx.hhdm->offset;
+    pmm_find_biggest_usable_region(boot_ctx.mmap, boot_ctx.hhdm);
+
+    // Now we have biggest USABLE region,
+    // so to populate the free list we just iterate through it
+    pmm_init_freelist();
+}