elf: start writing elf loader

GNUmakefile

@@ -182,6 +182,7 @@ $(IMAGE_NAME).iso: limine/limine kernel
 	cp -v limine.conf iso_root/boot/limine/
 	mkdir -p iso_root/EFI/BOOT
 ifeq ($(ARCH),x86_64)
+	cp -v testing/sk-hello.elf iso_root/
 	cp -v limine/limine-bios.sys limine/limine-bios-cd.bin limine/limine-uefi-cd.bin iso_root/boot/limine/
 	cp -v limine/BOOTX64.EFI iso_root/EFI/BOOT/
 	cp -v limine/BOOTIA32.EFI iso_root/EFI/BOOT/

kernel/src/exec/elf.c

@@ -0,0 +1,43 @@
+#include <exec/elf.h>
+#include <stdint.h>
+#include <sys/log.h>
+
+void elf_load(char *data) {
+    Elf64_Ehdr *ehdr = (Elf64_Ehdr*)data;
+    if (   ehdr->e_ident[EI_MAG0] != ELFMAG0
+        || ehdr->e_ident[EI_MAG1] != ELFMAG1
+        || ehdr->e_ident[EI_MAG2] != ELFMAG2
+        || ehdr->e_ident[EI_MAG3] != ELFMAG3)
+    {
+        log("elf - loading failed: magic is incorrect\n");
+        return;
+    }
+
+    log("elf - e_ident[EI_DATA]: %d\n", ehdr->e_ident[EI_DATA]);
+    log("elf - e_ident[EI_CLASS]: %d\n", ehdr->e_ident[EI_CLASS]);
+    log("elf - e_ident[EI_OSABI]: %d\n", ehdr->e_ident[EI_OSABI]);
+    log("elf - e_machine: %d\n", ehdr->e_machine);
+    log("elf - e_entry: %p\n", ehdr->e_entry);
+    log("elf - e_type: %p\n", ehdr->e_type);
+
+    if (   ehdr->e_ident[EI_CLASS] != ELFCLASS64
+        || ehdr->e_machine != EM_X86_64)
+    {
+        log("elf - loading failed: is the file built for amd64?\n");
+        return;
+    }
+
+    if (ehdr->e_type != ET_EXEC)
+    {
+        log("elf - loading failed: ELF type isn't ET_EXEC\n");
+        return;
+    }
+
+    Elf64_Phdr *phdr = (Elf64_Phdr*)data + ehdr->e_phoff;
+    for (uint16_t i = 0; i < ehdr->e_phnum; i++) {
+        if (phdr[i].p_type != PT_LOAD)
+            continue;
+
+        log("elf - Loadable program header: vaddr: %p", phdr[i].p_vaddr);
+    }
+}

kernel/src/exec/elf.h

@@ -0,0 +1,118 @@
+#pragma once
+
+#include <stdint.h>
+
+// ELF magic.
+#define EI_MAG0		 0
+#define ELFMAG0	 	 0x7f
+
+#define EI_MAG1		 1
+#define ELFMAG1      'E'
+
+#define EI_MAG2		 2
+#define ELFMAG2		 'L'
+
+#define EI_MAG3		 3
+#define ELFMAG3		 'F'
+
+// ELF class
+#define EI_CLASS     4
+#define ELFCLASSNONE 0
+#define ELFCLASS32   1
+#define ELFCLASS64   2
+
+// Is processor-specific data little-endian or big-endian?
+#define EI_DATA      5
+#define ELFDATANONE  0
+#define ELFDATA2LSB  1
+#define ELFDATA2MSB  2
+
+// ELF version
+#define EI_VERSION   6
+#define EV_NONE      0
+#define EV_CURRENT   1
+
+// ELF ABI
+#define EI_OSABI     7
+#define ELFOSABI_NONE      0
+#define ELFOSABI_SYSV   0
+#define ELFOSABI_HPUX      1
+#define ELFOSABI_NETBSD   2
+#define ELFOSABI_LINUX      3
+#define ELFOSABI_SOLARIS   6
+#define ELFOSABI_IRIX      8
+#define ELFOSABI_FREEBSD   9
+#define ELFOSABI_TRU64   10
+#define ELFOSABI_ARM      97
+#define ELFOSABI_STANDALONE   255
+
+// ABI version
+#define EI_ABIVERSION 8
+
+// Unused bytes.
+#define EI_PAD 9
+
+// Magic size.
+#define EI_NIDENT 16
+
+// e_type
+#define ET_NONE		0
+#define ET_REL		1
+#define ET_EXEC		2
+#define ET_DYN		3
+#define ET_CORE		4
+
+// e_machine (we only included machines supported by Soaplin.)
+#define EM_X86_64	62
+
+typedef uint64_t Elf64_Addr;
+typedef uint64_t Elf64_Off;
+typedef uint16_t Elf64_Section;
+typedef uint16_t Elf64_Versym;
+typedef uint8_t Elf_Byte;
+typedef uint16_t Elf64_Half;       
+typedef int32_t Elf64_Sword;      
+typedef uint32_t Elf64_Word;       
+typedef int64_t Elf64_Sxword;     
+typedef uint64_t Elf64_Xword;
+
+typedef struct {
+    unsigned char e_ident[EI_NIDENT];
+    uint16_t      e_type;
+    uint16_t      e_machine;
+    uint32_t      e_version;
+    Elf64_Addr     e_entry;
+    Elf64_Off      e_phoff;
+    Elf64_Off      e_shoff;
+    uint32_t      e_flags;
+    uint16_t      e_ehsize;
+    uint16_t      e_phentsize;
+    uint16_t      e_phnum;
+    uint16_t      e_shentsize;
+    uint16_t      e_shnum;
+    uint16_t      e_shstrndx;
+} Elf64_Ehdr;
+
+#define	PT_NULL		0
+#define PT_LOAD		1
+#define PT_DYNAMIC	2
+#define PT_INTERP	3
+#define PT_NOTE		4
+#define PT_SHLIB	5
+
+#define PF_X		(1 << 0)
+#define PF_W		(1 << 1)
+#define PF_R		(1 << 2)
+
+typedef struct {
+    uint32_t   p_type;
+    uint32_t   p_flags;
+    Elf64_Off  p_offset;
+    Elf64_Addr p_vaddr;
+    Elf64_Addr p_paddr;
+    uint64_t   p_filesz;
+    uint64_t   p_memsz;
+    uint64_t   p_align;
+} Elf64_Phdr;
+
+void elf_load(char *data);

kernel/src/fs/vfs.h

@@ -1,66 +1 @@
 #pragma once
-
-#include <stdint.h>
-
-struct vfs {
-  struct vfs *vfs_next;           /* next vfs in list */
-  struct vfsops *vfs_op;          /* operations on vfs */
-  struct vnode *vfs_vnodecovered; /* vnode we cover */
-  int vfs_flag;                   /* flags */
-  int vfs_bsize;                  /* native block size */
-  uint64_t vfs_data;               /* private data */
-};
-
-struct vfsops {
-  int (*vfs_mount)();
-  int (*vfs_unmount)();
-  int (*vfs_root)();
-  int (*vfs_statfs)();
-  int (*vfs_sync)();
-  int (*vfs_fid)();
-  int (*vfs_vget)();
-};
-
-enum vtype { VNON, VREG, VDIR, VBLK, VCHR, VLNK, VSOCK, VBAD };
-struct vnode {
-  uint16_t v_flag;               /* vnode flags */
-  uint16_t v_count;              /* reference count */
-  uint16_t v_shlockc;            /* # of shared locks */
-  uint16_t v_exlockc;            /* # of exclusive locks */
-  struct vfs *v_vfsmountedhere; /* covering vfs */
-  struct vnodeops *v_op;        /* vnode operations */
-  union {
-    struct socket *v_Socket; /* unix ipc */
-    struct stdata *v_Stream; /* stream */
-  };
-  struct vfs *v_vfsp; /* vfs we are in */
-  enum vtype v_type;  /* vnode type */
-  uint64_t v_data;     /* private data */
-};
-
-struct vnodeops {
-  int (*vn_open)();
-  int (*vn_close)();
-  int (*vn_rdwr)();
-  int (*vn_ioctl)();
-  int (*vn_select)();
-  int (*vn_getattr)();
-  int (*vn_setattr)();
-  int (*vn_access)();
-  int (*vn_lookup)();
-  int (*vn_create)();
-  int (*vn_remove)();
-  int (*vn_link)();
-  int (*vn_rename)();
-  int (*vn_mkdir)();
-  int (*vn_rmdir)();
-  int (*vn_readdir)();
-  int (*vn_symlink)();
-  int (*vn_readlink)();
-  int (*vn_fsync)();
-  int (*vn_inactive)();
-  int (*vn_bmap)();
-  int (*vn_strategy)();
-  int (*vn_bread)();
-  int (*vn_brelse)();
-};

kernel/src/main.c

@@ -1,3 +1,4 @@
+#include "exec/elf.h"
 #include "mm/pmm.h"
 #include "mm/vmm.h"
 #include "rt.h"
@@ -35,6 +36,12 @@ static volatile struct limine_framebuffer_request framebuffer_request = {
     .revision = 0
 };
 
+__attribute__((used, section(".limine_requests")))
+static volatile struct limine_module_request module_request = {
+    .id = LIMINE_MODULE_REQUEST,
+    .revision = 0
+};
+
 /*__attribute__((used, section(".limine_requests")))
 static volatile struct limine_entry_point_request entrypoint_request = {
     .id = LIMINE_ENTRY_POINT_REQUEST,
@@ -112,18 +119,23 @@ void kmain(void) {
     vmm_init();
 
     pit_init(1000);
-    //sched_init();
+    sched_init();
     //user_init();
 
-    uint8_t *mem = pmm_request_page();
+    struct limine_file *f = module_request.response->modules[0];
-    mem[0] = 0xCD;
+    log("kmain - %s\n", f->path);
-    mem[1] = 0x80;
+
+    elf_load((char*)f->address);
+
+    //uint8_t *mem = pmm_request_page();
+    //mem[0] = 0xCD;
+    //mem[1] = 0x80;
     //mem[2] = 0xF4;
 
     //mem[3] = 0xFE;
-    pagemap_t* pm = vmm_alloc_pm();
+    //pagemap_t* pm = vmm_alloc_pm();
-    vmm_map(pm, 0x1000, (uint64_t)mem, VMM_PRESENT | VMM_USER);
+    //vmm_map(pm, 0x1000, (uint64_t)mem, VMM_PRESENT | VMM_USER);
-    sched_create("Init", 0x1000, pm, SCHED_USER_PROCESS);
+    //sched_create("Init", 0x1000, pm, SCHED_USER_PROCESS);
 
 
     log("kernel - Soaplin initialized sucessfully.\n");

kernel/src/sched/sched.c

@@ -90,6 +90,8 @@ sched_process *sched_create(char *name, uint64_t entry_point, pagemap_t* pm, uin
         log("sched - Standby mode has been"
         "disabled.\n");
     }
+    
+    log("sched - created process '%s' (pid: %d, rip: %p)\n", proc->name, proc->pid, proc->regs.rip);
     return proc;
 }
 

limine.conf

@@ -6,3 +6,4 @@ verbose: yes
     protocol: limine
 
     path: boot():/boot/soaplin
+    module_path: boot():/sk-hello.elf

testing/link.ld

@@ -0,0 +1,20 @@
+SECTIONS {
+  . = 0x1000;
+
+  .text : {
+    *(.text*)
+  }
+
+  .rodata : {
+    *(.rodata*)
+  }
+
+  .data : {
+    *(.data*)
+  }
+
+  .bss : {
+    *(.bss*)
+    *(COMMON)
+  }
+}

testing/test.asm

@@ -0,0 +1,8 @@
+bits 64
+section .text
+    global _start
+
+_start:
+    int 0x80
+lol:
+    jmp lol