Add first C user program

2026-06-11 20:19:24 +03:00
parent b32c12b311
commit 1c935cf154
55 changed files with 365 additions and 276 deletions
@@ -0,0 +1,120 @@
+#include "src/kernel/memory.h"
+#include "src/kernel/panic.h"
+#include "src/lib/layout.h"
+#include "src/lib/memory.h"
+
+#define MAP_UNIT 64
+#define FULL_UNIT 0xFFFFFFFFFFFFFFFF
+
+// TODO keep aligned with `src/lib/layout.h`.
+static uint16_t free_page = MAP_UNIT * 12;
+static uint64_t allocation[PAGE_COUNT / MAP_UNIT] = {
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    FULL_UNIT,
+    [59] = 0x8000000000000000ULL,
+};
+
+static uint8_t get_allocated(uint16_t page) {
+  return !!allocation[page / MAP_UNIT] & ((uint64_t)1 << (page % MAP_UNIT));
+}
+
+static void set_allocated(uint16_t page, uint8_t allocated) {
+  if (allocated) {
+    allocation[page / MAP_UNIT] |= ((uint64_t)1 << (page % MAP_UNIT));
+  } else {
+    allocation[page / MAP_UNIT] &= ~((uint64_t)1 << (page % MAP_UNIT));
+  }
+}
+
+void *memory_page_allocate() {
+  ASSERT(free_page < PAGE_COUNT, "memory_page_allocate: out of memory");
+  const uint16_t page = free_page;
+  set_allocated(page, 1);
+  for (uint16_t unit = free_page / MAP_UNIT; unit < PAGE_COUNT / MAP_UNIT; unit++) {
+    if (allocation[unit] != FULL_UNIT) {
+      uint16_t bit = (uint16_t)__builtin_ctzll(~allocation[unit]);
+      free_page = unit * MAP_UNIT + bit;
+      break;
+    }
+  }
+  return (void *)((uint64_t)page * PAGE_SIZE);
+}
+
+void memory_page_free(void *address) {
+  uint16_t page = (uint16_t)((uint64_t)address / PAGE_SIZE);
+  ASSERT(get_allocated(page), "memory_page_free: page not allocated")
+  set_allocated(page, 0);
+  if (page < free_page) {
+    free_page = page;
+  }
+}
+
+void memory_page_map(uint64_t *pml4, void *virt, void *phys, uint64_t flags) {
+  const uint64_t ivirt = (uint64_t)virt;
+  const uint64_t pml4_index = (ivirt >> 39) & 0x1FF;
+  const uint64_t pdpt_index = (ivirt >> 30) & 0x1FF;
+  const uint64_t pd_index = (ivirt >> 21) & 0x1FF;
+  const uint64_t pt_index = (ivirt >> 12) & 0x1FF;
+
+  if (!(pml4[pml4_index] & PAGE_PRESENT)) {
+    uint64_t *pdpt = memory_page_allocate();
+    memory_set(0, PAGE_SIZE, PHYS_TO_VIRT(pdpt));
+    pml4[pml4_index] = (uint64_t)pdpt | PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER;
+  }
+
+  uint64_t *pdpt = PHYS_TO_VIRT(pml4[pml4_index] & ~(uint64_t)0xFFF);
+  if (!(pdpt[pdpt_index] & PAGE_PRESENT)) {
+    uint64_t *pd = memory_page_allocate();
+    memory_set(0, PAGE_SIZE, PHYS_TO_VIRT(pd));
+    pdpt[pdpt_index] = (uint64_t)pd | PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER;
+  }
+
+  uint64_t *pd = PHYS_TO_VIRT(pdpt[pdpt_index] & ~(uint64_t)0xFFF);
+  ASSERT(!(pd[pd_index] & 0x80), "memory_page_map: huge page in PD");
+  if (!(pd[pd_index] & PAGE_PRESENT)) {
+    uint64_t *pt = memory_page_allocate();
+    memory_set(0, PAGE_SIZE, PHYS_TO_VIRT(pt));
+    pd[pd_index] = (uint64_t)pt | PAGE_PRESENT | PAGE_WRITABLE | PAGE_USER;
+  }
+
+  uint64_t *pt = PHYS_TO_VIRT(pd[pd_index] & ~(uint64_t)0xFFF);
+  pt[pt_index] = (uint64_t)phys | flags | PAGE_PRESENT;
+}
+
+void memory_page_unmap(uint64_t *pml4, void *virt) {
+  const uint64_t ivirt = (uint64_t)virt;
+  const uint64_t pml4_index = (ivirt >> 39) & 0x1FF;
+  const uint64_t pdpt_index = (ivirt >> 30) & 0x1FF;
+  const uint64_t pd_index = (ivirt >> 21) & 0x1FF;
+  const uint64_t pt_index = (ivirt >> 12) & 0x1FF;
+
+  if (!(pml4[pml4_index] & PAGE_PRESENT)) {
+    return;
+  }
+
+  uint64_t *pdpt = PHYS_TO_VIRT(pml4[pml4_index] & ~(uint64_t)0xFFF);
+  if (!(pdpt[pdpt_index] & PAGE_PRESENT)) {
+    return;
+  }
+
+  uint64_t *pd = PHYS_TO_VIRT(pdpt[pdpt_index] & ~(uint64_t)0xFFF);
+  if (!(pd[pd_index] & PAGE_PRESENT)) {
+    return;
+  }
+
+  uint64_t *pt = PHYS_TO_VIRT(pd[pd_index] & ~(uint64_t)0xFFF);
+  memory_page_free((void *)(pt[pt_index] & ~(uint64_t)0xFFF));
+  pt[pt_index] = 0;
+
+  __asm__ volatile("invlpg (%0)" : : "r"(virt) : "memory");
+}