/*
* Copyright (c) 2007 Petr Stepan
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup arm32
* @{
*/
/** @file
@brief Exception handlers and exception initialization routines.
*/
#include <arch/exception.h>
#include <arch/debug_print/print.h>
#include <arch/memstr.h>
#include <arch/regutils.h>
#include <interrupt.h>
#include <arch/drivers/gxemul.h>
#include <arch/mm/page_fault.h>
#define PREFETCH_OFFSET 0x8
#define BRANCH_OPCODE 0xea000000
#define LDR_OPCODE 0xe59ff000
#define VALID_BRANCH_MASK 0xff000000
#define EXC_VECTORS_SIZE 0x20
#define EXC_VECTORS 0x8
#define SAVE_REGS_TO_STACK \
asm("stmfd sp!, {r0-r12, sp, lr}"); \
asm("mrs r14, spsr"); \
asm("stmfd sp!, {r14}");
#define CALL_EXC_DISPATCH(exception) \
asm("mov r0, %0" : : "i" (exception)); \
asm("mov r1, sp"); \
asm("bl exc_dispatch");
/**Loads registers from the stack and resets SPSR before exitting exception
* handler.
*/
#define LOAD_REGS_FROM_STACK \
asm("ldmfd sp!, {r14}"); \
asm("msr spsr, r14"); \
asm("ldmfd sp!, {r0-r12, sp, pc}^");
/** General exception handler.
* Stores registers, dispatches the exception,
* and finally restores registers and returns from exception processing.
*/
#define PROCESS_EXCEPTION(exception) \
SAVE_REGS_TO_STACK \
CALL_EXC_DISPATCH(exception) \
LOAD_REGS_FROM_STACK
/** Updates specified exception vector to jump to given handler.
* Addresses of handlers are stored in memory following exception vectors.
*/
static void install_handler (unsigned handler_addr, unsigned* vector)
{
/* relative address (related to exc. vector) of the word
* where handler's address is stored
*/
volatile uint32_t handler_address_ptr = EXC_VECTORS_SIZE - PREFETCH_OFFSET;
/* make it LDR instruction and store at exception vector */
*vector = handler_address_ptr | LDR_OPCODE;
/* store handler's address */
*(vector + EXC_VECTORS) = handler_addr;
}
static void reset_exception_entry()
{
PROCESS_EXCEPTION(EXC_RESET);
}
/** Low-level Software Interrupt Exception handler */
static void swi_exception_entry()
{
PROCESS_EXCEPTION(EXC_SWI);
}
/** Low-level Undefined Instruction Exception handler */
static void undef_instr_exception_entry()
{
PROCESS_EXCEPTION(EXC_UNDEF_INSTR);
}
/** Low-level Fast Interrupt Exception handler */
static void fiq_exception_entry()
{
PROCESS_EXCEPTION(EXC_FIQ);
}
/** Low-level Prefetch Abort Exception handler */
static void prefetch_abort_exception_entry()
{
asm("sub lr, lr, #4");
PROCESS_EXCEPTION(EXC_PREFETCH_ABORT);
}
/** Low-level Data Abort Exception handler */
static void data_abort_exception_entry()
{
asm("sub lr, lr, #8");
PROCESS_EXCEPTION(EXC_DATA_ABORT);
}
/** Low-level Interrupt Exception handler */
static void irq_exception_entry()
{
asm("sub lr, lr, #4");
PROCESS_EXCEPTION(EXC_IRQ);
}
/** Interrupt Exception handler.
* Determines the sources of interrupt, and calls their handlers.
*/
static void irq_exception(int exc_no, istate_t* istate)
{
// TODO: move somewhere to gxemul.c and use machine_irq_exception (or some similar
// name) to avoid using MACHINE == MACHINE_GXEMUL_TESTARM
#if MACHINE == MACHINE_GXEMUL_TESTARM
uint32_t sources = gxemul_irqc_get_sources();
int i = 0;
for (; i < GXEMUL_IRQC_MAX_IRQ; i++) {
if (sources & (1 << i)) {
irq_t *irq = irq_dispatch_and_lock(i);
if (irq) {
/* The IRQ handler was found. */
irq->handler(irq, irq->arg);
spinlock_unlock(&irq->lock);
} else {
/* Spurious interrupt.*/
dprintf("cpu%d: spurious interrupt (inum=%d)\n", CPU->id, i);
}
}
}
#endif
/* TODO remove after testing the above code
noirq = 0;
if (i == CONSOLE_IRQ) {
char readchar = *(char*)0x10000000;
if (readchar == 0) {
aux_puts("?");
}
else {
dprintf("%c", readchar);
}
}
else if (i == TIMER_IRQ) {
dprintf("\n.\n");
//acknowledge
*(uint32_t*)0x15000110 = 0;
}
}
}
if (noirq)
aux_puts("IRQ exception without source\n");*/
}
/** Fills exception vectors with appropriate exception handlers.
*/
void install_exception_handlers(void)
{
install_handler((unsigned)reset_exception_entry,
(unsigned*)EXC_RESET_VEC);
install_handler((unsigned)undef_instr_exception_entry,
(unsigned*)EXC_UNDEF_INSTR_VEC);
install_handler((unsigned)swi_exception_entry,
(unsigned*)EXC_SWI_VEC);
install_handler((unsigned)prefetch_abort_exception_entry,
(unsigned*)EXC_PREFETCH_ABORT_VEC);
install_handler((unsigned)data_abort_exception_entry,
(unsigned*)EXC_DATA_ABORT_VEC);
install_handler((unsigned)irq_exception_entry,
(unsigned*)EXC_IRQ_VEC);
install_handler((unsigned)fiq_exception_entry,
(unsigned*)EXC_FIQ_VEC);
}
/** Activates using high exception vectors addresses. */
static void high_vectors()
{
uint32_t control_reg;
asm volatile( "mrc p15, 0, %0, c1, c1": "=r" (control_reg));
//switch on the high vectors bit
control_reg |= CP15_R1_HIGH_VECTORS_BIT;
asm volatile( "mcr p15, 0, %0, c1, c1" : : "r" (control_reg));
}
/** Initializes exception handling.
*
* Installs low-level exception handlers and then registers
* exceptions and their handlers to kernel exception dispatcher.
*/
void exception_init(void)
{
#ifdef HIGH_EXCEPTION_VECTORS
high_vectors();
#endif
install_exception_handlers();
exc_register(EXC_IRQ, "interrupt", (iroutine) irq_exception);
exc_register(EXC_PREFETCH_ABORT, "prefetch abort", (iroutine) prefetch_abort);
exc_register(EXC_DATA_ABORT, "data abort", (iroutine) data_abort);
/* TODO add next */
}
/* TODO change soon, temporary hack. */
void setup_exception_stacks()
{
/* switch to particular mode and set "sp" there */
uint32_t cspr = current_status_reg_read();
/* IRQ stack */
current_status_reg_control_write(
(cspr & ~STATUS_REG_MODE_MASK) | IRQ_MODE
);
asm("ldr sp, =irq_stack");
/* abort stack */
current_status_reg_control_write(
(cspr & ~STATUS_REG_MODE_MASK) | ABORT_MODE
);
asm("ldr sp, =abort_stack");
/* TODO if you want to test other exceptions than IRQ,
make stack analogous to irq_stack (in start.S),
and then set stack pointer here */
current_status_reg_control_write( cspr);
}
/** @}
*/