iris/boot-programs/init.ccp

#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// bootstrap/init.ccp: Bootstrapping code.
// Copyright 2009 Bas Wijnen <wijnen@debian.org>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

#include "devices.hh"
#include "iris.hh"
#include <elf.h>

#define NUM_SLOTS 4
#define NUM_CAPS 16

static unsigned _free
extern unsigned _end

void init_alloc ():
	_free = _end

char *alloc_space (unsigned pages):
	unsigned ret = (_free + PAGE_SIZE - 1) & PAGE_MASK
	_free = ret + pages * PAGE_SIZE
	return (char *)ret

void *operator new[] (unsigned size):
	void *ret = (void *)_free
	size = (size + 3) & ~3
	unsigned rest = PAGE_SIZE - (size & ~PAGE_MASK)
	if rest <= size:
		_free += size
		return ret
	unsigned pages = ((size - rest) + PAGE_SIZE - 1) & PAGE_MASK
	char *space = alloc_space (pages)
	for unsigned p = 0; p < pages; ++p:
		Kernel::Page page = Kernel::my_memory.create_page ()
		page.set_flags (Kernel::Page::PAYING | Kernel::Page::FRAME, Kernel::Page::PAYING | Kernel::Page::FRAME)
		Kernel::my_memory.map (page, (unsigned)&space[p << PAGE_BITS])
		Kernel::free_cap (page)
	_free += size
	return ret

struct file:
	unsigned size
	// Only the first 16 characters of the name are used, because that's much easier.
	// This means that file names must be different in the first 16 characters if sort order matters.
	char name[16]
	String string

static unsigned num_files
static file *files
static unsigned *index
static Kernel::Memory top_memory
static unsigned slot
static unsigned max_pages
static char *mapping
static unsigned current_thread

// Get the initial block device and filesystem.
static Directory receive_devices ():
	String data
	Filesystem fs
	bool have_data = false, have_fs = false
	for unsigned i = 0; i < 2; ++i:
		Device dev
		Kernel::wait ()
		if Kernel::recv.data[0].l != Parent::PROVIDE_DEVICE:
			kdebug ("Invalid bootstrap request.\n")
			Kernel::panic (0)
		switch Kernel::recv.data[1].l:
			case String::ID:
				if have_data:
					kdebug ("duplicate device.\n")
					Kernel::panic (0)
				dev = Kernel::get_arg ()
				have_data = true
				Kernel::recv.reply.invoke ()
				data = dev.create_user (Kernel::my_memory)
				dev.use (data)
				Kernel::free_cap (dev)
				break
			case Filesystem::ID:
				if have_fs:
					kdebug ("duplicate filesystem.\n")
					Kernel::panic (0)
				dev = Kernel::get_arg ()
				have_fs = true
				fs = dev.create_user (Kernel::my_memory)
				dev.use (fs)
				Kernel::free_cap (dev)
				Kernel::recv.reply.invoke ()
				break
			default:
				kdebug ("unexpected device: ")
				kdebug_num (Kernel::recv.data[1].l)
				kdebug_char ('\n')
				Kernel::panic (0)
	// Initialize the root file system.
	Directory root = fs.use_device_ro (data.copy ())
	Kernel::free_cap (data)
	Kernel::free_cap (fs)
	return root

// Make a list of all files.
static void list_files (Directory root):
	Kernel::Num fullsize = root.get_size ()
	if fullsize.h != 0:
		kdebug ("Too many files in bootstrap directory.\n")
		Kernel::panic (0)
	num_files = fullsize.l
	files = new file[num_files]
	Kernel::Caps caps = Kernel::my_memory.create_caps (num_files * 2)
	unsigned slot = Kernel::alloc_slot ()
	caps.use (slot)
	for unsigned i = 0; i < num_files; ++i:
		Kernel::set_recv_arg (Kernel::Cap (slot, i * 2))
		String n = root.get_name (i)
		n.get_chars (0, files[i].name)
		Kernel::set_recv_arg (Kernel::Cap (slot, i * 2 + 1))
		files[i].string = root.get_file_ro (i)
		Kernel::Num fullsize = files[i].string.get_size ()
		if fullsize.h != 0:
			kdebug ("initial file size too large.\n")
			Kernel::panic (0)
		files[i].size = fullsize.l
		if max_pages < (fullsize.l + PAGE_SIZE - 1) & PAGE_MASK:
			max_pages = (fullsize.l + PAGE_SIZE - 1) & PAGE_MASK

// Sort the list of files.
static bool is_less (file *f1, file *f2):
	for unsigned i = 0; i < 16; ++i:
		if f1->name[i] < f2->name[i]:
			return true
		if f1->name[i] > f2->name[i]:
			return false
	return false

// Bubble sort.
static void sort ():
	index = new unsigned[num_files]
	index[0] = 0
	// Invariant: index[0...f-1] is sorted.
	for unsigned f = 1; f < num_files; ++f:
		// Bubble up until top.  Test for less-than, because it wraps to maxunsigned.
		unsigned i
		// Invariant: index[0...f] \ index[i+1] is sorted and index[i+1...f] is sorted.
		for i = f - 1; i < f; --i:
			if is_less (&files[index[i]], &files[f]):
				break
			index[i + 1] = index[i]
		index[i + 1] = f

static void run (file *f, bool priv):
	Kernel::Memory mem = top_memory.create_memory ()
	unsigned num_pages = (f->size + PAGE_SIZE - 1) & PAGE_MASK
	for unsigned p = 0; p < num_pages; ++p:
		Kernel::set_recv_arg (Kernel::Cap (slot, p))
		mem.create_page ()
		f->string.get_page (p << PAGE_BITS, Kernel::Cap (slot, p))
		Kernel::my_memory.map (Kernel::Cap (slot, p), (unsigned)&mapping[p << PAGE_BITS])
	Kernel::Thread thread = mem.create_thread (NUM_SLOTS)
	if priv:
		thread.make_priv ()
	Elf32_Ehdr *header = (Elf32_Ehdr *)mapping
	for unsigned j = 0; j < SELFMAG; ++j:
		if header->e_ident[j] != ELFMAG[j]:
			kdebug ("invalid ELF magic\n")
			Kernel::panic (0)
			return
	if header->e_ident[EI_CLASS] != ELFCLASS32:
		kdebug ("invalid ELF class\n")
		Kernel::panic (0)
		return
	if header->e_ident[EI_DATA] != ELFDATA2LSB:
		kdebug ("invalid ELF data\n")
		Kernel::panic (0)
		return
	if header->e_ident[EI_VERSION] != EV_CURRENT:
		kdebug ("invalid ELF version\n")
		Kernel::panic (0)
		return
	if header->e_type != ET_EXEC:
		kdebug ("invalid ELF type\n")
		Kernel::panic (0)
		return
	if header->e_machine != EM_MIPS_RS3_LE && header->e_machine != EM_MIPS:
		kdebug ("invalid ELF machine\n")
		Kernel::panic (0)
		return
	thread.set_pc (header->e_entry)
	thread.set_sp (0x80000000)
	for unsigned section = 0; section < header->e_shnum; ++section:
		Elf32_Shdr *shdr = (Elf32_Shdr *)((unsigned)mapping + header->e_shoff + section * header->e_shentsize)
		if ~shdr->sh_flags & SHF_ALLOC:
			continue
		bool readonly = !(shdr->sh_flags & SHF_WRITE)
		//bool executable = shdr->sh_flags & SHF_EXEC_INSTR
		if shdr->sh_type != SHT_NOBITS:
			unsigned file_offset = shdr->sh_offset >> PAGE_BITS
			if (file_offset + ((shdr->sh_size + PAGE_SIZE - 1) >> PAGE_BITS)) >= (PAGE_SIZE >> 2):
				kdebug ("thread too large\n")
				Kernel::panic (0)
				return
			for unsigned p = (shdr->sh_addr & PAGE_MASK); p < shdr->sh_addr + shdr->sh_size; p += PAGE_SIZE:
				unsigned section_offset = (p - (shdr->sh_addr & PAGE_MASK)) >> PAGE_BITS
				unsigned idx = file_offset + section_offset
				Kernel::Page page = mem.mapping ((void *)p)
				if Kernel::recv.data[0].l == Kernel::NO_ERROR:
					// The address already has a mapping; assume that it is correct.
					Kernel::free_cap (page)
					continue
				page = mem.create_page ()
				Kernel::Page (slot, idx).share (page, 0)
				if !mem.map (page, p, readonly):
					kdebug ("unable to map page\n")
					Kernel::panic (0)
					return
				Kernel::free_cap (page)
		else:
			if readonly:
				kdebug ("unwritable bss section\n")
				Kernel::panic (0)
				return
			for unsigned p = (shdr->sh_addr & PAGE_MASK); p < shdr->sh_addr + shdr->sh_size; p += PAGE_SIZE:
				Kernel::Page page = mem.mapping ((void *)p)
				if Kernel::recv.data[0].l == Kernel::NO_ERROR:
					// No error means there is no mapping.
					page = mem.create_page ()
					if Kernel::recv.data[0].l != Kernel::NO_ERROR:
						kdebug ("out of memory\n")
						Kernel::panic (0)
						return
					if !page.set_flags (Kernel::Page::PAYING | Kernel::Page::FRAME, Kernel::Page::PAYING | Kernel::Page::FRAME):
						kdebug ("out of memory\n")
						Kernel::panic (0)
						return
					if !mem.map (page, p):
						kdebug ("unable to map bss page\n")
						Kernel::panic (0)
						return
					Kernel::free_cap (page)
				else:
					for unsigned a = p; a < ((p + PAGE_SIZE) & PAGE_MASK); a += 4:
						if a >= shdr->sh_addr + shdr->sh_size:
							break
						if a < shdr->sh_addr:
							continue
						((unsigned *)&mapping[p])[(a & ~PAGE_MASK) >> 2] = 0
	for unsigned p = 0; p <= num_pages; ++p:
		mem.destroy (Kernel::Page (slot, p))
	Kernel::Page stackpage = mem.create_page ()
	stackpage.set_flags (Kernel::Page::PAYING | Kernel::Page::FRAME, Kernel::Page::PAYING | Kernel::Page::FRAME)
	if Kernel::recv.data[0].l != Kernel::NO_ERROR || !mem.map (stackpage, 0x7ffff000):
		kdebug ("unable to map initial stack page\n")
		Kernel::panic (0)
		return
	Kernel::free_cap (stackpage)
	Kernel::Caps caps = mem.create_caps (NUM_CAPS)
	thread.use (caps, 0)
	thread.set_info (Kernel::Thread::A0, NUM_SLOTS)
	thread.set_info (Kernel::Thread::A1, NUM_CAPS)
	Kernel::Receiver receiver = mem.create_receiver ()
	receiver.set_owner (thread.copy ())
	Kernel::Cap call = receiver.create_call_capability ()
	Kernel::Cap parent = Kernel::my_receiver.create_capability (++current_thread)
	caps.set (__receiver_num, receiver.copy ())
	caps.set (__thread_num, thread.copy ())
	caps.set (__memory_num, mem.copy ())
	caps.set (__call_num, call.copy ())
	caps.set (__parent_num, parent.copy ())
	thread.run ()
	Kernel::free_cap (receiver)
	Kernel::free_cap (thread)
	Kernel::free_cap (mem)
	Kernel::free_cap (call)
	Kernel::free_cap (parent)

Kernel::Num start ():
	// Wait for the debugging device to be active, in case there is one.
	Kernel::schedule ()
	top_memory = Kernel::get_top_memory ()
	Directory root = receive_devices ()
	root.lock_ro ()
	list_files (root)
	sort ()
	Kernel::Caps caps = Kernel::my_memory.create_caps (max_pages)
	slot = caps.use ()
	mapping = alloc_space (max_pages)
	for unsigned i = 0; i < num_files; ++i:
		run (&files[index[i]], files[index[i]].name[0] == '#')
	root.unlock_ro ()
	Kernel::free_slot (slot)
	Kernel::my_memory.destroy (caps)
	return 0