source: mainline/kernel/arch/arm32/src/exception.c@ 2ba48bf1

/*
 * 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 kernel_arm32
 * @{
 */
/** @file
 *  @brief Exception handlers and exception initialization routines.
 */

#include <arch/exception.h>
#include <arch/regutils.h>
#include <arch/machine_func.h>
#include <interrupt.h>
#include <arch/mm/page_fault.h>
#include <arch/cp15.h>
#include <barrier.h>
#include <stdio.h>
#include <syscall/syscall.h>
#include <stacktrace.h>

/** Offset used in calculation of exception handler's relative address.
 *
 * @see install_handler()
 */
#define PREFETCH_OFFSET      0x8

/** LDR instruction's code */
#define LDR_OPCODE           0xe59ff000

/** Number of exception vectors. */
#define EXC_VECTORS          8

/** Size of memory block occupied by exception vectors. */
#define EXC_VECTORS_SIZE     (EXC_VECTORS * 4)

/** 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;
        smc_coherence(vector, 4);

        /* Store handler's address */
        *(vector + EXC_VECTORS) = handler_addr;

}

/** Software Interrupt handler.
 *
 * Dispatches the syscall.
 *
 */
static void swi_exception(unsigned int exc_no, istate_t *istate)
{
        interrupts_enable();
        istate->r0 = syscall_handler(istate->r0, istate->r1, istate->r2,
            istate->r3, istate->r4, istate->r5, istate->r6);
        interrupts_disable();
}

/** 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);
}

#ifdef HIGH_EXCEPTION_VECTORS
/** Activates use of high exception vectors addresses.
 *
 * "High vectors were introduced into some implementations of ARMv4 and are
 * required in ARMv6 implementations. High vectors allow the exception vector
 * locations to be moved from their normal address range 0x00000000-0x0000001C
 * at the bottom of the 32-bit address space, to an alternative address range
 * 0xFFFF0000-0xFFFF001C near the top of the address space. These alternative
 * locations are known as the high vectors.
 *
 * Prior to ARMv6, it is IMPLEMENTATION DEFINED whether the high vectors are
 * supported. When they are, a hardware configuration input selects whether
 * the normal vectors or the high vectors are to be used from
 * reset." ARM Architecture Reference Manual A2.6.11 (p. 64 in the PDF).
 *
 * ARM920T (gta02) TRM A2.3.5 (PDF p. 36) and ARM926EJ-S (icp) 2.3.2 (PDF p. 42)
 * say that armv4 an armv5 chips that we support implement this.
 */
static void high_vectors(void)
{
        uint32_t control_reg = SCTLR_read();

        /* switch on the high vectors bit */
        control_reg |= SCTLR_HIGH_VECTORS_EN_FLAG;

        SCTLR_write(control_reg);
}
#endif

/** Interrupt Exception handler.
 *
 * Determines the sources of interrupt and calls their handlers.
 */
static void irq_exception(unsigned int exc_no, istate_t *istate)
{
        machine_irq_exception(exc_no, istate);
}

/** Undefined instruction exception handler.
 *
 * Calls scheduler_fpu_lazy_request
 */
static void undef_insn_exception(unsigned int exc_no, istate_t *istate)
{
#ifdef CONFIG_FPU
        if (handle_if_fpu_exception()) {
                /*
                 * Retry the failing instruction,
                 * ARM Architecture Reference Manual says on p.B1-1169
                 * that offset for undef instruction exception is 4
                 */
                istate->pc -= 4;
                return;
        }
#endif
        fault_if_from_uspace(istate, "Undefined instruction.");
        panic_badtrap(istate, exc_no, "Undefined instruction.");
}

/** Initializes exception handling.
 *
 * Installs low-level exception handlers and then registers
 * exceptions and their handlers to kernel exception dispatcher.
 */
void exception_init(void)
{
        // TODO check for availability of high vectors for <= armv5
#ifdef HIGH_EXCEPTION_VECTORS
        high_vectors();
#endif
        install_exception_handlers();

        exc_register(EXC_UNDEF_INSTR, "undefined instruction", true,
            (iroutine_t) undef_insn_exception);
        exc_register(EXC_IRQ, "interrupt", true,
            (iroutine_t) irq_exception);
        exc_register(EXC_PREFETCH_ABORT, "prefetch abort", true,
            (iroutine_t) prefetch_abort);
        exc_register(EXC_DATA_ABORT, "data abort", true,
            (iroutine_t) data_abort);
        exc_register(EXC_SWI, "software interrupt", true,
            (iroutine_t) swi_exception);
}

/** Prints #istate_t structure content.
 *
 * @param istate Structure to be printed.
 */
void istate_decode(istate_t *istate)
{
        printf("r0 =%0#10" PRIx32 "\tr1 =%0#10" PRIx32 "\t"
            "r2 =%0#10" PRIx32 "\tr3 =%0#10" PRIx32 "\n",
            istate->r0, istate->r1, istate->r2, istate->r3);
        printf("r4 =%0#10" PRIx32 "\tr5 =%0#10" PRIx32 "\t"
            "r6 =%0#10" PRIx32 "\tr7 =%0#10" PRIx32 "\n",
            istate->r4, istate->r5, istate->r6, istate->r7);
        printf("r8 =%0#10" PRIx32 "\tr9 =%0#10" PRIx32 "\t"
            "r10=%0#10" PRIx32 "\tfp =%0#10" PRIx32 "\n",
            istate->r8, istate->r9, istate->r10, istate->fp);
        printf("r12=%0#10" PRIx32 "\tsp =%0#10" PRIx32 "\t"
            "lr =%0#10" PRIx32 "\tspsr=%0#10" PRIx32 "\n",
            istate->r12, istate->sp, istate->lr, istate->spsr);
}

/** @}
 */