trap.c

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#include <hvmm_trace.h>
#include <armv7_p15.h>
#include "trap.h"
#include "context.h"
#include "gic.h"
#include "sched_policy.h"
#include "trap_dabort.h"

#include <log/print.h>

/* By holding the address to the saved regs struct, 
   context or other modules can access to this structure
   through trap_saved_regs() call when it's needed. 
   For example, copying register values for context switching can be 
   performed this way.
 */

static struct arch_regs *_trap_hyp_saved_regs = 0;

hvmm_status_t _hyp_trap_dabort( struct arch_regs *regs )
{

    _trap_hyp_saved_regs = regs;

    context_dump_regs( regs );
    hyp_abort_infinite();

    return HVMM_STATUS_UNKNOWN_ERROR;
}

hvmm_status_t _hyp_trap_irq( struct arch_regs *regs )
{

    _trap_hyp_saved_regs = regs;

    gic_interrupt(0, regs);

    context_perform_switch();
    return HVMM_STATUS_SUCCESS;
}

hvmm_status_t _hyp_trap_unhandled( struct arch_regs *regs )
{
    _trap_hyp_saved_regs = regs;

    context_dump_regs( regs );
    hyp_abort_infinite();

    return HVMM_STATUS_UNKNOWN_ERROR;
}

static void _trap_dump_bregs(void)
{
    uint32_t spsr, lr, sp;
    printh( " - banked regs\n" );
    asm volatile (" mrs     %0, sp_usr\n\t" :"=r" (sp)::"memory", "cc");
    asm volatile (" mrs     %0, lr_usr\n\t" :"=r" (lr)::"memory", "cc");
    printh( " - usr: sp:%x lr:%x\n", sp, lr );

    asm volatile (" mrs     %0, spsr_svc\n\t" :"=r" (spsr)::"memory", "cc");
    asm volatile (" mrs     %0, sp_svc\n\t" :"=r" (sp)::"memory", "cc");
    asm volatile (" mrs     %0, lr_svc\n\t" :"=r" (lr)::"memory", "cc");
    printh( " - svc: spsr:%x sp:%x lr:%x\n", spsr, sp, lr );

    asm volatile (" mrs     %0, spsr_irq\n\t" :"=r" (spsr)::"memory", "cc");
    asm volatile (" mrs     %0, sp_irq\n\t" :"=r" (sp)::"memory", "cc");
    asm volatile (" mrs     %0, lr_irq\n\t" :"=r" (lr)::"memory", "cc");
    printh( " - irq: spsr:%x sp:%x lr:%x\n", spsr, sp, lr );
}

/*
 * hvc #imm handler
 *
 * HYP Syndrome Register(HSR) 
 * EC[31:26] is an exception class for the exception that is taken to HYP mode
 * IL[25] is an instruction length for the trapped insruction that is 16 bit or 32 bit
 * ISS[24:0] is an instruction-specific syndrome for the instruction information included. It depends on EC field.
 * END OF HSR DESCRIPTION FROM ARM DDI0406_C ARCHITECTURE MANUAL
 */ 
hyp_hvc_result_t _hyp_hvc_service(struct arch_regs *regs)
{
        unsigned int hsr = read_hsr();
        unsigned int iss = hsr & 0x1FFFFFF;
        unsigned int ec = (hsr >> 26);

        _trap_hyp_saved_regs = regs;

        printh("[hvc] _hyp_hvc_service: enter\n\r");

    if ( ec == 0x12 && ((iss & 0xFFFF) == 0xFFFF) ) {
        /* Internal request to stay in hyp mode */
        printh("[hvc] enter hyp\n\r");
        context_dump_regs( regs );
        return HYP_RESULT_STAY;
    }

    if ( ec == 0x24) {
        /* Handle data abort at the priority */
        printh("[hyp] data abort handler: hsr.iss=%x\n", iss);
        _trap_dump_bregs();

        if ( trap_hvc_dabort(iss, regs) != HVMM_STATUS_SUCCESS ) {
            printh( "[hyp] === Unhandled dabort ===\n" );
            printh( "[hyp] current guest vmid:%d\n", context_current_vmid() );
            context_dump_regs( regs );

            _trap_dump_bregs();

            hyp_abort_infinite();
        }
        _trap_dump_bregs();
    } else {
        /* Handle the other cases */
        switch( iss ) {
            case 0xFFFE:
                /* hyp_ping */
                printh("[hyp] _hyp_hvc_service:ping\n\r");
                context_dump_regs( regs );
                break;
            case 0xFFFD:
                {
                    /* hsvc_yield() */
                    printh("[hyp] _hyp_hvc_service:yield\n\r");
                    context_dump_regs( regs );
                    context_switchto(sched_policy_determ_next());
                }
                break;
            default:
                if ( ec == 0x20 ) {
                    // Prefetch Abort routed to Hyp mode
                    printh( "[hyp]: prefetch abort routed to Hyp mode\n");
                }
    
                printh("[hyp] _hyp_hvc_service:unknown hsr.iss= %x\n", iss);
                printh("[hyp] hsr.ec= %x\n", ec);
                printh("[hyp] hsr= %x\n", hsr);
                context_dump_regs( regs );
                _trap_dump_bregs();
                hyp_abort_infinite();
                break;
        }
    }
    printh("[hyp] _hyp_hvc_service: done\n\r");

    context_perform_switch();
    return HYP_RESULT_ERET;
}

/* API */

struct arch_regs * trap_saved_regs(void)
{
    return _trap_hyp_saved_regs;
}