Initial Commit

src/fs/elf.c

@@ -0,0 +1,146 @@
+#include "elf.h"
+#include "stdio.h"
+#include "string.h"
+#include "mm/pmm.h"
+#include "mm/vmm.h"
+#include "mm/memory.h"
+#include "fs/ext2.h"
+
+extern uintptr_t g_hhdm_offset;
+extern struct pagemap *kernel_pagemap;
+
+#define ELF_BUFFER_SIZE (1024 * 1024)
+
+
+#define PTE_PRESENT  (1ULL << 0)
+#define PTE_WRITABLE (1ULL << 1)
+#define PTE_USER     (1ULL << 2)
+
+bool ELF_Read(const char* path, void** entryPoint)
+{
+    uint32_t size;
+
+    uint8_t* elf_buffer = kmalloc(ELF_BUFFER_SIZE);
+    if (!elf_buffer) {
+        printf("ELF: kmalloc failed\n");
+        return false;
+    }
+
+    // ── load file ─────────────────────────────────────
+    if (!ext2_read_file_from_root(path, elf_buffer, &size)) {
+        printf("ELF: failed to read file\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    if (size < sizeof(ELFHeader)) {
+        printf("ELF: file too small\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    ELFHeader* header = (ELFHeader*)elf_buffer;
+
+    // ── validate ELF ──────────────────────────────────
+    if (memcmp(header->Magic, ELF_MAGIC, 4) != 0) {
+        printf("ELF: bad magic\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    if (header->Bitness != ELF_BITNESS_64BIT) {
+        printf("ELF: not 64-bit\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    if (header->Endianness != ELF_ENDIANNESS_LITTLE) {
+        printf("ELF: wrong endianness\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    if (header->Type != ELF_TYPE_EXECUTABLE) {
+        printf("ELF: not executable\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    if (header->InstructionSet != ELF_INSTRUCTION_SET_X64) {
+        printf("ELF: wrong arch\n");
+        kfree(elf_buffer);
+        return false;
+    }
+
+    *entryPoint = (void*)header->ProgramEntryPosition;
+
+    // ── program headers ───────────────────────────────
+    uint8_t* ph_table = elf_buffer + header->ProgramHeaderTablePosition;
+
+    for (uint32_t i = 0; i < header->ProgramHeaderTableEntryCount; i++)
+    {
+        ELFProgramHeader* ph = (ELFProgramHeader*)(ph_table +
+            i * header->ProgramHeaderTableEntrySize);
+
+        if (ph->Type != ELF_PROGRAM_TYPE_LOAD)
+            continue;
+
+        uint64_t virt   = ph->VirtualAddress;
+        uint64_t offset = ph->Offset;
+        uint64_t memsz  = ph->MemorySize;
+        uint64_t filesz = ph->FileSize;
+
+        if (memsz == 0)
+            continue;
+
+        // ── align to page boundary ─────────────────────
+        uint64_t aligned_virt   = ALIGN_DOWN(virt, PAGE_SIZE);
+        uint64_t page_offset    = virt & 0xFFF;
+        uint64_t aligned_memsz  = ALIGN_UP(memsz + page_offset, PAGE_SIZE);
+
+        uint64_t pages = aligned_memsz / PAGE_SIZE;
+
+        // Allocate physical pages
+        uint64_t phys_base = (uint64_t)pmm_alloc(pages);
+        if (!phys_base) {
+            printf("ELF: pmm_alloc failed for %lu pages\n", pages);
+            kfree(elf_buffer);
+            return false;
+        }
+
+        // ── map each page individually using new vmm_map_page ─────
+        for (uint64_t p = 0; p < pages; p++) {
+            uint64_t virt_addr = aligned_virt + p * PAGE_SIZE;
+            uint64_t phys_addr = phys_base + p * PAGE_SIZE;
+
+            bool success = vmm_map_page(
+                kernel_pagemap,
+                virt_addr,
+                phys_addr,
+                PAGE_READ | PAGE_WRITE | PAGE_USER,   // RW + User mode
+                Size4KiB
+            );
+
+            if (!success) {
+                printf("ELF: failed to map page at 0x%lx\n", virt_addr);
+                // TODO: cleanup previously mapped pages + free phys
+                kfree(elf_buffer);
+                return false;
+            }
+        }
+
+        // ── copy segment data ───────────────────────────────
+        uint8_t* dst = (uint8_t*)(phys_base + MEM_PHYS_OFFSET);  // via HHDM
+        uint8_t* src = elf_buffer + offset;
+
+        memcpy(dst + page_offset, src, filesz);
+
+        // ── zero BSS section ────────────────────────────────
+        if (memsz > filesz) {
+            memset(dst + page_offset + filesz, 0, memsz - filesz);
+        }
+    }
+
+    kfree(elf_buffer);
+    return true;
+}