xnu-4570.20.62.tar.gz

[apple/xnu.git] / osfmk / kern / kern_stackshot.c

/*
 * Copyright (c) 2013-2017 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 <mach/mach_types.h>
#include <mach/vm_param.h>
#include <mach/mach_vm.h>
#include <mach/clock_types.h>
#include <sys/errno.h>
#include <sys/stackshot.h>
#ifdef IMPORTANCE_INHERITANCE
#include <ipc/ipc_importance.h>
#endif
#include <sys/appleapiopts.h>
#include <kern/debug.h>
#include <kern/block_hint.h>
#include <uuid/uuid.h>

#include <kdp/kdp_dyld.h>
#include <kdp/kdp_en_debugger.h>

#include <libsa/types.h>
#include <libkern/version.h>

#include <string.h> /* bcopy */

#include <kern/coalition.h>
#include <kern/processor.h>
#include <kern/thread.h>
#include <kern/thread_group.h>
#include <kern/task.h>
#include <kern/telemetry.h>
#include <kern/clock.h>
#include <kern/policy_internal.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <vm/vm_pageout.h>
#include <vm/vm_fault.h>
#include <vm/vm_shared_region.h>
#include <libkern/OSKextLibPrivate.h>

#if CONFIG_EMBEDDED
#include <pexpert/pexpert.h> /* For gPanicBase/gPanicBase */
#endif

#if MONOTONIC
#include <kern/monotonic.h>
#endif /* MONOTONIC */

#include <san/kasan.h>

extern unsigned int not_in_kdp;

#if CONFIG_EMBEDDED
uuid_t kernelcache_uuid;
#endif

/* indicate to the compiler that some accesses are unaligned */
typedef uint64_t unaligned_u64 __attribute__((aligned(1)));

extern addr64_t kdp_vtophys(pmap_t pmap, addr64_t va);
extern void * proc_get_uthread_uu_threadlist(void * uthread_v);

int kdp_snapshot                            = 0;
static kern_return_t stack_snapshot_ret     = 0;
static uint32_t stack_snapshot_bytes_traced = 0;

static kcdata_descriptor_t stackshot_kcdata_p = NULL;
static void *stack_snapshot_buf;
static uint32_t stack_snapshot_bufsize;
int stack_snapshot_pid;
static uint32_t stack_snapshot_flags;
static uint64_t stack_snapshot_delta_since_timestamp;
static boolean_t panic_stackshot;

static boolean_t stack_enable_faulting = FALSE;
static struct stackshot_fault_stats fault_stats;

static unaligned_u64 * stackshot_duration_outer;
static uint64_t stackshot_microsecs;

void * kernel_stackshot_buf   = NULL; /* Pointer to buffer for stackshots triggered from the kernel and retrieved later */
int kernel_stackshot_buf_size = 0;

void * stackshot_snapbuf = NULL; /* Used by stack_snapshot2 (to be removed) */

__private_extern__ void stackshot_init( void );
static boolean_t memory_iszero(void *addr, size_t size);
#if CONFIG_TELEMETRY
kern_return_t           stack_microstackshot(user_addr_t tracebuf, uint32_t tracebuf_size, uint32_t flags, int32_t *retval);
#endif
uint32_t                get_stackshot_estsize(uint32_t prev_size_hint);
kern_return_t           kern_stack_snapshot_internal(int stackshot_config_version, void *stackshot_config,
                                                size_t stackshot_config_size, boolean_t stackshot_from_user);
kern_return_t           do_stackshot(void *);
void                    kdp_snapshot_preflight(int pid, void * tracebuf, uint32_t tracebuf_size, uint32_t flags, kcdata_descriptor_t data_p, uint64_t since_timestamp);
boolean_t               stackshot_thread_is_idle_worker_unsafe(thread_t thread);
static int              kdp_stackshot_kcdata_format(int pid, uint32_t trace_flags, uint32_t *pBytesTraced);
uint32_t                kdp_stack_snapshot_bytes_traced(void);
static void             kdp_mem_and_io_snapshot(struct mem_and_io_snapshot *memio_snap);
static boolean_t        kdp_copyin(vm_map_t map, uint64_t uaddr, void *dest, size_t size, boolean_t try_fault, uint32_t *kdp_fault_result);
static boolean_t        kdp_copyin_word(task_t task, uint64_t addr, uint64_t *result, boolean_t try_fault, uint32_t *kdp_fault_results);
static uint64_t         proc_was_throttled_from_task(task_t task);
static void             stackshot_thread_wait_owner_info(thread_t thread, thread_waitinfo_t * waitinfo);
static int              stackshot_thread_has_valid_waitinfo(thread_t thread);

#if CONFIG_COALITIONS
static void             stackshot_coalition_jetsam_count(void *arg, int i, coalition_t coal);
static void             stackshot_coalition_jetsam_snapshot(void *arg, int i, coalition_t coal);
#endif /* CONFIG_COALITIONS */


extern uint32_t workqueue_get_pwq_state_kdp(void *proc);

extern int              proc_pid(void *p);
extern uint64_t         proc_uniqueid(void *p);
extern uint64_t         proc_was_throttled(void *p);
extern uint64_t         proc_did_throttle(void *p);
static uint64_t proc_did_throttle_from_task(task_t task);
extern void proc_name_kdp(task_t task, char * buf, int size);
extern int proc_threadname_kdp(void * uth, char * buf, size_t size);
extern void proc_starttime_kdp(void * p, uint64_t * tv_sec, uint64_t * tv_usec, uint64_t * abstime);
extern int              memorystatus_get_pressure_status_kdp(void);
extern boolean_t memorystatus_proc_is_dirty_unsafe(void * v);

extern int count_busy_buffers(void); /* must track with declaration in bsd/sys/buf_internal.h */
extern void bcopy_phys(addr64_t, addr64_t, vm_size_t);

#if CONFIG_TELEMETRY
extern kern_return_t stack_microstackshot(user_addr_t tracebuf, uint32_t tracebuf_size, uint32_t flags, int32_t *retval);
#endif /* CONFIG_TELEMETRY */

extern kern_return_t kern_stack_snapshot_with_reason(char* reason);
extern kern_return_t kern_stack_snapshot_internal(int stackshot_config_version, void *stackshot_config, size_t stackshot_config_size, boolean_t stackshot_from_user);

/*
 * Validates that the given address is both a valid page and has
 * default caching attributes for the current map.  Returns
 * 0 if the address is invalid, and a kernel virtual address for
 * the given address if it is valid.
 */
vm_offset_t machine_trace_thread_get_kva(vm_offset_t cur_target_addr, vm_map_t map, uint32_t *thread_trace_flags);

#define KDP_FAULT_RESULT_PAGED_OUT   0x1 /* some data was unable to be retrieved */
#define KDP_FAULT_RESULT_TRIED_FAULT 0x2 /* tried to fault in data */
#define KDP_FAULT_RESULT_FAULTED_IN  0x4 /* successfully faulted in data */

/*
 * Looks up the physical translation for the given address in the target map, attempting
 * to fault data in if requested and it is not resident. Populates thread_trace_flags if requested
 * as well.
 */
vm_offset_t kdp_find_phys(vm_map_t map, vm_offset_t target_addr, boolean_t try_fault, uint32_t *kdp_fault_results);

static size_t stackshot_strlcpy(char *dst, const char *src, size_t maxlen);
static void stackshot_memcpy(void *dst, const void *src, size_t len);

/* Clears caching information used by the above validation routine
 * (in case the current map has been changed or cleared).
 */
void machine_trace_thread_clear_validation_cache(void);

#define MAX_FRAMES 1000
#define MAX_LOADINFOS 500
#define TASK_IMP_WALK_LIMIT 20

typedef struct thread_snapshot *thread_snapshot_t;
typedef struct task_snapshot *task_snapshot_t;

#if CONFIG_KDP_INTERACTIVE_DEBUGGING
extern kdp_send_t    kdp_en_send_pkt;
#endif 

/*
 * Globals to support machine_trace_thread_get_kva.
 */
static vm_offset_t prev_target_page = 0;
static vm_offset_t prev_target_kva = 0;
static boolean_t validate_next_addr = TRUE;

/*
 * Stackshot locking and other defines.
 */
static lck_grp_t       *stackshot_subsys_lck_grp;
static lck_grp_attr_t  *stackshot_subsys_lck_grp_attr;
static lck_attr_t      *stackshot_subsys_lck_attr;
static lck_mtx_t        stackshot_subsys_mutex;

#define STACKSHOT_SUBSYS_LOCK() lck_mtx_lock(&stackshot_subsys_mutex)
#define STACKSHOT_SUBSYS_TRY_LOCK() lck_mtx_try_lock(&stackshot_subsys_mutex)
#define STACKSHOT_SUBSYS_UNLOCK() lck_mtx_unlock(&stackshot_subsys_mutex)

#define SANE_BOOTPROFILE_TRACEBUF_SIZE (64 * 1024 * 1024)
#define SANE_TRACEBUF_SIZE (8 * 1024 * 1024)

/*
 * We currently set a ceiling of 3 milliseconds spent in the kdp fault path
 * for non-panic stackshots where faulting is requested.
 */
#define KDP_FAULT_PATH_MAX_TIME_PER_STACKSHOT_NSECS (3 * NSEC_PER_MSEC)

#define STACKSHOT_SUPP_SIZE (16 * 1024) /* Minimum stackshot size */
#define TASK_UUID_AVG_SIZE (16 * sizeof(uuid_t)) /* Average space consumed by UUIDs/task */

/*
 * Initialize the mutex governing access to the stack snapshot subsystem
 * and other stackshot related bits.
 */
__private_extern__ void
stackshot_init( void )
{
        mach_timebase_info_data_t timebase;

        stackshot_subsys_lck_grp_attr = lck_grp_attr_alloc_init();

        stackshot_subsys_lck_grp = lck_grp_alloc_init("stackshot_subsys_lock", stackshot_subsys_lck_grp_attr);

        stackshot_subsys_lck_attr = lck_attr_alloc_init();

        lck_mtx_init(&stackshot_subsys_mutex, stackshot_subsys_lck_grp, stackshot_subsys_lck_attr);

        clock_timebase_info(&timebase);
        fault_stats.sfs_system_max_fault_time = ((KDP_FAULT_PATH_MAX_TIME_PER_STACKSHOT_NSECS * timebase.denom)/ timebase.numer);
}

/* 
 * Method for grabbing timer values safely, in the sense that no infinite loop will occur 
 * Certain flavors of the timer_grab function, which would seem to be the thing to use,   
 * can loop infinitely if called while the timer is in the process of being updated.      
 * Unfortunately, it is (rarely) possible to get inconsistent top and bottom halves of    
 * the timer using this method. This seems insoluble, since stackshot runs in a context   
 * where the timer might be half-updated, and has no way of yielding control just long    
 * enough to finish the update.                                                           
 */

static uint64_t safe_grab_timer_value(struct timer *t)
{
#if   defined(__LP64__)
  return t->all_bits;
#else
  uint64_t time = t->high_bits;    /* endian independent grab */
  time = (time << 32) | t->low_bits;
  return time;
#endif
}

/*
 * Called with interrupts disabled after stackshot context has been
 * initialized. Updates stack_snapshot_ret.
 */
static kern_return_t 
stackshot_trap()
{
        return DebuggerTrapWithState(DBOP_STACKSHOT, NULL, NULL, NULL, 0, FALSE, 0);
}


kern_return_t
stack_snapshot_from_kernel(int pid, void *buf, uint32_t size, uint32_t flags, uint64_t delta_since_timestamp, unsigned *bytes_traced)
{
        kern_return_t error = KERN_SUCCESS;
        boolean_t istate;

#if DEVELOPMENT || DEBUG
        if (kern_feature_override(KF_STACKSHOT_OVRD) == TRUE) {
                error = KERN_NOT_SUPPORTED;
                goto out;
        }
#endif
        if ((buf == NULL) || (size <= 0) || (bytes_traced == NULL)) {
                return KERN_INVALID_ARGUMENT;
        }

        /* cap in individual stackshot to SANE_TRACEBUF_SIZE */
        if (size > SANE_TRACEBUF_SIZE) {
                size = SANE_TRACEBUF_SIZE;
        }

        /* Serialize tracing */
        if (flags & STACKSHOT_TRYLOCK) {
                if (!STACKSHOT_SUBSYS_TRY_LOCK()) {
                        return KERN_LOCK_OWNED;
                }
        } else {
                STACKSHOT_SUBSYS_LOCK();
        }

        struct kcdata_descriptor kcdata;
        uint32_t hdr_tag = (flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) ?
                KCDATA_BUFFER_BEGIN_DELTA_STACKSHOT : KCDATA_BUFFER_BEGIN_STACKSHOT;

        error = kcdata_memory_static_init(&kcdata, (mach_vm_address_t)buf, hdr_tag, size,
                                                                          KCFLAG_USE_MEMCOPY | KCFLAG_NO_AUTO_ENDBUFFER);
        if (error) {
                goto out;
        }

        istate = ml_set_interrupts_enabled(FALSE);

        /* Preload trace parameters*/
        kdp_snapshot_preflight(pid, buf, size, flags, &kcdata, delta_since_timestamp);

        /*
         * Trap to the debugger to obtain a coherent stack snapshot; this populates
         * the trace buffer
         */
        error = stackshot_trap();

        ml_set_interrupts_enabled(istate);

        *bytes_traced = kdp_stack_snapshot_bytes_traced();

out:
        stackshot_kcdata_p = NULL;
        STACKSHOT_SUBSYS_UNLOCK();
        return error;
}

#if CONFIG_TELEMETRY
kern_return_t
stack_microstackshot(user_addr_t tracebuf, uint32_t tracebuf_size, uint32_t flags, int32_t *retval)
{
        int error = KERN_SUCCESS;
        uint32_t bytes_traced = 0;

        *retval = -1;

        /*
         * Control related operations
         */
        if (flags & STACKSHOT_GLOBAL_MICROSTACKSHOT_ENABLE) {
                telemetry_global_ctl(1);
                *retval = 0;
                goto exit;
        } else if (flags & STACKSHOT_GLOBAL_MICROSTACKSHOT_DISABLE) {
                telemetry_global_ctl(0);
                *retval = 0;
                goto exit;
        }

        /*
         * Data related operations
         */
        *retval = -1;

        if ((((void*)tracebuf) == NULL) || (tracebuf_size == 0)) {
                error = KERN_INVALID_ARGUMENT;
                goto exit;
        }

        STACKSHOT_SUBSYS_LOCK();

        if (flags & STACKSHOT_GET_MICROSTACKSHOT) {
                if (tracebuf_size > SANE_TRACEBUF_SIZE) {
                        error = KERN_INVALID_ARGUMENT;
                        goto unlock_exit;
                }

                bytes_traced = tracebuf_size;
                error = telemetry_gather(tracebuf, &bytes_traced,
                                         (flags & STACKSHOT_SET_MICROSTACKSHOT_MARK) ? TRUE : FALSE);
                *retval = (int)bytes_traced;
                goto unlock_exit;
        }

        if (flags & STACKSHOT_GET_BOOT_PROFILE) {

                if (tracebuf_size > SANE_BOOTPROFILE_TRACEBUF_SIZE) {
                        error = KERN_INVALID_ARGUMENT;
                        goto unlock_exit;
                }

                bytes_traced = tracebuf_size;
                error = bootprofile_gather(tracebuf, &bytes_traced);
                *retval = (int)bytes_traced;
        }

unlock_exit:
        STACKSHOT_SUBSYS_UNLOCK();
exit:
        return error;
}
#endif /* CONFIG_TELEMETRY */

/*
 * Return the estimated size of a stackshot based on the
 * number of currently running threads and tasks.
 */
uint32_t
get_stackshot_estsize(uint32_t prev_size_hint)
{
        vm_size_t thread_total;
        vm_size_t task_total;
        uint32_t estimated_size;

        thread_total = (threads_count * sizeof(struct thread_snapshot));
        task_total = (tasks_count  * (sizeof(struct task_snapshot) + TASK_UUID_AVG_SIZE));

        estimated_size = (uint32_t) VM_MAP_ROUND_PAGE((thread_total + task_total + STACKSHOT_SUPP_SIZE), PAGE_MASK);
        if (estimated_size < prev_size_hint) {
                estimated_size = (uint32_t) VM_MAP_ROUND_PAGE(prev_size_hint, PAGE_MASK);
        }

        return estimated_size;
}

/*
 * stackshot_remap_buffer:      Utility function to remap bytes_traced bytes starting at stackshotbuf
 *                              into the current task's user space and subsequently copy out the address
 *                              at which the buffer has been mapped in user space to out_buffer_addr.
 *
 * Inputs:                      stackshotbuf - pointer to the original buffer in the kernel's address space
 *                              bytes_traced - length of the buffer to remap starting from stackshotbuf
 *                              out_buffer_addr - pointer to placeholder where newly mapped buffer will be mapped.
 *                              out_size_addr - pointer to be filled in with the size of the buffer
 *
 * Outputs:                     ENOSPC if there is not enough free space in the task's address space to remap the buffer
 *                              EINVAL for all other errors returned by task_remap_buffer/mach_vm_remap
 *                              an error from copyout
 */
static kern_return_t
stackshot_remap_buffer(void *stackshotbuf, uint32_t bytes_traced, uint64_t out_buffer_addr, uint64_t out_size_addr)
{
        int                     error = 0;
        mach_vm_offset_t        stackshotbuf_user_addr = (mach_vm_offset_t)NULL;
        vm_prot_t               cur_prot, max_prot;

        error = mach_vm_remap_kernel(get_task_map(current_task()), &stackshotbuf_user_addr, bytes_traced, 0,
                        VM_FLAGS_ANYWHERE, VM_KERN_MEMORY_NONE, kernel_map, (mach_vm_offset_t)stackshotbuf, FALSE, &cur_prot, &max_prot, VM_INHERIT_DEFAULT);
        /*
         * If the call to mach_vm_remap fails, we return the appropriate converted error
         */
        if (error == KERN_SUCCESS) {
                /*
                 * If we fail to copy out the address or size of the new buffer, we remove the buffer mapping that
                 * we just made in the task's user space.
                 */
                error = copyout(CAST_DOWN(void *, &stackshotbuf_user_addr), (user_addr_t)out_buffer_addr, sizeof(stackshotbuf_user_addr));
                if (error != KERN_SUCCESS) {
                        mach_vm_deallocate(get_task_map(current_task()), stackshotbuf_user_addr, (mach_vm_size_t)bytes_traced);
                        return error;
                }
                error = copyout(&bytes_traced, (user_addr_t)out_size_addr, sizeof(bytes_traced));
                if (error != KERN_SUCCESS) {
                        mach_vm_deallocate(get_task_map(current_task()), stackshotbuf_user_addr, (mach_vm_size_t)bytes_traced);
                        return error;
                }
        }
        return error;
}

kern_return_t
kern_stack_snapshot_internal(int stackshot_config_version, void *stackshot_config, size_t stackshot_config_size, boolean_t stackshot_from_user)
{
        int error = 0;
        boolean_t prev_interrupt_state;
        uint32_t bytes_traced = 0;
        uint32_t stackshotbuf_size = 0;
        void * stackshotbuf = NULL;
        kcdata_descriptor_t kcdata_p = NULL;

        void * buf_to_free = NULL;
        int size_to_free = 0;

        /* Parsed arguments */
        uint64_t                out_buffer_addr;
        uint64_t                out_size_addr;
        int                     pid = -1;
        uint32_t                flags;
        uint64_t                since_timestamp;
        uint32_t                size_hint = 0;

        if(stackshot_config == NULL) {
                return  KERN_INVALID_ARGUMENT;
        }
#if DEVELOPMENT || DEBUG
        /* TBD: ask stackshot clients to avoid issuing stackshots in this
         * configuration in lieu of the kernel feature override.
         */
        if (kern_feature_override(KF_STACKSHOT_OVRD) == TRUE) {
                return KERN_NOT_SUPPORTED;
        }
#endif

        switch (stackshot_config_version) {
                case STACKSHOT_CONFIG_TYPE:
                        if (stackshot_config_size != sizeof(stackshot_config_t)) {
                                return KERN_INVALID_ARGUMENT;
                        }
                        stackshot_config_t *config = (stackshot_config_t *) stackshot_config;
                        out_buffer_addr = config->sc_out_buffer_addr;
                        out_size_addr = config->sc_out_size_addr;
                        pid = config->sc_pid;
                        flags = config->sc_flags;
                        since_timestamp = config->sc_delta_timestamp;
                        if (config->sc_size <= SANE_TRACEBUF_SIZE) {
                                size_hint = config->sc_size;
                        }
                        break;
                default:
                        return KERN_NOT_SUPPORTED;
            }

            /*
             * Currently saving a kernel buffer and trylock are only supported from the
             * internal/KEXT API.
             */
            if (stackshot_from_user) {
                    if (flags & (STACKSHOT_TRYLOCK | STACKSHOT_SAVE_IN_KERNEL_BUFFER | STACKSHOT_FROM_PANIC)) {
                            return KERN_NO_ACCESS;
                    }
            } else {
                if (!(flags & STACKSHOT_SAVE_IN_KERNEL_BUFFER)) {
                        return KERN_NOT_SUPPORTED;
                }
        }

        if (!((flags & STACKSHOT_KCDATA_FORMAT) || (flags & STACKSHOT_RETRIEVE_EXISTING_BUFFER))) {
                return KERN_NOT_SUPPORTED;
        }

        /*
         * If we're not saving the buffer in the kernel pointer, we need a place to copy into.
         */
        if ((!out_buffer_addr || !out_size_addr) && !(flags & STACKSHOT_SAVE_IN_KERNEL_BUFFER)) {
                return KERN_INVALID_ARGUMENT;
        }

        if (since_timestamp != 0 && ((flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) == 0)) {
                return KERN_INVALID_ARGUMENT;
        }

#if MONOTONIC
        if (!mt_core_supported) {
                flags &= ~STACKSHOT_INSTRS_CYCLES;
        }
#else /* MONOTONIC */
        flags &= ~STACKSHOT_INSTRS_CYCLES;
#endif /* !MONOTONIC */

        STACKSHOT_SUBSYS_LOCK();

        if (flags & STACKSHOT_SAVE_IN_KERNEL_BUFFER) {
                /*
                 * Don't overwrite an existing stackshot
                 */
                if (kernel_stackshot_buf != NULL) {
                        error = KERN_MEMORY_PRESENT;
                        goto error_exit;
                }
        } else if (flags & STACKSHOT_RETRIEVE_EXISTING_BUFFER) {
                if ((kernel_stackshot_buf == NULL) || (kernel_stackshot_buf_size <= 0)) {
                        error = KERN_NOT_IN_SET;
                        goto error_exit;
                }
                error = stackshot_remap_buffer(kernel_stackshot_buf, kernel_stackshot_buf_size,
                                                out_buffer_addr, out_size_addr);
                /*
                 * If we successfully remapped the buffer into the user's address space, we 
                 * set buf_to_free and size_to_free so the prior kernel mapping will be removed
                 * and then clear the kernel stackshot pointer and associated size.
                 */
                if (error == KERN_SUCCESS) {
                        buf_to_free = kernel_stackshot_buf;
                        size_to_free = (int) VM_MAP_ROUND_PAGE(kernel_stackshot_buf_size, PAGE_MASK);
                        kernel_stackshot_buf = NULL;
                        kernel_stackshot_buf_size = 0;
                }
                
                goto error_exit;
        }

        if (flags & STACKSHOT_GET_BOOT_PROFILE) {
                void *bootprofile = NULL;
                uint32_t len = 0;
#if CONFIG_TELEMETRY
                bootprofile_get(&bootprofile, &len);
#endif
                if (!bootprofile || !len) {
                        error = KERN_NOT_IN_SET;
                        goto error_exit;
                }
                error = stackshot_remap_buffer(bootprofile, len, out_buffer_addr, out_size_addr);
                goto error_exit;
        }

        stackshotbuf_size = get_stackshot_estsize(size_hint);

        for (; stackshotbuf_size <= SANE_TRACEBUF_SIZE; stackshotbuf_size <<= 1) {
                if (kmem_alloc(kernel_map, (vm_offset_t *)&stackshotbuf, stackshotbuf_size, VM_KERN_MEMORY_DIAG) != KERN_SUCCESS) {
                        error = KERN_RESOURCE_SHORTAGE;
                        goto error_exit;
                }


                uint32_t hdr_tag = (flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) ? KCDATA_BUFFER_BEGIN_DELTA_STACKSHOT : KCDATA_BUFFER_BEGIN_STACKSHOT;
                kcdata_p = kcdata_memory_alloc_init((mach_vm_address_t)stackshotbuf, hdr_tag, stackshotbuf_size,
                                                            KCFLAG_USE_MEMCOPY | KCFLAG_NO_AUTO_ENDBUFFER);

                stackshot_duration_outer = NULL;
                uint64_t time_start      = mach_absolute_time();

                /*
                 * Disable interrupts and save the current interrupt state.
                 */
                prev_interrupt_state = ml_set_interrupts_enabled(FALSE);

                /*
                 * Load stackshot parameters.
                 */
                kdp_snapshot_preflight(pid, stackshotbuf, stackshotbuf_size, flags, kcdata_p, since_timestamp);

                error = stackshot_trap();

                ml_set_interrupts_enabled(prev_interrupt_state);

                /* record the duration that interupts were disabled */

                uint64_t time_end = mach_absolute_time();
                if (stackshot_duration_outer) {
                        *stackshot_duration_outer = time_end - time_start;
                }

                if (error != KERN_SUCCESS) {
                        if (kcdata_p != NULL) {
                                kcdata_memory_destroy(kcdata_p);
                                kcdata_p = NULL;
                                stackshot_kcdata_p = NULL;
                        }
                        kmem_free(kernel_map, (vm_offset_t)stackshotbuf, stackshotbuf_size);
                        stackshotbuf = NULL;
                        if (error == KERN_INSUFFICIENT_BUFFER_SIZE) {
                                /*
                                 * If we didn't allocate a big enough buffer, deallocate and try again.
                                 */
                                continue;
                        } else {
                                goto error_exit;
                        }
                }

                bytes_traced = kdp_stack_snapshot_bytes_traced();

                if (bytes_traced <= 0) {
                        error = KERN_ABORTED;
                        goto error_exit;
                }

                assert(bytes_traced <= stackshotbuf_size);
                if (!(flags & STACKSHOT_SAVE_IN_KERNEL_BUFFER)) {
                        error = stackshot_remap_buffer(stackshotbuf, bytes_traced, out_buffer_addr, out_size_addr);
                        goto error_exit;
                }

                /*
                 * Save the stackshot in the kernel buffer.
                 */
                kernel_stackshot_buf = stackshotbuf;
                kernel_stackshot_buf_size =  bytes_traced;
                /*
                 * Figure out if we didn't use all the pages in the buffer. If so, we set buf_to_free to the beginning of
                 * the next page after the end of the stackshot in the buffer so that the kmem_free clips the buffer and
                 * update size_to_free for kmem_free accordingly.
                 */
                size_to_free = stackshotbuf_size - (int) VM_MAP_ROUND_PAGE(bytes_traced, PAGE_MASK);

                assert(size_to_free >= 0);

                if (size_to_free != 0) {
                        buf_to_free = (void *)((uint64_t)stackshotbuf + stackshotbuf_size - size_to_free);
                }

                stackshotbuf = NULL;
                stackshotbuf_size = 0;
                goto error_exit;
        }

        if (stackshotbuf_size > SANE_TRACEBUF_SIZE) {
                error = KERN_RESOURCE_SHORTAGE;
        }

error_exit:
        if (kcdata_p != NULL) {
                kcdata_memory_destroy(kcdata_p);
                kcdata_p = NULL;
                stackshot_kcdata_p = NULL;
        }

        if (stackshotbuf != NULL) {
                kmem_free(kernel_map, (vm_offset_t)stackshotbuf, stackshotbuf_size);
        }
        if (buf_to_free  != NULL) {
                kmem_free(kernel_map, (vm_offset_t)buf_to_free, size_to_free);
        }
        STACKSHOT_SUBSYS_UNLOCK();
        return error;
}

/*
 * Cache stack snapshot parameters in preparation for a trace.
 */
void
kdp_snapshot_preflight(int pid, void * tracebuf, uint32_t tracebuf_size, uint32_t flags,
                                           kcdata_descriptor_t data_p, uint64_t since_timestamp)
{
        uint64_t microsecs = 0, secs = 0;
        clock_get_calendar_microtime((clock_sec_t *)&secs, (clock_usec_t *)&microsecs);

        stackshot_microsecs = microsecs + (secs * USEC_PER_SEC);
        stack_snapshot_pid = pid;
        stack_snapshot_buf = tracebuf;
        stack_snapshot_bufsize = tracebuf_size;
        stack_snapshot_flags = flags;
        stack_snapshot_delta_since_timestamp = since_timestamp;

        panic_stackshot = ((flags & STACKSHOT_FROM_PANIC) != 0);

        assert(data_p != NULL);
        assert(stackshot_kcdata_p == NULL);
        stackshot_kcdata_p = data_p;

        stack_snapshot_bytes_traced = 0;
}

void
panic_stackshot_reset_state()
{
        stackshot_kcdata_p = NULL;
}

boolean_t
stackshot_active()
{
        return (stackshot_kcdata_p != NULL);
}

uint32_t
kdp_stack_snapshot_bytes_traced(void)
{
        return stack_snapshot_bytes_traced;
}

static boolean_t memory_iszero(void *addr, size_t size)
{
        char *data = (char *)addr;
        for (size_t i = 0; i < size; i++){
                if (data[i] != 0)
                        return FALSE;
        }
        return TRUE;
}

#define kcd_end_address(kcd) ((void *)((uint64_t)((kcd)->kcd_addr_begin) + kcdata_memory_get_used_bytes((kcd))))
#define kcd_max_address(kcd) ((void *)((kcd)->kcd_addr_begin + (kcd)->kcd_length))
/*
 * Use of the kcd_exit_on_error(action) macro requires a local
 * 'kern_return_t error' variable and 'error_exit' label.
 */
#define kcd_exit_on_error(action)                      \
        do {                                               \
                if (KERN_SUCCESS != (error = (action))) {      \
                        if (error == KERN_RESOURCE_SHORTAGE) {     \
                                error = KERN_INSUFFICIENT_BUFFER_SIZE; \
                        }                                          \
                        goto error_exit;                           \
                }                                              \
        } while (0); /* end kcd_exit_on_error */

static uint64_t
kcdata_get_task_ss_flags(task_t task)
{
        uint64_t ss_flags = 0;
        boolean_t task64 = task_has_64BitAddr(task);

        if (task64)
                ss_flags |= kUser64_p;
        if (!task->active || task_is_a_corpse(task))
                ss_flags |= kTerminatedSnapshot;
        if (task->pidsuspended)
                ss_flags |= kPidSuspended;
        if (task->frozen)
                ss_flags |= kFrozen;
        if (task->effective_policy.tep_darwinbg == 1)
                ss_flags |= kTaskDarwinBG;
        if (task->requested_policy.trp_role == TASK_FOREGROUND_APPLICATION)
                ss_flags |= kTaskIsForeground;
        if (task->requested_policy.trp_boosted == 1)
                ss_flags |= kTaskIsBoosted;
        if (task->effective_policy.tep_sup_active == 1)
                ss_flags |= kTaskIsSuppressed;
#if CONFIG_MEMORYSTATUS
        if (memorystatus_proc_is_dirty_unsafe(task->bsd_info))
                ss_flags |= kTaskIsDirty;
#endif

        ss_flags |= (0x7 & workqueue_get_pwq_state_kdp(task->bsd_info)) << 17;

#if IMPORTANCE_INHERITANCE
        if (task->task_imp_base) {
                if (task->task_imp_base->iit_donor)
                        ss_flags |= kTaskIsImpDonor;
                if (task->task_imp_base->iit_live_donor)
                        ss_flags |= kTaskIsLiveImpDonor;
        }
#endif

        return ss_flags;
}

static kern_return_t
kcdata_record_shared_cache_info(kcdata_descriptor_t kcd, task_t task, struct dyld_uuid_info_64_v2 *sys_shared_cache_loadinfo, unaligned_u64 *task_snap_ss_flags)
{
        kern_return_t error = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;

        uint64_t shared_cache_slide = 0;
        uint64_t shared_cache_base_address = 0;
        int task_pid = pid_from_task(task);
        uint32_t kdp_fault_results = 0;

        assert(task_snap_ss_flags != NULL);

        if (task->shared_region && ml_validate_nofault((vm_offset_t)task->shared_region, sizeof(struct vm_shared_region))) {
                struct vm_shared_region *sr = task->shared_region;
                shared_cache_base_address = sr->sr_base_address + sr->sr_first_mapping;
        } else {
                *task_snap_ss_flags |= kTaskSharedRegionInfoUnavailable;
                goto error_exit;
        }

        /* We haven't copied in the shared region UUID yet as part of setup */
        if (!shared_cache_base_address || !task->shared_region->sr_uuid_copied) {
                goto error_exit;
        }

        /*
         * No refcounting here, but we are in debugger
         * context, so that should be safe.
         */
        shared_cache_slide = task->shared_region->sr_slide_info.slide;

        if (sys_shared_cache_loadinfo) {
                if (task_pid == 1) {
                        /* save launchd's shared cache info as system level */
                        stackshot_memcpy(sys_shared_cache_loadinfo->imageUUID, &task->shared_region->sr_uuid, sizeof(task->shared_region->sr_uuid));
                        sys_shared_cache_loadinfo->imageLoadAddress = shared_cache_slide;
                        sys_shared_cache_loadinfo->imageSlidBaseAddress = shared_cache_slide + task->shared_region->sr_base_address;

                        goto error_exit;
                } else {
                        if (shared_cache_slide == sys_shared_cache_loadinfo->imageLoadAddress &&
                            0 == memcmp(&task->shared_region->sr_uuid, sys_shared_cache_loadinfo->imageUUID,
                                        sizeof(task->shared_region->sr_uuid))) {
                                /* skip adding shared cache info. its same as system level one */
                                goto error_exit;
                        }
                }
        }

        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_SHAREDCACHE_LOADINFO, sizeof(struct dyld_uuid_info_64_v2), &out_addr));
        struct dyld_uuid_info_64_v2 *shared_cache_data = (struct dyld_uuid_info_64_v2 *)out_addr;
        shared_cache_data->imageLoadAddress = shared_cache_slide;
        stackshot_memcpy(shared_cache_data->imageUUID, task->shared_region->sr_uuid, sizeof(task->shared_region->sr_uuid));
        shared_cache_data->imageSlidBaseAddress = shared_cache_base_address;

error_exit:
        if (kdp_fault_results & KDP_FAULT_RESULT_PAGED_OUT) {
                *task_snap_ss_flags |= kTaskUUIDInfoMissing;
        }

        if (kdp_fault_results & KDP_FAULT_RESULT_TRIED_FAULT) {
                *task_snap_ss_flags |= kTaskUUIDInfoTriedFault;
        }

        if (kdp_fault_results & KDP_FAULT_RESULT_FAULTED_IN) {
                *task_snap_ss_flags |= kTaskUUIDInfoFaultedIn;
        }

        return error;
}

static kern_return_t
kcdata_record_uuid_info(kcdata_descriptor_t kcd, task_t task, uint32_t trace_flags, boolean_t have_pmap, unaligned_u64 *task_snap_ss_flags)
{
        boolean_t save_loadinfo_p         = ((trace_flags & STACKSHOT_SAVE_LOADINFO) != 0);
        boolean_t save_kextloadinfo_p     = ((trace_flags & STACKSHOT_SAVE_KEXT_LOADINFO) != 0);
        boolean_t collect_delta_stackshot = ((trace_flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) != 0);
        boolean_t minimize_uuids          = collect_delta_stackshot && ((trace_flags & STACKSHOT_TAILSPIN) != 0);
        boolean_t should_fault            = (trace_flags & STACKSHOT_ENABLE_UUID_FAULTING);

        kern_return_t error        = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;

        uint32_t uuid_info_count         = 0;
        mach_vm_address_t uuid_info_addr = 0;
        uint64_t uuid_info_timestamp     = 0;
        uint32_t kdp_fault_results       = 0;

        assert(task_snap_ss_flags != NULL);

        int task_pid     = pid_from_task(task);
        boolean_t task64 = task_has_64BitAddr(task);

        if (save_loadinfo_p && have_pmap && task->active && task_pid > 0) {
                /* Read the dyld_all_image_infos struct from the task memory to get UUID array count and location */
                if (task64) {
                        struct user64_dyld_all_image_infos task_image_infos;
                        if (kdp_copyin(task->map, task->all_image_info_addr, &task_image_infos,
                                       sizeof(struct user64_dyld_all_image_infos), should_fault, &kdp_fault_results)) {
                                uuid_info_count = (uint32_t)task_image_infos.uuidArrayCount;
                                uuid_info_addr = task_image_infos.uuidArray;
                                if (task_image_infos.version >= DYLD_ALL_IMAGE_INFOS_TIMESTAMP_MINIMUM_VERSION) {
                                        uuid_info_timestamp = task_image_infos.timestamp;
                                }
                        }
                } else {
                        struct user32_dyld_all_image_infos task_image_infos;
                        if (kdp_copyin(task->map, task->all_image_info_addr, &task_image_infos,
                                       sizeof(struct user32_dyld_all_image_infos), should_fault, &kdp_fault_results)) {
                                uuid_info_count = task_image_infos.uuidArrayCount;
                                uuid_info_addr = task_image_infos.uuidArray;
                                if (task_image_infos.version >= DYLD_ALL_IMAGE_INFOS_TIMESTAMP_MINIMUM_VERSION) {
                                        uuid_info_timestamp = task_image_infos.timestamp;
                                }
                        }
                }

                /*
                 * If we get a NULL uuid_info_addr (which can happen when we catch dyld in the middle of updating
                 * this data structure), we zero the uuid_info_count so that we won't even try to save load info
                 * for this task.
                 */
                if (!uuid_info_addr) {
                        uuid_info_count = 0;
                }
        }

        if (have_pmap && task_pid == 0) {
                if (save_kextloadinfo_p && ml_validate_nofault((vm_offset_t)(gLoadedKextSummaries), sizeof(OSKextLoadedKextSummaryHeader))) {
                        uuid_info_count = gLoadedKextSummaries->numSummaries + 1; /* include main kernel UUID */
                } else {
                        uuid_info_count = 1; /* include kernelcache UUID (embedded) or kernel UUID (desktop) */
                }
        }

        if (task_pid > 0 && uuid_info_count > 0 && uuid_info_count < MAX_LOADINFOS) {
                if (minimize_uuids && uuid_info_timestamp != 0 && uuid_info_timestamp < stack_snapshot_delta_since_timestamp)
                        goto error_exit;

                uint32_t uuid_info_size       = (uint32_t)(task64 ? sizeof(struct user64_dyld_uuid_info) : sizeof(struct user32_dyld_uuid_info));
                uint32_t uuid_info_array_size = uuid_info_count * uuid_info_size;

                kcd_exit_on_error(kcdata_get_memory_addr_for_array(kcd, (task64 ? KCDATA_TYPE_LIBRARY_LOADINFO64 : KCDATA_TYPE_LIBRARY_LOADINFO),
                                                                        uuid_info_size, uuid_info_count, &out_addr));

                /* Copy in the UUID info array
                 * It may be nonresident, in which case just fix up nloadinfos to 0 in the task_snap
                 */
                if (have_pmap && !kdp_copyin(task->map, uuid_info_addr, (void *)out_addr, uuid_info_array_size, should_fault, &kdp_fault_results)) {
                        bzero((void *)out_addr, uuid_info_array_size);
                }

        } else if (task_pid == 0 && uuid_info_count > 0 && uuid_info_count < MAX_LOADINFOS) {
                if (minimize_uuids && gLoadedKextSummaries != 0 && gLoadedKextSummariesTimestamp < stack_snapshot_delta_since_timestamp)
                        goto error_exit;

                uintptr_t image_load_address;

                do {

#if CONFIG_EMBEDDED
                        if (!save_kextloadinfo_p) {
                                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_KERNELCACHE_LOADINFO, sizeof(struct dyld_uuid_info_64), &out_addr));
                                struct dyld_uuid_info_64 *kc_uuid = (struct dyld_uuid_info_64 *)out_addr;
                                kc_uuid->imageLoadAddress = VM_MIN_KERNEL_AND_KEXT_ADDRESS;
                                stackshot_memcpy(&kc_uuid->imageUUID, &kernelcache_uuid, sizeof(uuid_t));
                                break;
                        }
#endif /* CONFIG_EMBEDDED */

                        if (!kernel_uuid || !ml_validate_nofault((vm_offset_t)kernel_uuid, sizeof(uuid_t))) {
                                /* Kernel UUID not found or inaccessible */
                                break;
                        }

                        kcd_exit_on_error(kcdata_get_memory_addr_for_array(
                            kcd, (sizeof(kernel_uuid_info) == sizeof(struct user64_dyld_uuid_info)) ? KCDATA_TYPE_LIBRARY_LOADINFO64
                                                                                                    : KCDATA_TYPE_LIBRARY_LOADINFO,
                            sizeof(kernel_uuid_info), uuid_info_count, &out_addr));
                        kernel_uuid_info *uuid_info_array = (kernel_uuid_info *)out_addr;
                        image_load_address = (uintptr_t)VM_KERNEL_UNSLIDE(vm_kernel_stext);
                        uuid_info_array[0].imageLoadAddress = image_load_address;
                        stackshot_memcpy(&uuid_info_array[0].imageUUID, kernel_uuid, sizeof(uuid_t));

                        if (save_kextloadinfo_p && 
                                ml_validate_nofault((vm_offset_t)(gLoadedKextSummaries), sizeof(OSKextLoadedKextSummaryHeader)) &&
                                ml_validate_nofault((vm_offset_t)(&gLoadedKextSummaries->summaries[0]),
                                                                        gLoadedKextSummaries->entry_size * gLoadedKextSummaries->numSummaries)) {
                                uint32_t kexti;
                                for (kexti=0 ; kexti < gLoadedKextSummaries->numSummaries; kexti++) {
                                        image_load_address = (uintptr_t)VM_KERNEL_UNSLIDE(gLoadedKextSummaries->summaries[kexti].address);
                                        uuid_info_array[kexti + 1].imageLoadAddress = image_load_address;
                                        stackshot_memcpy(&uuid_info_array[kexti + 1].imageUUID, &gLoadedKextSummaries->summaries[kexti].uuid, sizeof(uuid_t));
                                }
                        }
                } while(0);
        }

error_exit:
        if (kdp_fault_results & KDP_FAULT_RESULT_PAGED_OUT) {
                *task_snap_ss_flags |= kTaskUUIDInfoMissing;
        }

        if (kdp_fault_results & KDP_FAULT_RESULT_TRIED_FAULT) {
                *task_snap_ss_flags |= kTaskUUIDInfoTriedFault;
        }

        if (kdp_fault_results & KDP_FAULT_RESULT_FAULTED_IN) {
                *task_snap_ss_flags |= kTaskUUIDInfoFaultedIn;
        }

        return error;
}

static kern_return_t
kcdata_record_task_iostats(kcdata_descriptor_t kcd, task_t task)
{
        kern_return_t error = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;

        /* I/O Statistics if any counters are non zero */
        assert(IO_NUM_PRIORITIES == STACKSHOT_IO_NUM_PRIORITIES);
        if (task->task_io_stats && !memory_iszero(task->task_io_stats, sizeof(struct io_stat_info))) {
                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_IOSTATS, sizeof(struct io_stats_snapshot), &out_addr));
                struct io_stats_snapshot *_iostat = (struct io_stats_snapshot *)out_addr;
                _iostat->ss_disk_reads_count = task->task_io_stats->disk_reads.count;
                _iostat->ss_disk_reads_size = task->task_io_stats->disk_reads.size;
                _iostat->ss_disk_writes_count = (task->task_io_stats->total_io.count - task->task_io_stats->disk_reads.count);
                _iostat->ss_disk_writes_size = (task->task_io_stats->total_io.size - task->task_io_stats->disk_reads.size);
                _iostat->ss_paging_count = task->task_io_stats->paging.count;
                _iostat->ss_paging_size = task->task_io_stats->paging.size;
                _iostat->ss_non_paging_count = (task->task_io_stats->total_io.count - task->task_io_stats->paging.count);
                _iostat->ss_non_paging_size = (task->task_io_stats->total_io.size - task->task_io_stats->paging.size);
                _iostat->ss_metadata_count = task->task_io_stats->metadata.count;
                _iostat->ss_metadata_size = task->task_io_stats->metadata.size;
                _iostat->ss_data_count = (task->task_io_stats->total_io.count - task->task_io_stats->metadata.count);
                _iostat->ss_data_size = (task->task_io_stats->total_io.size - task->task_io_stats->metadata.size);
                for(int i = 0; i < IO_NUM_PRIORITIES; i++) {
                        _iostat->ss_io_priority_count[i] = task->task_io_stats->io_priority[i].count;
                        _iostat->ss_io_priority_size[i] = task->task_io_stats->io_priority[i].size;
                }
        }

error_exit:
        return error;
}

static kern_return_t
kcdata_record_task_snapshot(kcdata_descriptor_t kcd, task_t task, uint32_t trace_flags, boolean_t have_pmap, unaligned_u64 **task_snap_ss_flags)
{
        boolean_t collect_delta_stackshot = ((trace_flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) != 0);
        boolean_t collect_iostats         = !collect_delta_stackshot && !(trace_flags & STACKSHOT_TAILSPIN) && !(trace_flags & STACKSHOT_NO_IO_STATS);
#if MONOTONIC
        boolean_t collect_instrs_cycles   = ((trace_flags & STACKSHOT_INSTRS_CYCLES) != 0);
#endif /* MONOTONIC */

        kern_return_t error                 = KERN_SUCCESS;
        mach_vm_address_t out_addr          = 0;
        struct task_snapshot_v2 * cur_tsnap = NULL;

        assert(task_snap_ss_flags != NULL);

        int task_pid           = pid_from_task(task);
        uint64_t task_uniqueid = get_task_uniqueid(task);
        uint64_t proc_starttime_secs = 0;

        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_TASK_SNAPSHOT, sizeof(struct task_snapshot_v2), &out_addr));

        cur_tsnap = (struct task_snapshot_v2 *)out_addr;

        cur_tsnap->ts_unique_pid = task_uniqueid;
        cur_tsnap->ts_ss_flags = kcdata_get_task_ss_flags(task);
        *task_snap_ss_flags = (unaligned_u64 *)&cur_tsnap->ts_ss_flags;
        cur_tsnap->ts_user_time_in_terminated_threads = task->total_user_time;
        cur_tsnap->ts_system_time_in_terminated_threads = task->total_system_time;

        proc_starttime_kdp(task->bsd_info, &proc_starttime_secs, NULL, NULL);
        cur_tsnap->ts_p_start_sec = proc_starttime_secs;

#if CONFIG_EMBEDDED
        cur_tsnap->ts_task_size = have_pmap ? get_task_phys_footprint(task) : 0;
#else
        cur_tsnap->ts_task_size = have_pmap ? (pmap_resident_count(task->map->pmap) * PAGE_SIZE) : 0;
#endif
        cur_tsnap->ts_max_resident_size = get_task_resident_max(task);
        cur_tsnap->ts_suspend_count = task->suspend_count;
        cur_tsnap->ts_faults = task->faults;
        cur_tsnap->ts_pageins = task->pageins;
        cur_tsnap->ts_cow_faults = task->cow_faults;
        cur_tsnap->ts_was_throttled = (uint32_t) proc_was_throttled_from_task(task);
        cur_tsnap->ts_did_throttle = (uint32_t) proc_did_throttle_from_task(task);
        cur_tsnap->ts_latency_qos = (task->effective_policy.tep_latency_qos == LATENCY_QOS_TIER_UNSPECIFIED) ?
                LATENCY_QOS_TIER_UNSPECIFIED : ((0xFF << 16) | task->effective_policy.tep_latency_qos);
        cur_tsnap->ts_pid = task_pid;

        /* Add the BSD process identifiers */
        if (task_pid != -1 && task->bsd_info != NULL) {
                proc_name_kdp(task, cur_tsnap->ts_p_comm, sizeof(cur_tsnap->ts_p_comm));
#if CONFIG_COALITIONS
                if (trace_flags & STACKSHOT_SAVE_JETSAM_COALITIONS) {
                        uint64_t jetsam_coal_id = coalition_id(task->coalition[COALITION_TYPE_JETSAM]);
                        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_JETSAM_COALITION, sizeof(jetsam_coal_id), &out_addr));
                        stackshot_memcpy((void*)out_addr, &jetsam_coal_id, sizeof(jetsam_coal_id));
                }
#endif /* CONFIG_COALITIONS */
        }
        else {
                cur_tsnap->ts_p_comm[0] = '\0';
#if IMPORTANCE_INHERITANCE && (DEVELOPMENT || DEBUG)
                if (task->task_imp_base != NULL) {
                        stackshot_strlcpy(cur_tsnap->ts_p_comm, &task->task_imp_base->iit_procname[0],
                                MIN((int)sizeof(task->task_imp_base->iit_procname), (int)sizeof(cur_tsnap->ts_p_comm)));
                }
#endif /* IMPORTANCE_INHERITANCE && (DEVELOPMENT || DEBUG) */
        }

        if (collect_iostats) {
                kcd_exit_on_error(kcdata_record_task_iostats(kcd, task));
        }

#if MONOTONIC
        if (collect_instrs_cycles) {
                uint64_t instrs = 0, cycles = 0;
                mt_stackshot_task(task, &instrs, &cycles);

                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_INSTRS_CYCLES, sizeof(struct instrs_cycles_snapshot), &out_addr));
                struct instrs_cycles_snapshot *instrs_cycles = (struct instrs_cycles_snapshot *)out_addr;
                instrs_cycles->ics_instructions = instrs;
                instrs_cycles->ics_cycles = cycles;
        }
#endif /* MONOTONIC */

error_exit:
        return error;
}

static kern_return_t
kcdata_record_task_delta_snapshot(kcdata_descriptor_t kcd, task_t task, boolean_t have_pmap, unaligned_u64 **task_snap_ss_flags)
{
        kern_return_t error                       = KERN_SUCCESS;
        struct task_delta_snapshot_v2 * cur_tsnap = NULL;
        mach_vm_address_t out_addr                = 0;

        uint64_t task_uniqueid = get_task_uniqueid(task);
        assert(task_snap_ss_flags != NULL);

        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_TASK_DELTA_SNAPSHOT, sizeof(struct task_delta_snapshot_v2), &out_addr));

        cur_tsnap = (struct task_delta_snapshot_v2 *)out_addr;

        cur_tsnap->tds_unique_pid = task_uniqueid;
        cur_tsnap->tds_ss_flags = kcdata_get_task_ss_flags(task);
        *task_snap_ss_flags = (unaligned_u64 *)&cur_tsnap->tds_ss_flags;

        cur_tsnap->tds_user_time_in_terminated_threads = task->total_user_time;
        cur_tsnap->tds_system_time_in_terminated_threads = task->total_system_time;

#if CONFIG_EMBEDDED
        cur_tsnap->tds_task_size = have_pmap ? get_task_phys_footprint(task) : 0;
#else
        cur_tsnap->tds_task_size = have_pmap ? (pmap_resident_count(task->map->pmap) * PAGE_SIZE) : 0;
#endif

        cur_tsnap->tds_max_resident_size = get_task_resident_max(task);
        cur_tsnap->tds_suspend_count = task->suspend_count;
        cur_tsnap->tds_faults            = task->faults;
        cur_tsnap->tds_pageins           = task->pageins;
        cur_tsnap->tds_cow_faults        = task->cow_faults;
        cur_tsnap->tds_was_throttled     = (uint32_t)proc_was_throttled_from_task(task);
        cur_tsnap->tds_did_throttle      = (uint32_t)proc_did_throttle_from_task(task);
        cur_tsnap->tds_latency_qos       = (task-> effective_policy.tep_latency_qos == LATENCY_QOS_TIER_UNSPECIFIED)
                                         ? LATENCY_QOS_TIER_UNSPECIFIED
                                         : ((0xFF << 16) | task-> effective_policy.tep_latency_qos);

error_exit:
        return error;
}

static kern_return_t
kcdata_record_thread_iostats(kcdata_descriptor_t kcd, thread_t thread)
{
        kern_return_t error = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;

        /* I/O Statistics */
        assert(IO_NUM_PRIORITIES == STACKSHOT_IO_NUM_PRIORITIES);
        if (thread->thread_io_stats && !memory_iszero(thread->thread_io_stats, sizeof(struct io_stat_info))) {
                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_IOSTATS, sizeof(struct io_stats_snapshot), &out_addr));
                struct io_stats_snapshot *_iostat = (struct io_stats_snapshot *)out_addr;
                _iostat->ss_disk_reads_count = thread->thread_io_stats->disk_reads.count;
                _iostat->ss_disk_reads_size = thread->thread_io_stats->disk_reads.size;
                _iostat->ss_disk_writes_count = (thread->thread_io_stats->total_io.count - thread->thread_io_stats->disk_reads.count);
                _iostat->ss_disk_writes_size = (thread->thread_io_stats->total_io.size - thread->thread_io_stats->disk_reads.size);
                _iostat->ss_paging_count = thread->thread_io_stats->paging.count;
                _iostat->ss_paging_size = thread->thread_io_stats->paging.size;
                _iostat->ss_non_paging_count = (thread->thread_io_stats->total_io.count - thread->thread_io_stats->paging.count);
                _iostat->ss_non_paging_size = (thread->thread_io_stats->total_io.size - thread->thread_io_stats->paging.size);
                _iostat->ss_metadata_count = thread->thread_io_stats->metadata.count;
                _iostat->ss_metadata_size = thread->thread_io_stats->metadata.size;
                _iostat->ss_data_count = (thread->thread_io_stats->total_io.count - thread->thread_io_stats->metadata.count);
                _iostat->ss_data_size = (thread->thread_io_stats->total_io.size - thread->thread_io_stats->metadata.size);
                for(int i = 0; i < IO_NUM_PRIORITIES; i++) {
                        _iostat->ss_io_priority_count[i] = thread->thread_io_stats->io_priority[i].count;
                        _iostat->ss_io_priority_size[i] = thread->thread_io_stats->io_priority[i].size;
                }
        }

error_exit:
        return error;
}

static kern_return_t
kcdata_record_thread_snapshot(
    kcdata_descriptor_t kcd, thread_t thread, task_t task, uint32_t trace_flags, boolean_t have_pmap, boolean_t thread_on_core)
{
        boolean_t dispatch_p              = ((trace_flags & STACKSHOT_GET_DQ) != 0);
        boolean_t active_kthreads_only_p  = ((trace_flags & STACKSHOT_ACTIVE_KERNEL_THREADS_ONLY) != 0);
        boolean_t trace_fp_p              = false;
        boolean_t collect_delta_stackshot = ((trace_flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) != 0);
        boolean_t collect_iostats         = !collect_delta_stackshot && !(trace_flags & STACKSHOT_TAILSPIN) && !(trace_flags & STACKSHOT_NO_IO_STATS);
#if MONOTONIC
        boolean_t collect_instrs_cycles   = ((trace_flags & STACKSHOT_INSTRS_CYCLES) != 0);
#endif /* MONOTONIC */

        kern_return_t error        = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;
        int saved_count            = 0;

        struct thread_snapshot_v4 * cur_thread_snap = NULL;
        char cur_thread_name[STACKSHOT_MAX_THREAD_NAME_SIZE];
        uint64_t tval    = 0;
        boolean_t task64 = task_has_64BitAddr(task);

        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_THREAD_SNAPSHOT, sizeof(struct thread_snapshot_v4), &out_addr));
        cur_thread_snap = (struct thread_snapshot_v4 *)out_addr;

        /* Populate the thread snapshot header */
        cur_thread_snap->ths_thread_id      = thread_tid(thread);
        cur_thread_snap->ths_wait_event = VM_KERNEL_UNSLIDE_OR_PERM(thread->wait_event);
        cur_thread_snap->ths_continuation = VM_KERNEL_UNSLIDE(thread->continuation);
        cur_thread_snap->ths_total_syscalls = thread->syscalls_mach + thread->syscalls_unix;

        if (IPC_VOUCHER_NULL != thread->ith_voucher)
                cur_thread_snap->ths_voucher_identifier = VM_KERNEL_ADDRPERM(thread->ith_voucher);
        else
                cur_thread_snap->ths_voucher_identifier = 0;

        cur_thread_snap->ths_dqserialnum = 0;
        if (dispatch_p && (task != kernel_task) && (task->active) && have_pmap) {
                uint64_t dqkeyaddr = thread_dispatchqaddr(thread);
                if (dqkeyaddr != 0) {
                        uint64_t dqaddr = 0;
                        boolean_t copyin_ok = kdp_copyin_word(task, dqkeyaddr, &dqaddr, FALSE, NULL);
                        if (copyin_ok && dqaddr != 0) {
                                uint64_t dqserialnumaddr = dqaddr + get_task_dispatchqueue_serialno_offset(task);
                                uint64_t dqserialnum = 0;
                                copyin_ok = kdp_copyin_word(task, dqserialnumaddr, &dqserialnum, FALSE, NULL);
                                if (copyin_ok) {
                                        cur_thread_snap->ths_ss_flags |= kHasDispatchSerial;
                                        cur_thread_snap->ths_dqserialnum = dqserialnum;
                                }
                        }
                }
        }

        tval = safe_grab_timer_value(&thread->user_timer);
        cur_thread_snap->ths_user_time = tval;
        tval = safe_grab_timer_value(&thread->system_timer);

        if (thread->precise_user_kernel_time) {
                cur_thread_snap->ths_sys_time = tval;
        } else {
                cur_thread_snap->ths_user_time += tval;
                cur_thread_snap->ths_sys_time = 0;
        }

        cur_thread_snap->ths_ss_flags = 0;
        if (thread->thread_tag & THREAD_TAG_MAINTHREAD)
                cur_thread_snap->ths_ss_flags |= kThreadMain;
        if (thread->effective_policy.thep_darwinbg)
                cur_thread_snap->ths_ss_flags |= kThreadDarwinBG;
        if (proc_get_effective_thread_policy(thread, TASK_POLICY_PASSIVE_IO))
                cur_thread_snap->ths_ss_flags |= kThreadIOPassive;
        if (thread->suspend_count > 0)
                cur_thread_snap->ths_ss_flags |= kThreadSuspended;
        if (thread->options & TH_OPT_GLOBAL_FORCED_IDLE)
                cur_thread_snap->ths_ss_flags |= kGlobalForcedIdle;
        if (thread_on_core)
                cur_thread_snap->ths_ss_flags |= kThreadOnCore;
        if (stackshot_thread_is_idle_worker_unsafe(thread))
                cur_thread_snap->ths_ss_flags |= kThreadIdleWorker;

        /* make sure state flags defined in kcdata.h still match internal flags */
        static_assert(SS_TH_WAIT == TH_WAIT);
        static_assert(SS_TH_SUSP == TH_SUSP);
        static_assert(SS_TH_RUN == TH_RUN);
        static_assert(SS_TH_UNINT == TH_UNINT);
        static_assert(SS_TH_TERMINATE == TH_TERMINATE);
        static_assert(SS_TH_TERMINATE2 == TH_TERMINATE2);
        static_assert(SS_TH_IDLE == TH_IDLE);

        cur_thread_snap->ths_last_run_time           = thread->last_run_time;
        cur_thread_snap->ths_last_made_runnable_time = thread->last_made_runnable_time;
        cur_thread_snap->ths_state                   = thread->state;
        cur_thread_snap->ths_sched_flags             = thread->sched_flags;
        cur_thread_snap->ths_base_priority = thread->base_pri;
        cur_thread_snap->ths_sched_priority = thread->sched_pri;
        cur_thread_snap->ths_eqos = thread->effective_policy.thep_qos;
        cur_thread_snap->ths_rqos = thread->requested_policy.thrp_qos;
        cur_thread_snap->ths_rqos_override = thread->requested_policy.thrp_qos_override;
        cur_thread_snap->ths_io_tier = proc_get_effective_thread_policy(thread, TASK_POLICY_IO);
        cur_thread_snap->ths_thread_t = VM_KERNEL_UNSLIDE_OR_PERM(thread);

        static_assert(sizeof(thread->effective_policy) == sizeof(uint64_t));
        static_assert(sizeof(thread->requested_policy) == sizeof(uint64_t));
        cur_thread_snap->ths_requested_policy = *(unaligned_u64 *) &thread->requested_policy;
        cur_thread_snap->ths_effective_policy = *(unaligned_u64 *) &thread->effective_policy;

        /* if there is thread name then add to buffer */
        cur_thread_name[0] = '\0';
        proc_threadname_kdp(thread->uthread, cur_thread_name, STACKSHOT_MAX_THREAD_NAME_SIZE);
        if (strnlen(cur_thread_name, STACKSHOT_MAX_THREAD_NAME_SIZE) > 0) {
                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_THREAD_NAME, sizeof(cur_thread_name), &out_addr));
                stackshot_memcpy((void *)out_addr, (void *)cur_thread_name, sizeof(cur_thread_name));
        }

        /* record system and user cpu times */
        time_value_t user_time;
        time_value_t system_time;
        thread_read_times(thread, &user_time, &system_time);
        kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_CPU_TIMES, sizeof(struct stackshot_cpu_times), &out_addr));
        struct stackshot_cpu_times * stackshot_cpu_times = (struct stackshot_cpu_times *)out_addr;
        stackshot_cpu_times->user_usec                   = ((uint64_t)user_time.seconds) * USEC_PER_SEC + user_time.microseconds;
        stackshot_cpu_times->system_usec                 = ((uint64_t)system_time.seconds) * USEC_PER_SEC + system_time.microseconds;

        /* Trace user stack, if any */
        if (!active_kthreads_only_p && task->active && thread->task->map != kernel_map) {
                uint32_t thread_snapshot_flags = 0;
                /* 64-bit task? */
                if (task64) {
                        out_addr    = (mach_vm_address_t)kcd_end_address(kcd);
                        saved_count = machine_trace_thread64(thread, (char *)out_addr, (char *)kcd_max_address(kcd), MAX_FRAMES, TRUE,
                                                             trace_fp_p, &thread_snapshot_flags);
                        if (saved_count > 0) {
                                int frame_size = trace_fp_p ? sizeof(struct stack_snapshot_frame64) : sizeof(uint64_t);
                                kcd_exit_on_error(kcdata_get_memory_addr_for_array(kcd, trace_fp_p ? STACKSHOT_KCTYPE_USER_STACKFRAME64
                                                                                                   : STACKSHOT_KCTYPE_USER_STACKLR64,
                                                                                   frame_size, saved_count / frame_size, &out_addr));
                                cur_thread_snap->ths_ss_flags |= kUser64_p;
                        }
                } else {
                        out_addr    = (mach_vm_address_t)kcd_end_address(kcd);
                        saved_count = machine_trace_thread(thread, (char *)out_addr, (char *)kcd_max_address(kcd), MAX_FRAMES, TRUE, trace_fp_p,
                                                           &thread_snapshot_flags);
                        if (saved_count > 0) {
                                int frame_size = trace_fp_p ? sizeof(struct stack_snapshot_frame32) : sizeof(uint32_t);
                                kcd_exit_on_error(kcdata_get_memory_addr_for_array(kcd, trace_fp_p ? STACKSHOT_KCTYPE_USER_STACKFRAME
                                                                                                   : STACKSHOT_KCTYPE_USER_STACKLR,
                                                                                   frame_size, saved_count / frame_size, &out_addr));
                        }
                }

                if (thread_snapshot_flags != 0) {
                        cur_thread_snap->ths_ss_flags |= thread_snapshot_flags;
                }
        }

        /* Call through to the machine specific trace routines
         * Frames are added past the snapshot header.
         */
        if (thread->kernel_stack != 0) {
                uint32_t thread_snapshot_flags = 0;
#if defined(__LP64__)
                out_addr    = (mach_vm_address_t)kcd_end_address(kcd);
                saved_count = machine_trace_thread64(thread, (char *)out_addr, (char *)kcd_max_address(kcd), MAX_FRAMES, FALSE, trace_fp_p,
                                                     &thread_snapshot_flags);
                if (saved_count > 0) {
                        int frame_size = trace_fp_p ? sizeof(struct stack_snapshot_frame64) : sizeof(uint64_t);
                        cur_thread_snap->ths_ss_flags |= kKernel64_p;
                        kcd_exit_on_error(kcdata_get_memory_addr_for_array(kcd, trace_fp_p ? STACKSHOT_KCTYPE_KERN_STACKFRAME64
                                                                                           : STACKSHOT_KCTYPE_KERN_STACKLR64,
                                                                           frame_size, saved_count / frame_size, &out_addr));
                }
#else
                out_addr             = (mach_vm_address_t)kcd_end_address(kcd);
                saved_count = machine_trace_thread(thread, (char *)out_addr, (char *)kcd_max_address(kcd), MAX_FRAMES, FALSE, trace_fp_p,
                                                   &thread_snapshot_flags);
                if (saved_count > 0) {
                        int frame_size = trace_fp_p ? sizeof(struct stack_snapshot_frame32) : sizeof(uint32_t);
                        kcd_exit_on_error(
                            kcdata_get_memory_addr_for_array(kcd, trace_fp_p ? STACKSHOT_KCTYPE_KERN_STACKFRAME : STACKSHOT_KCTYPE_KERN_STACKLR,
                                                             frame_size, saved_count / frame_size, &out_addr));
                }
#endif
                if (thread_snapshot_flags != 0) {
                        cur_thread_snap->ths_ss_flags |= thread_snapshot_flags;
                }
        }


        if (collect_iostats) {
                kcd_exit_on_error(kcdata_record_thread_iostats(kcd, thread));
        }

#if MONOTONIC
        if (collect_instrs_cycles) {
                uint64_t instrs = 0, cycles = 0;
                mt_stackshot_thread(thread, &instrs, &cycles);

                kcd_exit_on_error(kcdata_get_memory_addr(kcd, STACKSHOT_KCTYPE_INSTRS_CYCLES, sizeof(struct instrs_cycles_snapshot), &out_addr));
                struct instrs_cycles_snapshot *instrs_cycles = (struct instrs_cycles_snapshot *)out_addr;
                instrs_cycles->ics_instructions = instrs;
                instrs_cycles->ics_cycles = cycles;
        }
#endif /* MONOTONIC */

error_exit:
        return error;
}

static int
kcdata_record_thread_delta_snapshot(struct thread_delta_snapshot_v2 * cur_thread_snap, thread_t thread, boolean_t thread_on_core)
{
        cur_thread_snap->tds_thread_id = thread_tid(thread);
        if (IPC_VOUCHER_NULL != thread->ith_voucher)
                cur_thread_snap->tds_voucher_identifier  = VM_KERNEL_ADDRPERM(thread->ith_voucher);
        else
                cur_thread_snap->tds_voucher_identifier = 0;

        cur_thread_snap->tds_ss_flags = 0;
        if (thread->effective_policy.thep_darwinbg)
                cur_thread_snap->tds_ss_flags |= kThreadDarwinBG;
        if (proc_get_effective_thread_policy(thread, TASK_POLICY_PASSIVE_IO))
                cur_thread_snap->tds_ss_flags |= kThreadIOPassive;
        if (thread->suspend_count > 0)
                cur_thread_snap->tds_ss_flags |= kThreadSuspended;
        if (thread->options & TH_OPT_GLOBAL_FORCED_IDLE)
                cur_thread_snap->tds_ss_flags |= kGlobalForcedIdle;
        if (thread_on_core)
                cur_thread_snap->tds_ss_flags |= kThreadOnCore;
        if (stackshot_thread_is_idle_worker_unsafe(thread))
                cur_thread_snap->tds_ss_flags |= kThreadIdleWorker;

        cur_thread_snap->tds_last_made_runnable_time = thread->last_made_runnable_time;
        cur_thread_snap->tds_state                   = thread->state;
        cur_thread_snap->tds_sched_flags             = thread->sched_flags;
        cur_thread_snap->tds_base_priority           = thread->base_pri;
        cur_thread_snap->tds_sched_priority          = thread->sched_pri;
        cur_thread_snap->tds_eqos                    = thread->effective_policy.thep_qos;
        cur_thread_snap->tds_rqos                    = thread->requested_policy.thrp_qos;
        cur_thread_snap->tds_rqos_override           = thread->requested_policy.thrp_qos_override;
        cur_thread_snap->tds_io_tier                 = proc_get_effective_thread_policy(thread, TASK_POLICY_IO);

        return 0;
}

/*
 * Why 12?  12 strikes a decent balance between allocating a large array on
 * the stack and having large kcdata item overheads for recording nonrunable
 * tasks.
 */
#define UNIQUEIDSPERFLUSH 12

struct saved_uniqueids {
        uint64_t ids[UNIQUEIDSPERFLUSH];
        unsigned count;
};

static kern_return_t
flush_nonrunnable_tasks(struct saved_uniqueids * ids)
{
        if (ids->count == 0)
                return KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;
        kern_return_t ret = kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_NONRUNNABLE_TASKS, sizeof(uint64_t),
                                                             ids->count, &out_addr);
        if (ret != KERN_SUCCESS) {
                return ret;
        }
        stackshot_memcpy((void *)out_addr, ids->ids, sizeof(uint64_t) * ids->count);
        ids->count = 0;
        return ret;
}

static kern_return_t
handle_nonrunnable_task(struct saved_uniqueids * ids, uint64_t pid)
{
        kern_return_t ret    = KERN_SUCCESS;
        ids->ids[ids->count] = pid;
        ids->count++;
        assert(ids->count <= UNIQUEIDSPERFLUSH);
        if (ids->count == UNIQUEIDSPERFLUSH)
                ret = flush_nonrunnable_tasks(ids);
        return ret;
}

enum thread_classification {
        tc_full_snapshot,  /* take a full snapshot */
        tc_delta_snapshot, /* take a delta snapshot */
        tc_nonrunnable,    /* only report id */
};

static enum thread_classification
classify_thread(thread_t thread, boolean_t * thread_on_core_p, uint32_t trace_flags)
{
        boolean_t collect_delta_stackshot = ((trace_flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) != 0);
        boolean_t minimize_nonrunnables   = ((trace_flags & STACKSHOT_TAILSPIN) != 0);

        processor_t last_processor = thread->last_processor;

        boolean_t thread_on_core =
            (last_processor != PROCESSOR_NULL && last_processor->state == PROCESSOR_RUNNING && last_processor->active_thread == thread);

        *thread_on_core_p = thread_on_core;

        /* Capture the full thread snapshot if this is not a delta stackshot or if the thread has run subsequent to the
         * previous full stackshot */
        if (!collect_delta_stackshot || thread_on_core || (thread->last_run_time > stack_snapshot_delta_since_timestamp)) {
                return tc_full_snapshot;
        } else {
                if (minimize_nonrunnables && !(thread->state & TH_RUN)) {
                        return tc_nonrunnable;
                } else {
                        return tc_delta_snapshot;
                }
        }
}

static kern_return_t
kdp_stackshot_kcdata_format(int pid, uint32_t trace_flags, uint32_t * pBytesTraced)
{
        kern_return_t error        = KERN_SUCCESS;
        mach_vm_address_t out_addr = 0;
        uint64_t abs_time = 0, abs_time_end = 0;
        uint64_t *abs_time_addr = NULL;
        uint64_t system_state_flags = 0;
        int saved_count = 0;
        task_t task = TASK_NULL;
        thread_t thread = THREAD_NULL;
        mach_timebase_info_data_t timebase = {0, 0};
        uint32_t length_to_copy = 0, tmp32 = 0;

        abs_time = mach_absolute_time();

        /* process the flags */
        boolean_t active_kthreads_only_p  = ((trace_flags & STACKSHOT_ACTIVE_KERNEL_THREADS_ONLY) != 0);
        boolean_t save_donating_pids_p    = ((trace_flags & STACKSHOT_SAVE_IMP_DONATION_PIDS) != 0);
        boolean_t collect_delta_stackshot = ((trace_flags & STACKSHOT_COLLECT_DELTA_SNAPSHOT) != 0);
        boolean_t minimize_nonrunnables   = ((trace_flags & STACKSHOT_TAILSPIN) != 0);
        boolean_t use_fault_path          = ((trace_flags & (STACKSHOT_ENABLE_UUID_FAULTING | STACKSHOT_ENABLE_BT_FAULTING)) != 0);
        boolean_t save_owner_info         = ((trace_flags & STACKSHOT_THREAD_WAITINFO) != 0);
        stack_enable_faulting = (trace_flags & (STACKSHOT_ENABLE_BT_FAULTING));

#if CONFIG_EMBEDDED
        /* KEXTs can't be described by just a base address on embedded */
        trace_flags &= ~(STACKSHOT_SAVE_KEXT_LOADINFO);
#endif

        struct saved_uniqueids saved_uniqueids = {.count = 0};

        if (use_fault_path) {
                fault_stats.sfs_pages_faulted_in = 0;
                fault_stats.sfs_time_spent_faulting = 0;
                fault_stats.sfs_stopped_faulting = (uint8_t) FALSE;
        }

        if (sizeof(void *) == 8)
                system_state_flags |= kKernel64_p;

        if (stackshot_kcdata_p == NULL || pBytesTraced == NULL) {
                error = KERN_INVALID_ARGUMENT;
                goto error_exit;
        }

        /* setup mach_absolute_time and timebase info -- copy out in some cases and needed to convert since_timestamp to seconds for proc start time */
        clock_timebase_info(&timebase);

        /* begin saving data into the buffer */
        *pBytesTraced = 0;
        kcd_exit_on_error(kcdata_add_uint32_with_description(stackshot_kcdata_p, trace_flags, "stackshot_in_flags"));
        kcd_exit_on_error(kcdata_add_uint32_with_description(stackshot_kcdata_p, (uint32_t)pid, "stackshot_in_pid"));
        kcd_exit_on_error(kcdata_add_uint64_with_description(stackshot_kcdata_p, system_state_flags, "system_state_flags"));

#if CONFIG_JETSAM
        tmp32 = memorystatus_get_pressure_status_kdp();
        kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_JETSAM_LEVEL, sizeof(uint32_t), &out_addr));
        stackshot_memcpy((void *)out_addr, &tmp32, sizeof(tmp32));
#endif

        if (!collect_delta_stackshot) {
                tmp32 = THREAD_POLICY_INTERNAL_STRUCT_VERSION;
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_THREAD_POLICY_VERSION, sizeof(uint32_t), &out_addr));
                stackshot_memcpy((void *)out_addr, &tmp32, sizeof(tmp32));

                tmp32 = PAGE_SIZE;
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_KERN_PAGE_SIZE, sizeof(uint32_t), &out_addr));
                stackshot_memcpy((void *)out_addr, &tmp32, sizeof(tmp32));

                /* save boot-args and osversion string */
                length_to_copy =  MIN((uint32_t)(strlen(version) + 1), OSVERSIZE);
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_OSVERSION, length_to_copy, &out_addr));
                stackshot_strlcpy((char*)out_addr, &version[0], length_to_copy);

                length_to_copy =  MIN((uint32_t)(strlen(PE_boot_args()) + 1), OSVERSIZE);
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_BOOTARGS, length_to_copy, &out_addr));
                stackshot_strlcpy((char*)out_addr, PE_boot_args(), length_to_copy);

                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, KCDATA_TYPE_TIMEBASE, sizeof(timebase), &out_addr));
                stackshot_memcpy((void *)out_addr, &timebase, sizeof(timebase));
        } else {
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_DELTA_SINCE_TIMESTAMP, sizeof(uint64_t), &out_addr));
                stackshot_memcpy((void*)out_addr, &stack_snapshot_delta_since_timestamp, sizeof(stack_snapshot_delta_since_timestamp));
        }

        kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, KCDATA_TYPE_MACH_ABSOLUTE_TIME, sizeof(uint64_t), &out_addr));
        abs_time_addr = (uint64_t *)out_addr;
        stackshot_memcpy((void *)abs_time_addr, &abs_time, sizeof(uint64_t));

        kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, KCDATA_TYPE_USECS_SINCE_EPOCH, sizeof(uint64_t), &out_addr));
        stackshot_memcpy((void *)out_addr, &stackshot_microsecs, sizeof(uint64_t));

        /* reserve space of system level shared cache load info */
        struct dyld_uuid_info_64_v2 * sys_shared_cache_loadinfo = NULL;
        if (!collect_delta_stackshot) {
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_SHAREDCACHE_LOADINFO,
                                                         sizeof(struct dyld_uuid_info_64_v2), &out_addr));
                sys_shared_cache_loadinfo = (struct dyld_uuid_info_64_v2 *)out_addr;
                bzero((void *)sys_shared_cache_loadinfo, sizeof(struct dyld_uuid_info_64_v2));
        }

        /* Add requested information first */
        if (trace_flags & STACKSHOT_GET_GLOBAL_MEM_STATS) {
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_GLOBAL_MEM_STATS, sizeof(struct mem_and_io_snapshot), &out_addr));
                kdp_mem_and_io_snapshot((struct mem_and_io_snapshot *)out_addr);
        }

#if CONFIG_COALITIONS
        int num_coalitions = 0;
        struct jetsam_coalition_snapshot *coalitions = NULL;
        /* Iterate over coalitions */
        if (trace_flags & STACKSHOT_SAVE_JETSAM_COALITIONS) {
                if (coalition_iterate_stackshot(stackshot_coalition_jetsam_count, &num_coalitions, COALITION_TYPE_JETSAM) != KERN_SUCCESS) {
                        trace_flags &= ~(STACKSHOT_SAVE_JETSAM_COALITIONS);
                }
        }
        if (trace_flags & STACKSHOT_SAVE_JETSAM_COALITIONS) {
                if (num_coalitions > 0) {
                        kcd_exit_on_error(kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_JETSAM_COALITION_SNAPSHOT, sizeof(struct jetsam_coalition_snapshot), num_coalitions, &out_addr));
                        coalitions = (struct jetsam_coalition_snapshot*)out_addr;
                }

                if (coalition_iterate_stackshot(stackshot_coalition_jetsam_snapshot, coalitions, COALITION_TYPE_JETSAM) != KERN_SUCCESS) {
                        error = KERN_FAILURE;
                        goto error_exit;
                }

        }
#else
        trace_flags &= ~(STACKSHOT_SAVE_JETSAM_COALITIONS);
#endif /* CONFIG_COALITIONS */

        trace_flags &= ~(STACKSHOT_THREAD_GROUP);

        /* Iterate over tasks */
        queue_head_t *task_list = &tasks;
        queue_iterate(task_list, task, task_t, tasks) {
                int task_pid                   = 0;
                uint64_t task_uniqueid         = 0;
                int num_delta_thread_snapshots = 0;
                int num_nonrunnable_threads    = 0;
                int num_waitinfo_threads       = 0;

                uint64_t task_start_abstime    = 0;
                boolean_t task_delta_stackshot = FALSE;
                boolean_t task64 = FALSE, have_map = FALSE, have_pmap = FALSE;
                boolean_t some_thread_ran = FALSE;
                unaligned_u64 *task_snap_ss_flags = NULL;

                if ((task == NULL) || !ml_validate_nofault((vm_offset_t)task, sizeof(struct task))) {
                        error = KERN_FAILURE;
                        goto error_exit;
                }

                have_map = (task->map != NULL) && (ml_validate_nofault((vm_offset_t)(task->map), sizeof(struct _vm_map)));
                have_pmap = have_map && (task->map->pmap != NULL) && (ml_validate_nofault((vm_offset_t)(task->map->pmap), sizeof(struct pmap)));

                task_pid = pid_from_task(task);
                task_uniqueid = get_task_uniqueid(task);
                task64 = task_has_64BitAddr(task);

                if (!task->active || task_is_a_corpse(task)) {
                        /*
                         * Not interested in terminated tasks without threads, and
                         * at the moment, stackshot can't handle a task  without a name.
                         */
                        if (queue_empty(&task->threads) || task_pid == -1) {
                                continue;
                        }
                }

                if (collect_delta_stackshot) {
                        proc_starttime_kdp(task->bsd_info, NULL, NULL, &task_start_abstime);
                }

                /* Trace everything, unless a process was specified */
                if ((pid == -1) || (pid == task_pid)) {
#if DEBUG || DEVELOPMENT
                        /* we might want to call kcdata_undo_add_container_begin(), which is
                         * only safe if we call it after kcdata_add_container_marker() but
                         * before adding any other kcdata items.  In development kernels,
                         * we'll remember where the buffer end was and confirm after calling
                         * kcdata_undo_add_container_begin() that it's in exactly the same
                         * place.*/
                        mach_vm_address_t revert_addr = stackshot_kcdata_p->kcd_addr_end;
#endif

                        /* add task snapshot marker */
                        kcd_exit_on_error(kcdata_add_container_marker(stackshot_kcdata_p, KCDATA_TYPE_CONTAINER_BEGIN,
                                                                      STACKSHOT_KCCONTAINER_TASK, task_uniqueid));

                        if (!collect_delta_stackshot || (task_start_abstime == 0) ||
                            (task_start_abstime > stack_snapshot_delta_since_timestamp)) {
                                kcd_exit_on_error(kcdata_record_task_snapshot(stackshot_kcdata_p, task, trace_flags, have_pmap, &task_snap_ss_flags));
                        } else {
                                task_delta_stackshot = TRUE;
                                if (minimize_nonrunnables) {
                                        // delay taking the task snapshot.  If there are no runnable threads we'll skip it.
                                } else {
                                        kcd_exit_on_error(kcdata_record_task_delta_snapshot(stackshot_kcdata_p, task, have_pmap, &task_snap_ss_flags));
                                }
                        }

                        /* Iterate over task threads */
                        queue_iterate(&task->threads, thread, thread_t, task_threads)
                        {
                                uint64_t thread_uniqueid;

                                if ((thread == NULL) || !ml_validate_nofault((vm_offset_t)thread, sizeof(struct thread))) {
                                        error = KERN_FAILURE;
                                        goto error_exit;
                                }

                                if (active_kthreads_only_p && thread->kernel_stack == 0)
                                        continue;

                                thread_uniqueid = thread_tid(thread);

                                boolean_t thread_on_core;
                                enum thread_classification thread_classification = classify_thread(thread, &thread_on_core, trace_flags);

                                switch (thread_classification) {
                                case tc_full_snapshot:
                                        /* add thread marker */
                                        kcd_exit_on_error(kcdata_add_container_marker(stackshot_kcdata_p, KCDATA_TYPE_CONTAINER_BEGIN,
                                                                                      STACKSHOT_KCCONTAINER_THREAD, thread_uniqueid));
                                        kcd_exit_on_error(
                                            kcdata_record_thread_snapshot(stackshot_kcdata_p, thread, task, trace_flags, have_pmap, thread_on_core));

                                        /* mark end of thread snapshot data */
                                        kcd_exit_on_error(kcdata_add_container_marker(stackshot_kcdata_p, KCDATA_TYPE_CONTAINER_END,
                                                                                      STACKSHOT_KCCONTAINER_THREAD, thread_uniqueid));

                                        some_thread_ran = TRUE;
                                        break;

                                case tc_delta_snapshot:
                                        num_delta_thread_snapshots++;
                                        break;

                                case tc_nonrunnable:
                                        num_nonrunnable_threads++;
                                        break;
                                }

                                /* We want to report owner information regardless of whether a thread
                                 * has changed since the last delta, whether it's a normal stackshot,
                                 * or whether it's nonrunnable */
                                if (save_owner_info && stackshot_thread_has_valid_waitinfo(thread))
                                        num_waitinfo_threads++;
                        }

                        if (task_delta_stackshot && minimize_nonrunnables) {
                                if (some_thread_ran || num_delta_thread_snapshots > 0) {
                                        kcd_exit_on_error(kcdata_record_task_delta_snapshot(stackshot_kcdata_p, task, have_pmap, &task_snap_ss_flags));
                                } else {
                                        kcd_exit_on_error(kcdata_undo_add_container_begin(stackshot_kcdata_p));

#if DEBUG || DEVELOPMENT
                                        mach_vm_address_t undo_addr = stackshot_kcdata_p->kcd_addr_end;
                                        if (revert_addr != undo_addr) {
                                                panic("tried to revert a container begin but we already moved past it. revert=%p undo=%p",
                                                      (void *)revert_addr, (void *)undo_addr);
                                        }
#endif
                                        kcd_exit_on_error(handle_nonrunnable_task(&saved_uniqueids, task_uniqueid));
                                        continue;
                                }
                        }

                        struct thread_delta_snapshot_v2 * delta_snapshots = NULL;
                        int current_delta_snapshot_index                  = 0;

                        if (num_delta_thread_snapshots > 0) {
                                kcd_exit_on_error(kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_THREAD_DELTA_SNAPSHOT,
                                                                                   sizeof(struct thread_delta_snapshot_v2),
                                                                                   num_delta_thread_snapshots, &out_addr));
                                delta_snapshots = (struct thread_delta_snapshot_v2 *)out_addr;
                        }

                        uint64_t * nonrunnable_tids   = NULL;
                        int current_nonrunnable_index = 0;

                        if (num_nonrunnable_threads > 0) {
                                kcd_exit_on_error(kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_NONRUNNABLE_TIDS,
                                                                                   sizeof(uint64_t), num_nonrunnable_threads, &out_addr));
                                nonrunnable_tids = (uint64_t *)out_addr;
                        }

                        thread_waitinfo_t *thread_waitinfo = NULL;
                        int current_waitinfo_index         = 0;

                        if (num_waitinfo_threads > 0) {
                                kcd_exit_on_error(kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_THREAD_WAITINFO,
                                                                           sizeof(thread_waitinfo_t), num_waitinfo_threads, &out_addr));
                                thread_waitinfo = (thread_waitinfo_t *)out_addr;
                        }

                        if (num_delta_thread_snapshots > 0 || num_nonrunnable_threads > 0 || num_waitinfo_threads > 0) {
                                queue_iterate(&task->threads, thread, thread_t, task_threads)
                                {
                                        if (active_kthreads_only_p && thread->kernel_stack == 0)
                                                continue;

                                        /* If we want owner info, we should capture it regardless of its classification */
                                        if (save_owner_info && stackshot_thread_has_valid_waitinfo(thread)) {
                                                stackshot_thread_wait_owner_info(
                                                                thread,
                                                                &thread_waitinfo[current_waitinfo_index++]);
                                        }

                                        boolean_t thread_on_core;
                                        enum thread_classification thread_classification = classify_thread(thread, &thread_on_core, trace_flags);

                                        switch (thread_classification) {
                                        case tc_full_snapshot:
                                                /* full thread snapshot captured above */
                                                continue;

                                        case tc_delta_snapshot:
                                                kcd_exit_on_error(kcdata_record_thread_delta_snapshot(&delta_snapshots[current_delta_snapshot_index++],
                                                                                                      thread, thread_on_core));
                                                break;

                                        case tc_nonrunnable:
                                                nonrunnable_tids[current_nonrunnable_index++] = thread_tid(thread);
                                                continue;
                                        }
                                }

#if DEBUG || DEVELOPMENT
                                if (current_delta_snapshot_index != num_delta_thread_snapshots) {
                                        panic("delta thread snapshot count mismatch while capturing snapshots for task %p. expected %d, found %d", task,
                                              num_delta_thread_snapshots, current_delta_snapshot_index);
                                }
                                if (current_nonrunnable_index != num_nonrunnable_threads) {
                                        panic("nonrunnable thread count mismatch while capturing snapshots for task %p. expected %d, found %d", task,
                                              num_nonrunnable_threads, current_nonrunnable_index);
                                }
                                if (current_waitinfo_index != num_waitinfo_threads) {
                                        panic("thread wait info count mismatch while capturing snapshots for task %p. expected %d, found %d", task,
                                              num_waitinfo_threads, current_waitinfo_index);
                                }
#endif
                        }

#if IMPORTANCE_INHERITANCE
                        if (save_donating_pids_p) {
                                kcd_exit_on_error(
                                    ((((mach_vm_address_t)kcd_end_address(stackshot_kcdata_p) + (TASK_IMP_WALK_LIMIT * sizeof(int32_t))) <
                                      (mach_vm_address_t)kcd_max_address(stackshot_kcdata_p))
                                         ? KERN_SUCCESS
                                         : KERN_RESOURCE_SHORTAGE));
                                saved_count = task_importance_list_pids(task, TASK_IMP_LIST_DONATING_PIDS,
                                                                        (void *)kcd_end_address(stackshot_kcdata_p), TASK_IMP_WALK_LIMIT);
                                if (saved_count > 0)
                                        kcd_exit_on_error(kcdata_get_memory_addr_for_array(stackshot_kcdata_p, STACKSHOT_KCTYPE_DONATING_PIDS,
                                                                                           sizeof(int32_t), saved_count, &out_addr));
                        }
#endif

                        if (!collect_delta_stackshot || (num_delta_thread_snapshots != task->thread_count) || !task_delta_stackshot) {
                                /*
                                 * Collect shared cache info and UUID info in these scenarios
                                 * 1) a full stackshot
                                 * 2) a delta stackshot where the task started after the previous full stackshot OR
                                 *    any thread from the task has run since the previous full stackshot
                                 */

                                kcd_exit_on_error(kcdata_record_shared_cache_info(stackshot_kcdata_p, task, sys_shared_cache_loadinfo, task_snap_ss_flags));
                                kcd_exit_on_error(kcdata_record_uuid_info(stackshot_kcdata_p, task, trace_flags, have_pmap, task_snap_ss_flags));
                        }
                        /* mark end of task snapshot data */
                        kcd_exit_on_error(kcdata_add_container_marker(stackshot_kcdata_p, KCDATA_TYPE_CONTAINER_END, STACKSHOT_KCCONTAINER_TASK,
                                                                      task_uniqueid));
                }
        }

        if (minimize_nonrunnables) {
                flush_nonrunnable_tasks(&saved_uniqueids);
        }

        if (use_fault_path) {
                kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_STACKSHOT_FAULT_STATS,
                                                                sizeof(struct stackshot_fault_stats), &out_addr));
                stackshot_memcpy((void*)out_addr, &fault_stats, sizeof(struct stackshot_fault_stats));
        }

        /* update timestamp of the stackshot */
        abs_time_end = mach_absolute_time();
#if DEVELOPMENT || DEBUG
        kcd_exit_on_error(kcdata_get_memory_addr(stackshot_kcdata_p, STACKSHOT_KCTYPE_STACKSHOT_DURATION,
                                                 sizeof(struct stackshot_duration), &out_addr));
        struct stackshot_duration * stackshot_duration = (struct stackshot_duration *)out_addr;
        stackshot_duration->stackshot_duration         = (abs_time_end - abs_time);
        stackshot_duration->stackshot_duration_outer   = 0;
        stackshot_duration_outer                       = (unaligned_u64 *)&stackshot_duration->stackshot_duration_outer;
#endif
        stackshot_memcpy((void *)abs_time_addr, &abs_time_end, sizeof(uint64_t));

        kcd_exit_on_error(kcdata_add_uint32_with_description(stackshot_kcdata_p, trace_flags, "stackshot_out_flags"));

        kcd_exit_on_error(kcdata_write_buffer_end(stackshot_kcdata_p));

        /*  === END of populating stackshot data === */

        *pBytesTraced = (uint32_t) kcdata_memory_get_used_bytes(stackshot_kcdata_p);
error_exit:

#if INTERRUPT_MASKED_DEBUG
        if (!panic_stackshot) {
                /*
                 * Try to catch instances where stackshot takes too long BEFORE returning from
                 * the debugger
                 */
                ml_check_interrupts_disabled_duration(current_thread());
        }
#endif

        stack_enable_faulting = FALSE;

        return error;
}

static uint64_t
proc_was_throttled_from_task(task_t task)
{
        uint64_t was_throttled = 0;

        if (task->bsd_info)
                was_throttled = proc_was_throttled(task->bsd_info);
        
        return was_throttled;
}

static uint64_t
proc_did_throttle_from_task(task_t task)
{
        uint64_t did_throttle = 0;

        if (task->bsd_info)
                did_throttle = proc_did_throttle(task->bsd_info);
        
        return did_throttle;
}

static void
kdp_mem_and_io_snapshot(struct mem_and_io_snapshot *memio_snap)
{
        unsigned int pages_reclaimed;
        unsigned int pages_wanted;
        kern_return_t kErr;

        processor_t processor;
        vm_statistics64_t stat;
        vm_statistics64_data_t host_vm_stat;

        processor = processor_list;
        stat = &PROCESSOR_DATA(processor, vm_stat);
        host_vm_stat = *stat;

        if (processor_count > 1) {
                /*
                 * processor_list may be in the process of changing as we are
                 * attempting a stackshot.  Ordinarily it will be lock protected,
                 * but it is not safe to lock in the context of the debugger.
                 * Fortunately we never remove elements from the processor list,
                 * and only add to to the end of the list, so we SHOULD be able
                 * to walk it.  If we ever want to truly tear down processors,
                 * this will have to change.
                 */
                while ((processor = processor->processor_list) != NULL) {
                        stat = &PROCESSOR_DATA(processor, vm_stat);
                        host_vm_stat.compressions += stat->compressions;
                        host_vm_stat.decompressions += stat->decompressions;
                }
        }

        memio_snap->snapshot_magic = STACKSHOT_MEM_AND_IO_SNAPSHOT_MAGIC;
        memio_snap->free_pages = vm_page_free_count;
        memio_snap->active_pages = vm_page_active_count;
        memio_snap->inactive_pages = vm_page_inactive_count;
        memio_snap->purgeable_pages = vm_page_purgeable_count;
        memio_snap->wired_pages = vm_page_wire_count;
        memio_snap->speculative_pages = vm_page_speculative_count;
        memio_snap->throttled_pages = vm_page_throttled_count;
        memio_snap->busy_buffer_count = count_busy_buffers();
        memio_snap->filebacked_pages = vm_page_pageable_external_count;
        memio_snap->compressions = (uint32_t)host_vm_stat.compressions;
        memio_snap->decompressions = (uint32_t)host_vm_stat.decompressions;
        memio_snap->compressor_size = VM_PAGE_COMPRESSOR_COUNT;
        kErr = mach_vm_pressure_monitor(FALSE, VM_PRESSURE_TIME_WINDOW, &pages_reclaimed, &pages_wanted);

        if ( ! kErr ) {
                memio_snap->pages_wanted = (uint32_t)pages_wanted;
                memio_snap->pages_reclaimed = (uint32_t)pages_reclaimed;
                memio_snap->pages_wanted_reclaimed_valid = 1;
        } else {
                memio_snap->pages_wanted = 0;
                memio_snap->pages_reclaimed = 0;
                memio_snap->pages_wanted_reclaimed_valid = 0;
        }
}

void
stackshot_memcpy(void *dst, const void *src, size_t len)
{
#if CONFIG_EMBEDDED
        if (panic_stackshot) {
                uint8_t *dest_bytes = (uint8_t *)dst;
                const uint8_t *src_bytes = (const uint8_t *)src;
                for (size_t i = 0; i < len; i++) {
                        dest_bytes[i] = src_bytes[i];
                }
        } else
#endif
                memcpy(dst, src, len);
}

size_t
stackshot_strlcpy(char *dst, const char *src, size_t maxlen)
{
        const size_t srclen = strlen(src);

        if (srclen < maxlen) {
                stackshot_memcpy(dst, src, srclen+1);
        } else if (maxlen != 0) {
                stackshot_memcpy(dst, src, maxlen-1);
                dst[maxlen-1] = '\0';
        }

        return srclen;
}


/*
 * Returns the physical address of the specified map:target address,
 * using the kdp fault path if requested and the page is not resident.
 */
vm_offset_t
kdp_find_phys(vm_map_t map, vm_offset_t target_addr, boolean_t try_fault, uint32_t *kdp_fault_results)
{
        vm_offset_t cur_phys_addr;
        unsigned cur_wimg_bits;
        uint64_t fault_start_time = 0;

        if (map == VM_MAP_NULL) {
                return 0;
        }

        cur_phys_addr = kdp_vtophys(map->pmap, target_addr);
        if (!pmap_valid_page((ppnum_t) atop(cur_phys_addr))) {
                if (!try_fault || fault_stats.sfs_stopped_faulting) {
                        if (kdp_fault_results)
                                *kdp_fault_results |= KDP_FAULT_RESULT_PAGED_OUT;

                        return 0;
                }

                /*
                 * The pmap doesn't have a valid page so we start at the top level
                 * vm map and try a lightweight fault. Update fault path usage stats.
                 */
                fault_start_time = mach_absolute_time();
                cur_phys_addr = kdp_lightweight_fault(map, (target_addr & ~PAGE_MASK));
                fault_stats.sfs_time_spent_faulting += (mach_absolute_time() - fault_start_time);

                if ((fault_stats.sfs_time_spent_faulting >= fault_stats.sfs_system_max_fault_time) && !panic_stackshot) {
                        fault_stats.sfs_stopped_faulting = (uint8_t) TRUE;
                }

                cur_phys_addr += (target_addr & PAGE_MASK);

                if (!pmap_valid_page((ppnum_t) atop(cur_phys_addr))) {
                        if (kdp_fault_results)
                                *kdp_fault_results |= (KDP_FAULT_RESULT_TRIED_FAULT | KDP_FAULT_RESULT_PAGED_OUT);

                        return 0;
                }

                if (kdp_fault_results)
                        *kdp_fault_results |= KDP_FAULT_RESULT_FAULTED_IN;

                fault_stats.sfs_pages_faulted_in++;
        } else {
                /*
                 * This check is done in kdp_lightweight_fault for the fault path.
                 */
                cur_wimg_bits = pmap_cache_attributes((ppnum_t) atop(cur_phys_addr));

                if ((cur_wimg_bits & VM_WIMG_MASK) != VM_WIMG_DEFAULT) {
                        return 0;
                }
        }

        return cur_phys_addr;
}

boolean_t
kdp_copyin_word(
        task_t task, uint64_t addr, uint64_t *result, boolean_t try_fault, uint32_t *kdp_fault_results)
{
        if (task_has_64BitAddr(task)) {
                return kdp_copyin(task->map, addr, result, sizeof(uint64_t), try_fault, kdp_fault_results);
        } else {
                uint32_t buf;
                boolean_t r = kdp_copyin(task->map, addr, &buf, sizeof(uint32_t), try_fault, kdp_fault_results);
                *result = buf;
                return r;
        }
}

boolean_t
kdp_copyin(vm_map_t map, uint64_t uaddr, void *dest, size_t size, boolean_t try_fault, uint32_t *kdp_fault_results)
{
        size_t rem = size;
        char *kvaddr = dest;

#if CONFIG_EMBEDDED
        /* Identify if destination buffer is in panic storage area */
        if (panic_stackshot && ((vm_offset_t)dest >= gPanicBase) && ((vm_offset_t)dest < (gPanicBase + gPanicSize))) {
                if (((vm_offset_t)dest + size) > (gPanicBase + gPanicSize)) {
                        return FALSE;
                }
        }
#endif

        while (rem) {
                uint64_t phys_src = kdp_find_phys(map, uaddr, try_fault, kdp_fault_results);
                uint64_t phys_dest = kvtophys((vm_offset_t)kvaddr);
                uint64_t src_rem = PAGE_SIZE - (phys_src & PAGE_MASK);
                uint64_t dst_rem = PAGE_SIZE - (phys_dest & PAGE_MASK);
                size_t cur_size = (uint32_t) MIN(src_rem, dst_rem);
                cur_size = MIN(cur_size, rem);

                if (phys_src && phys_dest) {
#if CONFIG_EMBEDDED
                        /*
                         * On embedded the panic buffer is mapped as device memory and doesn't allow
                         * unaligned accesses. To prevent these, we copy over bytes individually here.
                         */
                        if (panic_stackshot)
                                stackshot_memcpy(kvaddr, (const void *)phystokv(phys_src), cur_size);
                        else
#endif /* CONFIG_EMBEDDED */
                                bcopy_phys(phys_src, phys_dest, cur_size);
                } else {
                        break;
                }

                uaddr += cur_size;
                kvaddr += cur_size;
                rem -= cur_size;
        }

        return (rem == 0);
}

kern_return_t
do_stackshot(void *context)
{
#pragma unused(context)
        kdp_snapshot++;

        stack_snapshot_ret = kdp_stackshot_kcdata_format(stack_snapshot_pid,
            stack_snapshot_flags,
            &stack_snapshot_bytes_traced);

        kdp_snapshot--;
        return stack_snapshot_ret;
}

/*
 * A fantastical routine that tries to be fast about returning
 * translations.  Caches the last page we found a translation
 * for, so that we can be quick about multiple queries to the
 * same page.  It turns out this is exactly the workflow
 * machine_trace_thread and its relatives tend to throw at us.
 *
 * Please zero the nasty global this uses after a bulk lookup;
 * this isn't safe across a switch of the map or changes
 * to a pmap.
 *
 * This also means that if zero is a valid KVA, we are
 * screwed.  Sucks to be us.  Fortunately, this should never
 * happen.
 */
vm_offset_t
machine_trace_thread_get_kva(vm_offset_t cur_target_addr, vm_map_t map, uint32_t *thread_trace_flags)
{
        vm_offset_t cur_target_page;
        vm_offset_t cur_phys_addr;
        vm_offset_t kern_virt_target_addr;
        uint32_t kdp_fault_results = 0;

        cur_target_page = atop(cur_target_addr);

        if ((cur_target_page != prev_target_page) || validate_next_addr) {

                /*
                 * Alright; it wasn't our previous page.  So
                 * we must validate that there is a page
                 * table entry for this address under the
                 * current pmap, and that it has default
                 * cache attributes (otherwise it may not be
                 * safe to access it).
                 */
                cur_phys_addr = kdp_find_phys(map, cur_target_addr, stack_enable_faulting, &kdp_fault_results);
                if (thread_trace_flags) {
                        if (kdp_fault_results & KDP_FAULT_RESULT_PAGED_OUT) {
                                *thread_trace_flags |= kThreadTruncatedBT;
                        }

                        if (kdp_fault_results & KDP_FAULT_RESULT_TRIED_FAULT) {
                                *thread_trace_flags |= kThreadTriedFaultBT;
                        }

                        if (kdp_fault_results & KDP_FAULT_RESULT_FAULTED_IN) {
                                *thread_trace_flags |= kThreadFaultedBT;
                        }
                }

                if (cur_phys_addr == 0) {
                        return 0;
                }
#if __x86_64__
                kern_virt_target_addr = (vm_offset_t) PHYSMAP_PTOV(cur_phys_addr);
#elif __arm__ || __arm64__
                kern_virt_target_addr = phystokv(cur_phys_addr);
#else
#error Oh come on... we should really unify the physical -> kernel virtual interface
#endif
                prev_target_page = cur_target_page;
                prev_target_kva = (kern_virt_target_addr & ~PAGE_MASK);
                validate_next_addr = FALSE;
        } else {
                /* We found a translation, so stash this page */
                kern_virt_target_addr = prev_target_kva + (cur_target_addr & PAGE_MASK);
        }

#if KASAN
        kasan_notify_address(kern_virt_target_addr, sizeof(uint64_t));
#endif
        return kern_virt_target_addr;
}

void
machine_trace_thread_clear_validation_cache(void)
{
        validate_next_addr = TRUE;
}

boolean_t
stackshot_thread_is_idle_worker_unsafe(thread_t thread)
{
        /* When the pthread kext puts a worker thread to sleep, it will
         * set kThreadWaitParkedWorkQueue in the block_hint of the thread
         * struct. See parkit() in kern/kern_support.c in libpthread.
         */
        return (thread->state & TH_WAIT) &&
                (thread->block_hint == kThreadWaitParkedWorkQueue);
}

#if CONFIG_COALITIONS
static void
stackshot_coalition_jetsam_count(void *arg, int i, coalition_t coal)
{
#pragma unused(i, coal)
        unsigned int *coalition_count = (unsigned int*)arg;
        (*coalition_count)++;
}

static void
stackshot_coalition_jetsam_snapshot(void *arg, int i, coalition_t coal)
{
        if (coalition_type(coal) != COALITION_TYPE_JETSAM)
                return;

        struct jetsam_coalition_snapshot *coalitions = (struct jetsam_coalition_snapshot*)arg;
        struct jetsam_coalition_snapshot *jcs = &coalitions[i];
        task_t leader = TASK_NULL;
        jcs->jcs_id = coalition_id(coal);
        jcs->jcs_flags = 0;

        if (coalition_term_requested(coal))
                jcs->jcs_flags |= kCoalitionTermRequested;
        if (coalition_is_terminated(coal))
                jcs->jcs_flags |= kCoalitionTerminated;
        if (coalition_is_reaped(coal))
                jcs->jcs_flags |= kCoalitionReaped;
        if (coalition_is_privileged(coal))
                jcs->jcs_flags |= kCoalitionPrivileged;


        leader = kdp_coalition_get_leader(coal);
        if (leader)
                jcs->jcs_leader_task_uniqueid = get_task_uniqueid(leader);
        else
                jcs->jcs_leader_task_uniqueid = 0;
}
#endif /* CONFIG_COALITIONS */


/* Determine if a thread has waitinfo that stackshot can provide */
static int
stackshot_thread_has_valid_waitinfo(thread_t thread)
{
        if (!(thread->state & TH_WAIT))
                return 0;

        switch (thread->block_hint) {
                // If set to None or is a parked work queue, ignore it
                case kThreadWaitParkedWorkQueue:
                case kThreadWaitNone:
                        return 0;
                // There is a short window where the pthread kext removes a thread
                // from its ksyn wait queue before waking the thread up
                case kThreadWaitPThreadMutex:
                case kThreadWaitPThreadRWLockRead:
                case kThreadWaitPThreadRWLockWrite:
                case kThreadWaitPThreadCondVar:
                        return (kdp_pthread_get_thread_kwq(thread) != NULL);
                // All other cases are valid block hints if in a wait state
                default:
                        return 1;
        }
}

static void
stackshot_thread_wait_owner_info(thread_t thread, thread_waitinfo_t *waitinfo)
{
        waitinfo->waiter    = thread_tid(thread);
        waitinfo->wait_type = thread->block_hint;
        switch (waitinfo->wait_type) {
                case kThreadWaitKernelMutex:
                        kdp_lck_mtx_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitPortReceive:
                        kdp_mqueue_recv_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitPortSend:
                        kdp_mqueue_send_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitSemaphore:
                        kdp_sema_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitUserLock:
                        kdp_ulock_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitKernelRWLockRead:
                case kThreadWaitKernelRWLockWrite:
                case kThreadWaitKernelRWLockUpgrade:
                        kdp_rwlck_find_owner(thread->waitq, thread->wait_event, waitinfo);
                        break;
                case kThreadWaitPThreadMutex:
                case kThreadWaitPThreadRWLockRead:
                case kThreadWaitPThreadRWLockWrite:
                case kThreadWaitPThreadCondVar:
                        kdp_pthread_find_owner(thread, waitinfo);
                        break;
                case kThreadWaitWorkloopSyncWait:
                        kdp_workloop_sync_wait_find_owner(thread, thread->wait_event, waitinfo);
                        break;
                default:
                        waitinfo->owner = 0;
                        waitinfo->context = 0;
                        break;
        }
}