[USER] Load and run ELF module in userspace

.gitignore

@@ -7,3 +7,4 @@ kernel/obj/
 *.o
 *.a
 tags
+init/init

Makefile

@@ -4,14 +4,14 @@ ifeq ($(MITTOS64),)
   $(error Build environment is not activated. Please source activate)
 endif
 
-.PHONY: all clean kernel libc
+.PHONY: all clean kernel libc init
 SHELL := bash
 
 CC=$(TARGET)-gcc
 FLAGS_TO_PASS:= \
 	CC=$(CC)
 
-all: kernel libc
+all: kernel libc init
 
 # A trick to only build phony target if necessary
 kernel:
@@ -26,6 +26,12 @@ ifeq ($(shell make -sqC libc || echo 1), 1)
 	$(MAKE) -C libc install $(FLAGS_TO_PASS)
 endif
 
+init:
+ifeq ($(shell make -sqC init || echo 1), 1)
+	@(. util/helpers.sh; print_info "Building init")
+	$(MAKE) -C init install $(FLAGS_TO_PASS)
+endif
+
 tags:
 	ctags -R kernel
 
@@ -34,5 +40,6 @@ clean:
 	$(MAKE) -C kernel clean
 	rm -f mittos64.iso
 	$(MAKE) -C libc clean
+	$(MAKE) -C init clean
 	rm -f qemu-error.log
 	rm -f serial.log

init/Makefile

@@ -0,0 +1,23 @@
+ifeq ($(MITTOS64),)
+  $(error Build environment is not activated. Please source activate)
+endif
+
+
+installdir := $(SYSROOT)/boot
+
+
+CFLAGS ?= -Wall -Wextra -ggdb -O0
+
+
+all: init
+
+$(installdir)/init: init
+	mkdir -p $(dir $@)
+	cp $< $@
+
+install: $(installdir)/init
+
+clean:
+	rm -rf init
+
+.PHONY: all clean install

init/init.c

@@ -0,0 +1,8 @@
+int main(int argc, char **argv)
+{
+  (void) argc;
+  (void) argv;
+  int i=0;
+  for(;;)i++;
+  return 0;
+}

kernel/boot/kmain.c

@@ -7,15 +7,8 @@
 #include <cpu.h>
 #include <timer.h>
 #include <string.h>
-
-void thread_function()
-{
-  int i = 0;
-  while(1)
-  {
-    i++;
-  }
-}
+#include <cpu.h>
+#include <elf.h>
 
 int kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
@@ -32,18 +25,11 @@ int kmain(uint64_t multiboot_magic, void *multiboot_data)
   pit_init();
 
   process_t *p1 = process_spawn(0);
-  uint64_t addr = 0x200000;
-  thread_t *th = new_thread((void *)addr, 1);
-
-  // Write thread code to address
-  procmm_map(p1->mmap, addr, addr+PAGE_SIZE, 0);
-  vmm_p4_memcpy(p1->mmap->P4, (void *)addr, 0, thread_function, PAGE_SIZE);
-  procmm_setup(p1);
+  thread_t *th = exec_elf(p1, mboot_data.init);
+  scheduler_insert(th);
 
   procmm_print_map(p1->mmap);
 
-  process_attach(p1, th);
-  scheduler_insert(th);
 
   asm("sti");
   debug_info("BOOT COMPLETE\n");

kernel/boot/multiboot.c

@@ -25,6 +25,16 @@ void parse_multiboot1()
     mboot_data.mmap_size = data->mmap_len/sizeof(mboot1_mmap_entry);
     mboot_data.mmap = P2V(data->mmap_addr);
   }
+  if(data->flags & (1<<3))
+  {
+    if(data->mods_count)
+    {
+      mboot1_module_entry *mod = P2V(data->mods_addr);
+      mboot_data.init = P2V(mod->mod_start);
+      mboot_data.init_len = mod->mod_end - mod->mod_start;
+      debug_ok("[MBOOT1] init executable: %x (%x bytes)\n", mboot_data.init, mboot_data.init_len);
+    }
+  }
 }
 
 char *mboot_tags_type[] = {
@@ -120,6 +130,8 @@ void multiboot_init(uint64_t magic, void *data)
 
 int multiboot_page_used(uintptr_t addr)
 {
+  if(overlapsz(addr, PAGE_SIZE, V2P(mboot_data.init), mboot_data.init_len))
+    return 1;
   if(mboot_data.version == 1)
   {
     mboot1_info *data = mboot_data.data;

kernel/include/elf.h

@@ -0,0 +1,7 @@
+#pragma once
+#include <stdint.h>
+#include <process.h>
+#include <thread.h>
+
+void *load_elf(process_t *p, void *data);
+thread_t *exec_elf(process_t *p, void *image);

kernel/include/multiboot.h

@@ -51,6 +51,12 @@ typedef struct {
   uint32_t len_hi;
   uint32_t type;
 } mboot1_mmap_entry;
+typedef struct {
+  uint32_t mod_start;
+  uint32_t mod_end;
+  uint32_t str_ptr;
+  uint32_t reserved;
+} mboot1_module_entry;
 
 // MULTIBOOT 2
 
@@ -95,6 +101,8 @@ typedef struct {
     void *mmap;
     uint32_t mmap_size;
     void *rsdp;
+    void *init;
+    uint64_t init_len;
   };
   extern struct mboot_data_st mboot_data;
 

kernel/proc/elf.c

@@ -0,0 +1,75 @@
+#include <stdint.h>
+#include <string.h>
+#include <mem.h>
+#include <debug.h>
+#include <process.h>
+
+typedef struct
+{
+  uint8_t identity[16];
+  uint16_t type;
+  uint16_t machine;
+  uint32_t version;
+  uint64_t entry;
+  uint64_t ph_offset;
+  uint64_t sh_offset;
+  uint32_t flags;
+  uint16_t header_size;
+  uint16_t ph_size;
+  uint16_t ph_num;
+  uint16_t sh_size;
+  uint16_t sh_num;
+  uint16_t strtab_index;
+}__attribute__((packed)) elf_header;
+
+#define ELF_TYPE_EXECUTABLE 2
+
+typedef struct
+{
+  uint32_t type;
+  uint32_t flags;
+  uint64_t offset;
+  uint64_t virtual_address;
+  uint64_t physical_address;
+  uint64_t file_size;
+  uint64_t mem_size;
+  uint64_t align;
+}__attribute__((packed)) elf_phead;
+
+#define ELF_PT_LOAD 1
+
+void load_elf_segment(process_t *p, uint8_t *file, elf_phead *phead)
+{
+  uint64_t memsize = phead->mem_size;
+  uint64_t filesize = phead->file_size;
+  uint64_t mempos = phead->virtual_address;
+  uint64_t filepos = phead->offset;
+  debug("  Load segment %x to %x-%x\n", filepos, mempos, mempos+memsize);
+
+  procmm_map(p->mmap, mempos, mempos+memsize, 0);
+  vmm_p4_memcpy(p->mmap->P4, (void *)mempos, 0, &file[filepos], filesize);
+  vmm_p4_memset(p->mmap->P4, incptr(mempos, filesize), 0, memsize - filesize);
+}
+
+void *load_elf(process_t *p, void *data)
+{
+  elf_header *elf = data;
+  if(memcmp(elf->identity, "\x7f""ELF", 4))
+  {
+    debug_error("ELF - No elf magic at %x\n", elf->identity);
+    return 0;
+  }
+  if(elf->type != ELF_TYPE_EXECUTABLE)
+    return 0;
+
+  debug_info("ELF - Loading ELF executable\n");
+  elf_phead *phead = incptr(data, elf->ph_offset);
+  for(uint32_t i = 0; i < elf->ph_num; i++)
+  {
+    if(phead[i].type == ELF_PT_LOAD)
+    {
+      load_elf_segment(p, data, &phead[i]);
+    }
+  }
+  return (void *)elf->entry;
+}

kernel/proc/exec_elf.c

@@ -0,0 +1,14 @@
+#include <elf.h>
+#include <stdint.h>
+#include <debug.h>
+
+thread_t *exec_elf(process_t *p, void *image)
+{
+  void *entry = load_elf(p, image);
+  debug("Address:%x\n", entry);
+  procmm_setup(p);
+  thread_t *th = new_thread((void *)entry, 1);
+  process_attach(p, th);
+
+  return th;
+}

util/grub.cfg

@@ -1,9 +1,10 @@
 set timeout=1
-set default=0
+set default=1
 
 menuentry "mittos64" {
   multiboot2 /boot/kernel
 }
 menuentry "mittos64 MultiBoot1" {
   multiboot /boot/kernel
+  module /boot/init
 }