iris/source/crt0.ccp

#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// boot-programs/init.S: Startup code for initial Threads.
// 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 "iris.hh"
#include "devices.hh"

// For some unknown reason, gcc needs this to be defined.
unsigned __gxx_personality_v0

struct list:
	list *prev, *next

static unsigned __slots, __caps
static list *__slot_admin, *__cap_admin
static list *__first_free_slot, *__first_free_cap

namespace Iris:
	bool enable_debug
	Caps my_caps
	Receiver my_receiver
	Thread my_thread
	Memory my_memory
	Cap my_call
	Parent my_parent
	__recv_data_t recv

	void print_caps ():
		// __caps cannot be larger than 63.
		bool used[63]
		for unsigned i = 0; i < __caps; ++i:
			used[i] = true
		unsigned num = 0
		for list *i = __first_free_cap; i; i = i->next:
			if used[i - __cap_admin] == false:
				panic (0, "inconsistent userspace cap db")
			used[i - __cap_admin] = false
			++num
		kdebug_num (num, 2)
		kdebug (":")
		for unsigned i = 0; i < __caps; ++i:
			kdebug_char (used[i] ? '#' : '.')
		kdebug_char ('\n')

	void free_slot (unsigned slot):
		//kdebug ("free slot\n")
		for list *i = __first_free_slot; i; i = i->next:
			if slot == i - __slot_admin:
				panic (0, "double free of userspace slot")
		__slot_admin[slot].prev = NULL
		__slot_admin[slot].next = __first_free_slot
		if __slot_admin[slot].next:
			__slot_admin[slot].next->prev = &__slot_admin[slot]
		__first_free_slot = &__slot_admin[slot]

	void free_cap (Cap cap):
		if enable_debug:
			kdebug ("free cap ")
			kdebug_num (cap.idx (), 2)
			kdebug ("\n")
		for list *i = __first_free_cap; i; i = i->next:
			if cap.idx () == i - __cap_admin:
				panic (0, "double free of userspace cap")
		if cap.slot () != 0:
			kdebug ("trying to free capability from non-0 slot\n")
			Iris::panic (0)
			return
		list *l = &__cap_admin[cap.idx ()]
		l->prev = NULL
		l->next = __first_free_cap
		if l->next:
			l->next->prev = l
		__first_free_cap = l

	unsigned alloc_slot ():
		//kdebug ("alloc slot\n")
		if !__first_free_slot:
			// Out of slots...  Probably best to raise an exception.  For now, just return NO_SLOT.
			kdebug ("out of slots!\n")
			Iris::panic (0)
			return ~0
		list *ret = __first_free_slot
		__first_free_slot = ret->next
		if ret->next:
			ret->next->prev = NULL
		return ret - __slot_admin

	Cap alloc_cap ():
		if !__first_free_cap:
			// Out of caps...  Probably best to raise an exception.  For now, just return CAP_NONE
			kdebug ("out of capabilities!\n")
			Iris::panic (0)
			return Cap (0, CAP_NONE)
		list *ret = __first_free_cap
		__first_free_cap = ret->next
		if ret->next:
			ret->next->prev = NULL
		if enable_debug:
			kdebug ("alloc cap ")
			kdebug_num (ret - __cap_admin, 2)
			kdebug ("\n")
		return Cap (0, ret - __cap_admin)

extern "C":
	void run__main (unsigned slots, unsigned caps, list *slot_admin, list *cap_admin):
		Iris::enable_debug = false
		__slots = slots
		__caps = caps
		__slot_admin = slot_admin
		__cap_admin = cap_admin
		__first_free_slot = NULL
		for unsigned i = 1; i < __slots; ++i:
			Iris::free_slot (i)
		__first_free_cap = NULL
		for unsigned i = 6; i < __caps; ++i:
			Iris::free_cap (Iris::Cap (0, i))
		Iris::my_caps = Iris::Cap (0, __caps_num)
		Iris::my_receiver = Iris::Cap (0, __receiver_num)
		Iris::my_thread = Iris::Cap (0, __thread_num)
		Iris::my_memory = Iris::Cap (0, __memory_num)
		Iris::my_call = Iris::Cap (0, __call_num)
		Iris::my_parent = Iris::Cap (0, __parent_num)
		Iris::recv.reply = Iris::alloc_cap ()
		Iris::recv.arg = Iris::alloc_cap ()
		Iris::Num ret = start ()
		Iris::my_parent.exit (ret)
		Iris::my_memory.destroy (Iris::my_thread)
		// The program no longer exists.  If it somehow does, die again.
		while true:
			Iris::panic (0, "this program should no longer exist.")
			*(volatile unsigned *)~0

__asm__ volatile ("\t.text\n"
	"\t.globl __start\n"
	"\t.set noreorder\n"
	"__start:\n"
	"\tbal 1f\n"
	"__hack_label:\n"
	"\tnop\n"
	"\t.word _gp\n"
	"1:\n"
	"\tlw $gp, 0($ra)\n"
	"\tsll $v0, $a0, 3\n"
	"\tsll $v1, $a1, 3\n"
	"\tsubu $sp, $sp, $v0\n"
	"\tmove $a2, $sp\n"
	"\tsubu $sp, $sp, $v1\n"
	"\tmove $a3, $sp\n"
	"\tla $t9, run__main\n"
	"\tjr $t9\n"
	"\tnop\n"
	"\t.set reorder")