// SPDX-License-Identifier: GPL-2.0
#include <dirent.h>
#include <errno.h>
#include <inttypes.h>
#include <regex.h>
#include <stdlib.h>
#include "callchain.h"
#include "debug.h"
#include "dso.h"
#include "env.h"
#include "event.h"
#include "evsel.h"
#include "hist.h"
#include "machine.h"
#include "map.h"
#include "map_symbol.h"
#include "branch.h"
#include "mem-events.h"
#include "path.h"
#include "srcline.h"
#include "symbol.h"
#include "sort.h"
#include "strlist.h"
#include "target.h"
#include "thread.h"
#include "util.h"
#include "vdso.h"
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include "unwind.h"
#include "linux/hash.h"
#include "asm/bug.h"
#include "bpf-event.h"
#include <internal/lib.h> // page_size
#include "cgroup.h"
#include "arm64-frame-pointer-unwind-support.h"

#include <linux/ctype.h>
#include <symbol/kallsyms.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/zalloc.h>

static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock);

static struct dso *machine__kernel_dso(struct machine *machine)
{
        return machine->vmlinux_map->dso;
}

static void dsos__init(struct dsos *dsos)
{
        INIT_LIST_HEAD(&dsos->head);
        dsos->root = RB_ROOT;
        init_rwsem(&dsos->lock);
}

static void machine__threads_init(struct machine *machine)
{
        int i;

        for (i = 0; i < THREADS__TABLE_SIZE; i++) {
                struct threads *threads = &machine->threads[i];
                threads->entries = RB_ROOT_CACHED;
                init_rwsem(&threads->lock);
                threads->nr = 0;
                INIT_LIST_HEAD(&threads->dead);
                threads->last_match = NULL;
        }
}

static int machine__set_mmap_name(struct machine *machine)
{
        if (machine__is_host(machine))
                machine->mmap_name = strdup("[kernel.kallsyms]");
        else if (machine__is_default_guest(machine))
                machine->mmap_name = strdup("[guest.kernel.kallsyms]");
        else if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
                          machine->pid) < 0)
                machine->mmap_name = NULL;

        return machine->mmap_name ? 0 : -ENOMEM;
}

int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
{
        int err = -ENOMEM;

        memset(machine, 0, sizeof(*machine));
        maps__init(&machine->kmaps, machine);
        RB_CLEAR_NODE(&machine->rb_node);
        dsos__init(&machine->dsos);

        machine__threads_init(machine);

        machine->vdso_info = NULL;
        machine->env = NULL;

        machine->pid = pid;

        machine->id_hdr_size = 0;
        machine->kptr_restrict_warned = false;
        machine->comm_exec = false;
        machine->kernel_start = 0;
        machine->vmlinux_map = NULL;

        machine->root_dir = strdup(root_dir);
        if (machine->root_dir == NULL)
                return -ENOMEM;

        if (machine__set_mmap_name(machine))
                goto out;

        if (pid != HOST_KERNEL_ID) {
                struct thread *thread = machine__findnew_thread(machine, -1,
                                                                pid);
                char comm[64];

                if (thread == NULL)
                        goto out;

                snprintf(comm, sizeof(comm), "[guest/%d]", pid);
                thread__set_comm(thread, comm, 0);
                thread__put(thread);
        }

        machine->current_tid = NULL;
        err = 0;

out:
        if (err) {
                zfree(&machine->root_dir);
                zfree(&machine->mmap_name);
        }
        return 0;
}

struct machine *machine__new_host(void)
{
        struct machine *machine = malloc(sizeof(*machine));

        if (machine != NULL) {
                machine__init(machine, "", HOST_KERNEL_ID);

                if (machine__create_kernel_maps(machine) < 0)
                        goto out_delete;
        }

        return machine;
out_delete:
        free(machine);
        return NULL;
}

struct machine *machine__new_kallsyms(void)
{
        struct machine *machine = machine__new_host();
        /*
         * FIXME:
         * 1) We should switch to machine__load_kallsyms(), i.e. not explicitly
         *    ask for not using the kcore parsing code, once this one is fixed
         *    to create a map per module.
         */
        if (machine && machine__load_kallsyms(machine, "/proc/kallsyms") <= 0) {
                machine__delete(machine);
                machine = NULL;
        }

        return machine;
}

static void dsos__purge(struct dsos *dsos)
{
        struct dso *pos, *n;

        down_write(&dsos->lock);

        list_for_each_entry_safe(pos, n, &dsos->head, node) {
                RB_CLEAR_NODE(&pos->rb_node);
                pos->root = NULL;
                list_del_init(&pos->node);
                dso__put(pos);
        }

        up_write(&dsos->lock);
}

static void dsos__exit(struct dsos *dsos)
{
        dsos__purge(dsos);
        exit_rwsem(&dsos->lock);
}

void machine__delete_threads(struct machine *machine)
{
        struct rb_node *nd;
        int i;

        for (i = 0; i < THREADS__TABLE_SIZE; i++) {
                struct threads *threads = &machine->threads[i];
                down_write(&threads->lock);
                nd = rb_first_cached(&threads->entries);
                while (nd) {
                        struct thread *t = rb_entry(nd, struct thread, rb_node);

                        nd = rb_next(nd);
                        __machine__remove_thread(machine, t, false);
                }
                up_write(&threads->lock);
        }
}

void machine__exit(struct machine *machine)
{
        int i;

        if (machine == NULL)
                return;

        machine__destroy_kernel_maps(machine);
        maps__exit(&machine->kmaps);
        dsos__exit(&machine->dsos);
        machine__exit_vdso(machine);
        zfree(&machine->root_dir);
        zfree(&machine->mmap_name);
        zfree(&machine->current_tid);

        for (i = 0; i < THREADS__TABLE_SIZE; i++) {
                struct threads *threads = &machine->threads[i];
                struct thread *thread, *n;
                /*
                 * Forget about the dead, at this point whatever threads were
                 * left in the dead lists better have a reference count taken
                 * by who is using them, and then, when they drop those references
                 * and it finally hits zero, thread__put() will check and see that
                 * its not in the dead threads list and will not try to remove it
                 * from there, just calling thread__delete() straight away.
                 */
                list_for_each_entry_safe(thread, n, &threads->dead, node)
                        list_del_init(&thread->node);

                exit_rwsem(&threads->lock);
        }
}

void machine__delete(struct machine *machine)
{
        if (machine) {
                machine__exit(machine);
                free(machine);
        }
}

void machines__init(struct machines *machines)
{
        machine__init(&machines->host, "", HOST_KERNEL_ID);
        machines->guests = RB_ROOT_CACHED;
}

void machines__exit(struct machines *machines)
{
        machine__exit(&machines->host);
        /* XXX exit guest */
}

struct machine *machines__add(struct machines *machines, pid_t pid,
                              const char *root_dir)
{
        struct rb_node **p = &machines->guests.rb_root.rb_node;
        struct rb_node *parent = NULL;
        struct machine *pos, *machine = malloc(sizeof(*machine));
        bool leftmost = true;

        if (machine == NULL)
                return NULL;

        if (machine__init(machine, root_dir, pid) != 0) {
                free(machine);
                return NULL;
        }

        while (*p != NULL) {
                parent = *p;
                pos = rb_entry(parent, struct machine, rb_node);
                if (pid < pos->pid)
                        p = &(*p)->rb_left;
                else {
                        p = &(*p)->rb_right;
                        leftmost = false;
                }
        }

        rb_link_node(&machine->rb_node, parent, p);
        rb_insert_color_cached(&machine->rb_node, &machines->guests, leftmost);

        return machine;
}

void machines__set_comm_exec(struct machines *machines, bool comm_exec)
{
        struct rb_node *nd;

        machines->host.comm_exec = comm_exec;

        for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
                struct machine *machine = rb_entry(nd, struct machine, rb_node);

                machine->comm_exec = comm_exec;
        }
}

struct machine *machines__find(struct machines *machines, pid_t pid)
{
        struct rb_node **p = &machines->guests.rb_root.rb_node;
        struct rb_node *parent = NULL;
        struct machine *machine;
        struct machine *default_machine = NULL;

        if (pid == HOST_KERNEL_ID)
                return &machines->host;

        while (*p != NULL) {
                parent = *p;
                machine = rb_entry(parent, struct machine, rb_node);
                if (pid < machine->pid)
                        p = &(*p)->rb_left;
                else if (pid > machine->pid)
                        p = &(*p)->rb_right;
                else
                        return machine;
                if (!machine->pid)
                        default_machine = machine;
        }

        return default_machine;
}

struct machine *machines__findnew(struct machines *machines, pid_t pid)
{
        char path[PATH_MAX];
        const char *root_dir = "";
        struct machine *machine = machines__find(machines, pid);

        if (machine && (machine->pid == pid))
                goto out;

        if ((pid != HOST_KERNEL_ID) &&
            (pid != DEFAULT_GUEST_KERNEL_ID) &&
            (symbol_conf.guestmount)) {
                sprintf(path, "%s/%d", symbol_conf.guestmount, pid);
                if (access(path, R_OK)) {
                        static struct strlist *seen;

                        if (!seen)
                                seen = strlist__new(NULL, NULL);

                        if (!strlist__has_entry(seen, path)) {
                                pr_err("Can't access file %s\n", path);
                                strlist__add(seen, path);
                        }
                        machine = NULL;
                        goto out;
                }
                root_dir = path;
        }

        machine = machines__add(machines, pid, root_dir);
out:
        return machine;
}

struct machine *machines__find_guest(struct machines *machines, pid_t pid)
{
        struct machine *machine = machines__find(machines, pid);

        if (!machine)
                machine = machines__findnew(machines, DEFAULT_GUEST_KERNEL_ID);
        return machine;
}

void machines__process_guests(struct machines *machines,
                              machine__process_t process, void *data)
{
        struct rb_node *nd;

        for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
                struct machine *pos = rb_entry(nd, struct machine, rb_node);
                process(pos, data);
        }
}

void machines__set_id_hdr_size(struct machines *machines, u16 id_hdr_size)
{
        struct rb_node *node;
        struct machine *machine;

        machines->host.id_hdr_size = id_hdr_size;

        for (node = rb_first_cached(&machines->guests); node;
             node = rb_next(node)) {
                machine = rb_entry(node, struct machine, rb_node);
                machine->id_hdr_size = id_hdr_size;
        }

        return;
}

static void machine__update_thread_pid(struct machine *machine,
                                       struct thread *th, pid_t pid)
{
        struct thread *leader;

        if (pid == th->pid_ || pid == -1 || th->pid_ != -1)
                return;

        th->pid_ = pid;

        if (th->pid_ == th->tid)
                return;

        leader = __machine__findnew_thread(machine, th->pid_, th->pid_);
        if (!leader)
                goto out_err;

        if (!leader->maps)
                leader->maps = maps__new(machine);

        if (!leader->maps)
                goto out_err;

        if (th->maps == leader->maps)
                return;

        if (th->maps) {
                /*
                 * Maps are created from MMAP events which provide the pid and
                 * tid.  Consequently there never should be any maps on a thread
                 * with an unknown pid.  Just print an error if there are.
                 */
                if (!maps__empty(th->maps))
                        pr_err("Discarding thread maps for %d:%d\n",
                               th->pid_, th->tid);
                maps__put(th->maps);
        }

        th->maps = maps__get(leader->maps);
out_put:
        thread__put(leader);
        return;
out_err:
        pr_err("Failed to join map groups for %d:%d\n", th->pid_, th->tid);
        goto out_put;
}

/*
 * Front-end cache - TID lookups come in blocks,
 * so most of the time we dont have to look up
 * the full rbtree:
 */
static struct thread*
__threads__get_last_match(struct threads *threads, struct machine *machine,
                          int pid, int tid)
{
        struct thread *th;

        th = threads->last_match;
        if (th != NULL) {
                if (th->tid == tid) {
                        machine__update_thread_pid(machine, th, pid);
                        return thread__get(th);
                }

                threads->last_match = NULL;
        }

        return NULL;
}

static struct thread*
threads__get_last_match(struct threads *threads, struct machine *machine,
                        int pid, int tid)
{
        struct thread *th = NULL;

        if (perf_singlethreaded)
                th = __threads__get_last_match(threads, machine, pid, tid);

        return th;
}

static void
__threads__set_last_match(struct threads *threads, struct thread *th)
{
        threads->last_match = th;
}

static void
threads__set_last_match(struct threads *threads, struct thread *th)
{
        if (perf_singlethreaded)
                __threads__set_last_match(threads, th);
}

/*
 * Caller must eventually drop thread->refcnt returned with a successful
 * lookup/new thread inserted.
 */
static struct thread *____machine__findnew_thread(struct machine *machine,
                                                  struct threads *threads,
                                                  pid_t pid, pid_t tid,
                                                  bool create)
{
        struct rb_node **p = &threads->entries.rb_root.rb_node;
        struct rb_node *parent = NULL;
        struct thread *th;
        bool leftmost = true;

        th = threads__get_last_match(threads, machine, pid, tid);
        if (th)
                return th;

        while (*p != NULL) {
                parent = *p;
                th = rb_entry(parent, struct thread, rb_node);

                if (th->tid == tid) {
                        threads__set_last_match(threads, th);
                        machine__update_thread_pid(machine, th, pid);
                        return thread__get(th);
                }

                if (tid < th->tid)
                        p = &(*p)->rb_left;
                else {
                        p = &(*p)->rb_right;
                        leftmost = false;
                }
        }

        if (!create)
                return NULL;

        th = thread__new(pid, tid);
        if (th != NULL) {
                rb_link_node(&th->rb_node, parent, p);
                rb_insert_color_cached(&th->rb_node, &threads->entries, leftmost);

                /*
                 * We have to initialize maps separately after rb tree is updated.
                 *
                 * The reason is that we call machine__findnew_thread
                 * within thread__init_maps to find the thread
                 * leader and that would screwed the rb tree.
                 */
                if (thread__init_maps(th, machine)) {
                        rb_erase_cached(&th->rb_node, &threads->entries);
                        RB_CLEAR_NODE(&th->rb_node);
                        thread__put(th);
                        return NULL;
                }
                /*
                 * It is now in the rbtree, get a ref
                 */
                thread__get(th);
                threads__set_last_match(threads, th);
                ++threads->nr;
        }

        return th;
}

struct thread *__machine__findnew_thread(struct machine *machine, pid_t pid, pid_t tid)
{
        return ____machine__findnew_thread(machine, machine__threads(machine, tid), pid, tid, true);
}

struct thread *machine__findnew_thread(struct machine *machine, pid_t pid,
                                       pid_t tid)
{
        struct threads *threads = machine__threads(machine, tid);
        struct thread *th;

        down_write(&threads->lock);
        th = __machine__findnew_thread(machine, pid, tid);
        up_write(&threads->lock);
        return th;
}

struct thread *machine__find_thread(struct machine *machine, pid_t pid,
                                    pid_t tid)
{
        struct threads *threads = machine__threads(machine, tid);
        struct thread *th;

        down_read(&threads->lock);
        th =  ____machine__findnew_thread(machine, threads, pid, tid, false);
        up_read(&threads->lock);
        return th;
}

/*
 * Threads are identified by pid and tid, and the idle task has pid == tid == 0.
 * So here a single thread is created for that, but actually there is a separate
 * idle task per cpu, so there should be one 'struct thread' per cpu, but there
 * is only 1. That causes problems for some tools, requiring workarounds. For
 * example get_idle_thread() in builtin-sched.c, or thread_stack__per_cpu().
 */
struct thread *machine__idle_thread(struct machine *machine)
{
        struct thread *thread = machine__findnew_thread(machine, 0, 0);

        if (!thread || thread__set_comm(thread, "swapper", 0) ||
            thread__set_namespaces(thread, 0, NULL))
                pr_err("problem inserting idle task for machine pid %d\n", machine->pid);

        return thread;
}

struct comm *machine__thread_exec_comm(struct machine *machine,
                                       struct thread *thread)
{
        if (machine->comm_exec)
                return thread__exec_comm(thread);
        else
                return thread__comm(thread);
}

int machine__process_comm_event(struct machine *machine, union perf_event *event,
                                struct perf_sample *sample)
{
        struct thread *thread = machine__findnew_thread(machine,
                                                        event->comm.pid,
                                                        event->comm.tid);
        bool exec = event->header.misc & PERF_RECORD_MISC_COMM_EXEC;
        int err = 0;

        if (exec)
                machine->comm_exec = true;

        if (dump_trace)
                perf_event__fprintf_comm(event, stdout);

        if (thread == NULL ||
            __thread__set_comm(thread, event->comm.comm, sample->time, exec)) {
                dump_printf("problem processing PERF_RECORD_COMM, skipping event.\n");
                err = -1;
        }

        thread__put(thread);

        return err;
}

int machine__process_namespaces_event(struct machine *machine __maybe_unused,
                                      union perf_event *event,
                                      struct perf_sample *sample __maybe_unused)
{
        struct thread *thread = machine__findnew_thread(machine,
                                                        event->namespaces.pid,
                                                        event->namespaces.tid);
        int err = 0;

        WARN_ONCE(event->namespaces.nr_namespaces > NR_NAMESPACES,
                  "\nWARNING: kernel seems to support more namespaces than perf"
                  " tool.\nTry updating the perf tool..\n\n");

        WARN_ONCE(event->namespaces.nr_namespaces < NR_NAMESPACES,
                  "\nWARNING: perf tool seems to support more namespaces than"
                  " the kernel.\nTry updating the kernel..\n\n");

        if (dump_trace)
                perf_event__fprintf_namespaces(event, stdout);

        if (thread == NULL ||
            thread__set_namespaces(thread, sample->time, &event->namespaces)) {
                dump_printf("problem processing PERF_RECORD_NAMESPACES, skipping event.\n");
                err = -1;
        }

        thread__put(thread);

        return err;
}

int machine__process_cgroup_event(struct machine *machine,
                                  union perf_event *event,
                                  struct perf_sample *sample __maybe_unused)
{
        struct cgroup *cgrp;

        if (dump_trace)
                perf_event__fprintf_cgroup(event, stdout);

        cgrp = cgroup__findnew(machine->env, event->cgroup.id, event->cgroup.path);
        if (cgrp == NULL)
                return -ENOMEM;

        return 0;
}

int machine__process_lost_event(struct machine *machine __maybe_unused,
                                union perf_event *event, struct perf_sample *sample __maybe_unused)
{
        dump_printf(": id:%" PRI_lu64 ": lost:%" PRI_lu64 "\n",
                    event->lost.id, event->lost.lost);
        return 0;
}

int machine__process_lost_samples_event(struct machine *machine __maybe_unused,
                                        union perf_event *event, struct perf_sample *sample)
{
        dump_printf(": id:%" PRIu64 ": lost samples :%" PRI_lu64 "\n",
                    sample->id, event->lost_samples.lost);
        return 0;
}

static struct dso *machine__findnew_module_dso(struct machine *machine,
                                               struct kmod_path *m,
                                               const char *filename)
{
        struct dso *dso;

        down_write(&machine->dsos.lock);

        dso = __dsos__find(&machine->dsos, m->name, true);
        if (!dso) {
                dso = __dsos__addnew(&machine->dsos, m->name);
                if (dso == NULL)
                        goto out_unlock;

                dso__set_module_info(dso, m, machine);
                dso__set_long_name(dso, strdup(filename), true);
                dso->kernel = DSO_SPACE__KERNEL;
        }

        dso__get(dso);
out_unlock:
        up_write(&machine->dsos.lock);
        return dso;
}

int machine__process_aux_event(struct machine *machine __maybe_unused,
                               union perf_event *event)
{
        if (dump_trace)
                perf_event__fprintf_aux(event, stdout);
        return 0;
}

int machine__process_itrace_start_event(struct machine *machine __maybe_unused,
                                        union perf_event *event)
{
        if (dump_trace)
                perf_event__fprintf_itrace_start(event, stdout);
        return 0;
}

int machine__process_aux_output_hw_id_event(struct machine *machine __maybe_unused,
                                            union perf_event *event)
{
        if (dump_trace)
                perf_event__fprintf_aux_output_hw_id(event, stdout);
        return 0;
}

int machine__process_switch_event(struct machine *machine __maybe_unused,
                                  union perf_event *event)
{
        if (dump_trace)
                perf_event__fprintf_switch(event, stdout);
        return 0;
}

static int machine__process_ksymbol_register(struct machine *machine,
                                             union perf_event *event,
                                             struct perf_sample *sample __maybe_unused)
{
        struct symbol *sym;
        struct map *map = maps__find(&machine->kmaps, event->ksymbol.addr);

        if (!map) {
                struct dso *dso = dso__new(event->ksymbol.name);

                if (dso) {
                        dso->kernel = DSO_SPACE__KERNEL;
                        map = map__new2(0, dso);
                        dso__put(dso);
                }

                if (!dso || !map) {
                        return -ENOMEM;
                }

                if (event->ksymbol.ksym_type == PERF_RECORD_KSYMBOL_TYPE_OOL) {
                        map->dso->binary_type = DSO_BINARY_TYPE__OOL;
                        map->dso->data.file_size = event->ksymbol.len;
                        dso__set_loaded(map->dso);
                }

                map->start = event->ksymbol.addr;
                map->end = map->start + event->ksymbol.len;
                maps__insert(&machine->kmaps, map);
                map__put(map);
                dso__set_loaded(dso);

                if (is_bpf_image(event->ksymbol.name)) {
                        dso->binary_type = DSO_BINARY_TYPE__BPF_IMAGE;
                        dso__set_long_name(dso, "", false);
                }
        }

        sym = symbol__new(map->map_ip(map, map->start),
                          event->ksymbol.len,
                          0, 0, event->ksymbol.name);
        if (!sym)
                return -ENOMEM;
        dso__insert_symbol(map->dso, sym);
        return 0;
}

static int machine__process_ksymbol_unregister(struct machine *machine,
                                               union perf_event *event,
                                               struct perf_sample *sample __maybe_unused)
{
        struct symbol *sym;
        struct map *map;

        map = maps__find(&machine->kmaps, event->ksymbol.addr);
        if (!map)
                return 0;

        if (map != machine->vmlinux_map)
                maps__remove(&machine->kmaps, map);
        else {
                sym = dso__find_symbol(map->dso, map->map_ip(map, map->start));
                if (sym)
                        dso__delete_symbol(map->dso, sym);
        }

        return 0;
}

int machine__process_ksymbol(struct machine *machine __maybe_unused,
                             union perf_event *event,
                             struct perf_sample *sample)
{
        if (dump_trace)
                perf_event__fprintf_ksymbol(event, stdout);

        if (event->ksymbol.flags & PERF_RECORD_KSYMBOL_FLAGS_UNREGISTER)
                return machine__process_ksymbol_unregister(machine, event,
                                                           sample);
        return machine__process_ksymbol_register(machine, event, sample);
}

int machine__process_text_poke(struct machine *machine, union perf_event *event,
                               struct perf_sample *sample __maybe_unused)
{
        struct map *map = maps__find(&machine->kmaps, event->text_poke.addr);
        u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

        if (dump_trace)
                perf_event__fprintf_text_poke(event, machine, stdout);

        if (!event->text_poke.new_len)
                return 0;

        if (cpumode != PERF_RECORD_MISC_KERNEL) {
                pr_debug("%s: unsupported cpumode - ignoring\n", __func__);
                return 0;
        }

        if (map && map->dso) {
                u8 *new_bytes = event->text_poke.bytes + event->text_poke.old_len;
                int ret;

                /*
                 * Kernel maps might be changed when loading symbols so loading
                 * must be done prior to using kernel maps.
                 */
                map__load(map);
                ret = dso__data_write_cache_addr(map->dso, map, machine,
                                                 event->text_poke.addr,
                                                 new_bytes,
                                                 event->text_poke.new_len);
                if (ret != event->text_poke.new_len)
                        pr_debug("Failed to write kernel text poke at %#" PRI_lx64 "\n",
                                 event->text_poke.addr);
        } else {
                pr_debug("Failed to find kernel text poke address map for %#" PRI_lx64 "\n",
                         event->text_poke.addr);
        }

        return 0;
}

static struct map *machine__addnew_module_map(struct machine *machine, u64 start,
                                              const char *filename)
{
        struct map *map = NULL;
        struct kmod_path m;
        struct dso *dso;

        if (kmod_path__parse_name(&m, filename))
                return NULL;

        dso = machine__findnew_module_dso(machine, &m, filename);
        if (dso == NULL)
                goto out;

        map = map__new2(start, dso);
        if (map == NULL)
                goto out;

        maps__insert(&machine->kmaps, map);

        /* Put the map here because maps__insert already got it */
        map__put(map);
out:
        /* put the dso here, corresponding to  machine__findnew_module_dso */
        dso__put(dso);
        zfree(&m.name);
        return map;
}

size_t machines__fprintf_dsos(struct machines *machines, FILE *fp)
{
        struct rb_node *nd;
        size_t ret = __dsos__fprintf(&machines->host.dsos.head, fp);

        for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
                struct machine *pos = rb_entry(nd, struct machine, rb_node);
                ret += __dsos__fprintf(&pos->dsos.head, fp);
        }

        return ret;
}

size_t machine__fprintf_dsos_buildid(struct machine *m, FILE *fp,
                                     bool (skip)(struct dso *dso, int parm), int parm)
{
        return __dsos__fprintf_buildid(&m->dsos.head, fp, skip, parm);
}

size_t machines__fprintf_dsos_buildid(struct machines *machines, FILE *fp,
                                     bool (skip)(struct dso *dso, int parm), int parm)
{
        struct rb_node *nd;
        size_t ret = machine__fprintf_dsos_buildid(&machines->host, fp, skip, parm);

        for (nd = rb_first_cached(&machines->guests); nd; nd = rb_next(nd)) {
                struct machine *pos = rb_entry(nd, struct machine, rb_node);
                ret += machine__fprintf_dsos_buildid(pos, fp, skip, parm);
        }
        return ret;
}

size_t machine__fprintf_vmlinux_path(struct machine *machine, FILE *fp)
{
        int i;
        size_t printed = 0;
        struct dso *kdso = machine__kernel_dso(machine);

        if (kdso->has_build_id) {
                char filename[PATH_MAX];
                if (dso__build_id_filename(kdso, filename, sizeof(filename),
                                           false))
                        printed += fprintf(fp, "[0] %s\n", filename);
        }

        for (i = 0; i < vmlinux_path__nr_entries; ++i)
                printed += fprintf(fp, "[%d] %s\n",
                                   i + kdso->has_build_id, vmlinux_path[i]);

        return printed;
}

size_t machine__fprintf(struct machine *machine, FILE *fp)
{
        struct rb_node *nd;
        size_t ret;
        int i;

        for (i = 0; i < THREADS__TABLE_SIZE; i++) {
                struct threads *threads = &machine->threads[i];

                down_read(&threads->lock);

                ret = fprintf(fp, "Threads: %u\n", threads->nr);

                for (nd = rb_first_cached(&threads->entries); nd;
                     nd = rb_next(nd)) {
                        struct thread *pos = rb_entry(nd, struct thread, rb_node);

                        ret += thread__fprintf(pos, fp);
                }

                up_read(&threads->lock);

        }
        return ret;
}

static struct dso *machine__get_kernel(struct machine *machine)
{
        const char *vmlinux_name = machine->mmap_name;
        struct dso *kernel;

        if (machine__is_host(machine)) {
                if (symbol_conf.vmlinux_name)
                        vmlinux_name = symbol_conf.vmlinux_name;

                kernel = machine__findnew_kernel(machine, vmlinux_name,
                                                 "[kernel]", DSO_SPACE__KERNEL);
        } else {
                if (symbol_conf.default_guest_vmlinux_name)
                        vmlinux_name = symbol_conf.default_guest_vmlinux_name;

                kernel = machine__findnew_kernel(machine, vmlinux_name,
                                                 "[guest.kernel]",
                                                 DSO_SPACE__KERNEL_GUEST);
        }

        if (kernel != NULL && (!kernel->has_build_id))
                dso__read_running_kernel_build_id(kernel, machine);

        return kernel;
}

struct process_args {
        u64 start;
};

void machine__get_kallsyms_filename(struct machine *machine, char *buf,
                                    size_t bufsz)
{
        if (machine__is_default_guest(machine))
                scnprintf(buf, bufsz, "%s", symbol_conf.default_guest_kallsyms);
        else
                scnprintf(buf, bufsz, "%s/proc/kallsyms", machine->root_dir);
}

const char *ref_reloc_sym_names[] = {"_text", "_stext", NULL};

/* Figure out the start address of kernel map from /proc/kallsyms.
 * Returns the name of the start symbol in *symbol_name. Pass in NULL as
 * symbol_name if it's not that important.
 */
static int machine__get_running_kernel_start(struct machine *machine,
                                             const char **symbol_name,
                                             u64 *start, u64 *end)
{
        char filename[PATH_MAX];
        int i, err = -1;
        const char *name;
        u64 addr = 0;

        machine__get_kallsyms_filename(machine, filename, PATH_MAX);

        if (symbol__restricted_filename(filename, "/proc/kallsyms"))
                return 0;

        for (i = 0; (name = ref_reloc_sym_names[i]) != NULL; i++) {
                err = kallsyms__get_function_start(filename, name, &addr);
                if (!err)
                        break;
        }

        if (err)
                return -1;

        if (symbol_name)
                *symbol_name = name;

        *start = addr;

        err = kallsyms__get_function_start(filename, "_etext", &addr);
        if (!err)
                *end = addr;

        return 0;
}

int machine__create_extra_kernel_map(struct machine *machine,
                                     struct dso *kernel,
                                     struct extra_kernel_map *xm)
{
        struct kmap *kmap;
        struct map *map;

        map = map__new2(xm->start, kernel);
        if (!map)
                return -1;

        map->end   = xm->end;
        map->pgoff = xm->pgoff;

        kmap = map__kmap(map);

        strlcpy(kmap->name, xm->name, KMAP_NAME_LEN);

        maps__insert(&machine->kmaps, map);

        pr_debug2("Added extra kernel map %s %" PRIx64 "-%" PRIx64 "\n",
                  kmap->name, map->start, map->end);

        map__put(map);

        return 0;
}

static u64 find_entry_trampoline(struct dso *dso)
{
        /* Duplicates are removed so lookup all aliases */
        const char *syms[] = {
                "_entry_trampoline",
                "__entry_trampoline_start",
                "entry_SYSCALL_64_trampoline",
        };
        struct symbol *sym = dso__first_symbol(dso);
        unsigned int i;

        for (; sym; sym = dso__next_symbol(sym)) {
                if (sym->binding != STB_GLOBAL)
                        continue;
                for (i = 0; i < ARRAY_SIZE(syms); i++) {
                        if (!strcmp(sym->name, syms[i]))
                                return sym->start;
                }
        }

        return 0;
}

/*
 * These values can be used for kernels that do not have symbols for the entry
 * trampolines in kallsyms.
 */
#define X86_64_CPU_ENTRY_AREA_PER_CPU   0xfffffe0000000000ULL
#define X86_64_CPU_ENTRY_AREA_SIZE      0x2c000
#define X86_64_ENTRY_TRAMPOLINE         0x6000

/* Map x86_64 PTI entry trampolines */
int machine__map_x86_64_entry_trampolines(struct machine *machine,
                                          struct dso *kernel)
{
        struct maps *kmaps = &machine->kmaps;
        int nr_cpus_avail, cpu;
        bool found = false;
        struct map *map;
        u64 pgoff;

        /*
         * In the vmlinux case, pgoff is a virtual address which must now be
         * mapped to a vmlinux offset.
         */
        maps__for_each_entry(kmaps, map) {
                struct kmap *kmap = __map__kmap(map);
                struct map *dest_map;

                if (!kmap || !is_entry_trampoline(kmap->name))
                        continue;

                dest_map = maps__find(kmaps, map->pgoff);
                if (dest_map != map)
                        map->pgoff = dest_map->map_ip(dest_map, map->pgoff);
                found = true;
        }
        if (found || machine->trampolines_mapped)
                return 0;

        pgoff = find_entry_trampoline(kernel);
        if (!pgoff)
                return 0;

        nr_cpus_avail = machine__nr_cpus_avail(machine);

        /* Add a 1 page map for each CPU's entry trampoline */
        for (cpu = 0; cpu < nr_cpus_avail; cpu++) {
                u64 va = X86_64_CPU_ENTRY_AREA_PER_CPU +
                         cpu * X86_64_CPU_ENTRY_AREA_SIZE +
                         X86_64_ENTRY_TRAMPOLINE;
                struct extra_kernel_map xm = {
                        .start = va,
                        .end   = va + page_size,
                        .pgoff = pgoff,
                };

                strlcpy(xm.name, ENTRY_TRAMPOLINE_NAME, KMAP_NAME_LEN);

                if (machine__create_extra_kernel_map(machine, kernel, &xm) < 0)
                        return -1;
        }

        machine->trampolines_mapped = nr_cpus_avail;

        return 0;
}

int __weak machine__create_extra_kernel_maps(struct machine *machine __maybe_unused,
                                             struct dso *kernel __maybe_unused)
{
        return 0;
}

static int
__machine__create_kernel_maps(struct machine *machine, struct dso *kernel)
{
        /* In case of renewal the kernel map, destroy previous one */
        machine__destroy_kernel_maps(machine);

        machine->vmlinux_map = map__new2(0, kernel);
        if (machine->vmlinux_map == NULL)
                return -1;

        machine->vmlinux_map->map_ip = machine->vmlinux_map->unmap_ip = identity__map_ip;
        maps__insert(&machine->kmaps, machine->vmlinux_map);
        return 0;
}

void machine__destroy_kernel_maps(struct machine *machine)
{
        struct kmap *kmap;
        struct map *map = machine__kernel_map(machine);

        if (map == NULL)
                return;

        kmap = map__kmap(map);
        maps__remove(&machine->kmaps, map);
        if (kmap && kmap->ref_reloc_sym) {
                zfree((char **)&kmap->ref_reloc_sym->name);
                zfree(&kmap->ref_reloc_sym);
        }

        map__zput(machine->vmlinux_map);
}

int machines__create_guest_kernel_maps(struct machines *machines)
{
        int ret = 0;
        struct dirent **namelist = NULL;
        int i, items = 0;
        char path[PATH_MAX];
        pid_t pid;
        char *endp;

        if (symbol_conf.default_guest_vmlinux_name ||
            symbol_conf.default_guest_modules ||
            symbol_conf.default_guest_kallsyms) {
                machines__create_kernel_maps(machines, DEFAULT_GUEST_KERNEL_ID);
        }

        if (symbol_conf.guestmount) {
                items = scandir(symbol_conf.guestmount, &namelist, NULL, NULL);
                if (items <= 0)
                        return -ENOENT;
                for (i = 0; i < items; i++) {
                        if (!isdigit(namelist[i]->d_name[0])) {
                                /* Filter out . and .. */
                                continue;
                        }
                        pid = (pid_t)strtol(namelist[i]->d_name, &endp, 10);
                        if ((*endp != '\0') ||
                            (endp == namelist[i]->d_name) ||
                            (errno == ERANGE)) {
                                pr_debug("invalid directory (%s). Skipping.\n",
                                         namelist[i]->d_name);
                                continue;
                        }
                        sprintf(path, "%s/%s/proc/kallsyms",
                                symbol_conf.guestmount,
                                namelist[i]->d_name);
                        ret = access(path, R_OK);
                        if (ret) {
                                pr_debug("Can't access file %s\n", path);
                                goto failure;
                        }
                        machines__create_kernel_maps(machines, pid);
                }
failure:
                free(namelist);
        }

        return ret;
}

void machines__destroy_kernel_maps(struct machines *machines)
{
        struct rb_node *next = rb_first_cached(&machines->guests);

        machine__destroy_kernel_maps(&machines->host);

        while (next) {
                struct machine *pos = rb_entry(next, struct machine, rb_node);

                next = rb_next(&pos->rb_node);
                rb_erase_cached(&pos->rb_node, &machines->guests);
                machine__delete(pos);
        }
}

int machines__create_kernel_maps(struct machines *machines, pid_t pid)
{
        struct machine *machine = machines__findnew(machines, pid);

        if (machine == NULL)
                return -1;

        return machine__create_kernel_maps(machine);
}

int machine__load_kallsyms(struct machine *machine, const char *filename)
{
        struct map *map = machine__kernel_map(machine);
        int ret = __dso__load_kallsyms(map->dso, filename, map, true);

        if (ret > 0) {
                dso__set_loaded(map->dso);
                /*
                 * Since /proc/kallsyms will have multiple sessions for the
                 * kernel, with modules between them, fixup the end of all
                 * sections.
                 */
                maps__fixup_end(&machine->kmaps);
        }

        return ret;
}

int machine__load_vmlinux_path(struct machine *machine)
{
        struct map *map = machine__kernel_map(machine);
        int ret = dso__load_vmlinux_path(map->dso, map);

        if (ret > 0)
                dso__set_loaded(map->dso);

        return ret;
}

static char *get_kernel_version(const char *root_dir)
{
        char version[PATH_MAX];
        FILE *file;
        char *name, *tmp;
        const char *prefix = "Linux version ";

        sprintf(version, "%s/proc/version", root_dir);
        file = fopen(version, "r");
        if (!file)
                return NULL;

        tmp = fgets(version, sizeof(version), file);
        fclose(file);
        if (!tmp)
                return NULL;

        name = strstr(version, prefix);
        if (!name)
                return NULL;
        name += strlen(prefix);
        tmp = strchr(name, ' ');
        if (tmp)
                *tmp = '\0';

        return strdup(name);
}

static bool is_kmod_dso(struct dso *dso)
{
        return dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
               dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE;
}

static int maps__set_module_path(struct maps *maps, const char *path, struct kmod_path *m)
{
        char *long_name;
        struct map *map = maps__find_by_name(maps, m->name);

        if (map == NULL)
                return 0;

        long_name = strdup(path);
        if (long_name == NULL)
                return -ENOMEM;

        dso__set_long_name(map->dso, long_name, true);
        dso__kernel_module_get_build_id(map->dso, "");

        /*
         * Full name could reveal us kmod compression, so
         * we need to update the symtab_type if needed.
         */
        if (m->comp && is_kmod_dso(map->dso)) {
                map->dso->symtab_type++;
                map->dso->comp = m->comp;
        }

        return 0;
}

static int maps__set_modules_path_dir(struct maps *maps, const char *dir_name, int depth)
{
        struct dirent *dent;
        DIR *dir = opendir(dir_name);
        int ret = 0;

        if (!dir) {
                pr_debug("%s: cannot open %s dir\n", __func__, dir_name);
                return -1;
        }

        while ((dent = readdir(dir)) != NULL) {
                char path[PATH_MAX];
                struct stat st;

                /*sshfs might return bad dent->d_type, so we have to stat*/
                path__join(path, sizeof(path), dir_name, dent->d_name);
                if (stat(path, &st))
                        continue;

                if (S_ISDIR(st.st_mode)) {
                        if (!strcmp(dent->d_name, ".") ||
                            !strcmp(dent->d_name, ".."))
                                continue;

                        /* Do not follow top-level source and build symlinks */
                        if (depth == 0) {
                                if (!strcmp(dent->d_name, "source") ||
                                    !strcmp(dent->d_name, "build"))
                                        continue;
                        }

                        ret = maps__set_modules_path_dir(maps, path, depth + 1);
                        if (ret < 0)
                                goto out;
                } else {
                        struct kmod_path m;

                        ret = kmod_path__parse_name(&m, dent->d_name);
                        if (ret)
                                goto out;

                        if (m.kmod)
                                ret = maps__set_module_path(maps, path, &m);

                        zfree(&m.name);

                        if (ret)
                                goto out;
                }
        }

out:
        closedir(dir);
        return ret;
}

static int machine__set_modules_path(struct machine *machine)
{
        char *version;
        char modules_path[PATH_MAX];

        version = get_kernel_version(machine->root_dir);
        if (!version)
                return -1;

        snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s",
                 machine->root_dir, version);
        free(version);

        return maps__set_modules_path_dir(&machine->kmaps, modules_path, 0);
}
int __weak arch__fix_module_text_start(u64 *start __maybe_unused,
                                u64 *size __maybe_unused,
                                const char *name __maybe_unused)
{
        return 0;
}

static int machine__create_module(void *arg, const char *name, u64 start,
                                  u64 size)
{
        struct machine *machine = arg;
        struct map *map;

        if (arch__fix_module_text_start(&start, &size, name) < 0)
                return -1;

        map = machine__addnew_module_map(machine, start, name);
        if (map == NULL)
                return -1;
        map->end = start + size;

        dso__kernel_module_get_build_id(map->dso, machine->root_dir);

        return 0;
}

static int machine__create_modules(struct machine *machine)
{
        const char *modules;
        char path[PATH_MAX];

        if (machine__is_default_guest(machine)) {
                modules = symbol_conf.default_guest_modules;
        } else {
                snprintf(path, PATH_MAX, "%s/proc/modules", machine->root_dir);
                modules = path;
        }

        if (symbol__restricted_filename(modules, "/proc/modules"))
                return -1;

        if (modules__parse(modules, machine, machine__create_module))
                return -1;

        if (!machine__set_modules_path(machine))
                return 0;

        pr_debug("Problems setting modules path maps, continuing anyway...\n");

        return 0;
}

static void machine__set_kernel_mmap(struct machine *machine,
                                     u64 start, u64 end)
{
        machine->vmlinux_map->start = start;
        machine->vmlinux_map->end   = end;
        /*
         * Be a bit paranoid here, some perf.data file came with
         * a zero sized synthesized MMAP event for the kernel.
         */
        if (start == 0 && end == 0)
                machine->vmlinux_map->end = ~0ULL;
}

static void machine__update_kernel_mmap(struct machine *machine,
                                     u64 start, u64 end)
{
        struct map *map = machine__kernel_map(machine);

        map__get(map);
        maps__remove(&machine->kmaps, map);

        machine__set_kernel_mmap(machine, start, end);

        maps__insert(&machine->kmaps, map);
        map__put(map);
}

int machine__create_kernel_maps(struct machine *machine)
{
        struct dso *kernel = machine__get_kernel(machine);
        const char *name = NULL;
        struct map *map;
        u64 start = 0, end = ~0ULL;
        int ret;

        if (kernel == NULL)
                return -1;

        ret = __machine__create_kernel_maps(machine, kernel);
        if (ret < 0)
                goto out_put;

        if (symbol_conf.use_modules && machine__create_modules(machine) < 0) {
                if (machine__is_host(machine))
                        pr_debug("Problems creating module maps, "
                                 "continuing anyway...\n");
                else
                        pr_debug("Problems creating module maps for guest %d, "
                                 "continuing anyway...\n", machine->pid);
        }

        if (!machine__get_running_kernel_start(machine, &name, &start, &end)) {
                if (name &&
                    map__set_kallsyms_ref_reloc_sym(machine->vmlinux_map, name, start)) {
                        machine__destroy_kernel_maps(machine);
                        ret = -1;
                        goto out_put;
                }

                /*
                 * we have a real start address now, so re-order the kmaps
                 * assume it's the last in the kmaps
                 */
                machine__update_kernel_mmap(machine, start, end);
        }

        if (machine__create_extra_kernel_maps(machine, kernel))
                pr_debug("Problems creating extra kernel maps, continuing anyway...\n");

        if (end == ~0ULL) {
                /* update end address of the kernel map using adjacent module address */
                map = map__next(machine__kernel_map(machine));
                if (map)
                        machine__set_kernel_mmap(machine, start, map->start);
        }

out_put:
        dso__put(kernel);
        return ret;
}

static bool machine__uses_kcore(struct machine *machine)
{
        struct dso *dso;

        list_for_each_entry(dso, &machine->dsos.head, node) {
                if (dso__is_kcore(dso))
                        return true;
        }

        return false;
}

static bool perf_event__is_extra_kernel_mmap(struct machine *machine,
                                             struct extra_kernel_map *xm)
{
        return machine__is(machine, "x86_64") &&
               is_entry_trampoline(xm->name);
}

static int machine__process_extra_kernel_map(struct machine *machine,
                                             struct extra_kernel_map *xm)
{
        struct dso *kernel = machine__kernel_dso(machine);

        if (kernel == NULL)
                return -1;

        return machine__create_extra_kernel_map(machine, kernel, xm);
}

static int machine__process_kernel_mmap_event(struct machine *machine,
                                              struct extra_kernel_map *xm,
                                              struct build_id *bid)
{
        struct map *map;
        enum dso_space_type dso_space;
        bool is_kernel_mmap;

        /* If we have maps from kcore then we do not need or want any others */
        if (machine__uses_kcore(machine))
                return 0;

        if (machine__is_host(machine))
                dso_space = DSO_SPACE__KERNEL;
        else
                dso_space = DSO_SPACE__KERNEL_GUEST;

        is_kernel_mmap = memcmp(xm->name, machine->mmap_name,
                                strlen(machine->mmap_name) - 1) == 0;
        if (xm->name[0] == '/' ||
            (!is_kernel_mmap && xm->name[0] == '[')) {
                map = machine__addnew_module_map(machine, xm->start,
                                                 xm->name);
                if (map == NULL)
                        goto out_problem;

                map->end = map->start + xm->end - xm->start;

                if (build_id__is_defined(bid))
                        dso__set_build_id(map->dso, bid);

        } else if (is_kernel_mmap) {
                const char *symbol_name = (xm->name + strlen(machine->mmap_name));
                /*
                 * Should be there already, from the build-id table in
                 * the header.
                 */
                struct dso *kernel = NULL;
                struct dso *dso;

                down_read(&machine->dsos.lock);

                list_for_each_entry(dso, &machine->dsos.head, node) {

                        /*
                         * The cpumode passed to is_kernel_module is not the
                         * cpumode of *this* event. If we insist on passing
                         * correct cpumode to is_kernel_module, we should
                         * record the cpumode when we adding this dso to the
                         * linked list.
                         *
                         * However we don't really need passing correct
                         * cpumode.  We know the correct cpumode must be kernel
                         * mode (if not, we should not link it onto kernel_dsos
                         * list).
                         *
                         * Therefore, we pass PERF_RECORD_MISC_CPUMODE_UNKNOWN.
                         * is_kernel_module() treats it as a kernel cpumode.
                         */

                        if (!dso->kernel ||
                            is_kernel_module(dso->long_name,
                                             PERF_RECORD_MISC_CPUMODE_UNKNOWN))
                                continue;


                        kernel = dso;
                        break;
                }

                up_read(&machine->dsos.lock);

                if (kernel == NULL)
                        kernel = machine__findnew_dso(machine, machine->mmap_name);
                if (kernel == NULL)
                        goto out_problem;

                kernel->kernel = dso_space;
                if (__machine__create_kernel_maps(machine, kernel) < 0) {
                        dso__put(kernel);
                        goto out_problem;
                }

                if (strstr(kernel->long_name, "vmlinux"))
                        dso__set_short_name(kernel, "[kernel.vmlinux]", false);

                machine__update_kernel_mmap(machine, xm->start, xm->end);

                if (build_id__is_defined(bid))
                        dso__set_build_id(kernel, bid);

                /*
                 * Avoid using a zero address (kptr_restrict) for the ref reloc
                 * symbol. Effectively having zero here means that at record
                 * time /proc/sys/kernel/kptr_restrict was non zero.
                 */
                if (xm->pgoff != 0) {
                        map__set_kallsyms_ref_reloc_sym(machine->vmlinux_map,
                                                        symbol_name,
                                                        xm->pgoff);
                }

                if (machine__is_default_guest(machine)) {
                        /*
                         * preload dso of guest kernel and modules
                         */
                        dso__load(kernel, machine__kernel_map(machine));
                }
        } else if (perf_event__is_extra_kernel_mmap(machine, xm)) {
                return machine__process_extra_kernel_map(machine, xm);
        }
        return 0;
out_problem:
        return -1;
}

int machine__process_mmap2_event(struct machine *machine,
                                 union perf_event *event,
                                 struct perf_sample *sample)
{
        struct thread *thread;
        struct map *map;
        struct dso_id dso_id = {
                .maj = event->mmap2.maj,
                .min = event->mmap2.min,
                .ino = event->mmap2.ino,
                .ino_generation = event->mmap2.ino_generation,
        };
        struct build_id __bid, *bid = NULL;
        int ret = 0;

        if (dump_trace)
                perf_event__fprintf_mmap2(event, stdout);

        if (event->header.misc & PERF_RECORD_MISC_MMAP_BUILD_ID) {
                bid = &__bid;
                build_id__init(bid, event->mmap2.build_id, event->mmap2.build_id_size);
        }

        if (sample->cpumode == PERF_RECORD_MISC_GUEST_KERNEL ||
            sample->cpumode == PERF_RECORD_MISC_KERNEL) {
                struct extra_kernel_map xm = {
                        .start = event->mmap2.start,
                        .end   = event->mmap2.start + event->mmap2.len,
                        .pgoff = event->mmap2.pgoff,
                };

                strlcpy(xm.name, event->mmap2.filename, KMAP_NAME_LEN);
                ret = machine__process_kernel_mmap_event(machine, &xm, bid);
                if (ret < 0)
                        goto out_problem;
                return 0;
        }

        thread = machine__findnew_thread(machine, event->mmap2.pid,
                                        event->mmap2.tid);
        if (thread == NULL)
                goto out_problem;

        map = map__new(machine, event->mmap2.start,
                        event->mmap2.len, event->mmap2.pgoff,
                        &dso_id, event->mmap2.prot,
                        event->mmap2.flags, bid,
                        event->mmap2.filename, thread);

        if (map == NULL)
                goto out_problem_map;

        ret = thread__insert_map(thread, map);
        if (ret)
                goto out_problem_insert;

        thread__put(thread);
        map__put(map);
        return 0;

out_problem_insert:
        map__put(map);
out_problem_map:
        thread__put(thread);
out_problem:
        dump_printf("problem processing PERF_RECORD_MMAP2, skipping event.\n");
        return 0;
}

int machine__process_mmap_event(struct machine *machine, union perf_event *event,
                                struct perf_sample *sample)
{
        struct thread *thread;
        struct map *map;
        u32 prot = 0;
        int ret = 0;

        if (dump_trace)
                perf_event__fprintf_mmap(event, stdout);

        if (sample->cpumode == PERF_RECORD_MISC_GUEST_KERNEL ||
            sample->cpumode == PERF_RECORD_MISC_KERNEL) {
                struct extra_kernel_map xm = {
                        .start = event->mmap.start,
                        .end   = event->mmap.start + event->mmap.len,
                        .pgoff = event->mmap.pgoff,
                };

                strlcpy(xm.name, event->mmap.filename, KMAP_NAME_LEN);
                ret = machine__process_kernel_mmap_event(machine, &xm, NULL);
                if (ret < 0)
                        goto out_problem;
                return 0;
        }

        thread = machine__findnew_thread(machine, event->mmap.pid,
                                         event->mmap.tid);
        if (thread == NULL)
                goto out_problem;

        if (!(event->header.misc & PERF_RECORD_MISC_MMAP_DATA))
                prot = PROT_EXEC;

        map = map__new(machine, event->mmap.start,
                        event->mmap.len, event->mmap.pgoff,
                        NULL, prot, 0, NULL, event->mmap.filename, thread);

        if (map == NULL)
                goto out_problem_map;

        ret = thread__insert_map(thread, map);
        if (ret)
                goto out_problem_insert;

        thread__put(thread);
        map__put(map);
        return 0;

out_problem_insert:
        map__put(map);
out_problem_map:
        thread__put(thread);
out_problem:
        dump_printf("problem processing PERF_RECORD_MMAP, skipping event.\n");
        return 0;
}

static void __machine__remove_thread(struct machine *machine, struct thread *th, bool lock)
{
        struct threads *threads = machine__threads(machine, th->tid);

        if (threads->last_match == th)
                threads__set_last_match(threads, NULL);

        if (lock)
                down_write(&threads->lock);

        BUG_ON(refcount_read(&th->refcnt) == 0);

        rb_erase_cached(&th->rb_node, &threads->entries);
        RB_CLEAR_NODE(&th->rb_node);
        --threads->nr;
        /*
         * Move it first to the dead_threads list, then drop the reference,
         * if this is the last reference, then the thread__delete destructor
         * will be called and we will remove it from the dead_threads list.
         */
        list_add_tail(&th->node, &threads->dead);

        /*
         * We need to do the put here because if this is the last refcount,
         * then we will be touching the threads->dead head when removing the
         * thread.
         */
        thread__put(th);

        if (lock)
                up_write(&threads->lock);
}

void machine__remove_thread(struct machine *machine, struct thread *th)
{
        return __machine__remove_thread(machine, th, true);
}

int machine__process_fork_event(struct machine *machine, union perf_event *event,
                                struct perf_sample *sample)
{
        struct thread *thread = machine__find_thread(machine,
                                                     event->fork.pid,
                                                     event->fork.tid);
        struct thread *parent = machine__findnew_thread(machine,
                                                        event->fork.ppid,
                                                        event->fork.ptid);
        bool do_maps_clone = true;
        int err = 0;

        if (dump_trace)
                perf_event__fprintf_task(event, stdout);

        /*
         * There may be an existing thread that is not actually the parent,
         * either because we are processing events out of order, or because the
         * (fork) event that would have removed the thread was lost. Assume the
         * latter case and continue on as best we can.
         */
        if (parent->pid_ != (pid_t)event->fork.ppid) {
                dump_printf("removing erroneous parent thread %d/%d\n",
                            parent->pid_, parent->tid);
                machine__remove_thread(machine, parent);
                thread__put(parent);
                parent = machine__findnew_thread(machine, event->fork.ppid,
                                                 event->fork.ptid);
        }

        /* if a thread currently exists for the thread id remove it */
        if (thread != NULL) {
                machine__remove_thread(machine, thread);
                thread__put(thread);
        }

        thread = machine__findnew_thread(machine, event->fork.pid,
                                         event->fork.tid);
        /*
         * When synthesizing FORK events, we are trying to create thread
         * objects for the already running tasks on the machine.
         *
         * Normally, for a kernel FORK event, we want to clone the parent's
         * maps because that is what the kernel just did.
         *
         * But when synthesizing, this should not be done.  If we do, we end up
         * with overlapping maps as we process the synthesized MMAP2 events that
         * get delivered shortly thereafter.
         *
         * Use the FORK event misc flags in an internal way to signal this
         * situation, so we can elide the map clone when appropriate.
         */
        if (event->fork.header.misc & PERF_RECORD_MISC_FORK_EXEC)
                do_maps_clone = false;

        if (thread == NULL || parent == NULL ||
            thread__fork(thread, parent, sample->time, do_maps_clone) < 0) {
                dump_printf("problem processing PERF_RECORD_FORK, skipping event.\n");
                err = -1;
        }
        thread__put(thread);
        thread__put(parent);

        return err;
}

int machine__process_exit_event(struct machine *machine, union perf_event *event,
                                struct perf_sample *sample __maybe_unused)
{
        struct thread *thread = machine__find_thread(machine,
                                                     event->fork.pid,
                                                     event->fork.tid);

        if (dump_trace)
                perf_event__fprintf_task(event, stdout);

        if (thread != NULL) {
                thread__exited(thread);
                thread__put(thread);
        }

        return 0;
}

int machine__process_event(struct machine *machine, union perf_event *event,
                           struct perf_sample *sample)
{
        int ret;

        switch (event->header.type) {
        case PERF_RECORD_COMM:
                ret = machine__process_comm_event(machine, event, sample); break;
        case PERF_RECORD_MMAP:
                ret = machine__process_mmap_event(machine, event, sample); break;
        case PERF_RECORD_NAMESPACES:
                ret = machine__process_namespaces_event(machine, event, sample); break;
        case PERF_RECORD_CGROUP:
                ret = machine__process_cgroup_event(machine, event, sample); break;
        case PERF_RECORD_MMAP2:
                ret = machine__process_mmap2_event(machine, event, sample); break;
        case PERF_RECORD_FORK:
                ret = machine__process_fork_event(machine, event, sample); break;
        case PERF_RECORD_EXIT:
                ret = machine__process_exit_event(machine, event, sample); break;
        case PERF_RECORD_LOST:
                ret = machine__process_lost_event(machine, event, sample); break;
        case PERF_RECORD_AUX:
                ret = machine__process_aux_event(machine, event); break;
        case PERF_RECORD_ITRACE_START:
                ret = machine__process_itrace_start_event(machine, event); break;
        case PERF_RECORD_LOST_SAMPLES:
                ret = machine__process_lost_samples_event(machine, event, sample); break;
        case PERF_RECORD_SWITCH:
        case PERF_RECORD_SWITCH_CPU_WIDE:
                ret = machine__process_switch_event(machine, event); break;
        case PERF_RECORD_KSYMBOL:
                ret = machine__process_ksymbol(machine, event, sample); break;
        case PERF_RECORD_BPF_EVENT:
                ret = machine__process_bpf(machine, event, sample); break;
        case PERF_RECORD_TEXT_POKE:
                ret = machine__process_text_poke(machine, event, sample); break;
        case PERF_RECORD_AUX_OUTPUT_HW_ID:
                ret = machine__process_aux_output_hw_id_event(machine, event); break;
        default:
                ret = -1;
                break;
        }

        return ret;
}

static bool symbol__match_regex(struct symbol *sym, regex_t *regex)
{
        if (!regexec(regex, sym->name, 0, NULL, 0))
                return true;
        return false;
}

static void ip__resolve_ams(struct thread *thread,
                            struct addr_map_symbol *ams,
                            u64 ip)
{
        struct addr_location al;

        memset(&al, 0, sizeof(al));
        /*
         * We cannot use the header.misc hint to determine whether a
         * branch stack address is user, kernel, guest, hypervisor.
         * Branches may straddle the kernel/user/hypervisor boundaries.
         * Thus, we have to try consecutively until we find a match
         * or else, the symbol is unknown
         */
        thread__find_cpumode_addr_location(thread, ip, &al);

        ams->addr = ip;
        ams->al_addr = al.addr;
        ams->al_level = al.level;
        ams->ms.maps = al.maps;
        ams->ms.sym = al.sym;
        ams->ms.map = al.map;
        ams->phys_addr = 0;
        ams->data_page_size = 0;
}

static void ip__resolve_data(struct thread *thread,
                             u8 m, struct addr_map_symbol *ams,
                             u64 addr, u64 phys_addr, u64 daddr_page_size)
{
        struct addr_location al;

        memset(&al, 0, sizeof(al));

        thread__find_symbol(thread, m, addr, &al);

        ams->addr = addr;
        ams->al_addr = al.addr;
        ams->al_level = al.level;
        ams->ms.maps = al.maps;
        ams->ms.sym = al.sym;
        ams->ms.map = al.map;
        ams->phys_addr = phys_addr;
        ams->data_page_size = daddr_page_size;
}

struct mem_info *sample__resolve_mem(struct perf_sample *sample,
                                     struct addr_location *al)
{
        struct mem_info *mi = mem_info__new();

        if (!mi)
                return NULL;

        ip__resolve_ams(al->thread, &mi->iaddr, sample->ip);
        ip__resolve_data(al->thread, al->cpumode, &mi->daddr,
                         sample->addr, sample->phys_addr,
                         sample->data_page_size);
        mi->data_src.val = sample->data_src;

        return mi;
}

static char *callchain_srcline(struct map_symbol *ms, u64 ip)
{
        struct map *map = ms->map;
        char *srcline = NULL;

        if (!map || callchain_param.key == CCKEY_FUNCTION)
                return srcline;

        srcline = srcline__tree_find(&map->dso->srclines, ip);
        if (!srcline) {
                bool show_sym = false;
                bool show_addr = callchain_param.key == CCKEY_ADDRESS;

                srcline = get_srcline(map->dso, map__rip_2objdump(map, ip),
                                      ms->sym, show_sym, show_addr, ip);
                srcline__tree_insert(&map->dso->srclines, ip, srcline);
        }

        return srcline;
}

struct iterations {
        int nr_loop_iter;
        u64 cycles;
};

static int add_callchain_ip(struct thread *thread,
                            struct callchain_cursor *cursor,
                            struct symbol **parent,
                            struct addr_location *root_al,
                            u8 *cpumode,
                            u64 ip,
                            bool branch,
                            struct branch_flags *flags,
                            struct iterations *iter,
                            u64 branch_from)
{
        struct map_symbol ms;
        struct addr_location al;
        int nr_loop_iter = 0;
        u64 iter_cycles = 0;
        const char *srcline = NULL;

        al.filtered = 0;
        al.sym = NULL;
        al.srcline = NULL;
        if (!cpumode) {
                thread__find_cpumode_addr_location(thread, ip, &al);
        } else {
                if (ip >= PERF_CONTEXT_MAX) {
                        switch (ip) {
                        case PERF_CONTEXT_HV:
                                *cpumode = PERF_RECORD_MISC_HYPERVISOR;
                                break;
                        case PERF_CONTEXT_KERNEL:
                                *cpumode = PERF_RECORD_MISC_KERNEL;
                                break;
                        case PERF_CONTEXT_USER:
                                *cpumode = PERF_RECORD_MISC_USER;
                                break;
                        default:
                                pr_debug("invalid callchain context: "
                                         "%"PRId64"\n", (s64) ip);
                                /*
                                 * It seems the callchain is corrupted.
                                 * Discard all.
                                 */
                                callchain_cursor_reset(cursor);
                                return 1;
                        }
                        return 0;
                }
                thread__find_symbol(thread, *cpumode, ip, &al);
        }

        if (al.sym != NULL) {
                if (perf_hpp_list.parent && !*parent &&
                    symbol__match_regex(al.sym, &parent_regex))
                        *parent = al.sym;
                else if (have_ignore_callees && root_al &&
                  symbol__match_regex(al.sym, &ignore_callees_regex)) {
                        /* Treat this symbol as the root,
                           forgetting its callees. */
                        *root_al = al;
                        callchain_cursor_reset(cursor);
                }
        }

        if (symbol_conf.hide_unresolved && al.sym == NULL)
                return 0;

        if (iter) {
                nr_loop_iter = iter->nr_loop_iter;
                iter_cycles = iter->cycles;
        }

        ms.maps = al.maps;
        ms.map = al.map;
        ms.sym = al.sym;
        srcline = callchain_srcline(&ms, al.addr);
        return callchain_cursor_append(cursor, ip, &ms,
                                       branch, flags, nr_loop_iter,
                                       iter_cycles, branch_from, srcline);
}

struct branch_info *sample__resolve_bstack(struct perf_sample *sample,
                                           struct addr_location *al)
{
        unsigned int i;
        const struct branch_stack *bs = sample->branch_stack;
        struct branch_entry *entries = perf_sample__branch_entries(sample);
        struct branch_info *bi = calloc(bs->nr, sizeof(struct branch_info));

        if (!bi)
                return NULL;

        for (i = 0; i < bs->nr; i++) {
                ip__resolve_ams(al->thread, &bi[i].to, entries[i].to);
                ip__resolve_ams(al->thread, &bi[i].from, entries[i].from);
                bi[i].flags = entries[i].flags;
        }
        return bi;
}

static void save_iterations(struct iterations *iter,
                            struct branch_entry *be, int nr)
{
        int i;

        iter->nr_loop_iter++;
        iter->cycles = 0;

        for (i = 0; i < nr; i++)
                iter->cycles += be[i].flags.cycles;
}

#define CHASHSZ 127
#define CHASHBITS 7
#define NO_ENTRY 0xff

#define PERF_MAX_BRANCH_DEPTH 127

/* Remove loops. */
static int remove_loops(struct branch_entry *l, int nr,
                        struct iterations *iter)
{
        int i, j, off;
        unsigned char chash[CHASHSZ];

        memset(chash, NO_ENTRY, sizeof(chash));

        BUG_ON(PERF_MAX_BRANCH_DEPTH > 255);

        for (i = 0; i < nr; i++) {
                int h = hash_64(l[i].from, CHASHBITS) % CHASHSZ;

                /* no collision handling for now */
                if (chash[h] == NO_ENTRY) {
                        chash[h] = i;
                } else if (l[chash[h]].from == l[i].from) {
                        bool is_loop = true;
                        /* check if it is a real loop */
                        off = 0;
                        for (j = chash[h]; j < i && i + off < nr; j++, off++)
                                if (l[j].from != l[i + off].from) {
                                        is_loop = false;
                                        break;
                                }
                        if (is_loop) {
                                j = nr - (i + off);
                                if (j > 0) {
                                        save_iterations(iter + i + off,
                                                l + i, off);

                                        memmove(iter + i, iter + i + off,
                                                j * sizeof(*iter));

                                        memmove(l + i, l + i + off,
                                                j * sizeof(*l));
                                }

                                nr -= off;
                        }
                }
        }
        return nr;
}

static int lbr_callchain_add_kernel_ip(struct thread *thread,
                                       struct callchain_cursor *cursor,
                                       struct perf_sample *sample,
                                       struct symbol **parent,
                                       struct addr_location *root_al,
                                       u64 branch_from,
                                       bool callee, int end)
{
        struct ip_callchain *chain = sample->callchain;
        u8 cpumode = PERF_RECORD_MISC_USER;
        int err, i;

        if (callee) {
                for (i = 0; i < end + 1; i++) {
                        err = add_callchain_ip(thread, cursor, parent,
                                               root_al, &cpumode, chain->ips[i],
                                               false, NULL, NULL, branch_from);
                        if (err)
                                return err;
                }
                return 0;
        }

        for (i = end; i >= 0; i--) {
                err = add_callchain_ip(thread, cursor, parent,
                                       root_al, &cpumode, chain->ips[i],
                                       false, NULL, NULL, branch_from);
                if (err)
                        return err;
        }

        return 0;
}

static void save_lbr_cursor_node(struct thread *thread,
                                 struct callchain_cursor *cursor,
                                 int idx)
{
        struct lbr_stitch *lbr_stitch = thread->lbr_stitch;

        if (!lbr_stitch)
                return;

        if (cursor->pos == cursor->nr) {
                lbr_stitch->prev_lbr_cursor[idx].valid = false;
                return;
        }

        if (!cursor->curr)
                cursor->curr = cursor->first;
        else
                cursor->curr = cursor->curr->next;
        memcpy(&lbr_stitch->prev_lbr_cursor[idx], cursor->curr,
               sizeof(struct callchain_cursor_node));

        lbr_stitch->prev_lbr_cursor[idx].valid = true;
        cursor->pos++;
}

static int lbr_callchain_add_lbr_ip(struct thread *thread,
                                    struct callchain_cursor *cursor,
                                    struct perf_sample *sample,
                                    struct symbol **parent,
                                    struct addr_location *root_al,
                                    u64 *branch_from,
                                    bool callee)
{
        struct branch_stack *lbr_stack = sample->branch_stack;
        struct branch_entry *entries = perf_sample__branch_entries(sample);
        u8 cpumode = PERF_RECORD_MISC_USER;
        int lbr_nr = lbr_stack->nr;
        struct branch_flags *flags;
        int err, i;
        u64 ip;

        /*
         * The curr and pos are not used in writing session. They are cleared
         * in callchain_cursor_commit() when the writing session is closed.
         * Using curr and pos to track the current cursor node.
         */
        if (thread->lbr_stitch) {
                cursor->curr = NULL;
                cursor->pos = cursor->nr;
                if (cursor->nr) {
                        cursor->curr = cursor->first;
                        for (i = 0; i < (int)(cursor->nr - 1); i++)
                                cursor->curr = cursor->curr->next;
                }
        }

        if (callee) {
                /* Add LBR ip from first entries.to */
                ip = entries[0].to;
                flags = &entries[0].flags;
                *branch_from = entries[0].from;
                err = add_callchain_ip(thread, cursor, parent,
                                       root_al, &cpumode, ip,
                                       true, flags, NULL,
                                       *branch_from);
                if (err)
                        return err;

                /*
                 * The number of cursor node increases.
                 * Move the current cursor node.
                 * But does not need to save current cursor node for entry 0.
                 * It's impossible to stitch the whole LBRs of previous sample.
                 */
                if (thread->lbr_stitch && (cursor->pos != cursor->nr)) {
                        if (!cursor->curr)
                                cursor->curr = cursor->first;
                        else
                                cursor->curr = cursor->curr->next;
                        cursor->pos++;
                }

                /* Add LBR ip from entries.from one by one. */
                for (i = 0; i < lbr_nr; i++) {
                        ip = entries[i].from;
                        flags = &entries[i].flags;
                        err = add_callchain_ip(thread, cursor, parent,
                                               root_al, &cpumode, ip,
                                               true, flags, NULL,
                                               *branch_from);
                        if (err)
                                return err;
                        save_lbr_cursor_node(thread, cursor, i);
                }
                return 0;
        }

        /* Add LBR ip from entries.from one by one. */
        for (i = lbr_nr - 1; i >= 0; i--) {
                ip = entries[i].from;
                flags = &entries[i].flags;
                err = add_callchain_ip(thread, cursor, parent,
                                       root_al, &cpumode, ip,
                                       true, flags, NULL,
                                       *branch_from);
                if (err)
                        return err;
                save_lbr_cursor_node(thread, cursor, i);
        }

        /* Add LBR ip from first entries.to */
        ip = entries[0].to;
        flags = &entries[0].flags;
        *branch_from = entries[0].from;
        err = add_callchain_ip(thread, cursor, parent,
                               root_al, &cpumode, ip,
                               true, flags, NULL,
                               *branch_from);
        if (err)
                return err;

        return 0;
}

static int lbr_callchain_add_stitched_lbr_ip(struct thread *thread,
                                             struct callchain_cursor *cursor)
{
        struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
        struct callchain_cursor_node *cnode;
        struct stitch_list *stitch_node;
        int err;

        list_for_each_entry(stitch_node, &lbr_stitch->lists, node) {
                cnode = &stitch_node->cursor;

                err = callchain_cursor_append(cursor, cnode->ip,
                                              &cnode->ms,
                                              cnode->branch,
                                              &cnode->branch_flags,
                                              cnode->nr_loop_iter,
                                              cnode->iter_cycles,
                                              cnode->branch_from,
                                              cnode->srcline);
                if (err)
                        return err;
        }
        return 0;
}

static struct stitch_list *get_stitch_node(struct thread *thread)
{
        struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
        struct stitch_list *stitch_node;

        if (!list_empty(&lbr_stitch->free_lists)) {
                stitch_node = list_first_entry(&lbr_stitch->free_lists,
                                               struct stitch_list, node);
                list_del(&stitch_node->node);

                return stitch_node;
        }

        return malloc(sizeof(struct stitch_list));
}

static bool has_stitched_lbr(struct thread *thread,
                             struct perf_sample *cur,
                             struct perf_sample *prev,
                             unsigned int max_lbr,
                             bool callee)
{
        struct branch_stack *cur_stack = cur->branch_stack;
        struct branch_entry *cur_entries = perf_sample__branch_entries(cur);
        struct branch_stack *prev_stack = prev->branch_stack;
        struct branch_entry *prev_entries = perf_sample__branch_entries(prev);
        struct lbr_stitch *lbr_stitch = thread->lbr_stitch;
        int i, j, nr_identical_branches = 0;
        struct stitch_list *stitch_node;
        u64 cur_base, distance;

        if (!cur_stack || !prev_stack)
                return false;

        /* Find the physical index of the base-of-stack for current sample. */
        cur_base = max_lbr - cur_stack->nr + cur_stack->hw_idx + 1;

        distance = (prev_stack->hw_idx > cur_base) ? (prev_stack->hw_idx - cur_base) :
                                                     (max_lbr + prev_stack->hw_idx - cur_base);
        /* Previous sample has shorter stack. Nothing can be stitched. */
        if (distance + 1 > prev_stack->nr)
                return false;

        /*
         * Check if there are identical LBRs between two samples.
         * Identical LBRs must have same from, to and flags values. Also,
         * they have to be saved in the same LBR registers (same physical
         * index).
         *
         * Starts from the base-of-stack of current sample.
         */
        for (i = distance, j = cur_stack->nr - 1; (i >= 0) && (j >= 0); i--, j--) {
                if ((prev_entries[i].from != cur_entries[j].from) ||
                    (prev_entries[i].to != cur_entries[j].to) ||
                    (prev_entries[i].flags.value != cur_entries[j].flags.value))
                        break;
                nr_identical_branches++;
        }

        if (!nr_identical_branches)
                return false;

        /*
         * Save the LBRs between the base-of-stack of previous sample
         * and the base-of-stack of current sample into lbr_stitch->lists.
         * These LBRs will be stitched later.
         */
        for (i = prev_stack->nr - 1; i > (int)distance; i--) {

                if (!lbr_stitch->prev_lbr_cursor[i].valid)
                        continue;

                stitch_node = get_stitch_node(thread);
                if (!stitch_node)
                        return false;

                memcpy(&stitch_node->cursor, &lbr_stitch->prev_lbr_cursor[i],
                       sizeof(struct callchain_cursor_node));

                if (callee)
                        list_add(&stitch_node->node, &lbr_stitch->lists);
                else
                        list_add_tail(&stitch_node->node, &lbr_stitch->lists);
        }

        return true;
}

static bool alloc_lbr_stitch(struct thread *thread, unsigned int max_lbr)
{
        if (thread->lbr_stitch)
                return true;

        thread->lbr_stitch = zalloc(sizeof(*thread->lbr_stitch));
        if (!thread->lbr_stitch)
                goto err;

        thread->lbr_stitch->prev_lbr_cursor = calloc(max_lbr + 1, sizeof(struct callchain_cursor_node));
        if (!thread->lbr_stitch->prev_lbr_cursor)
                goto free_lbr_stitch;

        INIT_LIST_HEAD(&thread->lbr_stitch->lists);
        INIT_LIST_HEAD(&thread->lbr_stitch->free_lists);

        return true;

free_lbr_stitch:
        zfree(&thread->lbr_stitch);
err:
        pr_warning("Failed to allocate space for stitched LBRs. Disable LBR stitch\n");
        thread->lbr_stitch_enable = false;
        return false;
}

/*
 * Resolve LBR callstack chain sample
 * Return:
 * 1 on success get LBR callchain information
 * 0 no available LBR callchain information, should try fp
 * negative error code on other errors.
 */
static int resolve_lbr_callchain_sample(struct thread *thread,
                                        struct callchain_cursor *cursor,
                                        struct perf_sample *sample,
                                        struct symbol **parent,
                                        struct addr_location *root_al,
                                        int max_stack,
                                        unsigned int max_lbr)
{
        bool callee = (callchain_param.order == ORDER_CALLEE);
        struct ip_callchain *chain = sample->callchain;
        int chain_nr = min(max_stack, (int)chain->nr), i;
        struct lbr_stitch *lbr_stitch;
        bool stitched_lbr = false;
        u64 branch_from = 0;
        int err;

        for (i = 0; i < chain_nr; i++) {
                if (chain->ips[i] == PERF_CONTEXT_USER)
                        break;
        }

        /* LBR only affects the user callchain */
        if (i == chain_nr)
                return 0;

        if (thread->lbr_stitch_enable && !sample->no_hw_idx &&
            (max_lbr > 0) && alloc_lbr_stitch(thread, max_lbr)) {
                lbr_stitch = thread->lbr_stitch;

                stitched_lbr = has_stitched_lbr(thread, sample,
                                                &lbr_stitch->prev_sample,
                                                max_lbr, callee);

                if (!stitched_lbr && !list_empty(&lbr_stitch->lists)) {
                        list_replace_init(&lbr_stitch->lists,
                                          &lbr_stitch->free_lists);
                }
                memcpy(&lbr_stitch->prev_sample, sample, sizeof(*sample));
        }

        if (callee) {
                /* Add kernel ip */
                err = lbr_callchain_add_kernel_ip(thread, cursor, sample,
                                                  parent, root_al, branch_from,
                                                  true, i);
                if (err)
                        goto error;

                err = lbr_callchain_add_lbr_ip(thread, cursor, sample, parent,
                                               root_al, &branch_from, true);
                if (err)
                        goto error;

                if (stitched_lbr) {
                        err = lbr_callchain_add_stitched_lbr_ip(thread, cursor);
                        if (err)
                                goto error;
                }

        } else {
                if (stitched_lbr) {
                        err = lbr_callchain_add_stitched_lbr_ip(thread, cursor);
                        if (err)
                                goto error;
                }
                err = lbr_callchain_add_lbr_ip(thread, cursor, sample, parent,
                                               root_al, &branch_from, false);
                if (err)
                        goto error;

                /* Add kernel ip */
                err = lbr_callchain_add_kernel_ip(thread, cursor, sample,
                                                  parent, root_al, branch_from,
                                                  false, i);
                if (err)
                        goto error;
        }
        return 1;

error:
        return (err < 0) ? err : 0;
}

static int find_prev_cpumode(struct ip_callchain *chain, struct thread *thread,
                             struct callchain_cursor *cursor,
                             struct symbol **parent,
                             struct addr_location *root_al,
                             u8 *cpumode, int ent)
{
        int err = 0;

        while (--ent >= 0) {
                u64 ip = chain->ips[ent];

                if (ip >= PERF_CONTEXT_MAX) {
                        err = add_callchain_ip(thread, cursor, parent,
                                               root_al, cpumode, ip,
                                               false, NULL, NULL, 0);
                        break;
                }
        }
        return err;
}

static u64 get_leaf_frame_caller(struct perf_sample *sample,
                struct thread *thread, int usr_idx)
{
        if (machine__normalized_is(thread->maps->machine, "arm64"))
                return get_leaf_frame_caller_aarch64(sample, thread, usr_idx);
        else
                return 0;
}

static int thread__resolve_callchain_sample(struct thread *thread,
                                            struct callchain_cursor *cursor,
                                            struct evsel *evsel,
                                            struct perf_sample *sample,
                                            struct symbol **parent,
                                            struct addr_location *root_al,
                                            int max_stack)
{
        struct branch_stack *branch = sample->branch_stack;
        struct branch_entry *entries = perf_sample__branch_entries(sample);
        struct ip_callchain *chain = sample->callchain;
        int chain_nr = 0;
        u8 cpumode = PERF_RECORD_MISC_USER;
        int i, j, err, nr_entries, usr_idx;
        int skip_idx = -1;
        int first_call = 0;
        u64 leaf_frame_caller;

        if (chain)
                chain_nr = chain->nr;

        if (evsel__has_branch_callstack(evsel)) {
                struct perf_env *env = evsel__env(evsel);

                err = resolve_lbr_callchain_sample(thread, cursor, sample, parent,
                                                   root_al, max_stack,
                                                   !env ? 0 : env->max_branches);
                if (err)
                        return (err < 0) ? err : 0;
        }

        /*
         * Based on DWARF debug information, some architectures skip
         * a callchain entry saved by the kernel.
         */
        skip_idx = arch_skip_callchain_idx(thread, chain);

        /*
         * Add branches to call stack for easier browsing. This gives
         * more context for a sample than just the callers.
         *
         * This uses individual histograms of paths compared to the
         * aggregated histograms the normal LBR mode uses.
         *
         * Limitations for now:
         * - No extra filters
         * - No annotations (should annotate somehow)
         */

        if (branch && callchain_param.branch_callstack) {
                int nr = min(max_stack, (int)branch->nr);
                struct branch_entry be[nr];
                struct iterations iter[nr];

                if (branch->nr > PERF_MAX_BRANCH_DEPTH) {
                        pr_warning("corrupted branch chain. skipping...\n");
                        goto check_calls;
                }

                for (i = 0; i < nr; i++) {
                        if (callchain_param.order == ORDER_CALLEE) {
                                be[i] = entries[i];

                                if (chain == NULL)
                                        continue;

                                /*
                                 * Check for overlap into the callchain.
                                 * The return address is one off compared to
                                 * the branch entry. To adjust for this
                                 * assume the calling instruction is not longer
                                 * than 8 bytes.
                                 */
                                if (i == skip_idx ||
                                    chain->ips[first_call] >= PERF_CONTEXT_MAX)
                                        first_call++;
                                else if (be[i].from < chain->ips[first_call] &&
                                    be[i].from >= chain->ips[first_call] - 8)
                                        first_call++;
                        } else
                                be[i] = entries[branch->nr - i - 1];
                }

                memset(iter, 0, sizeof(struct iterations) * nr);
                nr = remove_loops(be, nr, iter);

                for (i = 0; i < nr; i++) {
                        err = add_callchain_ip(thread, cursor, parent,
                                               root_al,
                                               NULL, be[i].to,
                                               true, &be[i].flags,
                                               NULL, be[i].from);

                        if (!err)
                                err = add_callchain_ip(thread, cursor, parent, root_al,
                                                       NULL, be[i].from,
                                                       true, &be[i].flags,
                                                       &iter[i], 0);
                        if (err == -EINVAL)
                                break;
                        if (err)
                                return err;
                }

                if (chain_nr == 0)
                        return 0;

                chain_nr -= nr;
        }

check_calls:
        if (chain && callchain_param.order != ORDER_CALLEE) {
                err = find_prev_cpumode(chain, thread, cursor, parent, root_al,
                                        &cpumode, chain->nr - first_call);
                if (err)
                        return (err < 0) ? err : 0;
        }
        for (i = first_call, nr_entries = 0;
             i < chain_nr && nr_entries < max_stack; i++) {
                u64 ip;

                if (callchain_param.order == ORDER_CALLEE)
                        j = i;
                else
                        j = chain->nr - i - 1;

#ifdef HAVE_SKIP_CALLCHAIN_IDX
                if (j == skip_idx)
                        continue;
#endif
                ip = chain->ips[j];
                if (ip < PERF_CONTEXT_MAX)
                       ++nr_entries;
                else if (callchain_param.order != ORDER_CALLEE) {
                        err = find_prev_cpumode(chain, thread, cursor, parent,
                                                root_al, &cpumode, j);
                        if (err)
                                return (err < 0) ? err : 0;
                        continue;
                }

                /*
                 * PERF_CONTEXT_USER allows us to locate where the user stack ends.
                 * Depending on callchain_param.order and the position of PERF_CONTEXT_USER,
                 * the index will be different in order to add the missing frame
                 * at the right place.
                 */

                usr_idx = callchain_param.order == ORDER_CALLEE ? j-2 : j-1;

                if (usr_idx >= 0 && chain->ips[usr_idx] == PERF_CONTEXT_USER) {

                        leaf_frame_caller = get_leaf_frame_caller(sample, thread, usr_idx);

                        /*
                         * check if leaf_frame_Caller != ip to not add the same
                         * value twice.
                         */

                        if (leaf_frame_caller && leaf_frame_caller != ip) {

                                err = add_callchain_ip(thread, cursor, parent,
                                               root_al, &cpumode, leaf_frame_caller,
                                               false, NULL, NULL, 0);
                                if (err)
                                        return (err < 0) ? err : 0;
                        }
                }

                err = add_callchain_ip(thread, cursor, parent,
                                       root_al, &cpumode, ip,
                                       false, NULL, NULL, 0);

                if (err)
                        return (err < 0) ? err : 0;
        }

        return 0;
}

static int append_inlines(struct callchain_cursor *cursor, struct map_symbol *ms, u64 ip)
{
        struct symbol *sym = ms->sym;
        struct map *map = ms->map;
        struct inline_node *inline_node;
        struct inline_list *ilist;
        u64 addr;
        int ret = 1;

        if (!symbol_conf.inline_name || !map || !sym)
                return ret;

        addr = map__map_ip(map, ip);
        addr = map__rip_2objdump(map, addr);

        inline_node = inlines__tree_find(&map->dso->inlined_nodes, addr);
        if (!inline_node) {
                inline_node = dso__parse_addr_inlines(map->dso, addr, sym);
                if (!inline_node)
                        return ret;
                inlines__tree_insert(&map->dso->inlined_nodes, inline_node);
        }

        list_for_each_entry(ilist, &inline_node->val, list) {
                struct map_symbol ilist_ms = {
                        .maps = ms->maps,
                        .map = map,
                        .sym = ilist->symbol,
                };
                ret = callchain_cursor_append(cursor, ip, &ilist_ms, false,
                                              NULL, 0, 0, 0, ilist->srcline);

                if (ret != 0)
                        return ret;
        }

        return ret;
}

static int unwind_entry(struct unwind_entry *entry, void *arg)
{
        struct callchain_cursor *cursor = arg;
        const char *srcline = NULL;
        u64 addr = entry->ip;

        if (symbol_conf.hide_unresolved && entry->ms.sym == NULL)
                return 0;

        if (append_inlines(cursor, &entry->ms, entry->ip) == 0)
                return 0;

        /*
         * Convert entry->ip from a virtual address to an offset in
         * its corresponding binary.
         */
        if (entry->ms.map)
                addr = map__map_ip(entry->ms.map, entry->ip);

        srcline = callchain_srcline(&entry->ms, addr);
        return callchain_cursor_append(cursor, entry->ip, &entry->ms,
                                       false, NULL, 0, 0, 0, srcline);
}

static int thread__resolve_callchain_unwind(struct thread *thread,
                                            struct callchain_cursor *cursor,
                                            struct evsel *evsel,
                                            struct perf_sample *sample,
                                            int max_stack)
{
        /* Can we do dwarf post unwind? */
        if (!((evsel->core.attr.sample_type & PERF_SAMPLE_REGS_USER) &&
              (evsel->core.attr.sample_type & PERF_SAMPLE_STACK_USER)))
                return 0;

        /* Bail out if nothing was captured. */
        if ((!sample->user_regs.regs) ||
            (!sample->user_stack.size))
                return 0;

        return unwind__get_entries(unwind_entry, cursor,
                                   thread, sample, max_stack);
}

int thread__resolve_callchain(struct thread *thread,
                              struct callchain_cursor *cursor,
                              struct evsel *evsel,
                              struct perf_sample *sample,
                              struct symbol **parent,
                              struct addr_location *root_al,
                              int max_stack)
{
        int ret = 0;

        callchain_cursor_reset(cursor);