[apple/xnu.git] / osfmk / ppc / trap.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */

#include <mach_kdb.h>
#include <mach_kdp.h>
#include <debug.h>
#include <cpus.h>
#include <kern/thread.h>
#include <kern/exception.h>
#include <kern/syscall_sw.h>
#include <kern/cpu_data.h>
#include <kern/debug.h>
#include <mach/thread_status.h>
#include <vm/vm_fault.h>
#include <vm/vm_kern.h>         /* For kernel_map */
#include <ppc/misc_protos.h>
#include <ppc/trap.h>
#include <ppc/exception.h>
#include <ppc/proc_reg.h>       /* for SR_xxx definitions */
#include <ppc/pmap.h>
#include <ppc/mem.h>
#include <ppc/mappings.h>
#include <ppc/Firmware.h>
#include <ppc/low_trace.h>
#include <ppc/Diagnostics.h>
#include <ppc/hw_perfmon.h>

#include <sys/kdebug.h>

perfTrap perfTrapHook = 0;                                                      /* Pointer to performance trap hook routine */

#if     MACH_KDB
#include <ddb/db_watch.h>
#include <ddb/db_run.h>
#include <ddb/db_break.h>
#include <ddb/db_trap.h>

boolean_t let_ddb_vm_fault = FALSE;
boolean_t       debug_all_traps_with_kdb = FALSE;
extern struct db_watchpoint *db_watchpoint_list;
extern boolean_t db_watchpoints_inserted;
extern boolean_t db_breakpoints_inserted;



#endif  /* MACH_KDB */

extern int debugger_active[NCPUS];
extern task_t bsd_init_task;
extern char init_task_failure_data[];


#define PROT_EXEC       (VM_PROT_EXECUTE)
#define PROT_RO         (VM_PROT_READ)
#define PROT_RW         (VM_PROT_READ|VM_PROT_WRITE)

/* A useful macro to update the ppc_exception_state in the PCB
 * before calling doexception
 */
#define UPDATE_PPC_EXCEPTION_STATE {                                                    \
        thread_act_t thr_act = current_act();                                           \
        thr_act->mact.pcb->save_dar = (uint64_t)dar;                            \
        thr_act->mact.pcb->save_dsisr = dsisr;                                          \
        thr_act->mact.pcb->save_exception = trapno / T_VECTOR_SIZE;     /* back to powerpc */ \
}

static void unresolved_kernel_trap(int trapno,
                                   struct savearea *ssp,
                                   unsigned int dsisr,
                                   addr64_t dar,
                                   char *message);

struct savearea *trap(int trapno,
                             struct savearea *ssp,
                             unsigned int dsisr,
                             addr64_t dar)
{
        int exception;
        int code;
        int subcode;
        vm_map_t map;
    unsigned int sp;
        unsigned int space, space2;
        unsigned int offset;
        thread_act_t thr_act;
        boolean_t intr;
        
#ifdef MACH_BSD
        time_value_t tv;
#endif /* MACH_BSD */

        if(perfTrapHook) {                                                      /* Is there a hook? */
                if(perfTrapHook(trapno, ssp, dsisr, (unsigned int)dar) == KERN_SUCCESS) return ssp;     /* If it succeeds, we are done... */
        }

#if 0
        {
                extern void fctx_text(void);
                fctx_test();
        }
#endif

        thr_act = current_act();                                        /* Get current activation */
        exception = 0;                                                          /* Clear exception for now */

/*
 *      Remember that we are disabled for interruptions when we come in here.  Because
 *      of latency concerns, we need to enable interruptions in the interrupted process
 *      was enabled itself as soon as we can.
 */

        intr = (ssp->save_srr1 & MASK(MSR_EE)) != 0;    /* Remember if we were enabled */

        /* Handle kernel traps first */

        if (!USER_MODE(ssp->save_srr1)) {
                /*
                 * Trap came from kernel
                 */
                switch (trapno) {

                case T_PREEMPT:                 /* Handle a preempt trap */
                        ast_taken(AST_PREEMPT, FALSE);
                        break;  

                case T_PERF_MON:
                        perfmon_handle_pmi(ssp);
                        break;

                case T_RESET:                                   /* Reset interruption */
                        if (!Call_Debugger(trapno, ssp))
                                unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;                                          /* We just ignore these */
                
                /*
                 * These trap types should never be seen by trap()
                 * in kernel mode, anyway.
                 * Some are interrupts that should be seen by
                 * interrupt() others just don't happen because they
                 * are handled elsewhere. Some could happen but are
                 * considered to be fatal in kernel mode.
                 */
                case T_DECREMENTER:
                case T_IN_VAIN:                 /* Shouldn't ever see this, lowmem_vectors eats it */
                case T_MACHINE_CHECK:
                case T_SYSTEM_MANAGEMENT:
                case T_ALTIVEC_ASSIST:
                case T_INTERRUPT:
                case T_FP_UNAVAILABLE:
                case T_IO_ERROR:
                case T_RESERVED:
                default:
                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;


                case T_ALIGNMENT:
/*
*                       If enaNotifyEMb is set, we get here, and
*                       we have actually already emulated the unaligned access.
*                       All that we want to do here is to ignore the interrupt. This is to allow logging or
*                       tracing of unaligned accesses.  
*/
                        
                        KERNEL_DEBUG_CONSTANT(
                                MACHDBG_CODE(DBG_MACH_EXCP_ALNG, 0) | DBG_FUNC_NONE,
                                (int)ssp->save_srr0 - 4, (int)dar, (int)dsisr, (int)ssp->save_lr, 0);
                        break;

                case T_EMULATE:
/*
*                       If enaNotifyEMb is set we get here, and
*                       we have actually already emulated the instruction.
*                       All that we want to do here is to ignore the interrupt. This is to allow logging or
*                       tracing of emulated instructions.  
*/

                        KERNEL_DEBUG_CONSTANT(
                                MACHDBG_CODE(DBG_MACH_EXCP_EMUL, 0) | DBG_FUNC_NONE,
                                (int)ssp->save_srr0 - 4, (int)((savearea_comm *)ssp)->save_misc2, (int)dsisr, (int)ssp->save_lr, 0);
                        break;




                        
                case T_TRACE:
                case T_RUNMODE_TRACE:
                case T_INSTRUCTION_BKPT:
                        if (!Call_Debugger(trapno, ssp))
                                unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;

                case T_PROGRAM:
                        if (ssp->save_srr1 & MASK(SRR1_PRG_TRAP)) {
                                if (!Call_Debugger(trapno, ssp))
                                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        } else {
                                unresolved_kernel_trap(trapno, ssp, 
                                                        dsisr, dar, NULL);
                        }
                        break;

                case T_DATA_ACCESS:

#if     MACH_KDB
                        mp_disable_preemption();
                        if (debug_mode
                            && debugger_active[cpu_number()]
                            && !let_ddb_vm_fault) {
                                /*
                                 * Force kdb to handle this one.
                                 */
                                kdb_trap(trapno, ssp);
                        }
                        mp_enable_preemption();
#endif  /* MACH_KDB */

                        if(ssp->save_dsisr & dsiInvMode) {                      /* Did someone try to reserve cache inhibited? */
                                panic("trap: disallowed access to cache inhibited memory - %016llX\n", dar);
                        }

                        if(intr) ml_set_interrupts_enabled(TRUE);       /* Enable if we were */
                        
                        if(((dar >> 28) < 0xE) | ((dar >> 28) > 0xF))  {        /* Is this a copy in/out? */
                        
                                offset = (unsigned int)dar;                             /* Set the failing address */
                                map = kernel_map;                                               /* No, this is a normal kernel access */
                                
/*
 *      Note: Some ROM device drivers will access page 0 when they start.  The IOKit will 
 *      set a flag to tell us to ignore any access fault on page 0.  After the driver is
 *      opened, it will clear the flag.
 */
                                if((0 == (offset & -PAGE_SIZE)) &&              /* Check for access of page 0 and */
                                  ((thr_act->mact.specFlags) & ignoreZeroFault)) {      /* special case of ignoring page zero faults */
                                        ssp->save_srr0 += 4;                            /* Point to next instruction */
                                        break;
                                }

                                code = vm_fault(map, trunc_page_32(offset),
                                                dsisr & MASK(DSISR_WRITE) ? PROT_RW : PROT_RO,
                                                FALSE, THREAD_UNINT, NULL, 0);

                                if (code != KERN_SUCCESS) {
                                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                                } else { 
                                        ssp->save_hdr.save_flags |= SAVredrive; /* Tell low-level to re-try fault */
                                        ssp->save_dsisr = (ssp->save_dsisr & 
                                                ~((MASK(DSISR_NOEX) | MASK(DSISR_PROT)))) | MASK(DSISR_HASH);   /* Make sure this is marked as a miss */
                                }
                                break;
                        }

                        /* If we get here, the fault was due to a copyin/out */

                        map = thr_act->map;
                        
                        offset = (unsigned int)(thr_act->mact.cioRelo + dar);   /* Compute the user space address */

                        code = vm_fault(map, trunc_page_32(offset),
                                        dsisr & MASK(DSISR_WRITE) ? PROT_RW : PROT_RO,
                                        FALSE, THREAD_UNINT, NULL, 0);

                        /* If we failed, there should be a recovery
                         * spot to rfi to.
                         */
                        if (code != KERN_SUCCESS) {

                                if (thr_act->thread->recover) {
                                
                                        act_lock_thread(thr_act);
                                        ssp->save_srr0 = thr_act->thread->recover;
                                        thr_act->thread->recover =
                                                        (vm_offset_t)NULL;
                                        act_unlock_thread(thr_act);
                                } else {
                                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, "copyin/out has no recovery point");
                                }
                        }
                        else { 
                                ssp->save_hdr.save_flags |= SAVredrive; /* Tell low-level to re-try fault */
                                ssp->save_dsisr = (ssp->save_dsisr & 
                                        ~((MASK(DSISR_NOEX) | MASK(DSISR_PROT)))) | MASK(DSISR_HASH);   /* Make sure this is marked as a miss */
                        }
                        
                        break;
                        
                case T_INSTRUCTION_ACCESS:

#if     MACH_KDB
                        if (debug_mode
                            && debugger_active[cpu_number()]
                            && !let_ddb_vm_fault) {
                                /*
                                 * Force kdb to handle this one.
                                 */
                                kdb_trap(trapno, ssp);
                        }
#endif  /* MACH_KDB */

                        /* Same as for data access, except fault type
                         * is PROT_EXEC and addr comes from srr0
                         */

                        if(intr) ml_set_interrupts_enabled(TRUE);       /* Enable if we were */

                        map = kernel_map;
                        
                        code = vm_fault(map, trunc_page_64(ssp->save_srr0),
                                        PROT_EXEC, FALSE, THREAD_UNINT, NULL, 0);

                        if (code != KERN_SUCCESS) {
                                unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        } else { 
                                ssp->save_hdr.save_flags |= SAVredrive; /* Tell low-level to re-try fault */
                                ssp->save_srr1 = (ssp->save_srr1 & 
                                        ~((unsigned long long)(MASK(DSISR_NOEX) | MASK(DSISR_PROT)))) | MASK(DSISR_HASH);               /* Make sure this is marked as a miss */
                        }
                        break;

                /* Usually shandler handles all the system calls, but the
                 * atomic thread switcher may throwup (via thandler) and
                 * have to pass it up to the exception handler.
                 */

                case T_SYSTEM_CALL:
                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;

                case T_AST:
                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;
                }
        } else {

                ml_set_interrupts_enabled(TRUE);        /* Processing for user state traps is always enabled */

#ifdef MACH_BSD
                {
                void get_procrustime(time_value_t *);

                        get_procrustime(&tv);
                }
#endif /* MACH_BSD */

        
                /*
                 * Trap came from user task
                 */

                switch (trapno) {

                case T_PREEMPT:
                        unresolved_kernel_trap(trapno, ssp, dsisr, dar, NULL);
                        break;  

                case T_PERF_MON:
                        perfmon_handle_pmi(ssp);
                        break;

                        /*
                         * These trap types should never be seen by trap()
                         * Some are interrupts that should be seen by
                         * interrupt() others just don't happen because they
                         * are handled elsewhere.
                         */
                case T_DECREMENTER:
                case T_IN_VAIN:                                                         /* Shouldn't ever see this, lowmem_vectors eats it */
                case T_MACHINE_CHECK:
                case T_INTERRUPT:
                case T_FP_UNAVAILABLE:
                case T_SYSTEM_MANAGEMENT:
                case T_RESERVED:
                case T_IO_ERROR:
                        
                default:

                        ml_set_interrupts_enabled(FALSE);                                       /* Turn off interruptions */

                        panic("Unexpected user state trap(cpu %d): 0x%08X DSISR=0x%08X DAR=0x%016llX PC=0x%016llX, MSR=0x%016llX\n",
                               cpu_number(), trapno, dsisr, dar, ssp->save_srr0, ssp->save_srr1);
                        break;

                case T_RESET:
                        ml_set_interrupts_enabled(FALSE);                                       /* Turn off interruptions */
                        if (!Call_Debugger(trapno, ssp))
                                panic("Unexpected Reset exception: srr0 = %016llx, srr1 = %016llx\n",
                                        ssp->save_srr0, ssp->save_srr1);
                        break;                                          /* We just ignore these */

                case T_ALIGNMENT:
/*
*                       If enaNotifyEMb is set, we get here, and
*                       we have actually already emulated the unaligned access.
*                       All that we want to do here is to ignore the interrupt. This is to allow logging or
*                       tracing of unaligned accesses.  
*/
                        
                        KERNEL_DEBUG_CONSTANT(
                                MACHDBG_CODE(DBG_MACH_EXCP_ALNG, 0) | DBG_FUNC_NONE,
                                (int)ssp->save_srr0 - 4, (int)dar, (int)dsisr, (int)ssp->save_lr, 0);
                        break;

                case T_EMULATE:
/*
*                       If enaNotifyEMb is set we get here, and
*                       we have actually already emulated the instruction.
*                       All that we want to do here is to ignore the interrupt. This is to allow logging or
*                       tracing of emulated instructions.  
*/

                        KERNEL_DEBUG_CONSTANT(
                                MACHDBG_CODE(DBG_MACH_EXCP_EMUL, 0) | DBG_FUNC_NONE,
                                (int)ssp->save_srr0 - 4, (int)((savearea_comm *)ssp)->save_misc2, (int)dsisr, (int)ssp->save_lr, 0);
                        break;

                case T_TRACE:                   /* Real PPC chips */
                  if (be_tracing()) {
                    add_pcbuffer();
                    return ssp;
                  }
                  /* fall through */

                case T_INSTRUCTION_BKPT:
                        exception = EXC_BREAKPOINT;
                        code = EXC_PPC_TRACE;
                        subcode = (unsigned int)ssp->save_srr0;
                        break;

                case T_PROGRAM:
                        if (ssp->save_srr1 & MASK(SRR1_PRG_FE)) {
                                fpu_save(thr_act->mact.curctx);
                                UPDATE_PPC_EXCEPTION_STATE;
                                exception = EXC_ARITHMETIC;
                                code = EXC_ARITHMETIC;
                        
                                mp_disable_preemption();
                                subcode = ssp->save_fpscr;
                                mp_enable_preemption();
                        }       
                        else if (ssp->save_srr1 & MASK(SRR1_PRG_ILL_INS)) {
                                
                                UPDATE_PPC_EXCEPTION_STATE
                                exception = EXC_BAD_INSTRUCTION;
                                code = EXC_PPC_UNIPL_INST;
                                subcode = (unsigned int)ssp->save_srr0;
                        } else if ((unsigned int)ssp->save_srr1 & MASK(SRR1_PRG_PRV_INS)) {

                                UPDATE_PPC_EXCEPTION_STATE;
                                exception = EXC_BAD_INSTRUCTION;
                                code = EXC_PPC_PRIVINST;
                                subcode = (unsigned int)ssp->save_srr0;
                        } else if (ssp->save_srr1 & MASK(SRR1_PRG_TRAP)) {
                                unsigned int inst;
                                char *iaddr;
                                
                                iaddr = (char *)ssp->save_srr0;         /* Trim from long long and make a char pointer */
                                if (copyin(iaddr, (char *) &inst, 4 )) panic("copyin failed\n");
                                
                                if(dgWork.dgFlags & enaDiagTrap) {      /* Is the diagnostic trap enabled? */
                                        if((inst & 0xFFFFFFF0) == 0x0FFFFFF0) { /* Is this a TWI 31,R31,0xFFFx? */
                                                if(diagTrap(ssp, inst & 0xF)) { /* Call the trap code */
                                                        ssp->save_srr0 += 4ULL; /* If we eat the trap, bump pc */
                                                        exception = 0;                  /* Clear exception */
                                                        break;                                  /* All done here */
                                                }
                                        }
                                }
                                
                                UPDATE_PPC_EXCEPTION_STATE;
                                
                                if (inst == 0x7FE00008) {
                                        exception = EXC_BREAKPOINT;
                                        code = EXC_PPC_BREAKPOINT;
                                } else {
                                        exception = EXC_SOFTWARE;
                                        code = EXC_PPC_TRAP;
                                }
                                subcode = (unsigned int)ssp->save_srr0;
                        }
                        break;
                        
                case T_ALTIVEC_ASSIST:
                        UPDATE_PPC_EXCEPTION_STATE;
                        exception = EXC_ARITHMETIC;
                        code = EXC_PPC_ALTIVECASSIST;
                        subcode = (unsigned int)ssp->save_srr0;
                        break;

                case T_DATA_ACCESS:
                        map = thr_act->map;

                        if(ssp->save_dsisr & dsiInvMode) {                      /* Did someone try to reserve cache inhibited? */
                                UPDATE_PPC_EXCEPTION_STATE;                             /* Don't even bother VM with this one */
                                exception = EXC_BAD_ACCESS;
                                subcode = (unsigned int)dar;
                                break;
                        }
                        
                        code = vm_fault(map, trunc_page_64(dar),
                                 dsisr & MASK(DSISR_WRITE) ? PROT_RW : PROT_RO,
                                 FALSE, THREAD_ABORTSAFE, NULL, 0);

                        if ((code != KERN_SUCCESS) && (code != KERN_ABORTED)) {
                                UPDATE_PPC_EXCEPTION_STATE;
                                exception = EXC_BAD_ACCESS;
                                subcode = (unsigned int)dar;
                        } else { 
                                ssp->save_hdr.save_flags |= SAVredrive; /* Tell low-level to re-try fault */
                                ssp->save_dsisr = (ssp->save_dsisr & 
                                        ~((MASK(DSISR_NOEX) | MASK(DSISR_PROT)))) | MASK(DSISR_HASH);   /* Make sure this is marked as a miss */
                        }
                        break;
                        
                case T_INSTRUCTION_ACCESS:
                        /* Same as for data access, except fault type
                         * is PROT_EXEC and addr comes from srr0
                         */
                        map = thr_act->map;
                        
                        code = vm_fault(map, trunc_page_64(ssp->save_srr0),
                                        PROT_EXEC, FALSE, THREAD_ABORTSAFE, NULL, 0);

                        if ((code != KERN_SUCCESS) && (code != KERN_ABORTED)) {
                                UPDATE_PPC_EXCEPTION_STATE;
                                exception = EXC_BAD_ACCESS;
                                subcode = (unsigned int)ssp->save_srr0;
                        } else { 
                                ssp->save_hdr.save_flags |= SAVredrive; /* Tell low-level to re-try fault */
                                ssp->save_srr1 = (ssp->save_srr1 & 
                                        ~((unsigned long long)(MASK(DSISR_NOEX) | MASK(DSISR_PROT)))) | MASK(DSISR_HASH);               /* Make sure this is marked as a miss */
                        }
                        break;

                case T_AST:
                        ml_set_interrupts_enabled(FALSE);
                        ast_taken(AST_ALL, intr);
                        break;
                        
                }
#ifdef MACH_BSD
                {
                void bsd_uprofil(time_value_t *, unsigned int);

                bsd_uprofil(&tv, ssp->save_srr0);
                }
#endif /* MACH_BSD */
        }

        if (exception) {
                /* if this is the init task, save the exception information */
                /* this probably is a fatal exception */
#if 0
                if(bsd_init_task == current_task()) {
                        char *buf;
                        int i;

                        buf = init_task_failure_data;


                        buf += sprintf(buf, "Exception Code = 0x%x, Subcode = 0x%x\n", code, subcode);
                        buf += sprintf(buf, "DSISR = 0x%08x, DAR = 0x%016llx\n"
                                                                , dsisr, dar);

                        for (i=0; i<32; i++) {
                                if ((i % 8) == 0) {
                                        buf += sprintf(buf, "\n%4d :",i);
                                }
                                buf += sprintf(buf, " %08x",*(&ssp->save_r0+i));
                        }

                        buf += sprintf(buf, "\n\n");
                        buf += sprintf(buf, "cr        = 0x%08X\t\t",ssp->save_cr);
                        buf += sprintf(buf, "xer       = 0x%08X\n",ssp->save_xer);
                        buf += sprintf(buf, "lr        = 0x%016llX\t\t",ssp->save_lr);
                        buf += sprintf(buf, "ctr       = 0x%016llX\n",ssp->save_ctr); 
                        buf += sprintf(buf, "srr0(iar) = 0x%016llX\t\t",ssp->save_srr0);
                        buf += sprintf(buf, "srr1(msr) = 0x%016llX\n",ssp->save_srr1,
                           "\x10\x11""EE\x12PR\x13""FP\x14ME\x15""FE0\x16SE\x18"
                           "FE1\x19""AL\x1a""EP\x1bIT\x1c""DT");
                        buf += sprintf(buf, "\n\n");

                        /* generate some stack trace */
                        buf += sprintf(buf, "Application level back trace:\n");
                        if (ssp->save_srr1 & MASK(MSR_PR)) { 
                           char *addr = (char*)ssp->save_r1;
                           unsigned int stack_buf[3];
                           for (i = 0; i < 8; i++) {
                                if (addr == (char*)NULL)
                                        break;
                                if (!copyin(addr,(char*)stack_buf, 
                                                        3 * sizeof(int))) {
                                        buf += sprintf(buf, "0x%08X : 0x%08X\n"
                                                ,addr,stack_buf[2]);
                                        addr = (char*)stack_buf[0];
                                } else {
                                        break;
                                }
                           }
                        }
                        buf[0] = '\0';
                }
#endif
                doexception(exception, code, subcode);
        }
        /* AST delivery
         * Check to see if we need an AST, if so take care of it here
         */
        ml_set_interrupts_enabled(FALSE);
        if (USER_MODE(ssp->save_srr1))
                while (ast_needed(cpu_number())) {
                        ast_taken(AST_ALL, intr);
                        ml_set_interrupts_enabled(FALSE);
                }

        return ssp;
}

/* This routine is called from assembly before each and every system call.
 * It must preserve r3.
 */

extern int syscall_trace(int, struct savearea *);


extern int pmdebug;

int syscall_trace(int retval, struct savearea *ssp)
{
        int i, argc;
        int kdarg[3];
/* Always prepare to trace mach system calls */

        kdarg[0]=0;
        kdarg[1]=0;
        kdarg[2]=0;
        
        argc = mach_trap_table[-((unsigned int)ssp->save_r0)].mach_trap_arg_count;
        
        if (argc > 3)
                argc = 3;
        
        for (i=0; i < argc; i++)
                kdarg[i] = (int)*(&ssp->save_r3 + i);
        
        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_EXCP_SC, (-(ssp->save_r0))) | DBG_FUNC_START,
                kdarg[0], kdarg[1], kdarg[2], 0, 0);

        return retval;
}

/* This routine is called from assembly after each mach system call
 * It must preserve r3.
 */

extern int syscall_trace_end(int, struct savearea *);

int syscall_trace_end(int retval, struct savearea *ssp)
{
        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_EXCP_SC,(-((unsigned int)ssp->save_r0))) | DBG_FUNC_END,
                retval, 0, 0, 0, 0);
        return retval;
}

/*
 * called from syscall if there is an error
 */

int syscall_error(
        int exception,
        int code,
        int subcode,
        struct savearea *ssp)
{
        register thread_t thread;

        thread = current_thread();

        if (thread == 0)
            panic("syscall error in boot phase");

        if (!USER_MODE(ssp->save_srr1))
                panic("system call called from kernel");

        doexception(exception, code, subcode);

        return 0;
}

/* Pass up a server syscall/exception */
void
doexception(
            int exc,
            int code,
            int sub)
{
        exception_data_type_t   codes[EXCEPTION_CODE_MAX];

        codes[0] = code;        
        codes[1] = sub;
        exception(exc, codes, 2);
}

char *trap_type[] = {
        "Unknown",
        "0x100 - System reset",
        "0x200 - Machine check",
        "0x300 - Data access",
        "0x400 - Inst access",
        "0x500 - Ext int",
        "0x600 - Alignment",
        "0x700 - Program",
        "0x800 - Floating point",
        "0x900 - Decrementer",
        "0xA00 - n/a",
        "0xB00 - n/a",
        "0xC00 - System call",
        "0xD00 - Trace",
        "0xE00 - FP assist",
        "0xF00 - Perf mon",
        "0xF20 - VMX",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "0x1300 - Inst bkpnt",
        "0x1400 - Sys mgmt",
        "0x1600 - Altivec Assist",
        "0x1700 - Thermal",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "INVALID EXCEPTION",
        "Emulate",
        "0x2000 - Run Mode/Trace",
        "Signal Processor",
        "Preemption",
        "Context Switch",
        "Shutdown",
        "System Failure"
};
int TRAP_TYPES = sizeof (trap_type) / sizeof (trap_type[0]);

void unresolved_kernel_trap(int trapno,
                            struct savearea *ssp,
                            unsigned int dsisr,
                            addr64_t dar,
                            char *message)
{
        char *trap_name;
        extern void print_backtrace(struct savearea *);
        extern unsigned int debug_mode, disableDebugOuput;

        ml_set_interrupts_enabled(FALSE);                                       /* Turn off interruptions */
        lastTrace = LLTraceSet(0);                                                      /* Disable low-level tracing */

        if( logPanicDataToScreen )
                disableDebugOuput = FALSE;
        
        debug_mode++;
        if ((unsigned)trapno <= T_MAX)
                trap_name = trap_type[trapno / T_VECTOR_SIZE];
        else
                trap_name = "???? unrecognized exception";
        if (message == NULL)
                message = trap_name;

        kdb_printf("\n\nUnresolved kernel trap(cpu %d): %s DAR=0x%016llX PC=0x%016llX\n",
               cpu_number(), trap_name, dar, ssp->save_srr0);

        print_backtrace(ssp);

        draw_panic_dialog();
                
        if( panicDebugging )
                (void *)Call_Debugger(trapno, ssp);
        panic(message);
}

void
thread_syscall_return(
        kern_return_t ret)
{
        register thread_act_t   thr_act = current_act();
        register struct savearea *regs = USER_REGS(thr_act);

        if (kdebug_enable && ((unsigned int)regs->save_r0 & 0x80000000)) {
          /* Mach trap */
          KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_EXCP_SC,(-(regs->save_r0))) | DBG_FUNC_END,
                       ret, 0, 0, 0, 0);
        }           
        regs->save_r3 = ret;

        thread_exception_return();
        /*NOTREACHED*/
}


#if     MACH_KDB
void
thread_kdb_return(void)
{
        register thread_act_t   thr_act = current_act();
        register thread_t       cur_thr = current_thread();
        register struct savearea *regs = USER_REGS(thr_act);

        Call_Debugger(thr_act->mact.pcb->save_exception, regs);
#if             MACH_LDEBUG
        assert(cur_thr->mutex_count == 0); 
#endif          /* MACH_LDEBUG */
        check_simple_locks();
        thread_exception_return();
        /*NOTREACHED*/
}
#endif  /* MACH_KDB */