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

/*
 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * 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. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * 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_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/*
 * @APPLE_FREE_COPYRIGHT@
 */
/*
 *  (c) Copyright 1988 HEWLETT-PACKARD COMPANY
 *
 *  To anyone who acknowledges that this file is provided "AS IS"
 *  without any express or implied warranty:
 *      permission to use, copy, modify, and distribute this file
 *  for any purpose is hereby granted without fee, provided that
 *  the above copyright notice and this notice appears in all
 *  copies, and that the name of Hewlett-Packard Company not be
 *  used in advertising or publicity pertaining to distribution
 *  of the software without specific, written prior permission.
 *  Hewlett-Packard Company makes no representations about the
 *  suitability of this software for any purpose.
 */
/*
 * Copyright (c) 1990,1991,1992,1994 The University of Utah and
 * the Computer Systems Laboratory (CSL).  All rights reserved.
 *
 * THE UNIVERSITY OF UTAH AND CSL PROVIDE THIS SOFTWARE IN ITS "AS IS"
 * CONDITION, AND DISCLAIM ANY LIABILITY OF ANY KIND FOR ANY DAMAGES
 * WHATSOEVER RESULTING FROM ITS USE.
 *
 * CSL requests users of this software to return to csl-dist@cs.utah.edu any
 * improvements that they make and grant CSL redistribution rights.
 *
 *      Utah $Hdr: model_dep.c 1.34 94/12/14$
 */
/*
 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 */

#include <debug.h>
#include <mach_kdb.h>
#include <mach_kdp.h>
#include <db_machine_commands.h>

#include <kern/thread.h>
#include <machine/pmap.h>
#include <device/device_types.h>

#include <mach/vm_param.h>
#include <mach/clock_types.h>
#include <mach/machine.h>
#include <mach/kmod.h>
#include <ppc/boot.h>

#include <kern/misc_protos.h>
#include <kern/startup.h>
#include <ppc/misc_protos.h>
#include <ppc/proc_reg.h>
#include <ppc/thread.h>
#include <ppc/asm.h>
#include <ppc/mem.h>
#include <ppc/Firmware.h>
#include <ppc/low_trace.h>
#include <ppc/mappings.h>
#include <ppc/FirmwareCalls.h>
#include <ppc/cpu_internal.h>
#include <ppc/exception.h>
#include <ppc/hw_perfmon.h>
#include <ppc/lowglobals.h>
#include <ppc/machine_cpu.h>
#include <ppc/db_machdep.h>

#include <kern/clock.h>
#include <kern/debug.h>
#include <machine/trap.h>
#include <kern/spl.h>
#include <pexpert/pexpert.h>
#include <kern/sched.h>
#include <kern/task.h>
#include <kern/machine.h>
#include <vm/vm_map.h>

#include <IOKit/IOPlatformExpert.h>

#include <mach/vm_prot.h>
#include <vm/pmap.h>
#include <mach/time_value.h>
#include <mach/mach_types.h>
#include <mach/mach_vm.h>
#include <machine/machparam.h>  /* for btop */

#if     MACH_KDB
#include <ddb/db_aout.h>
#include <ddb/db_output.h>
#include <ddb/db_command.h>
#include <machine/db_machdep.h>

extern struct db_command ppc_db_commands[];
#endif  /* MACH_KDB */

char kernel_args_buf[256] = "/mach_kernel";
char boot_args_buf[256] = "/mach_servers/bootstrap";
char env_buf[256];

#define TRAP_DEBUGGER   __asm__ volatile("tw 4,r3,r3");
#define TRAP_DEBUGGER_INST      0x7c831808
#define TRAP_DIRECT     __asm__ volatile("tw 4,r4,r4");
#define TRAP_DIRECT_INST        0x7c842008
#define TRAP_INST_SIZE  4
#define BREAK_TO_KDP0 0x7fe00008
#define BREAK_TO_KDP1 0x7c800008
#define BREAK_TO_KDB0 0x7c810808

/*
 * Code used to synchronize debuggers among all cpus, one active at a time, switch
 * from on to another using kdb_on! #cpu or cpu #cpu
 */

hw_lock_data_t debugger_lock;   /* debugger lock */
hw_lock_data_t pbtlock;         /* backtrace print lock */

unsigned int debugger_cpu = (unsigned)-1; /* current cpu running debugger       */
int                     debugger_debug = 0;                     /* Debug debugger */
int             db_run_mode;                            /* Debugger run mode */
unsigned int debugger_sync = 0;                 /* Cross processor debugger entry sync */
extern          unsigned int NMIss;                     /* NMI debounce switch */

extern volatile int panicwait;
volatile unsigned int pbtcnt = 0;
volatile unsigned int pbtcpu = -1;

unsigned int lastTrace;                                 /* Value of low-level exception trace controls */


volatile unsigned int   cpus_holding_bkpts;     /* counter for number of cpus holding
                                                                                           breakpoints (ie: cpus that did not
                                                                                           insert back breakpoints) */
void unlock_debugger(void);
void lock_debugger(void);
void dump_backtrace(struct savearea *sv,
                    unsigned int stackptr,
                    unsigned int fence);
void dump_savearea(struct savearea *sv,
                   unsigned int fence);

#if !MACH_KDB
boolean_t       db_breakpoints_inserted = TRUE;
jmp_buf_t *db_recover;
#endif

#if     MACH_KDB
#include <ddb/db_run.h>
int     kdb_flag=0;
extern boolean_t db_breakpoints_inserted;
extern jmp_buf_t *db_recover;
#define KDB_READY       0x1
#endif

#if     MACH_KDP
extern int      kdp_flag;
#define KDP_READY       0x1
#endif

unsigned int db_im_stepping = 0xFFFFFFFF; /* Remember if we were stepping */


const char *failNames[] = {     
        "Debugging trap",                       /* failDebug */
        "Corrupt stack",                        /* failStack */
        "Corrupt mapping tables",       /* failMapping */
        "Corrupt context",                      /* failContext */
        "No saveareas",                         /* failNoSavearea */
        "Savearea corruption",          /* failSaveareaCorr */
        "Invalid live context",         /* failBadLiveContext */
        "Corrupt skip lists",           /* failSkipLists */
        "Unaligned stack",                      /* failUnalignedStk */
        "Invalid pmap",                         /* failPmap */
        "Lock timeout",                         /* failTimeout */
        "Unknown failure code"          /* Unknown failure code - must always be last */
};

const char *invxcption = "Unknown code";

static unsigned commit_paniclog_to_nvram;

#if !MACH_KDB
void kdb_trap(__unused int type, __unused struct savearea *regs) {}
#endif /* !MACH_KDB */

#if !MACH_KDP
void kdp_trap(__unused int type, __unused struct savearea *regs) {}
#endif /* !MACH_KDP */

extern int default_preemption_rate;
extern int max_unsafe_quanta;
extern int max_poll_quanta;

void
machine_startup(void)
{
        int     boot_arg;
        unsigned int wncpu;

        if (PE_parse_boot_arg("cpus", &wncpu)) {
                if ((wncpu > 0) && (wncpu < MAX_CPUS))
                        max_ncpus = wncpu;
        }

        if( PE_get_hotkey( kPEControlKey ))
            halt_in_debugger = halt_in_debugger ? 0 : 1;

        if (PE_parse_boot_arg("debug", &boot_arg)) {
                if (boot_arg & DB_HALT) halt_in_debugger=1;
                if (boot_arg & DB_PRT) disable_debug_output=FALSE; 
                if (boot_arg & DB_SLOG) systemLogDiags=TRUE; 
                if (boot_arg & DB_NMI) panicDebugging=TRUE; 
                if (boot_arg & DB_LOG_PI_SCRN) logPanicDataToScreen=TRUE; 
        }
        
        if (!PE_parse_boot_arg("nvram_paniclog", &commit_paniclog_to_nvram))
                commit_paniclog_to_nvram = 1;

        PE_parse_boot_arg("vmmforce", &lowGlo.lgVMMforcedFeats);

        hw_lock_init(&debugger_lock);                           /* initialize debugger lock */
        hw_lock_init(&pbtlock);                                         /* initialize print backtrace lock */

#if     MACH_KDB
        /*
         * Initialize KDB
         */
#if     DB_MACHINE_COMMANDS
        db_machine_commands_install(ppc_db_commands);
#endif  /* DB_MACHINE_COMMANDS */
        ddb_init();

        if (boot_arg & DB_KDB)
                current_debugger = KDB_CUR_DB;

        /*
         * Cause a breakpoint trap to the debugger before proceeding
         * any further if the proper option bit was specified in
         * the boot flags.
         */
        if (halt_in_debugger && (current_debugger == KDB_CUR_DB)) {
                Debugger("inline call to debugger(machine_startup)");
                halt_in_debugger = 0;
                active_debugger =1;
        }
#endif /* MACH_KDB */
        if (PE_parse_boot_arg("preempt", &boot_arg)) {
                default_preemption_rate = boot_arg;
        }
        if (PE_parse_boot_arg("unsafe", &boot_arg)) {
                max_unsafe_quanta = boot_arg;
        }
        if (PE_parse_boot_arg("poll", &boot_arg)) {
                max_poll_quanta = boot_arg;
        }
        if (PE_parse_boot_arg("yield", &boot_arg)) {
                sched_poll_yield_shift = boot_arg;
        }

        machine_conf();

        /*
         * Kick off the kernel bootstrap.
         */
        kernel_bootstrap();
        /*NOTREACHED*/
}

char *
machine_boot_info(__unused char *buf, __unused vm_size_t size)
{
        return(PE_boot_args());
}

void
machine_conf(void)
{
        machine_info.memory_size = mem_size;    /* Note that this will be 2 GB for >= 2 GB machines */
}

void
machine_init(void)
{
        debug_log_init();
        clock_config();
/*      Note that we must initialize the stepper tables AFTER the clock is configured!!!!! */
        if(pmsExperimental & 1) pmsCPUConf();   /* (EXPERIMENTAL) Initialize the stepper tables */
        perfmon_init();
        return;

}

void slave_machine_init(void)
{
        cpu_machine_init();                     /* Initialize the processor */
        clock_init();                           /* Init the clock */
}                               

void
halt_all_cpus(boolean_t reboot)
{
        if(reboot)
        {
                printf("MACH Reboot\n");
                PEHaltRestart(kPERestartCPU);
        }
        else
        {
                printf("CPU halted\n");
                PEHaltRestart(kPEHaltCPU);
        } 
        while(1);
}

void
halt_cpu(void)
{
        halt_all_cpus(FALSE);
}

#if     MACH_ASSERT
/*
 * Machine-dependent routine to fill in an array with up to callstack_max
 * levels of return pc information.
 */
void
machine_callstack(__unused natural_t *buf, __unused vm_size_t callstack_max)
{
}
#endif  /* MACH_ASSERT */

void
print_backtrace(struct savearea *ssp)
{
        unsigned int stackptr, fence;
        struct savearea *sv, *svssp, *psv;
        unsigned int cpu;

/*
 *      We need this lock to make sure we don't hang up when we double panic on an MP.
 */

        cpu  = cpu_number();                                    /* Just who are we anyways? */
        if(pbtcpu != cpu) {                                             /* Allow recursion */
                (void)hw_atomic_add(&pbtcnt, 1); /* Remember we are trying */
                while(!hw_lock_try(&pbtlock));          /* Spin here until we can get in. If we never do, well, we're crashing anyhow... */     
                pbtcpu = cpu;                                           /* Mark it as us */     
        }       

        svssp = (struct savearea *)ssp;                         /* Make this easier */
        sv = NULL;
        if(current_thread())
                sv = (struct savearea *)current_thread()->machine.pcb;  /* Find most current savearea if system has started */

        fence = 0xFFFFFFFF;                                             /* Show we go all the way */
        if(sv) fence = (unsigned int)sv->save_r1;       /* Stop at previous exception point */
        
        if(!svssp) {                                                    /* Should we start from stack? */
                kdb_printf("Latest stack backtrace for cpu %d:\n", cpu_number());
                __asm__ volatile("mr %0,r1" : "=r" (stackptr)); /* Get current stack */
                dump_backtrace((struct savearea *)0,stackptr, fence);   /* Dump the backtrace */
                if(!sv) {                                                       /* Leave if no saveareas */
                        hw_lock_unlock(&pbtlock);               /* Allow another back trace to happen */
                        goto pbt_exit;
                }
        }
        else {                                                                  /* Were we passed an exception? */
                fence = 0xFFFFFFFF;                                     /* Show we go all the way */
                if(svssp->save_hdr.save_prev) {
                        if((svssp->save_hdr.save_prev <= vm_last_addr) && ((unsigned int)pmap_find_phys(kernel_pmap, (addr64_t)svssp->save_hdr.save_prev))) {   /* Valid address? */    
                                psv = (struct savearea *)((unsigned int)svssp->save_hdr.save_prev);     /* Get the 64-bit back chain converted to a regualr pointer */
                                fence = (unsigned int)psv->save_r1;     /* Stop at previous exception point */
                        }
                }
        
                kdb_printf("Latest crash info for cpu %d:\n", cpu_number());
                kdb_printf("   Exception state (sv=%p)\n", svssp);
                dump_savearea(svssp, fence);            /* Dump this savearea */        
        }

        if(!sv) {                                                               /* Leave if no saveareas */
                hw_lock_unlock(&pbtlock);                       /* Allow another back trace to happen */
                goto pbt_exit;
        }
        
        kdb_printf("Proceeding back via exception chain:\n");

        while(sv) {                                                             /* Do them all... */
                if(!(((addr64_t)((uintptr_t)sv) <= vm_last_addr) && 
                        (unsigned int)pmap_find_phys(kernel_pmap, (addr64_t)((uintptr_t)sv)))) {        /* Valid address? */    
                        kdb_printf("   Exception state (sv=%p) Not mapped or invalid. stopping...\n", sv);
                        break;
                }
                
                kdb_printf("   Exception state (sv=%p)\n", sv);
                if(sv == svssp) {                                       /* Did we dump it already? */
                        kdb_printf("      previously dumped as \"Latest\" state. skipping...\n");
                }
                else {
                        fence = 0xFFFFFFFF;                             /* Show we go all the way */
                        if(sv->save_hdr.save_prev) {
                                if((sv->save_hdr.save_prev <= vm_last_addr) && ((unsigned int)pmap_find_phys(kernel_pmap, (addr64_t)sv->save_hdr.save_prev))) { /* Valid address? */    
                                        psv = (struct savearea *)((unsigned int)sv->save_hdr.save_prev);        /* Get the 64-bit back chain converted to a regualr pointer */
                                        fence = (unsigned int)psv->save_r1;     /* Stop at previous exception point */
                                }
                        }
                        dump_savearea(sv, fence);               /* Dump this savearea */        
                }       
                
                sv = CAST_DOWN(struct savearea *, sv->save_hdr.save_prev);      /* Back chain */ 
        }
        

        pbtcpu = -1;                                                    /* Mark as unowned */
        hw_lock_unlock(&pbtlock);                               /* Allow another back trace to happen */
        (void)hw_atomic_sub(&pbtcnt, 1);  /* Show we are done */

        while(pbtcnt);                                                  /* Wait for completion */
pbt_exit:
        panic_display_system_configuration();

        return;
}

void
dump_savearea(struct savearea *sv, unsigned int fence)
{
        const char *xcode;
        
        if(sv->save_exception > T_MAX)
                xcode = invxcption;     /* Too big for table */
        else
                xcode = trap_type[sv->save_exception / 4];              /* Point to the type */
        
        kdb_printf("      PC=0x%08X; MSR=0x%08X; DAR=0x%08X; DSISR=0x%08X; LR=0x%08X; R1=0x%08X; XCP=0x%08X (%s)\n",
                (unsigned int)sv->save_srr0, (unsigned int)sv->save_srr1, (unsigned int)sv->save_dar, sv->save_dsisr,
                (unsigned int)sv->save_lr, (unsigned int)sv->save_r1, sv->save_exception, xcode);
        
        if(!(sv->save_srr1 & MASK(MSR_PR))) {           /* Are we in the kernel? */
                dump_backtrace(sv, (unsigned int)sv->save_r1, fence);   /* Dump the stack back trace from  here if not user state */
        }
        
        return;
}

#define DUMPFRAMES 34
#define LRindex 2

void dump_backtrace(struct savearea *sv, unsigned int stackptr, unsigned int fence) {

        unsigned int bframes[DUMPFRAMES];
        unsigned int  sframe[8], raddr, dumbo;
        int i, index=0;
//      char syminfo[80];
        
        kdb_printf("      Backtrace:\n");
        if (sv != (struct savearea *)0) {
                bframes[0] = (unsigned int)sv->save_srr0;
                bframes[1] = (unsigned int)sv->save_lr;
                index = 2;
        }
        for(i = index; i < DUMPFRAMES; i++) {                   /* Dump up to max frames */
        
                if(!stackptr || (stackptr == fence)) break;             /* Hit stop point or end... */
                
                if(stackptr & 0x0000000F) {                             /* Is stack pointer valid? */
                        kdb_printf("\n         backtrace terminated - unaligned frame address: 0x%08X\n", stackptr);    /* No, tell 'em */
                        break;
                }

                raddr = (unsigned int)pmap_find_phys(kernel_pmap, (addr64_t)stackptr);  /* Get physical frame address */
                if(!raddr || (stackptr > vm_last_addr)) {               /* Is it mapped? */
                        kdb_printf("\n         backtrace terminated - frame not mapped or invalid: 0x%08X\n", stackptr);        /* No, tell 'em */
                        break;
                }
        
                if(!mapping_phys_lookup(raddr, &dumbo)) {       /* Is it within physical RAM? */
                        kdb_printf("\n         backtrace terminated - frame outside of RAM: v=0x%08X, p=%08X\n", stackptr, raddr);      /* No, tell 'em */
                        break;
                }
        
                ReadReal((addr64_t)((raddr << 12) | (stackptr & 4095)), &sframe[0]);    /* Fetch the stack frame */

                bframes[i] = sframe[LRindex];                           /* Save the link register */
                
//              syms_formataddr((vm_offset_t)bframes[i], syminfo, sizeof (syminfo));
//              kdb_printf("        %s\n", syminfo);
                if(!i) kdb_printf("         ");                         /* Indent first time */
                else if(!(i & 7)) kdb_printf("\n         ");    /* Skip to new line every 8 */
                kdb_printf("0x%08X ", bframes[i]);                      /* Dump the link register */
                
                stackptr = sframe[0];                                           /* Chain back */
        }
        kdb_printf("\n");
        if(i >= DUMPFRAMES) kdb_printf("      backtrace continues...\n");       /* Say we terminated early */
        if(i) kmod_dump((vm_offset_t *)&bframes[0], i); /* Show what kmods are in trace */
        
}
        
void commit_paniclog(void) {
        unsigned long pi_size = 0;

        if (debug_buf_size > 0) {
                if (commit_paniclog_to_nvram) {
                        unsigned int bufpos;
                        
                        /* XXX Consider using the WKdm compressor in the
                         * future, rather than just packing - would need to
                         * be co-ordinated with crashreporter, which decodes
                         * this post-restart. The compressor should be
                         * capable of in-place compression.
                         */
                        bufpos = packA(debug_buf, (unsigned) (debug_buf_ptr - debug_buf), debug_buf_size);
                        /* If compression was successful,
                         * use the compressed length
                         */
                        pi_size = bufpos ? bufpos : (unsigned) (debug_buf_ptr - debug_buf);

                        /* Truncate if the buffer is larger than a
                         * certain magic size - this really ought to
                         * be some appropriate fraction of the NVRAM
                         * image buffer, and is best done in the
                         * savePanicInfo() or PESavePanicInfo() calls
                         * This call must save data synchronously,
                         * since we can subsequently halt the system.
                         */
                        kprintf("Attempting to commit panic log to NVRAM\n");
                        /* N.B.: This routine (currently an IOKit wrapper that
                         * calls through to the appropriate platform NVRAM
                         * driver, must be panic context safe, i.e.
                         * acquire no locks or require kernel services.
                         * This does not appear to be the case currently
                         * on some platforms, unfortunately (the driver
                         * on command gate serialization).
                         */
                        pi_size = PESavePanicInfo((unsigned char *)debug_buf,
                            ((pi_size > 2040) ? 2040 : pi_size));
                        /* Uncompress in-place, to allow debuggers to examine
                         * the panic log.
                         */
                        if (bufpos) 
                                unpackA(debug_buf, bufpos);
                }
        }
}

void 
Debugger(const char     *message) {

        spl_t spl;
        
        spl = splhigh();                                                                /* No interruptions from here on */
        
/*
 *      backtrace for Debugger() call  from panic() if no current debugger
 *      backtrace and return for double panic() call
 */
        if ((panicstr != (char *)0) && 
          (((nestedpanic != 0) && (current_debugger == 1)) || (active_debugger == 0))) {
                print_backtrace(NULL);
                if (nestedpanic != 0)  {
                        splx(spl);
                        return;                                                                 /* Yeah, don't enter again... */
                }
        }
        
        if (debug_mode && getPerProc()->debugger_active) {      /* Are we already on debugger on this processor? */
                splx(spl);
                return;                                                                         /* Yeah, don't do it again... */
        }


/*
 * The above stuff catches the double panic case so we shouldn't have to worry about that here.
 */
        if ( panicstr != (char *)0 )
        {
                disable_preemption();
                /* Commit the panic log buffer to NVRAM, unless otherwise
                 * specified via a boot-arg.
                 */
                commit_paniclog();
                if(!panicDebugging) {
                        unsigned int my_cpu, tcpu;

                        my_cpu = cpu_number();
                        debugger_cpu = my_cpu;

                        (void)hw_atomic_add(&debug_mode, 1);
                        PerProcTable[my_cpu].ppe_vaddr->debugger_active++;
                        lock_debugger();

                        for(tcpu = 0; tcpu < real_ncpus; tcpu++) {
                                if(tcpu == my_cpu) continue;
                                (void)hw_atomic_add(&debugger_sync, 1);
                                (void)cpu_signal(tcpu, SIGPdebug, 0 ,0);
                        }
                        (void)hw_cpu_sync(&debugger_sync, LockTimeOut);
                        debugger_sync = 0;
                }

                draw_panic_dialog();
                
                if(!panicDebugging) {
#if CONFIG_EMBEDDED
                                        PEHaltRestart(kPEPanicRestartCPU);
#else
                                        PEHaltRestart( kPEHangCPU );
#endif
                }

                enable_preemption();
        }

        if ((current_debugger != NO_CUR_DB)) {                  /* If there is a debugger configured, enter it */
                printf("Debugger(%s)\n", message);
                TRAP_DEBUGGER;
                splx(spl);
                return;                                                                         /* Done debugging for a while */
        }

        printf("\nNo debugger configured - dumping debug information\n");
        printf("MSR=%08X\n",mfmsr());
        print_backtrace(NULL);
        splx(spl);
        return;
}

/*
 *              Here's where we attempt to get some diagnostic information dumped out
 *              when the system is really confused.  We will try to get into the 
 *              debugger as well.
 *
 *              We are here with interrupts disabled and on the debug stack.  The savearea
 *              that was passed in is NOT chained to the activation.
 *
 *              save_r3 contains the failure reason code.
 */

void
SysChoked(unsigned int type, struct savearea *sv)
{
        unsigned int failcode;
        const char * const pmsg = "System Failure: cpu=%d; code=%08X (%s)\n";
        mp_disable_preemption();
        disable_debug_output = FALSE;
        debug_mode = TRUE;

        failcode = (unsigned int)sv->save_r3;                   /* Get the failure code */
        if(failcode > failUnknown) failcode = failUnknown;      /* Set unknown code code */
        
        kprintf(pmsg, cpu_number(), (unsigned int)sv->save_r3, failNames[failcode]);
        kdb_printf(pmsg, cpu_number(), (unsigned int)sv->save_r3, failNames[failcode]);

        print_backtrace(sv);                                                    /* Attempt to print backtrace */

        /* Commit the panic log buffer to NVRAM, unless otherwise
         * specified via a boot-arg. For certain types of panics
         * which result in a "choke" exception, this may well
         * be inadvisable, and setting the nvram_paniclog=0
         * boot-arg may be useful.
         */

        if (panicDebugging)
                commit_paniclog();

        Call_DebuggerC(type, sv);                                               /* Attempt to get into debugger */

        if ((current_debugger != NO_CUR_DB))
                Call_DebuggerC(type, sv);       /* Attempt to get into debugger */
        panic_plain(pmsg, cpu_number(), (unsigned int)sv->save_r3, failNames[failcode]);
}



/*
 *      When we get here, interruptions are disabled and we are on the debugger stack
 *      Never, ever, ever, ever enable interruptions from here on
 */

int
Call_DebuggerC(unsigned int type, struct savearea *saved_state)
{
        int                             directcall, wait;
        addr64_t                instr_ptr = 0ULL;
        ppnum_t                 instr_pp;
        unsigned int    instr, tcpu, my_cpu;
        int                     wasdebugger;

        my_cpu = cpu_number();                                                          /* Get our CPU */

#if     MACH_KDB
        if((debugger_cpu == my_cpu) &&                                          /* Do we already own debugger? */
          PerProcTable[my_cpu].ppe_vaddr->debugger_active &&                                            /* and are we really active? */
          db_recover &&                                                                         /* and have we set up recovery? */
          (current_debugger == KDB_CUR_DB)) {                           /* and are we in KDB (only it handles recovery) */
                kdb_trap(type, saved_state);                                    /* Then reenter it... */
        }
#endif
        
        (void)hw_atomic_add(&debug_mode, 1); /* Indicate we are in debugger */
        PerProcTable[my_cpu].ppe_vaddr->debugger_active++;      /* Show active on our CPU */
        
        lock_debugger();                                                                        /* Insure that only one CPU is in debugger */

        if(db_im_stepping == my_cpu) {                                          /* Are we just back from a step? */
                enable_preemption_no_check();                                   /* Enable preemption now */
                db_im_stepping = 0xFFFFFFFF;                                    /* Nobody stepping right now */
        }

        if (debugger_debug) {
#if 0
                kprintf("Call_DebuggerC(%d): %08X %08X, debact = %d\n", my_cpu, type, (uint32_t)saved_state, debug_mode);       /* (TEST/DEBUG) */
#endif
                printf("Call_Debugger: enter - cpu %d, is_slave %d, debugger_cpu %d, pc %08llX\n",
                   my_cpu, PerProcTable[my_cpu].ppe_vaddr->debugger_is_slave, debugger_cpu, saved_state->save_srr0);
        }
        
        instr_pp = (vm_offset_t)pmap_find_phys(kernel_pmap, (addr64_t)(saved_state->save_srr0));

        if (instr_pp) {
                instr_ptr = (addr64_t)(((addr64_t)instr_pp << 12) | (saved_state->save_srr0 & 0xFFF));  /* Make physical address */
                instr = ml_phys_read_64(instr_ptr);                             /* Get the trap that caused entry */
        } 
        else instr = 0;

#if 0
        if (debugger_debug) kprintf("Call_DebuggerC(%d): instr_pp = %08X, instr_ptr = %016llX, instr = %08X\n", my_cpu, instr_pp, instr_ptr, instr);    /* (TEST/DEBUG) */
#endif

        if (db_breakpoints_inserted) cpus_holding_bkpts++;      /* Bump up the holding count */
        if ((debugger_cpu == (unsigned)-1) &&
                !PerProcTable[my_cpu].ppe_vaddr->debugger_is_slave) {
#if 0
                if (debugger_debug) kprintf("Call_DebuggerC(%d): lasttrace = %08X\n", my_cpu, lastTrace);       /* (TEST/DEBUG) */
#endif
                debugger_cpu = my_cpu;                                                  /* Show that we are debugger */


                lastTrace = LLTraceSet(0);                                              /* Disable low-level tracing */

                for(tcpu = 0; tcpu < real_ncpus; tcpu++) {              /* Stop all the other guys */
                        if(tcpu == my_cpu) continue;                            /* Don't diddle ourselves */
                        (void)hw_atomic_add(&debugger_sync, 1); /* Count signal sent */
                        (void)cpu_signal(tcpu, SIGPdebug, 0 ,0);        /* Tell 'em to enter debugger */
                }
                (void)hw_cpu_sync(&debugger_sync, LockTimeOut); /* Wait for the other processors to enter debug */
                debugger_sync = 0;                                                              /* We're done with it */
        } 
        else if (debugger_cpu != my_cpu)  goto debugger_exit;   /* We are not debugger, don't continue... */
        

        if (instr == TRAP_DIRECT_INST) {
                disable_debug_output = FALSE;
                print_backtrace(saved_state);
        }

        switch_debugger = 0;                                                            /* Make sure switch request is off */
        directcall = 1;                                                                         /* Assume direct call */

        if (saved_state->save_srr1 & MASK(SRR1_PRG_TRAP)) {     /* Trap instruction? */
                
                directcall = 0;                                                                 /* We had a trap not a direct call */

                switch (instr) {                                                                /* Select trap type */

#if     MACH_KDP
                        case BREAK_TO_KDP0:                                                     /* Breakpoint into KDP? */
                        case BREAK_TO_KDP1:                                                     /* Breakpoint into KDP? */
                                current_debugger = KDP_CUR_DB;                  /* Yes, set KDP */
                                kdp_trap(type, saved_state);                    /* Enter it */
                                break;
#endif
        
#if     MACH_KDB
                        case BREAK_TO_KDB0:                                             /* Breakpoint to KDB (the "good" debugger)? */
                                current_debugger = KDB_CUR_DB;                  /* Yes, set it */
                                kdb_trap(type, saved_state);                    /* Enter it */
                                break;
#endif
                                
                        case TRAP_DEBUGGER_INST:                                        /* Should we enter the current debugger? */
                        case TRAP_DIRECT_INST:                                          /* Should we enter the current debugger? */
                                if (current_debugger == KDP_CUR_DB)     /* Is current KDP? */
                                        kdp_trap(type, saved_state);            /* Yes, enter it */
                                else if (current_debugger == KDB_CUR_DB)        /* Is this KDB? */
                                        kdb_trap(type, saved_state);            /* Yes, go ahead and enter */
                                else goto debugger_error;                               /* No debugger active */
                                break;
                                
                        default:                                                                        /* Unknown/bogus trap type */
                                goto debugger_error;
                }
        }

        while(1) {                                                                                      /* We are here to handle debugger switches */
                
                if(!directcall) {                                                               /* Was this a direct call? */
                        if(!switch_debugger) break;                                     /* No, then leave if no switch requested... */

/*
 *                      Note: we can only switch to a debugger we have.  Ignore bogus switch requests.
 */
#if 0
                        if (debugger_debug) kprintf("Call_DebuggerC(%d): switching debuggers\n", my_cpu);       /* (TEST/DEBUG) */
#endif
#if MACH_KDB
                        if(current_debugger == KDP_CUR_DB) current_debugger = KDB_CUR_DB; /* Switch to KDB */
#if MACH_KDP
                        else 
#endif
#endif
#if MACH_KDP
                        if(current_debugger == KDB_CUR_DB) current_debugger = KDP_CUR_DB;               /* Switch to KDP */
#endif
                }
                
                switch_debugger = 0;                                                    /* Clear request */
                directcall = 0;                                                                 /* Clear first-time direct call indication */

                switch (current_debugger) {                                             /* Enter correct debugger */
                
                        case KDP_CUR_DB:                                                        /* Enter KDP */
                                kdp_trap(type, saved_state);
                                break;
                                
                        case KDB_CUR_DB:                                                        /* Enter KDB */
                                kdb_trap(type, saved_state);
                                break;
                                
                        default:                                                                        /* No debugger installed */
                                goto debugger_error;
                                break;
                }
        }

debugger_exit:
#if 0
        if (debugger_debug) kprintf("Call_DebuggerC(%d): exit - inst = %08X, cpu=%d(%d), run=%d\n", my_cpu, 
                instr, my_cpu, debugger_cpu, db_run_mode);      /* (TEST/DEBUG) */
#endif
        if ((instr == TRAP_DEBUGGER_INST) ||                            /* Did we trap to enter debugger? */
                (instr == TRAP_DIRECT_INST)) saved_state->save_srr0 += TRAP_INST_SIZE;  /* Yes, point past trap */

        wasdebugger = 0;                                                                        /* Assume not debugger */
        if(debugger_cpu == my_cpu) {                                            /* Are the debugger processor? */
                wasdebugger = 1;                                                                /* Remember that we were the debugger */
                LLTraceSet(lastTrace);                                                  /* Enable tracing on the way out if we are debugger */
        }

        wait = FALSE;                                                                           /* Assume we are not going to wait */
        if (db_run_mode == STEP_CONTINUE) {                                     /* Are we going to run? */
                wait = TRUE;                                                                    /* Yeah, remember to wait for breakpoints to clear */
                debugger_cpu = -1;                                                              /* Release other processor's debuggers */
                for(tcpu = 0; tcpu < real_ncpus; tcpu++)
                        PerProcTable[tcpu].ppe_vaddr->debugger_pending = 0;     /* Release request (this is a HACK) */
                NMIss = 0;                                                                              /* Let NMI bounce */
        }
        
        if(db_run_mode == STEP_ONCE) {                                          /* Are we about to step? */
                disable_preemption();                                                   /* Disable preemption for the step */
                db_im_stepping = my_cpu;                                                /* Remember that I am about to step */
        }

        if (db_breakpoints_inserted) cpus_holding_bkpts--;      /* If any breakpoints, back off count */
        if (PerProcTable[my_cpu].ppe_vaddr->debugger_is_slave) PerProcTable[my_cpu].ppe_vaddr->debugger_is_slave--;     /* If we were a slove, uncount us */
        if (debugger_debug)
                printf("Call_Debugger: exit - cpu %d, debugger_cpu %d, run_mode %d holds %d\n",
                          my_cpu, debugger_cpu, db_run_mode,
                          cpus_holding_bkpts);

        unlock_debugger();                                                                      /* Release the lock */
        PerProcTable[my_cpu].ppe_vaddr->debugger_active--;      /* Say we aren't active anymore */

        if (wait) while(cpus_holding_bkpts);                            /* Wait for breakpoints to clear */


        (void)hw_atomic_sub(&debug_mode, 1); /* Set out of debug now */

        return(1);                                                                                      /* Exit debugger normally */

debugger_error:
        if(db_run_mode != STEP_ONCE) enable_preemption_no_check();      /* Enable preemption, but don't preempt here */
        (void)hw_atomic_sub(&debug_mode, 1); /* Set out of debug now */
        return(0);                                                                                      /* Return in shame... */

}

void
lock_debugger(void)
{
        unsigned int my_cpu;

        my_cpu = cpu_number();                                                          /* Get our CPU number */

        while(1) { /* Check until we get it */
                if (debugger_cpu != (unsigned)-1 && debugger_cpu != my_cpu)
                        continue;       /* Someone, not us, is debugger... */
                if (hw_lock_try(&debugger_lock)) { /* Get the debug lock */                     
                        if (debugger_cpu == (unsigned)-1 || debugger_cpu == my_cpu)
                                break;  /* Is it us? */
                        hw_lock_unlock(&debugger_lock); /* Not us, release lock */
                }
        } 
}

void unlock_debugger(void) {

        hw_lock_unlock(&debugger_lock);

}

int patchInst(task_t task, addr64_t vaddr, uint32_t inst);
int patchInst(task_t task, addr64_t vaddr, uint32_t inst)
{
        vm_map_t map;
        addr64_t paddr;
        uint32_t instr, nestingDepth;
        kern_return_t ret;
        vm_region_submap_short_info_data_64_t info;
        mach_msg_type_number_t count;
        mach_vm_address_t address;
        mach_vm_size_t sizeOfRegion;
        vm_prot_t reprotect;

        if(task == TASK_NULL) return -1;                /* Leave if task is bogus... */

        task_lock(task);                                                /* Make sure the task doesn't go anywhaere */
        if (!task->active) {                                    /* Is is alive? */
                task_unlock(task);                                      /* Nope, unlock */
                return -1;                                                      /* Not a active task, fail... */
        }
        map = task->map;                                                /* Get his map */
        vm_map_reference_swap(map);                             /* Don't let it go away */
        task_unlock(task);                                              /* Unleash the task */

        /* Find the memory permissions. */
        nestingDepth=999999;                                    /* Limit recursion */
        
        count = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64;
        address = (mach_vm_address_t)vaddr;
        sizeOfRegion = (mach_vm_size_t)4;

        ret = mach_vm_region_recurse(map, &address, &sizeOfRegion, &nestingDepth, (vm_region_recurse_info_t)&info, &count);
        if (ret != KERN_SUCCESS) {                              /* Leave if it didn't work */
                vm_map_deallocate(map);                         /* Drop reference on map */
                return (-1);                    
        }

/*
 *      We need to check if there could be a problem if the dtrace probes are being removed and the code is being
 *      executed at the same time.  This sequence may leave us with no-execute turned on temporarily when we execute
 *      through it.
 */
 
        if (!(info.protection & VM_PROT_WRITE)) {
                /* Save the original protection values for restoration later */
                reprotect = info.protection;

                if (info.max_protection & VM_PROT_WRITE) {
                        /* The memory is not currently writable, but can be made writable. */
                        ret = mach_vm_protect(map, (mach_vm_offset_t)vaddr, (mach_vm_size_t)4, 0, reprotect | VM_PROT_WRITE);
                } 
                else {
                        /*
                         * The memory is not currently writable, and cannot be made writable. We need to COW this memory.
                         *
                         * Strange, we can't just say "reprotect | VM_PROT_COPY", that fails.
                         */
                        ret = mach_vm_protect(map, (mach_vm_offset_t)vaddr, (mach_vm_size_t)4, 0, VM_PROT_COPY | VM_PROT_READ | VM_PROT_WRITE);
                }

                if (ret != KERN_SUCCESS) {
                        vm_map_deallocate(map);                 /* Drop reference on map */
                        return (-1);            
                }
                
        } 
        else {
                /* The memory was already writable. */
                reprotect = VM_PROT_NONE;
        }

        instr = inst;                                                   /* Place instruction in local memory */
        ret = vm_map_write_user(map, &inst, (vm_map_address_t)vaddr, (vm_size_t)4);     /* Write the instruction */
        if (ret != KERN_SUCCESS) {                              /* Leave if it didn't work */
        
                if (reprotect != VM_PROT_NONE) {
                        ret = mach_vm_protect (map, (mach_vm_offset_t)vaddr, (mach_vm_size_t)4, 0, reprotect);
                }

                vm_map_deallocate(map);                         /* Drop reference on map */
                return (-1);                    
        }

        paddr = (addr64_t)pmap_find_phys(map->pmap, vaddr) << 12;       /* Find the physical address of the patched address */
        if(!paddr) {                                                    /* Is address mapped now? */
                vm_map_deallocate(map);                         /* Drop reference on map */
                return 0;                                                       /* Leave... */
        }
        paddr = paddr | (vaddr & 4095);                 /* Construct physical address */
        invalidate_icache64(paddr, 4, 1);               /* Flush out the instruction cache here */

        if (reprotect != VM_PROT_NONE) {
                ret = mach_vm_protect(map, (mach_vm_offset_t)vaddr, (mach_vm_size_t)4, 0, reprotect);
        }

        vm_map_deallocate(map);

        return (0);
}