xnu-4903.221.2.tar.gz

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

/*
 * Copyright (c) 2007-2013 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@
 */

#include <debug.h>
#include <mach_kdp.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 <pexpert/boot.h>
#include <pexpert/pexpert.h>


#include <kern/misc_protos.h>
#include <kern/startup.h>
#include <kern/clock.h>
#include <kern/debug.h>
#include <kern/processor.h>
#include <kdp/kdp_core.h>
#if ALTERNATE_DEBUGGER
#include <arm64/alternate_debugger.h>
#endif
#include <machine/atomic.h>
#include <machine/trap.h>
#include <kern/spl.h>
#include <pexpert/pexpert.h>
#include <kdp/kdp_callout.h>
#include <kdp/kdp_dyld.h>
#include <kdp/kdp_internal.h>
#include <uuid/uuid.h>
#include <sys/codesign.h>
#include <sys/time.h>

#include <IOKit/IOPlatformExpert.h>

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

#include <console/video_console.h>
#include <arm/cpu_data.h>
#include <arm/cpu_data_internal.h>
#include <arm/cpu_internal.h>
#include <arm/misc_protos.h>
#include <libkern/OSKextLibPrivate.h>
#include <vm/vm_kern.h>
#include <kern/kern_cdata.h>

#if     MACH_KDP
void    kdp_trap(unsigned int, struct arm_saved_state *);
#endif

extern kern_return_t    do_stackshot(void *);
extern void             kdp_snapshot_preflight(int pid, void *tracebuf,
                                               uint32_t tracebuf_size, uint32_t flags,
                                               kcdata_descriptor_t data_p,
                                                boolean_t enable_faulting);
extern int              kdp_stack_snapshot_bytes_traced(void);

/*
 * Increment the PANICLOG_VERSION if you change the format of the panic
 * log in any way.
 */
#define PANICLOG_VERSION 11
static struct kcdata_descriptor kc_panic_data;

extern char                 firmware_version[];
extern volatile uint32_t        debug_enabled;
extern unsigned int         not_in_kdp;

extern int                              copyinframe(vm_address_t fp, uint32_t * frame);
extern void                             kdp_callouts(kdp_event_t event);

/* #include <sys/proc.h> */
#define MAXCOMLEN 16
extern int                              proc_pid(void *p);
extern void                     proc_name_kdp(task_t, char *, int);

extern const char               version[];
extern char                             osversion[];
extern uint8_t          gPlatformECID[8];
extern uint32_t         gPlatformMemoryID;

extern uint64_t         last_hwaccess_thread;

/*Choosing the size for gTargetTypeBuffer as 8 and size for gModelTypeBuffer as 32
  since the target name and model name typically  doesn't exceed this size */
extern char  gTargetTypeBuffer[8];
extern char  gModelTypeBuffer[32];

decl_simple_lock_data(extern,clock_lock)
extern struct timeval    gIOLastSleepTime;
extern struct timeval    gIOLastWakeTime;
extern boolean_t                 is_clock_configured;
extern boolean_t kernelcache_uuid_valid;
extern uuid_t kernelcache_uuid;

/* Definitions for frame pointers */
#define FP_ALIGNMENT_MASK      ((uint32_t)(0x3))
#define FP_LR_OFFSET           ((uint32_t)4)
#define FP_LR_OFFSET64         ((uint32_t)8)
#define FP_MAX_NUM_TO_EVALUATE (50)

/* Timeout (in nanoseconds) for all processors responding to debug crosscall */
#define DEBUG_ACK_TIMEOUT ((uint64_t) 10000000)

/* Forward functions definitions */
void panic_display_times(void) ;
void panic_print_symbol_name(vm_address_t search);


/* Global variables */
static uint32_t       panic_bt_depth;
boolean_t             PanicInfoSaved = FALSE;
boolean_t             force_immediate_debug_halt = FALSE;
unsigned int          debug_ack_timeout_count = 0;
volatile unsigned int debugger_sync = 0;
volatile unsigned int mp_kdp_trap = 0; /* CPUs signalled by the debug CPU will spin on this */
unsigned int          DebugContextCount = 0;

#if defined(__arm64__)
uint8_t PE_smc_stashed_x86_system_state = 0xFF;
uint8_t PE_smc_stashed_x86_power_state = 0xFF;
uint8_t PE_smc_stashed_x86_efi_boot_state = 0xFF;
uint8_t PE_smc_stashed_x86_shutdown_cause = 0xFF;
uint64_t PE_smc_stashed_x86_prev_power_transitions = UINT64_MAX;
uint32_t PE_pcie_stashed_link_state = UINT32_MAX;
#endif

 
// Convenient macros to easily validate one or more pointers if 
// they have defined types
#define VALIDATE_PTR(ptr) \
        validate_ptr((vm_offset_t)(ptr), sizeof(*(ptr)), #ptr)

#define VALIDATE_PTR_2(ptr0, ptr1) \
        VALIDATE_PTR(ptr0) && VALIDATE_PTR(ptr1) 
        
#define VALIDATE_PTR_3(ptr0, ptr1, ptr2) \
        VALIDATE_PTR_2(ptr0, ptr1) && VALIDATE_PTR(ptr2)

#define VALIDATE_PTR_4(ptr0, ptr1, ptr2, ptr3) \
        VALIDATE_PTR_2(ptr0, ptr1) && VALIDATE_PTR_2(ptr2, ptr3)

#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME

#define VALIDATE_PTR_LIST(...) GET_MACRO(__VA_ARGS__, VALIDATE_PTR_4, VALIDATE_PTR_3, VALIDATE_PTR_2, VALIDATE_PTR)(__VA_ARGS__)

/*
 * Evaluate if a pointer is valid
 * Print a message if pointer is invalid
 */
static boolean_t validate_ptr(
        vm_offset_t ptr, vm_size_t size, const char * ptr_name)
{
        if (ptr) {
                if (ml_validate_nofault(ptr, size)) {
                        return TRUE;
                } else {
                        paniclog_append_noflush("Invalid %s pointer: %p size: %d\n",
                                ptr_name, (void *)ptr, (int)size);
                        return FALSE;
                }
        } else {
                paniclog_append_noflush("NULL %s pointer\n", ptr_name);
                return FALSE;
        }
}

/*
 * Backtrace a single frame.
 */
static void
print_one_backtrace(pmap_t pmap, vm_offset_t topfp, const char *cur_marker,
        boolean_t is_64_bit)
{
        int                 i = 0;
        addr64_t        lr;
        addr64_t        fp;
        addr64_t        fp_for_ppn;
        ppnum_t         ppn;
        boolean_t       dump_kernel_stack;

        fp = topfp;
        fp_for_ppn = 0;
        ppn = (ppnum_t)NULL;

        if (fp >= VM_MIN_KERNEL_ADDRESS)
                dump_kernel_stack = TRUE;
        else
                dump_kernel_stack = FALSE;

        do {
                if ((fp == 0) || ((fp & FP_ALIGNMENT_MASK) != 0))
                        break;
                if (dump_kernel_stack && ((fp < VM_MIN_KERNEL_ADDRESS) || (fp > VM_MAX_KERNEL_ADDRESS)))
                        break;
                if ((!dump_kernel_stack) && (fp >=VM_MIN_KERNEL_ADDRESS))
                        break;
                        
                /*
                 * Check to see if current address will result in a different
                 * ppn than previously computed (to avoid recomputation) via
                 * (addr) ^ fp_for_ppn) >> PAGE_SHIFT)
                 */
                if ((((fp + FP_LR_OFFSET) ^ fp_for_ppn) >> PAGE_SHIFT) != 0x0U) {
                        ppn = pmap_find_phys(pmap, fp + FP_LR_OFFSET);
                        fp_for_ppn = fp + (is_64_bit ? FP_LR_OFFSET64 : FP_LR_OFFSET);
                }
                if (ppn != (ppnum_t)NULL) {
                        if (is_64_bit) {
                                lr = ml_phys_read_double_64(((((vm_offset_t)ppn) << PAGE_SHIFT)) | ((fp + FP_LR_OFFSET64) & PAGE_MASK));
                        } else {
                                lr = ml_phys_read_word(((((vm_offset_t)ppn) << PAGE_SHIFT)) | ((fp + FP_LR_OFFSET) & PAGE_MASK));
                        }
                } else {
                        if (is_64_bit) {
                                paniclog_append_noflush("%s\t  Could not read LR from frame at 0x%016llx\n", cur_marker, fp + FP_LR_OFFSET64);
                        } else {
                                paniclog_append_noflush("%s\t  Could not read LR from frame at 0x%08x\n", cur_marker, (uint32_t)(fp + FP_LR_OFFSET));
                        }
                        break;
                }
                if (((fp ^ fp_for_ppn) >> PAGE_SHIFT) != 0x0U) {
                        ppn = pmap_find_phys(pmap, fp);
                        fp_for_ppn = fp;
                }
                if (ppn != (ppnum_t)NULL) {
                        if (is_64_bit) {
                                fp = ml_phys_read_double_64(((((vm_offset_t)ppn) << PAGE_SHIFT)) | (fp & PAGE_MASK));
                        } else {
                                fp = ml_phys_read_word(((((vm_offset_t)ppn) << PAGE_SHIFT)) | (fp & PAGE_MASK));
                        }
                } else {
                        if (is_64_bit) {
                                paniclog_append_noflush("%s\t  Could not read FP from frame at 0x%016llx\n", cur_marker, fp);
                        } else {
                                paniclog_append_noflush("%s\t  Could not read FP from frame at 0x%08x\n", cur_marker, (uint32_t)fp);
                        }
                        break;
                }

                if (lr) {
                        if (is_64_bit) {
                                paniclog_append_noflush("%s\t  lr: 0x%016llx  fp: 0x%016llx\n", cur_marker, lr, fp);
                        } else {
                                paniclog_append_noflush("%s\t  lr: 0x%08x  fp: 0x%08x\n", cur_marker, (uint32_t)lr, (uint32_t)fp);
                        }
                }
        } while ((++i < FP_MAX_NUM_TO_EVALUATE) && (fp != topfp));
}

#define SANE_TASK_LIMIT 256
#define TOP_RUNNABLE_LIMIT 5
#define PANICLOG_UUID_BUF_SIZE 256

extern void panic_print_vnodes(void);

static void
do_print_all_backtraces(
        const char      *message)
{
        int             logversion = PANICLOG_VERSION;
        thread_t        cur_thread = current_thread();
        uintptr_t       cur_fp;
        task_t          task;
        int             i;
        size_t          index;
        int             print_vnodes = 0;
        const char *nohilite_thread_marker="\t";

        /* end_marker_bytes set to 200 for printing END marker + stackshot summary info always */
        int bytes_traced = 0, bytes_remaining = 0, end_marker_bytes = 200;
        uint64_t bytes_used = 0ULL;
        int err = 0;
        char *stackshot_begin_loc = NULL;

#if defined(__arm__)
        __asm__         volatile("mov %0, r7":"=r"(cur_fp));
#elif defined(__arm64__)
        __asm__         volatile("add %0, xzr, fp":"=r"(cur_fp));
#else
#error Unknown architecture.
#endif
        if (panic_bt_depth != 0)
                return;
        panic_bt_depth++;

        /* Truncate panic string to 1200 bytes -- WDT log can be ~1100 bytes */
        paniclog_append_noflush("Debugger message: %.1200s\n", message);
        if (debug_enabled) {
                paniclog_append_noflush("Device: %s\n",
                        ('\0' != gTargetTypeBuffer[0]) ? gTargetTypeBuffer : "Not set yet");
                paniclog_append_noflush("Hardware Model: %s\n",
                        ('\0' != gModelTypeBuffer[0]) ? gModelTypeBuffer:"Not set yet");
                paniclog_append_noflush("ECID: %02X%02X%02X%02X%02X%02X%02X%02X\n", gPlatformECID[7],
                        gPlatformECID[6], gPlatformECID[5], gPlatformECID[4], gPlatformECID[3],
                        gPlatformECID[2], gPlatformECID[1], gPlatformECID[0]);
                if (last_hwaccess_thread) {
                        paniclog_append_noflush("AppleHWAccess Thread: 0x%llx\n", last_hwaccess_thread);
                }
                paniclog_append_noflush("Boot args: %s\n", PE_boot_args());
        }
        paniclog_append_noflush("Memory ID: 0x%x\n", gPlatformMemoryID);
        paniclog_append_noflush("OS version: %.256s\n",
                        ('\0' != osversion[0]) ? osversion : "Not set yet");
        paniclog_append_noflush("Kernel version: %.512s\n", version);

        if (kernelcache_uuid_valid) {
                paniclog_append_noflush("KernelCache UUID: ");
                for (index = 0; index < sizeof(uuid_t); index++) {
                        paniclog_append_noflush("%02X", kernelcache_uuid[index]);
                }
                paniclog_append_noflush("\n");
        }
        panic_display_kernel_uuid();

        paniclog_append_noflush("iBoot version: %.128s\n", firmware_version);
        paniclog_append_noflush("secure boot?: %s\n", debug_enabled ? "NO": "YES");
#if defined(XNU_TARGET_OS_BRIDGE)
        paniclog_append_noflush("x86 EFI Boot State: ");
        if (PE_smc_stashed_x86_efi_boot_state != 0xFF) {
                paniclog_append_noflush("0x%x\n", PE_smc_stashed_x86_efi_boot_state);
        } else {
                paniclog_append_noflush("not available\n");
        }
        paniclog_append_noflush("x86 System State: ");
        if (PE_smc_stashed_x86_system_state != 0xFF) {
                paniclog_append_noflush("0x%x\n", PE_smc_stashed_x86_system_state);
        } else {
                paniclog_append_noflush("not available\n");
        }
        paniclog_append_noflush("x86 Power State: ");
        if (PE_smc_stashed_x86_power_state != 0xFF) {
                paniclog_append_noflush("0x%x\n", PE_smc_stashed_x86_power_state);
        } else {
                paniclog_append_noflush("not available\n");
        }
        paniclog_append_noflush("x86 Shutdown Cause: ");
        if (PE_smc_stashed_x86_shutdown_cause != 0xFF) {
                paniclog_append_noflush("0x%x\n", PE_smc_stashed_x86_shutdown_cause);
        } else {
                paniclog_append_noflush("not available\n");
        }
        paniclog_append_noflush("x86 Previous Power Transitions: ");
        if (PE_smc_stashed_x86_prev_power_transitions != UINT64_MAX) {
                paniclog_append_noflush("0x%llx\n", PE_smc_stashed_x86_prev_power_transitions);
        } else {
                paniclog_append_noflush("not available\n");
        }
        paniclog_append_noflush("PCIeUp link state: ");
        if (PE_pcie_stashed_link_state != UINT32_MAX) {
                paniclog_append_noflush("0x%x\n", PE_pcie_stashed_link_state);
        } else {
                paniclog_append_noflush("not available\n");
        }
#endif
        paniclog_append_noflush("Paniclog version: %d\n", logversion);

        panic_display_kernel_aslr();
        panic_display_times();
        panic_display_zprint();
#if CONFIG_ZLEAKS
        panic_display_ztrace();
#endif /* CONFIG_ZLEAKS */
#if CONFIG_ECC_LOGGING
        panic_display_ecc_errors();
#endif /* CONFIG_ECC_LOGGING */

#if DEVELOPMENT || DEBUG
        if (cs_debug_unsigned_exec_failures != 0 || cs_debug_unsigned_mmap_failures != 0) {
                paniclog_append_noflush("Unsigned code exec failures: %u\n", cs_debug_unsigned_exec_failures);
                paniclog_append_noflush("Unsigned code mmap failures: %u\n", cs_debug_unsigned_mmap_failures);
        }
#endif

        // Just print threads with high CPU usage for WDT timeouts
        if (strncmp(message, "WDT timeout", 11) == 0) {
                thread_t        top_runnable[5] = {0};
                thread_t        thread;
                int                     total_cpu_usage = 0;

                print_vnodes = 1;

        
                for (thread = (thread_t)queue_first(&threads);
             VALIDATE_PTR(thread) && !queue_end(&threads, (queue_entry_t)thread);
             thread = (thread_t)queue_next(&thread->threads)) {
                                                         
                        total_cpu_usage += thread->cpu_usage;
                                                
                        // Look for the 5 runnable threads with highest priority
                        if (thread->state & TH_RUN) {
                                int                     k;
                                thread_t        comparison_thread = thread;
                                
                                for (k = 0; k < TOP_RUNNABLE_LIMIT; k++) {
                                        if (top_runnable[k] == 0) {
                                                top_runnable[k] = comparison_thread;
                                                break;
                                        } else if (comparison_thread->sched_pri > top_runnable[k]->sched_pri) {
                                                thread_t temp = top_runnable[k];
                                                top_runnable[k] = comparison_thread;
                                                comparison_thread = temp;
                                        } // if comparison thread has higher priority than previously saved thread
                                } // loop through highest priority runnable threads
                        } // Check if thread is runnable
                } // Loop through all threads
                
                // Print the relevant info for each thread identified
                paniclog_append_noflush("Total cpu_usage: %d\n", total_cpu_usage);
                paniclog_append_noflush("Thread task pri cpu_usage\n");

                for (i = 0; i < TOP_RUNNABLE_LIMIT; i++) {                      

                        if (top_runnable[i] && VALIDATE_PTR(top_runnable[i]->task) &&
                                validate_ptr((vm_offset_t)top_runnable[i]->task->bsd_info, 1, "bsd_info")) {
                                
                                char            name[MAXCOMLEN + 1];
                                proc_name_kdp(top_runnable[i]->task, name, sizeof(name));
                                paniclog_append_noflush("%p %s %d %d\n",
                                        top_runnable[i], name, top_runnable[i]->sched_pri, top_runnable[i]->cpu_usage);
                        } 
                } // Loop through highest priority runnable threads
                paniclog_append_noflush("\n");
        } // Check if message is "WDT timeout"

    // print current task info
        if (VALIDATE_PTR_LIST(cur_thread, cur_thread->task)) {

                task = cur_thread->task;

                if (VALIDATE_PTR_LIST(task->map, task->map->pmap)) {
                        paniclog_append_noflush("Panicked task %p: %d pages, %d threads: ",
                                task, task->map->pmap->stats.resident_count, task->thread_count);
                } else {
                        paniclog_append_noflush("Panicked task %p: %d threads: ",
                                task, task->thread_count);
                }

                if (validate_ptr((vm_offset_t)task->bsd_info, 1, "bsd_info")) {
                        char            name[MAXCOMLEN + 1];
                        int             pid = proc_pid(task->bsd_info);
                        proc_name_kdp(task, name, sizeof(name));
                        paniclog_append_noflush("pid %d: %s", pid, name);
                } else {
                        paniclog_append_noflush("unknown task");
                }

                paniclog_append_noflush("\n");
        }

        if (cur_fp < VM_MAX_KERNEL_ADDRESS) {
                paniclog_append_noflush("Panicked thread: %p, backtrace: 0x%llx, tid: %llu\n",
                        cur_thread, (addr64_t)cur_fp, thread_tid(cur_thread));
#if __LP64__
                print_one_backtrace(kernel_pmap, cur_fp, nohilite_thread_marker, TRUE);
#else
                print_one_backtrace(kernel_pmap, cur_fp, nohilite_thread_marker, FALSE);
#endif
        } else {
                paniclog_append_noflush("Could not print panicked thread backtrace:"
                           "frame pointer outside kernel vm.\n");
        }

        paniclog_append_noflush("\n");
        panic_info->eph_panic_log_len = PE_get_offset_into_panic_region(debug_buf_ptr) - panic_info->eph_panic_log_offset;

        if (debug_ack_timeout_count) {
                panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_FAILED_DEBUGGERSYNC;
                panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                paniclog_append_noflush("!! debugger synchronization failed, no stackshot !!\n");
        } else if (stackshot_active()) {
                panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_FAILED_NESTED;
                panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                paniclog_append_noflush("!! panicked during stackshot, skipping panic stackshot !!\n");
        } else {
                /* Align the stackshot buffer to an 8-byte address (especially important for armv7k devices) */
                debug_buf_ptr += (8 - ((uintptr_t)debug_buf_ptr % 8));
                stackshot_begin_loc = debug_buf_ptr;

                bytes_remaining = debug_buf_size - (unsigned int)((uintptr_t)stackshot_begin_loc - (uintptr_t)debug_buf_base);
                err = kcdata_memory_static_init(&kc_panic_data, (mach_vm_address_t)debug_buf_ptr,
                                                                                KCDATA_BUFFER_BEGIN_STACKSHOT, bytes_remaining - end_marker_bytes,
                                                                                KCFLAG_USE_MEMCOPY);
                if (err == KERN_SUCCESS) {
                        kdp_snapshot_preflight(-1, stackshot_begin_loc, bytes_remaining - end_marker_bytes,
                                                                   (STACKSHOT_GET_GLOBAL_MEM_STATS | STACKSHOT_SAVE_LOADINFO | STACKSHOT_KCDATA_FORMAT |
                                                                        STACKSHOT_ENABLE_BT_FAULTING | STACKSHOT_ENABLE_UUID_FAULTING | STACKSHOT_FROM_PANIC |
                                                                        STACKSHOT_NO_IO_STATS | STACKSHOT_THREAD_WAITINFO), &kc_panic_data, 0);
                        err = do_stackshot(NULL);
                        bytes_traced = kdp_stack_snapshot_bytes_traced();
                        if (bytes_traced > 0 && !err) {
                                debug_buf_ptr += bytes_traced;
                                panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_SUCCEEDED;
                                panic_info->eph_stackshot_offset = PE_get_offset_into_panic_region(stackshot_begin_loc);
                                panic_info->eph_stackshot_len = bytes_traced;

                                panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                                paniclog_append_noflush("\n** Stackshot Succeeded ** Bytes Traced %d **\n", bytes_traced);
                        } else {
                                bytes_used = kcdata_memory_get_used_bytes(&kc_panic_data);
                                if (bytes_used > 0) {
                                        /* Zero out the stackshot data */
                                        bzero(stackshot_begin_loc, bytes_used);
                                        panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_FAILED_INCOMPLETE;

                                        panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                                        paniclog_append_noflush("\n** Stackshot Incomplete ** Bytes Filled %llu **\n", bytes_used);
                                } else {
                                        bzero(stackshot_begin_loc, bytes_used);
                                        panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_FAILED_ERROR;

                                        panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                                        paniclog_append_noflush("\n!! Stackshot Failed !! Bytes Traced %d, err %d\n", bytes_traced, err);
                                }
                        }
                } else {
                        panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_STACKSHOT_FAILED_ERROR;
                        panic_info->eph_other_log_offset = PE_get_offset_into_panic_region(debug_buf_ptr);
                        paniclog_append_noflush("\n!! Stackshot Failed !!\nkcdata_memory_static_init returned %d", err);
                }
        }

        assert(panic_info->eph_other_log_offset != 0);

        if (print_vnodes != 0)
                panic_print_vnodes();

        panic_bt_depth--;
}

/*
 * Entry to print_all_backtraces is serialized by the debugger lock
 */
static void
print_all_backtraces(const char *message)
{
        unsigned int initial_not_in_kdp = not_in_kdp;

        cpu_data_t * cpu_data_ptr = getCpuDatap();

        assert(cpu_data_ptr->PAB_active == FALSE);
        cpu_data_ptr->PAB_active = TRUE;

        /*
         * Because print all backtraces uses the pmap routines, it needs to
         * avoid taking pmap locks.  Right now, this is conditionalized on
         * not_in_kdp.
         */
        not_in_kdp = 0;
        do_print_all_backtraces(message);

        not_in_kdp = initial_not_in_kdp;

        cpu_data_ptr->PAB_active = FALSE;
}

void
panic_display_times()
{
        if (kdp_clock_is_locked()) {
                paniclog_append_noflush("Warning: clock is locked.  Can't get time\n");
                return;
        }

        if ((is_clock_configured) && (simple_lock_try(&clock_lock))) {
                clock_sec_t     secs, boot_secs;
                clock_usec_t    usecs, boot_usecs;

                simple_unlock(&clock_lock);

                clock_get_calendar_microtime(&secs, &usecs);
                clock_get_boottime_microtime(&boot_secs, &boot_usecs);

                paniclog_append_noflush("Epoch Time:        sec       usec\n");
                paniclog_append_noflush("  Boot    : 0x%08x 0x%08x\n", (unsigned int)boot_secs, (unsigned int)boot_usecs);
                paniclog_append_noflush("  Sleep   : 0x%08x 0x%08x\n", (unsigned int)gIOLastSleepTime.tv_sec, (unsigned int)gIOLastSleepTime.tv_usec);
                paniclog_append_noflush("  Wake    : 0x%08x 0x%08x\n", (unsigned int)gIOLastWakeTime.tv_sec, (unsigned int)gIOLastWakeTime.tv_usec);
                paniclog_append_noflush("  Calendar: 0x%08x 0x%08x\n\n", (unsigned int)secs, (unsigned int)usecs);
        }
}

void panic_print_symbol_name(vm_address_t search)
{
#pragma unused(search)
        // empty stub. Really only used on x86_64.
        return;
}

void
SavePanicInfo(
        const char *message, __unused void *panic_data, __unused uint64_t panic_options)
{

        /* This should be initialized by the time we get here */
        assert(panic_info->eph_panic_log_offset != 0);

        if (panic_options & DEBUGGER_OPTION_PANICLOGANDREBOOT) {
                panic_info->eph_panic_flags  |= EMBEDDED_PANIC_HEADER_FLAG_BUTTON_RESET_PANIC;
        }

        if (panic_options & DEBUGGER_OPTION_COPROC_INITIATED_PANIC) {
                panic_info->eph_panic_flags |= EMBEDDED_PANIC_HEADER_FLAG_COPROC_INITIATED_PANIC;
        }

#if defined(XNU_TARGET_OS_BRIDGE)
        panic_info->eph_x86_power_state = PE_smc_stashed_x86_power_state;
        panic_info->eph_x86_efi_boot_state = PE_smc_stashed_x86_efi_boot_state;
        panic_info->eph_x86_system_state = PE_smc_stashed_x86_system_state;
#endif

        /*
         * On newer targets, panic data is stored directly into the iBoot panic region.
         * If we re-enter SavePanicInfo (e.g. on a double panic) on such a target, update the
         * panic CRC so that iBoot can hopefully find *something* useful in the panic region.
         */
        if (PanicInfoSaved && (debug_buf_base >= (char*)gPanicBase) && (debug_buf_base < (char*)gPanicBase + gPanicSize)) {
                unsigned int pi_size = (unsigned int)(debug_buf_ptr - gPanicBase);
                PE_save_buffer_to_vram((unsigned char*)gPanicBase, &pi_size);
                PE_sync_panic_buffers(); // extra precaution; panic path likely isn't reliable if we're here
        }

        if (PanicInfoSaved || (debug_buf_size == 0))
                return;

        PanicInfoSaved = TRUE;

        print_all_backtraces(message);

        assert(panic_info->eph_panic_log_len != 0);
        panic_info->eph_other_log_len = PE_get_offset_into_panic_region(debug_buf_ptr) - panic_info->eph_other_log_offset;

        PEHaltRestart(kPEPanicSync);

        /*
         * Notifies registered IOPlatformPanicAction callbacks
         * (which includes one to disable the memcache) and flushes
         * the buffer contents from the cache
         */
        paniclog_flush();
}

void
paniclog_flush()
{
        unsigned int panicbuf_length = 0;

        panicbuf_length = (unsigned int)(debug_buf_ptr - gPanicBase);
        if (!panicbuf_length)
                return;

        /*
         * Updates the log length of the last part of the panic log.
         */
        panic_info->eph_other_log_len = PE_get_offset_into_panic_region(debug_buf_ptr) - panic_info->eph_other_log_offset;

        /*
         * Updates the metadata at the beginning of the panic buffer,
         * updates the CRC.
         */
        PE_save_buffer_to_vram((unsigned char *)gPanicBase, &panicbuf_length);

        /*
         * This is currently unused by platform KEXTs on embedded but is
         * kept for compatibility with the published IOKit interfaces.
         */
        PESavePanicInfo((unsigned char *)gPanicBase, panicbuf_length);

        PE_sync_panic_buffers();
}

/*
 * @function DebuggerXCallEnter
 *
 * @abstract IPI other cores so this core can run in a single-threaded context.
 *
 * @discussion This function should be called with the debugger lock held.  It
 * signals the other cores to go into a busy loop so this core can run in a
 * single-threaded context and inspect kernel memory.
 *
 * @param proceed_on_sync_failure If true, then go ahead and try to debug even
 * if we can't synch with the other cores.  This is inherently unsafe and should
 * only be used if the kernel is going down in flames anyway.
 *
 * @result returns KERN_OPERATION_TIMED_OUT if synchronization times out and
 * proceed_on_sync_failure is false.
 */
kern_return_t
DebuggerXCallEnter(
        boolean_t proceed_on_sync_failure)
{
        uint64_t max_mabs_time, current_mabs_time;
        int cpu;
        int max_cpu;
        cpu_data_t      *target_cpu_datap;
        cpu_data_t      *cpu_data_ptr = getCpuDatap();

        /* Check for nested debugger entry. */
        cpu_data_ptr->debugger_active++;
        if (cpu_data_ptr->debugger_active != 1)
                return KERN_SUCCESS;

        /*
         * If debugger_sync is not 0, someone responded excessively late to the last
         * debug request (we zero the sync variable in the return function).  Zero it
         * again here.  This should prevent us from getting out of sync (heh) and
         * timing out on every entry to the debugger if we timeout once.
         */

        debugger_sync = 0;
        mp_kdp_trap = 1;

        /*
         * We need a barrier here to ensure CPUs see mp_kdp_trap and spin when responding
         * to the signal.
         */
        __builtin_arm_dmb(DMB_ISH);

        /*
         * Try to signal all CPUs (except ourselves, of course).  Use debugger_sync to
         * synchronize with every CPU that we appeared to signal successfully (cpu_signal
         * is not synchronous).
         */
        bool cpu_signal_failed = false;
        max_cpu = ml_get_max_cpu_number();

        boolean_t immediate_halt = FALSE;
        if (proceed_on_sync_failure && force_immediate_debug_halt)
                immediate_halt = TRUE; 

        if (!immediate_halt) {
                for (cpu=0; cpu <= max_cpu; cpu++) {
                        target_cpu_datap = (cpu_data_t *)CpuDataEntries[cpu].cpu_data_vaddr;

                        if ((target_cpu_datap == NULL) || (target_cpu_datap == cpu_data_ptr))
                                continue;

                        if(KERN_SUCCESS == cpu_signal(target_cpu_datap, SIGPdebug, (void *)NULL, NULL)) {
                                (void)hw_atomic_add(&debugger_sync, 1);
                        } else {
                                cpu_signal_failed = true;
                                kprintf("cpu_signal failed in DebuggerXCallEnter\n");
                        }
                }

                nanoseconds_to_absolutetime(DEBUG_ACK_TIMEOUT, &max_mabs_time);
                current_mabs_time = mach_absolute_time();
                max_mabs_time += current_mabs_time;
                assert(max_mabs_time > current_mabs_time);

                /*
                 * Wait for DEBUG_ACK_TIMEOUT ns for a response from everyone we IPI'd.  If we
                 * timeout, that is simply too bad; we don't have a true NMI, and one CPU may be
                 * uninterruptibly spinning on someone else.  The best we can hope for is that
                 * all other CPUs have either responded or are spinning in a context that is
                 * debugger safe.
                 */
                while ((debugger_sync != 0) && (current_mabs_time < max_mabs_time))
                        current_mabs_time = mach_absolute_time();

        }

        if (cpu_signal_failed && !proceed_on_sync_failure) {
                DebuggerXCallReturn();
                return KERN_FAILURE;
        } else if (immediate_halt || (current_mabs_time >= max_mabs_time)) {
                /*
                 * For the moment, we're aiming for a timeout that the user shouldn't notice,
                 * but will be sufficient to let the other core respond.
                 */
                __builtin_arm_dmb(DMB_ISH);
                for (cpu=0; cpu <= max_cpu; cpu++) {
                        target_cpu_datap = (cpu_data_t *)CpuDataEntries[cpu].cpu_data_vaddr;

                        if ((target_cpu_datap == NULL) || (target_cpu_datap == cpu_data_ptr))
                                continue;
                        if (!(target_cpu_datap->cpu_signal & SIGPdebug) && !immediate_halt)
                                continue;
                        if (proceed_on_sync_failure) {
                                paniclog_append_noflush("Attempting to forcibly halt cpu %d\n", cpu);
                                dbgwrap_status_t halt_status = ml_dbgwrap_halt_cpu(cpu, 0);
                                if (halt_status < 0)
                                        paniclog_append_noflush("cpu %d failed to halt with error %d: %s\n", cpu, halt_status, ml_dbgwrap_strerror(halt_status));
                                else {
                                        if (halt_status > 0)
                                                paniclog_append_noflush("cpu %d halted with warning %d: %s\n", cpu, halt_status, ml_dbgwrap_strerror(halt_status));
                                        else
                                                paniclog_append_noflush("cpu %d successfully halted\n", cpu);
                                        target_cpu_datap->halt_status = CPU_HALTED;
                                }
                        } else
                                kprintf("Debugger synch pending on cpu %d\n", cpu);
                }
                if (proceed_on_sync_failure) {
                        for (cpu = 0; cpu <= max_cpu; cpu++) {
                                target_cpu_datap = (cpu_data_t *)CpuDataEntries[cpu].cpu_data_vaddr;

                                if ((target_cpu_datap == NULL) || (target_cpu_datap == cpu_data_ptr) ||
                                    (target_cpu_datap->halt_status == CPU_NOT_HALTED))
                                        continue;
                                dbgwrap_status_t halt_status = ml_dbgwrap_halt_cpu_with_state(cpu,
                                    NSEC_PER_SEC, &target_cpu_datap->halt_state);
                                if ((halt_status < 0) || (halt_status == DBGWRAP_WARN_CPU_OFFLINE))
                                        paniclog_append_noflush("Unable to obtain state for cpu %d with status %d: %s\n", cpu, halt_status, ml_dbgwrap_strerror(halt_status));
                                else
                                        target_cpu_datap->halt_status = CPU_HALTED_WITH_STATE;
                        }
                        if (immediate_halt)
                                paniclog_append_noflush("Immediate halt requested on all cores\n");
                        else
                                paniclog_append_noflush("Debugger synchronization timed out; waited %llu nanoseconds\n", DEBUG_ACK_TIMEOUT);
                        debug_ack_timeout_count++;
                        return KERN_SUCCESS;
                } else {
                        DebuggerXCallReturn();
                        return KERN_OPERATION_TIMED_OUT;
                }
        } else {
                return KERN_SUCCESS;
        }
}

/*
 * @function DebuggerXCallReturn
 *
 * @abstract Resume normal multicore operation after DebuggerXCallEnter()
 *
 * @discussion This function should be called with debugger lock held.
 */
void
DebuggerXCallReturn(
        void)
{
        cpu_data_t      *cpu_data_ptr = getCpuDatap();

        cpu_data_ptr->debugger_active--;
        if (cpu_data_ptr->debugger_active != 0)
                return;

        mp_kdp_trap = 0;
        debugger_sync = 0;

        /* Do we need a barrier here? */
        __builtin_arm_dmb(DMB_ISH);
}

void
DebuggerXCall(
        void            *ctx)
{
        boolean_t               save_context = FALSE;
        vm_offset_t             kstackptr = 0;
        arm_saved_state_t       *regs = (arm_saved_state_t *) ctx;

        if (regs != NULL) {
#if defined(__arm64__)
                save_context = PSR64_IS_KERNEL(get_saved_state_cpsr(regs));
#else
                save_context = PSR_IS_KERNEL(regs->cpsr);
#endif
        }

        kstackptr = current_thread()->machine.kstackptr;
        arm_saved_state_t *state = (arm_saved_state_t *)kstackptr;

        if (save_context) {
                /* Save the interrupted context before acknowledging the signal */
                *state = *regs;

        } else if (regs) {
                /* zero old state so machine_trace_thread knows not to backtrace it */
                set_saved_state_fp(state, 0);
                set_saved_state_pc(state, 0);
                set_saved_state_lr(state, 0);
                set_saved_state_sp(state, 0);
        }

        (void)hw_atomic_sub(&debugger_sync, 1);
        __builtin_arm_dmb(DMB_ISH);
        while (mp_kdp_trap);

        /* Any cleanup for our pushed context should go here */
}


void
DebuggerCall(
        unsigned int    reason,
        void            *ctx)
{
#if     !MACH_KDP
#pragma unused(reason,ctx)
#endif /* !MACH_KDP */

#if ALTERNATE_DEBUGGER
        alternate_debugger_enter();
#endif

#if     MACH_KDP
        kdp_trap(reason, (struct arm_saved_state *)ctx);
#else
        /* TODO: decide what to do if no debugger config */
#endif
}