#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// mips/interrupts.ccp: Functions called by mips/entry.S.
// 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/>.

#define ARCH
#include "../kernel.hh"

/// A TLB miss has occurred.  This is the slow version.  It is only used
/// when k0 or k1 is not 0, or when an error occurs.
/// Otherwise, the ultra-fast code in entry.S is used.
Thread *tlb_refill ():
	//panic (0x88776655, "TLB refill")
	if !directory:
		panic (0x44449999, "No directory")
	unsigned EntryHi
	cp0_get (CP0_ENTRY_HI, EntryHi)
	unsigned *t = directory[EntryHi >> 21]
	if !t:
		unsigned a
		cp0_get (CP0_EPC, a)
		dbg_send (a)
		cp0_get (CP0_BAD_V_ADDR, a)
		dbg_send (a)
		panic (0x99992222, "No page table")
	// - 2 instead of - 1 means reset bit 0
	unsigned idx = (EntryHi >> 12) & ((1 << 9) - 2)
	cp0_set (CP0_ENTRY_LO0, t[idx])
	cp0_set (CP0_ENTRY_LO1, t[idx + 1])
	__asm__ volatile ("tlbwr")
	return current

/// An interrupt which is not an exception has occurred.
Thread *interrupt ():
	panic (0x88877722, "Interrupt")
	unsigned cause, status
	cp0_get (CP0_CAUSE, cause)
	cp0_get (CP0_STATUS, status)
	for unsigned i = 0; i < 8; ++i:
		if cause & (1 << (i + 8)):
			// Disable the interrupt while handling it.
			status &= ~(1 << (i + 8))
			// Send message to interrupt handler.
			if arch_interrupt_receiver[i]:
				Capability::Context c
				for unsigned j = 0; j < 4; ++j:
					c.data[j] = 0
					c.cap[j] = NULL
					c.copy[j] = false
				arch_interrupt_receiver[i]->send_message (i, &c)
	return current

/// A general exception has occurred.
Thread *exception ():
	unsigned cause
	cp0_get (CP0_CAUSE, cause)
	switch (cause >> 2) & 0x1f:
		case 0:
			// Interrupt.  This shouldn't happen, since CAUSE[IV] == 1.
			panic (0x11223344, "Interrupt on exception vector.")
		case 1:
			// TLB modification.
			panic (0x21223344, "TLB modification.")
		case 2:
			// TLB load or instruction fetch.
			unsigned a
			cp0_get (CP0_EPC, a)
			dbg_send (a)
			panic (0x31223344, "TLB load or instruction fetch.")
		case 3:
			// TLB store.
			panic (0x41223344, "TLB store.")
		case 4:
			// Address error load or instruction fetch.
			panic (0x51223344, "Address error load or instruction fetch.")
		case 5:
			// Address error store.
			unsigned a
			cp0_get (CP0_EPC, a)
			dbg_send (a, 16)
			panic (0x61223344, "Address error store.")
		case 6:
			// Bus error instruction fetch.
			panic (0x71223344, "Bus error instruction fetch.")
		case 7:
			// Bus error load or store.
			panic (0x81223344, "Bus error load or store.")
		case 8:
			// Syscall.
			current->pc += 4
			arch_invoke ()
			break
		case 9:
			// Breakpoint.
			panic (0x91223344, "Breakpoint.")
		case 10:
			// Reserved instruction.
			panic (0xa1223344, "Reserved instruction.")
		case 11:
			// Coprocessor unusable.
			panic (0xb1223344, "Coprocessor unusable.")
		case 12:
			// Arithmetic overflow.
			panic (0xc1223344, "Arithmetic overflow.")
		case 13:
			// Trap.
			panic (0xe1223344, "Trap.")
		case 15:
			// Floating point exception.
			panic (0xf1223344, "Floating point exception.")
		case 23:
			// Reference to WatchHi/WatchLo address.
			panic (0xf2223344, "Reference to WatchHi/WatchLo address.")
		case 24:
			// Machine check.
			panic (0xf3223344, "Machine check.")
		case 30:
			// Cache error (EJTAG only).
			panic (0xf4223344, "Cache error (EJTAG only).")
		case 14:
		case 16:
		case 17:
		case 18:
		case 19:
		case 20:
		case 21:
		case 22:
		case 25:
		case 26:
		case 27:
		case 28:
		case 29:
		case 31:
			// Reserved.
			panic (0xf5223344, "Reserved exception code")
		default:
			panic (0xf6223344, "Impossible exception code")
	return current

/// There's a cache error.  Big trouble.  Probably not worth trying to recover.
Thread *cache_error ():
	panic (0x33333333, "cache error")
	return current