symbol.c

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// SPDX-License-Identifier: GPL-2.0
#include <dirent.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <linux/kernel.h>
#include <linux/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <fcntl.h>
#include <unistd.h>
#include <inttypes.h>
#include "annotate.h"
#include "build-id.h"
#include "util.h"
#include "debug.h"
#include "machine.h"
#include "symbol.h"
#include "strlist.h"
#include "intlist.h"
#include "namespaces.h"
#include "header.h"
#include "path.h"
#include "sane_ctype.h"

#include <elf.h>
#include <limits.h>
#include <symbol/kallsyms.h>
#include <sys/utsname.h>

static int dso__load_kernel_sym(struct dso *dso, struct map *map);
static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map);
static bool symbol__is_idle(const char *name);

int vmlinux_path__nr_entries;
char **vmlinux_path;

struct symbol_conf symbol_conf = {
    .use_modules        = true,
    .try_vmlinux_path   = true,
    .demangle       = true,
    .demangle_kernel    = false,
    .cumulate_callchain = true,
    .show_hist_headers  = true,
    .symfs          = "",
    .event_group        = true,
    .inline_name        = true,
};

static enum dso_binary_type binary_type_symtab[] = {
    DSO_BINARY_TYPE__KALLSYMS,
    DSO_BINARY_TYPE__GUEST_KALLSYMS,
    DSO_BINARY_TYPE__JAVA_JIT,
    DSO_BINARY_TYPE__DEBUGLINK,
    DSO_BINARY_TYPE__BUILD_ID_CACHE,
    DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO,
    DSO_BINARY_TYPE__FEDORA_DEBUGINFO,
    DSO_BINARY_TYPE__UBUNTU_DEBUGINFO,
    DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
    DSO_BINARY_TYPE__SYSTEM_PATH_DSO,
    DSO_BINARY_TYPE__GUEST_KMODULE,
    DSO_BINARY_TYPE__GUEST_KMODULE_COMP,
    DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE,
    DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP,
    DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
    DSO_BINARY_TYPE__NOT_FOUND,
};

#define DSO_BINARY_TYPE__SYMTAB_CNT ARRAY_SIZE(binary_type_symtab)

static bool symbol_type__filter(char symbol_type)
{
    symbol_type = toupper(symbol_type);
    return symbol_type == 'T' || symbol_type == 'W' || symbol_type == 'D' || symbol_type == 'B';
}

static int prefix_underscores_count(const char *str)
{
    const char *tail = str;

    while (*tail == '_')
        tail++;

    return tail - str;
}

const char * __weak arch__normalize_symbol_name(const char *name)
{
    return name;
}

int __weak arch__compare_symbol_names(const char *namea, const char *nameb)
{
    return strcmp(namea, nameb);
}

int __weak arch__compare_symbol_names_n(const char *namea, const char *nameb,
                    unsigned int n)
{
    return strncmp(namea, nameb, n);
}

int __weak arch__choose_best_symbol(struct symbol *syma,
                    struct symbol *symb __maybe_unused)
{
    /* Avoid "SyS" kernel syscall aliases */
    if (strlen(syma->name) >= 3 && !strncmp(syma->name, "SyS", 3))
        return SYMBOL_B;
    if (strlen(syma->name) >= 10 && !strncmp(syma->name, "compat_SyS", 10))
        return SYMBOL_B;

    return SYMBOL_A;
}

static int choose_best_symbol(struct symbol *syma, struct symbol *symb)
{
    s64 a;
    s64 b;
    size_t na, nb;

    /* Prefer a symbol with non zero length */
    a = syma->end - syma->start;
    b = symb->end - symb->start;
    if ((b == 0) && (a > 0))
        return SYMBOL_A;
    else if ((a == 0) && (b > 0))
        return SYMBOL_B;

    /* Prefer a non weak symbol over a weak one */
    a = syma->binding == STB_WEAK;
    b = symb->binding == STB_WEAK;
    if (b && !a)
        return SYMBOL_A;
    if (a && !b)
        return SYMBOL_B;

    /* Prefer a global symbol over a non global one */
    a = syma->binding == STB_GLOBAL;
    b = symb->binding == STB_GLOBAL;
    if (a && !b)
        return SYMBOL_A;
    if (b && !a)
        return SYMBOL_B;

    /* Prefer a symbol with less underscores */
    a = prefix_underscores_count(syma->name);
    b = prefix_underscores_count(symb->name);
    if (b > a)
        return SYMBOL_A;
    else if (a > b)
        return SYMBOL_B;

    /* Choose the symbol with the longest name */
    na = strlen(syma->name);
    nb = strlen(symb->name);
    if (na > nb)
        return SYMBOL_A;
    else if (na < nb)
        return SYMBOL_B;

    return arch__choose_best_symbol(syma, symb);
}

void symbols__fixup_duplicate(struct rb_root *symbols)
{
    struct rb_node *nd;
    struct symbol *curr, *next;

    if (symbol_conf.allow_aliases)
        return;

    nd = rb_first(symbols);

    while (nd) {
        curr = rb_entry(nd, struct symbol, rb_node);
again:
        nd = rb_next(&curr->rb_node);
        next = rb_entry(nd, struct symbol, rb_node);

        if (!nd)
            break;

        if (curr->start != next->start)
            continue;

        if (choose_best_symbol(curr, next) == SYMBOL_A) {
            rb_erase(&next->rb_node, symbols);
            symbol__delete(next);
            goto again;
        } else {
            nd = rb_next(&curr->rb_node);
            rb_erase(&curr->rb_node, symbols);
            symbol__delete(curr);
        }
    }
}

void symbols__fixup_end(struct rb_root *symbols)
{
    struct rb_node *nd, *prevnd = rb_first(symbols);
    struct symbol *curr, *prev;

    if (prevnd == NULL)
        return;

    curr = rb_entry(prevnd, struct symbol, rb_node);

    for (nd = rb_next(prevnd); nd; nd = rb_next(nd)) {
        prev = curr;
        curr = rb_entry(nd, struct symbol, rb_node);

        if (prev->end == prev->start && prev->end != curr->start)
            prev->end = curr->start;
    }

    /* Last entry */
    if (curr->end == curr->start)
        curr->end = roundup(curr->start, 4096) + 4096;
}

void map_groups__fixup_end(struct map_groups *mg)
{
    struct maps *maps = &mg->maps;
    struct map *next, *curr;

    down_write(&maps->lock);

    curr = maps__first(maps);
    if (curr == NULL)
        goto out_unlock;

    for (next = map__next(curr); next; next = map__next(curr)) {
        if (!curr->end)
            curr->end = next->start;
        curr = next;
    }

    /*
     * We still haven't the actual symbols, so guess the
     * last map final address.
     */
    if (!curr->end)
        curr->end = ~0ULL;

out_unlock:
    up_write(&maps->lock);
}

struct symbol *symbol__new(u64 start, u64 len, u8 binding, u8 type, const char *name)
{
    size_t namelen = strlen(name) + 1;
    struct symbol *sym = calloc(1, (symbol_conf.priv_size +
                    sizeof(*sym) + namelen));
    if (sym == NULL)
        return NULL;

    if (symbol_conf.priv_size) {
        if (symbol_conf.init_annotation) {
            struct annotation *notes = (void *)sym;
            pthread_mutex_init(&notes->lock, NULL);
        }
        sym = ((void *)sym) + symbol_conf.priv_size;
    }

    sym->start   = start;
    sym->end     = len ? start + len : start;
    sym->type    = type;
    sym->binding = binding;
    sym->namelen = namelen - 1;

    pr_debug4("%s: %s %#" PRIx64 "-%#" PRIx64 "\n",
          __func__, name, start, sym->end);
    memcpy(sym->name, name, namelen);

    return sym;
}

void symbol__delete(struct symbol *sym)
{
    free(((void *)sym) - symbol_conf.priv_size);
}

void symbols__delete(struct rb_root *symbols)
{
    struct symbol *pos;
    struct rb_node *next = rb_first(symbols);

    while (next) {
        pos = rb_entry(next, struct symbol, rb_node);
        next = rb_next(&pos->rb_node);
        rb_erase(&pos->rb_node, symbols);
        symbol__delete(pos);
    }
}

void __symbols__insert(struct rb_root *symbols, struct symbol *sym, bool kernel)
{
    struct rb_node **p = &symbols->rb_node;
    struct rb_node *parent = NULL;
    const u64 ip = sym->start;
    struct symbol *s;

    if (kernel) {
        const char *name = sym->name;
        /*
         * ppc64 uses function descriptors and appends a '.' to the
         * start of every instruction address. Remove it.
         */
        if (name[0] == '.')
            name++;
        sym->idle = symbol__is_idle(name);
    }

    while (*p != NULL) {
        parent = *p;
        s = rb_entry(parent, struct symbol, rb_node);
        if (ip < s->start)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }
    rb_link_node(&sym->rb_node, parent, p);
    rb_insert_color(&sym->rb_node, symbols);
}

void symbols__insert(struct rb_root *symbols, struct symbol *sym)
{
    __symbols__insert(symbols, sym, false);
}

static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
{
    struct rb_node *n;

    if (symbols == NULL)
        return NULL;

    n = symbols->rb_node;

    while (n) {
        struct symbol *s = rb_entry(n, struct symbol, rb_node);

        if (ip < s->start)
            n = n->rb_left;
        else if (ip > s->end || (ip == s->end && ip != s->start))
            n = n->rb_right;
        else
            return s;
    }

    return NULL;
}

static struct symbol *symbols__first(struct rb_root *symbols)
{
    struct rb_node *n = rb_first(symbols);

    if (n)
        return rb_entry(n, struct symbol, rb_node);

    return NULL;
}

static struct symbol *symbols__last(struct rb_root *symbols)
{
    struct rb_node *n = rb_last(symbols);

    if (n)
        return rb_entry(n, struct symbol, rb_node);

    return NULL;
}

static struct symbol *symbols__next(struct symbol *sym)
{
    struct rb_node *n = rb_next(&sym->rb_node);

    if (n)
        return rb_entry(n, struct symbol, rb_node);

    return NULL;
}

static void symbols__insert_by_name(struct rb_root *symbols, struct symbol *sym)
{
    struct rb_node **p = &symbols->rb_node;
    struct rb_node *parent = NULL;
    struct symbol_name_rb_node *symn, *s;

    symn = container_of(sym, struct symbol_name_rb_node, sym);

    while (*p != NULL) {
        parent = *p;
        s = rb_entry(parent, struct symbol_name_rb_node, rb_node);
        if (strcmp(sym->name, s->sym.name) < 0)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }
    rb_link_node(&symn->rb_node, parent, p);
    rb_insert_color(&symn->rb_node, symbols);
}

static void symbols__sort_by_name(struct rb_root *symbols,
                  struct rb_root *source)
{
    struct rb_node *nd;

    for (nd = rb_first(source); nd; nd = rb_next(nd)) {
        struct symbol *pos = rb_entry(nd, struct symbol, rb_node);
        symbols__insert_by_name(symbols, pos);
    }
}

int symbol__match_symbol_name(const char *name, const char *str,
                  enum symbol_tag_include includes)
{
    const char *versioning;

    if (includes == SYMBOL_TAG_INCLUDE__DEFAULT_ONLY &&
        (versioning = strstr(name, "@@"))) {
        int len = strlen(str);

        if (len < versioning - name)
            len = versioning - name;

        return arch__compare_symbol_names_n(name, str, len);
    } else
        return arch__compare_symbol_names(name, str);
}

static struct symbol *symbols__find_by_name(struct rb_root *symbols,
                        const char *name,
                        enum symbol_tag_include includes)
{
    struct rb_node *n;
    struct symbol_name_rb_node *s = NULL;

    if (symbols == NULL)
        return NULL;

    n = symbols->rb_node;

    while (n) {
        int cmp;

        s = rb_entry(n, struct symbol_name_rb_node, rb_node);
        cmp = symbol__match_symbol_name(s->sym.name, name, includes);

        if (cmp > 0)
            n = n->rb_left;
        else if (cmp < 0)
            n = n->rb_right;
        else
            break;
    }

    if (n == NULL)
        return NULL;

    if (includes != SYMBOL_TAG_INCLUDE__DEFAULT_ONLY)
        /* return first symbol that has same name (if any) */
        for (n = rb_prev(n); n; n = rb_prev(n)) {
            struct symbol_name_rb_node *tmp;

            tmp = rb_entry(n, struct symbol_name_rb_node, rb_node);
            if (arch__compare_symbol_names(tmp->sym.name, s->sym.name))
                break;

            s = tmp;
        }

    return &s->sym;
}

void dso__reset_find_symbol_cache(struct dso *dso)
{
    dso->last_find_result.addr   = 0;
    dso->last_find_result.symbol = NULL;
}

void dso__insert_symbol(struct dso *dso, struct symbol *sym)
{
    __symbols__insert(&dso->symbols, sym, dso->kernel);

    /* update the symbol cache if necessary */
    if (dso->last_find_result.addr >= sym->start &&
        (dso->last_find_result.addr < sym->end ||
        sym->start == sym->end)) {
        dso->last_find_result.symbol = sym;
    }
}

struct symbol *dso__find_symbol(struct dso *dso, u64 addr)
{
    if (dso->last_find_result.addr != addr || dso->last_find_result.symbol == NULL) {
        dso->last_find_result.addr   = addr;
        dso->last_find_result.symbol = symbols__find(&dso->symbols, addr);
    }

    return dso->last_find_result.symbol;
}

struct symbol *dso__first_symbol(struct dso *dso)
{
    return symbols__first(&dso->symbols);
}

struct symbol *dso__last_symbol(struct dso *dso)
{
    return symbols__last(&dso->symbols);
}

struct symbol *dso__next_symbol(struct symbol *sym)
{
    return symbols__next(sym);
}

struct symbol *symbol__next_by_name(struct symbol *sym)
{
    struct symbol_name_rb_node *s = container_of(sym, struct symbol_name_rb_node, sym);
    struct rb_node *n = rb_next(&s->rb_node);

    return n ? &rb_entry(n, struct symbol_name_rb_node, rb_node)->sym : NULL;
}

 /*
  * Returns first symbol that matched with @name.
  */
struct symbol *dso__find_symbol_by_name(struct dso *dso, const char *name)
{
    struct symbol *s = symbols__find_by_name(&dso->symbol_names, name,
                         SYMBOL_TAG_INCLUDE__NONE);
    if (!s)
        s = symbols__find_by_name(&dso->symbol_names, name,
                      SYMBOL_TAG_INCLUDE__DEFAULT_ONLY);
    return s;
}

void dso__sort_by_name(struct dso *dso)
{
    dso__set_sorted_by_name(dso);
    return symbols__sort_by_name(&dso->symbol_names, &dso->symbols);
}

int modules__parse(const char *filename, void *arg,
           int (*process_module)(void *arg, const char *name,
                     u64 start, u64 size))
{
    char *line = NULL;
    size_t n;
    FILE *file;
    int err = 0;

    file = fopen(filename, "r");
    if (file == NULL)
        return -1;

    while (1) {
        char name[PATH_MAX];
        u64 start, size;
        char *sep, *endptr;
        ssize_t line_len;

        line_len = getline(&line, &n, file);
        if (line_len < 0) {
            if (feof(file))
                break;
            err = -1;
            goto out;
        }

        if (!line) {
            err = -1;
            goto out;
        }

        line[--line_len] = '\0'; /* \n */

        sep = strrchr(line, 'x');
        if (sep == NULL)
            continue;

        hex2u64(sep + 1, &start);

        sep = strchr(line, ' ');
        if (sep == NULL)
            continue;

        *sep = '\0';

        scnprintf(name, sizeof(name), "[%s]", line);

        size = strtoul(sep + 1, &endptr, 0);
        if (*endptr != ' ' && *endptr != '\t')
            continue;

        err = process_module(arg, name, start, size);
        if (err)
            break;
    }
out:
    free(line);
    fclose(file);
    return err;
}

/*
 * These are symbols in the kernel image, so make sure that
 * sym is from a kernel DSO.
 */
static bool symbol__is_idle(const char *name)
{
    const char * const idle_symbols[] = {
        "cpu_idle",
        "cpu_startup_entry",
        "intel_idle",
        "default_idle",
        "native_safe_halt",
        "enter_idle",
        "exit_idle",
        "mwait_idle",
        "mwait_idle_with_hints",
        "poll_idle",
        "ppc64_runlatch_off",
        "pseries_dedicated_idle_sleep",
        NULL
    };
    int i;

    for (i = 0; idle_symbols[i]; i++) {
        if (!strcmp(idle_symbols[i], name))
            return true;
    }

    return false;
}

static int map__process_kallsym_symbol(void *arg, const char *name,
                       char type, u64 start)
{
    struct symbol *sym;
    struct dso *dso = arg;
    struct rb_root *root = &dso->symbols;

    if (!symbol_type__filter(type))
        return 0;

    /*
     * module symbols are not sorted so we add all
     * symbols, setting length to 0, and rely on
     * symbols__fixup_end() to fix it up.
     */
    sym = symbol__new(start, 0, kallsyms2elf_binding(type), kallsyms2elf_type(type), name);
    if (sym == NULL)
        return -ENOMEM;
    /*
     * We will pass the symbols to the filter later, in
     * map__split_kallsyms, when we have split the maps per module
     */
    __symbols__insert(root, sym, !strchr(name, '['));

    return 0;
}

/*
 * Loads the function entries in /proc/kallsyms into kernel_map->dso,
 * so that we can in the next step set the symbol ->end address and then
 * call kernel_maps__split_kallsyms.
 */
static int dso__load_all_kallsyms(struct dso *dso, const char *filename)
{
    return kallsyms__parse(filename, dso, map__process_kallsym_symbol);
}

static int map_groups__split_kallsyms_for_kcore(struct map_groups *kmaps, struct dso *dso)
{
    struct map *curr_map;
    struct symbol *pos;
    int count = 0;
    struct rb_root old_root = dso->symbols;
    struct rb_root *root = &dso->symbols;
    struct rb_node *next = rb_first(root);

    if (!kmaps)
        return -1;

    *root = RB_ROOT;

    while (next) {
        char *module;

        pos = rb_entry(next, struct symbol, rb_node);
        next = rb_next(&pos->rb_node);

        rb_erase_init(&pos->rb_node, &old_root);

        module = strchr(pos->name, '\t');
        if (module)
            *module = '\0';

        curr_map = map_groups__find(kmaps, pos->start);

        if (!curr_map) {
            symbol__delete(pos);
            continue;
        }

        pos->start -= curr_map->start - curr_map->pgoff;
        if (pos->end)
            pos->end -= curr_map->start - curr_map->pgoff;
        symbols__insert(&curr_map->dso->symbols, pos);
        ++count;
    }

    /* Symbols have been adjusted */
    dso->adjust_symbols = 1;

    return count;
}

/*
 * Split the symbols into maps, making sure there are no overlaps, i.e. the
 * kernel range is broken in several maps, named [kernel].N, as we don't have
 * the original ELF section names vmlinux have.
 */
static int map_groups__split_kallsyms(struct map_groups *kmaps, struct dso *dso, u64 delta,
                      struct map *initial_map)
{
    struct machine *machine;
    struct map *curr_map = initial_map;
    struct symbol *pos;
    int count = 0, moved = 0;
    struct rb_root *root = &dso->symbols;
    struct rb_node *next = rb_first(root);
    int kernel_range = 0;
    bool x86_64;

    if (!kmaps)
        return -1;

    machine = kmaps->machine;

    x86_64 = machine__is(machine, "x86_64");

    while (next) {
        char *module;

        pos = rb_entry(next, struct symbol, rb_node);
        next = rb_next(&pos->rb_node);

        module = strchr(pos->name, '\t');
        if (module) {
            if (!symbol_conf.use_modules)
                goto discard_symbol;

            *module++ = '\0';

            if (strcmp(curr_map->dso->short_name, module)) {
                if (curr_map != initial_map &&
                    dso->kernel == DSO_TYPE_GUEST_KERNEL &&
                    machine__is_default_guest(machine)) {
                    /*
                     * We assume all symbols of a module are
                     * continuous in * kallsyms, so curr_map
                     * points to a module and all its
                     * symbols are in its kmap. Mark it as
                     * loaded.
                     */
                    dso__set_loaded(curr_map->dso);
                }

                curr_map = map_groups__find_by_name(kmaps, module);
                if (curr_map == NULL) {
                    pr_debug("%s/proc/{kallsyms,modules} "
                             "inconsistency while looking "
                         "for \"%s\" module!\n",
                         machine->root_dir, module);
                    curr_map = initial_map;
                    goto discard_symbol;
                }

                if (curr_map->dso->loaded &&
                    !machine__is_default_guest(machine))
                    goto discard_symbol;
            }
            /*
             * So that we look just like we get from .ko files,
             * i.e. not prelinked, relative to initial_map->start.
             */
            pos->start = curr_map->map_ip(curr_map, pos->start);
            pos->end   = curr_map->map_ip(curr_map, pos->end);
        } else if (x86_64 && is_entry_trampoline(pos->name)) {
            /*
             * These symbols are not needed anymore since the
             * trampoline maps refer to the text section and it's
             * symbols instead. Avoid having to deal with
             * relocations, and the assumption that the first symbol
             * is the start of kernel text, by simply removing the
             * symbols at this point.
             */
            goto discard_symbol;
        } else if (curr_map != initial_map) {
            char dso_name[PATH_MAX];
            struct dso *ndso;

            if (delta) {
                /* Kernel was relocated at boot time */
                pos->start -= delta;
                pos->end -= delta;
            }

            if (count == 0) {
                curr_map = initial_map;
                goto add_symbol;
            }

            if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
                snprintf(dso_name, sizeof(dso_name),
                    "[guest.kernel].%d",
                    kernel_range++);
            else
                snprintf(dso_name, sizeof(dso_name),
                    "[kernel].%d",
                    kernel_range++);

            ndso = dso__new(dso_name);
            if (ndso == NULL)
                return -1;

            ndso->kernel = dso->kernel;

            curr_map = map__new2(pos->start, ndso);
            if (curr_map == NULL) {
                dso__put(ndso);
                return -1;
            }

            curr_map->map_ip = curr_map->unmap_ip = identity__map_ip;
            map_groups__insert(kmaps, curr_map);
            ++kernel_range;
        } else if (delta) {
            /* Kernel was relocated at boot time */
            pos->start -= delta;
            pos->end -= delta;
        }
add_symbol:
        if (curr_map != initial_map) {
            rb_erase(&pos->rb_node, root);
            symbols__insert(&curr_map->dso->symbols, pos);
            ++moved;
        } else
            ++count;

        continue;
discard_symbol:
        rb_erase(&pos->rb_node, root);
        symbol__delete(pos);
    }

    if (curr_map != initial_map &&
        dso->kernel == DSO_TYPE_GUEST_KERNEL &&
        machine__is_default_guest(kmaps->machine)) {
        dso__set_loaded(curr_map->dso);
    }

    return count + moved;
}

bool symbol__restricted_filename(const char *filename,
                 const char *restricted_filename)
{
    bool restricted = false;

    if (symbol_conf.kptr_restrict) {
        char *r = realpath(filename, NULL);

        if (r != NULL) {
            restricted = strcmp(r, restricted_filename) == 0;
            free(r);
            return restricted;
        }
    }

    return restricted;
}

struct module_info {
    struct rb_node rb_node;
    char *name;
    u64 start;
};

static void add_module(struct module_info *mi, struct rb_root *modules)
{
    struct rb_node **p = &modules->rb_node;
    struct rb_node *parent = NULL;
    struct module_info *m;

    while (*p != NULL) {
        parent = *p;
        m = rb_entry(parent, struct module_info, rb_node);
        if (strcmp(mi->name, m->name) < 0)
            p = &(*p)->rb_left;
        else
            p = &(*p)->rb_right;
    }
    rb_link_node(&mi->rb_node, parent, p);
    rb_insert_color(&mi->rb_node, modules);
}

static void delete_modules(struct rb_root *modules)
{
    struct module_info *mi;
    struct rb_node *next = rb_first(modules);

    while (next) {
        mi = rb_entry(next, struct module_info, rb_node);
        next = rb_next(&mi->rb_node);
        rb_erase(&mi->rb_node, modules);
        zfree(&mi->name);
        free(mi);
    }
}

static struct module_info *find_module(const char *name,
                       struct rb_root *modules)
{
    struct rb_node *n = modules->rb_node;

    while (n) {
        struct module_info *m;
        int cmp;

        m = rb_entry(n, struct module_info, rb_node);
        cmp = strcmp(name, m->name);
        if (cmp < 0)
            n = n->rb_left;
        else if (cmp > 0)
            n = n->rb_right;
        else
            return m;
    }

    return NULL;
}

static int __read_proc_modules(void *arg, const char *name, u64 start,
                   u64 size __maybe_unused)
{
    struct rb_root *modules = arg;
    struct module_info *mi;

    mi = zalloc(sizeof(struct module_info));
    if (!mi)
        return -ENOMEM;

    mi->name = strdup(name);
    mi->start = start;

    if (!mi->name) {
        free(mi);
        return -ENOMEM;
    }

    add_module(mi, modules);

    return 0;
}

static int read_proc_modules(const char *filename, struct rb_root *modules)
{
    if (symbol__restricted_filename(filename, "/proc/modules"))
        return -1;

    if (modules__parse(filename, modules, __read_proc_modules)) {
        delete_modules(modules);
        return -1;
    }

    return 0;
}

int compare_proc_modules(const char *from, const char *to)
{
    struct rb_root from_modules = RB_ROOT;
    struct rb_root to_modules = RB_ROOT;
    struct rb_node *from_node, *to_node;
    struct module_info *from_m, *to_m;
    int ret = -1;

    if (read_proc_modules(from, &from_modules))
        return -1;

    if (read_proc_modules(to, &to_modules))
        goto out_delete_from;

    from_node = rb_first(&from_modules);
    to_node = rb_first(&to_modules);
    while (from_node) {
        if (!to_node)
            break;

        from_m = rb_entry(from_node, struct module_info, rb_node);
        to_m = rb_entry(to_node, struct module_info, rb_node);

        if (from_m->start != to_m->start ||
            strcmp(from_m->name, to_m->name))
            break;

        from_node = rb_next(from_node);
        to_node = rb_next(to_node);
    }

    if (!from_node && !to_node)
        ret = 0;

    delete_modules(&to_modules);
out_delete_from:
    delete_modules(&from_modules);

    return ret;
}

struct map *map_groups__first(struct map_groups *mg)
{
    return maps__first(&mg->maps);
}

static int do_validate_kcore_modules(const char *filename,
                  struct map_groups *kmaps)
{
    struct rb_root modules = RB_ROOT;
    struct map *old_map;
    int err;

    err = read_proc_modules(filename, &modules);
    if (err)
        return err;

    old_map = map_groups__first(kmaps);
    while (old_map) {
        struct map *next = map_groups__next(old_map);
        struct module_info *mi;

        if (!__map__is_kmodule(old_map)) {
            old_map = next;
            continue;
        }

        /* Module must be in memory at the same address */
        mi = find_module(old_map->dso->short_name, &modules);
        if (!mi || mi->start != old_map->start) {
            err = -EINVAL;
            goto out;
        }

        old_map = next;
    }
out:
    delete_modules(&modules);
    return err;
}

/*
 * If kallsyms is referenced by name then we look for filename in the same
 * directory.
 */
static bool filename_from_kallsyms_filename(char *filename,
                        const char *base_name,
                        const char *kallsyms_filename)
{
    char *name;

    strcpy(filename, kallsyms_filename);
    name = strrchr(filename, '/');
    if (!name)
        return false;

    name += 1;

    if (!strcmp(name, "kallsyms")) {
        strcpy(name, base_name);
        return true;
    }

    return false;
}

static int validate_kcore_modules(const char *kallsyms_filename,
                  struct map *map)
{
    struct map_groups *kmaps = map__kmaps(map);
    char modules_filename[PATH_MAX];

    if (!kmaps)
        return -EINVAL;

    if (!filename_from_kallsyms_filename(modules_filename, "modules",
                         kallsyms_filename))
        return -EINVAL;

    if (do_validate_kcore_modules(modules_filename, kmaps))
        return -EINVAL;

    return 0;
}

static int validate_kcore_addresses(const char *kallsyms_filename,
                    struct map *map)
{
    struct kmap *kmap = map__kmap(map);

    if (!kmap)
        return -EINVAL;

    if (kmap->ref_reloc_sym && kmap->ref_reloc_sym->name) {
        u64 start;

        if (kallsyms__get_function_start(kallsyms_filename,
                         kmap->ref_reloc_sym->name, &start))
            return -ENOENT;
        if (start != kmap->ref_reloc_sym->addr)
            return -EINVAL;
    }

    return validate_kcore_modules(kallsyms_filename, map);
}

struct kcore_mapfn_data {
    struct dso *dso;
    struct list_head maps;
};

static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
{
    struct kcore_mapfn_data *md = data;
    struct map *map;

    map = map__new2(start, md->dso);
    if (map == NULL)
        return -ENOMEM;

    map->end = map->start + len;
    map->pgoff = pgoff;

    list_add(&map->node, &md->maps);

    return 0;
}

static int dso__load_kcore(struct dso *dso, struct map *map,
               const char *kallsyms_filename)
{
    struct map_groups *kmaps = map__kmaps(map);
    struct kcore_mapfn_data md;
    struct map *old_map, *new_map, *replacement_map = NULL;
    struct machine *machine;
    bool is_64_bit;
    int err, fd;
    char kcore_filename[PATH_MAX];
    u64 stext;

    if (!kmaps)
        return -EINVAL;

    machine = kmaps->machine;

    /* This function requires that the map is the kernel map */
    if (!__map__is_kernel(map))
        return -EINVAL;

    if (!filename_from_kallsyms_filename(kcore_filename, "kcore",
                         kallsyms_filename))
        return -EINVAL;

    /* Modules and kernel must be present at their original addresses */
    if (validate_kcore_addresses(kallsyms_filename, map))
        return -EINVAL;

    md.dso = dso;
    INIT_LIST_HEAD(&md.maps);

    fd = open(kcore_filename, O_RDONLY);
    if (fd < 0) {
        pr_debug("Failed to open %s. Note /proc/kcore requires CAP_SYS_RAWIO capability to access.\n",
             kcore_filename);
        return -EINVAL;
    }

    /* Read new maps into temporary lists */
    err = file__read_maps(fd, map->prot & PROT_EXEC, kcore_mapfn, &md,
                  &is_64_bit);
    if (err)
        goto out_err;
    dso->is_64_bit = is_64_bit;

    if (list_empty(&md.maps)) {
        err = -EINVAL;
        goto out_err;
    }

    /* Remove old maps */
    old_map = map_groups__first(kmaps);
    while (old_map) {
        struct map *next = map_groups__next(old_map);

        if (old_map != map)
            map_groups__remove(kmaps, old_map);
        old_map = next;
    }
    machine->trampolines_mapped = false;

    /* Find the kernel map using the '_stext' symbol */
    if (!kallsyms__get_function_start(kallsyms_filename, "_stext", &stext)) {
        list_for_each_entry(new_map, &md.maps, node) {
            if (stext >= new_map->start && stext < new_map->end) {
                replacement_map = new_map;
                break;
            }
        }
    }

    if (!replacement_map)
        replacement_map = list_entry(md.maps.next, struct map, node);

    /* Add new maps */
    while (!list_empty(&md.maps)) {
        new_map = list_entry(md.maps.next, struct map, node);
        list_del_init(&new_map->node);
        if (new_map == replacement_map) {
            map->start  = new_map->start;
            map->end    = new_map->end;
            map->pgoff  = new_map->pgoff;
            map->map_ip = new_map->map_ip;
            map->unmap_ip   = new_map->unmap_ip;
            /* Ensure maps are correctly ordered */
            map__get(map);
            map_groups__remove(kmaps, map);
            map_groups__insert(kmaps, map);
            map__put(map);
        } else {
            map_groups__insert(kmaps, new_map);
        }

        map__put(new_map);
    }

    if (machine__is(machine, "x86_64")) {
        u64 addr;

        /*
         * If one of the corresponding symbols is there, assume the
         * entry trampoline maps are too.
         */
        if (!kallsyms__get_function_start(kallsyms_filename,
                          ENTRY_TRAMPOLINE_NAME,
                          &addr))
            machine->trampolines_mapped = true;
    }

    /*
     * Set the data type and long name so that kcore can be read via
     * dso__data_read_addr().
     */
    if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
        dso->binary_type = DSO_BINARY_TYPE__GUEST_KCORE;
    else
        dso->binary_type = DSO_BINARY_TYPE__KCORE;
    dso__set_long_name(dso, strdup(kcore_filename), true);

    close(fd);

    if (map->prot & PROT_EXEC)
        pr_debug("Using %s for kernel object code\n", kcore_filename);
    else
        pr_debug("Using %s for kernel data\n", kcore_filename);

    return 0;

out_err:
    while (!list_empty(&md.maps)) {
        map = list_entry(md.maps.next, struct map, node);
        list_del_init(&map->node);
        map__put(map);
    }
    close(fd);
    return -EINVAL;
}

/*
 * If the kernel is relocated at boot time, kallsyms won't match.  Compute the
 * delta based on the relocation reference symbol.
 */
static int kallsyms__delta(struct kmap *kmap, const char *filename, u64 *delta)
{
    u64 addr;

    if (!kmap->ref_reloc_sym || !kmap->ref_reloc_sym->name)
        return 0;

    if (kallsyms__get_function_start(filename, kmap->ref_reloc_sym->name, &addr))
        return -1;

    *delta = addr - kmap->ref_reloc_sym->addr;
    return 0;
}

int __dso__load_kallsyms(struct dso *dso, const char *filename,
             struct map *map, bool no_kcore)
{
    struct kmap *kmap = map__kmap(map);
    u64 delta = 0;

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

    if (!kmap || !kmap->kmaps)
        return -1;

    if (dso__load_all_kallsyms(dso, filename) < 0)
        return -1;

    if (kallsyms__delta(kmap, filename, &delta))
        return -1;

    symbols__fixup_end(&dso->symbols);
    symbols__fixup_duplicate(&dso->symbols);

    if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
        dso->symtab_type = DSO_BINARY_TYPE__GUEST_KALLSYMS;
    else
        dso->symtab_type = DSO_BINARY_TYPE__KALLSYMS;

    if (!no_kcore && !dso__load_kcore(dso, map, filename))
        return map_groups__split_kallsyms_for_kcore(kmap->kmaps, dso);
    else
        return map_groups__split_kallsyms(kmap->kmaps, dso, delta, map);
}

int dso__load_kallsyms(struct dso *dso, const char *filename,
               struct map *map)
{
    return __dso__load_kallsyms(dso, filename, map, false);
}

static int dso__load_perf_map(const char *map_path, struct dso *dso)
{
    char *line = NULL;
    size_t n;
    FILE *file;
    int nr_syms = 0;

    file = fopen(map_path, "r");
    if (file == NULL)
        goto out_failure;

    while (!feof(file)) {
        u64 start, size;
        struct symbol *sym;
        int line_len, len;

        line_len = getline(&line, &n, file);
        if (line_len < 0)
            break;

        if (!line)
            goto out_failure;

        line[--line_len] = '\0'; /* \n */

        len = hex2u64(line, &start);

        len++;
        if (len + 2 >= line_len)
            continue;

        len += hex2u64(line + len, &size);

        len++;
        if (len + 2 >= line_len)
            continue;

        sym = symbol__new(start, size, STB_GLOBAL, STT_FUNC, line + len);

        if (sym == NULL)
            goto out_delete_line;

        symbols__insert(&dso->symbols, sym);
        nr_syms++;
    }

    free(line);
    fclose(file);

    return nr_syms;

out_delete_line:
    free(line);
out_failure:
    return -1;
}

static bool dso__is_compatible_symtab_type(struct dso *dso, bool kmod,
                       enum dso_binary_type type)
{
    switch (type) {
    case DSO_BINARY_TYPE__JAVA_JIT:
    case DSO_BINARY_TYPE__DEBUGLINK:
    case DSO_BINARY_TYPE__SYSTEM_PATH_DSO:
    case DSO_BINARY_TYPE__FEDORA_DEBUGINFO:
    case DSO_BINARY_TYPE__UBUNTU_DEBUGINFO:
    case DSO_BINARY_TYPE__BUILDID_DEBUGINFO:
    case DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO:
        return !kmod && dso->kernel == DSO_TYPE_USER;

    case DSO_BINARY_TYPE__KALLSYMS:
    case DSO_BINARY_TYPE__VMLINUX:
    case DSO_BINARY_TYPE__KCORE:
        return dso->kernel == DSO_TYPE_KERNEL;

    case DSO_BINARY_TYPE__GUEST_KALLSYMS:
    case DSO_BINARY_TYPE__GUEST_VMLINUX:
    case DSO_BINARY_TYPE__GUEST_KCORE:
        return dso->kernel == DSO_TYPE_GUEST_KERNEL;

    case DSO_BINARY_TYPE__GUEST_KMODULE:
    case DSO_BINARY_TYPE__GUEST_KMODULE_COMP:
    case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE:
    case DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP:
        /*
         * kernel modules know their symtab type - it's set when
         * creating a module dso in machine__findnew_module_map().
         */
        return kmod && dso->symtab_type == type;

    case DSO_BINARY_TYPE__BUILD_ID_CACHE:
    case DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO:
        return true;

    case DSO_BINARY_TYPE__NOT_FOUND:
    default:
        return false;
    }
}

/* Checks for the existence of the perf-<pid>.map file in two different
 * locations.  First, if the process is a separate mount namespace, check in
 * that namespace using the pid of the innermost pid namespace.  If's not in a
 * namespace, or the file can't be found there, try in the mount namespace of
 * the tracing process using our view of its pid.
 */
static int dso__find_perf_map(char *filebuf, size_t bufsz,
                  struct nsinfo **nsip)
{
    struct nscookie nsc;
    struct nsinfo *nsi;
    struct nsinfo *nnsi;
    int rc = -1;

    nsi = *nsip;

    if (nsi->need_setns) {
        snprintf(filebuf, bufsz, "/tmp/perf-%d.map", nsi->nstgid);
        nsinfo__mountns_enter(nsi, &nsc);
        rc = access(filebuf, R_OK);
        nsinfo__mountns_exit(&nsc);
        if (rc == 0)
            return rc;
    }

    nnsi = nsinfo__copy(nsi);
    if (nnsi) {
        nsinfo__put(nsi);

        nnsi->need_setns = false;
        snprintf(filebuf, bufsz, "/tmp/perf-%d.map", nnsi->tgid);
        *nsip = nnsi;
        rc = 0;
    }

    return rc;
}

int dso__load(struct dso *dso, struct map *map)
{
    char *name;
    int ret = -1;
    u_int i;
    struct machine *machine;
    char *root_dir = (char *) "";
    int ss_pos = 0;
    struct symsrc ss_[2];
    struct symsrc *syms_ss = NULL, *runtime_ss = NULL;
    bool kmod;
    bool perfmap;
    unsigned char build_id[BUILD_ID_SIZE];
    struct nscookie nsc;
    char newmapname[PATH_MAX];
    const char *map_path = dso->long_name;

    perfmap = strncmp(dso->name, "/tmp/perf-", 10) == 0;
    if (perfmap) {
        if (dso->nsinfo && (dso__find_perf_map(newmapname,
            sizeof(newmapname), &dso->nsinfo) == 0)) {
            map_path = newmapname;
        }
    }

    nsinfo__mountns_enter(dso->nsinfo, &nsc);
    pthread_mutex_lock(&dso->lock);

    /* check again under the dso->lock */
    if (dso__loaded(dso)) {
        ret = 1;
        goto out;
    }

    if (map->groups && map->groups->machine)
        machine = map->groups->machine;
    else
        machine = NULL;

    if (dso->kernel) {
        if (dso->kernel == DSO_TYPE_KERNEL)
            ret = dso__load_kernel_sym(dso, map);
        else if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
            ret = dso__load_guest_kernel_sym(dso, map);

        if (machine__is(machine, "x86_64"))
            machine__map_x86_64_entry_trampolines(machine, dso);
        goto out;
    }

    dso->adjust_symbols = 0;

    if (perfmap) {
        struct stat st;

        if (lstat(map_path, &st) < 0)
            goto out;

        if (!symbol_conf.force && st.st_uid && (st.st_uid != geteuid())) {
            pr_warning("File %s not owned by current user or root, "
                   "ignoring it (use -f to override).\n", map_path);
            goto out;
        }

        ret = dso__load_perf_map(map_path, dso);
        dso->symtab_type = ret > 0 ? DSO_BINARY_TYPE__JAVA_JIT :
                         DSO_BINARY_TYPE__NOT_FOUND;
        goto out;
    }

    if (machine)
        root_dir = machine->root_dir;

    name = malloc(PATH_MAX);
    if (!name)
        goto out;

    kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
        dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP ||
        dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE ||
        dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;


    /*
     * Read the build id if possible. This is required for
     * DSO_BINARY_TYPE__BUILDID_DEBUGINFO to work
     */
    if (!dso->has_build_id &&
        is_regular_file(dso->long_name)) {
        __symbol__join_symfs(name, PATH_MAX, dso->long_name);
        if (filename__read_build_id(name, build_id, BUILD_ID_SIZE) > 0)
        dso__set_build_id(dso, build_id);
    }

    /*
     * Iterate over candidate debug images.
     * Keep track of "interesting" ones (those which have a symtab, dynsym,
     * and/or opd section) for processing.
     */
    for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) {
        struct symsrc *ss = &ss_[ss_pos];
        bool next_slot = false;
        bool is_reg;
        bool nsexit;
        int sirc = -1;

        enum dso_binary_type symtab_type = binary_type_symtab[i];

        nsexit = (symtab_type == DSO_BINARY_TYPE__BUILD_ID_CACHE ||
            symtab_type == DSO_BINARY_TYPE__BUILD_ID_CACHE_DEBUGINFO);

        if (!dso__is_compatible_symtab_type(dso, kmod, symtab_type))
            continue;

        if (dso__read_binary_type_filename(dso, symtab_type,
                           root_dir, name, PATH_MAX))
            continue;

        if (nsexit)
            nsinfo__mountns_exit(&nsc);

        is_reg = is_regular_file(name);
        if (is_reg)
            sirc = symsrc__init(ss, dso, name, symtab_type);

        if (nsexit)
            nsinfo__mountns_enter(dso->nsinfo, &nsc);

        if (!is_reg || sirc < 0)
            continue;

        if (!syms_ss && symsrc__has_symtab(ss)) {
            syms_ss = ss;
            next_slot = true;
            if (!dso->symsrc_filename)
                dso->symsrc_filename = strdup(name);
        }

        if (!runtime_ss && symsrc__possibly_runtime(ss)) {
            runtime_ss = ss;
            next_slot = true;
        }

        if (next_slot) {
            ss_pos++;

            if (syms_ss && runtime_ss)
                break;
        } else {
            symsrc__destroy(ss);
        }

    }

    if (!runtime_ss && !syms_ss)
        goto out_free;

    if (runtime_ss && !syms_ss) {
        syms_ss = runtime_ss;
    }

    /* We'll have to hope for the best */
    if (!runtime_ss && syms_ss)
        runtime_ss = syms_ss;

    if (syms_ss)
        ret = dso__load_sym(dso, map, syms_ss, runtime_ss, kmod);
    else
        ret = -1;

    if (ret > 0) {
        int nr_plt;

        nr_plt = dso__synthesize_plt_symbols(dso, runtime_ss);
        if (nr_plt > 0)
            ret += nr_plt;
    }

    for (; ss_pos > 0; ss_pos--)
        symsrc__destroy(&ss_[ss_pos - 1]);
out_free:
    free(name);
    if (ret < 0 && strstr(dso->name, " (deleted)") != NULL)
        ret = 0;
out:
    dso__set_loaded(dso);
    pthread_mutex_unlock(&dso->lock);
    nsinfo__mountns_exit(&nsc);

    return ret;
}

struct map *map_groups__find_by_name(struct map_groups *mg, const char *name)
{
    struct maps *maps = &mg->maps;
    struct map *map;

    down_read(&maps->lock);

    for (map = maps__first(maps); map; map = map__next(map)) {
        if (map->dso && strcmp(map->dso->short_name, name) == 0)
            goto out_unlock;
    }

    map = NULL;

out_unlock:
    up_read(&maps->lock);
    return map;
}

int dso__load_vmlinux(struct dso *dso, struct map *map,
              const char *vmlinux, bool vmlinux_allocated)
{
    int err = -1;
    struct symsrc ss;
    char symfs_vmlinux[PATH_MAX];
    enum dso_binary_type symtab_type;

    if (vmlinux[0] == '/')
        snprintf(symfs_vmlinux, sizeof(symfs_vmlinux), "%s", vmlinux);
    else
        symbol__join_symfs(symfs_vmlinux, vmlinux);

    if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
        symtab_type = DSO_BINARY_TYPE__GUEST_VMLINUX;
    else
        symtab_type = DSO_BINARY_TYPE__VMLINUX;

    if (symsrc__init(&ss, dso, symfs_vmlinux, symtab_type))
        return -1;

    err = dso__load_sym(dso, map, &ss, &ss, 0);
    symsrc__destroy(&ss);

    if (err > 0) {
        if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
            dso->binary_type = DSO_BINARY_TYPE__GUEST_VMLINUX;
        else
            dso->binary_type = DSO_BINARY_TYPE__VMLINUX;
        dso__set_long_name(dso, vmlinux, vmlinux_allocated);
        dso__set_loaded(dso);
        pr_debug("Using %s for symbols\n", symfs_vmlinux);
    }

    return err;
}

int dso__load_vmlinux_path(struct dso *dso, struct map *map)
{
    int i, err = 0;
    char *filename = NULL;

    pr_debug("Looking at the vmlinux_path (%d entries long)\n",
         vmlinux_path__nr_entries + 1);

    for (i = 0; i < vmlinux_path__nr_entries; ++i) {
        err = dso__load_vmlinux(dso, map, vmlinux_path[i], false);
        if (err > 0)
            goto out;
    }

    if (!symbol_conf.ignore_vmlinux_buildid)
        filename = dso__build_id_filename(dso, NULL, 0, false);
    if (filename != NULL) {
        err = dso__load_vmlinux(dso, map, filename, true);
        if (err > 0)
            goto out;
        free(filename);
    }
out:
    return err;
}

static bool visible_dir_filter(const char *name, struct dirent *d)
{
    if (d->d_type != DT_DIR)
        return false;
    return lsdir_no_dot_filter(name, d);
}

static int find_matching_kcore(struct map *map, char *dir, size_t dir_sz)
{
    char kallsyms_filename[PATH_MAX];
    int ret = -1;
    struct strlist *dirs;
    struct str_node *nd;

    dirs = lsdir(dir, visible_dir_filter);
    if (!dirs)
        return -1;

    strlist__for_each_entry(nd, dirs) {
        scnprintf(kallsyms_filename, sizeof(kallsyms_filename),
              "%s/%s/kallsyms", dir, nd->s);
        if (!validate_kcore_addresses(kallsyms_filename, map)) {
            strlcpy(dir, kallsyms_filename, dir_sz);
            ret = 0;
            break;
        }
    }

    strlist__delete(dirs);

    return ret;
}

/*
 * Use open(O_RDONLY) to check readability directly instead of access(R_OK)
 * since access(R_OK) only checks with real UID/GID but open() use effective
 * UID/GID and actual capabilities (e.g. /proc/kcore requires CAP_SYS_RAWIO).
 */
static bool filename__readable(const char *file)
{
    int fd = open(file, O_RDONLY);
    if (fd < 0)
        return false;
    close(fd);
    return true;
}

static char *dso__find_kallsyms(struct dso *dso, struct map *map)
{
    u8 host_build_id[BUILD_ID_SIZE];
    char sbuild_id[SBUILD_ID_SIZE];
    bool is_host = false;
    char path[PATH_MAX];

    if (!dso->has_build_id) {
        /*
         * Last resort, if we don't have a build-id and couldn't find
         * any vmlinux file, try the running kernel kallsyms table.
         */
        goto proc_kallsyms;
    }

    if (sysfs__read_build_id("/sys/kernel/notes", host_build_id,
                 sizeof(host_build_id)) == 0)
        is_host = dso__build_id_equal(dso, host_build_id);

    /* Try a fast path for /proc/kallsyms if possible */
    if (is_host) {
        /*
         * Do not check the build-id cache, unless we know we cannot use
         * /proc/kcore or module maps don't match to /proc/kallsyms.
         * To check readability of /proc/kcore, do not use access(R_OK)
         * since /proc/kcore requires CAP_SYS_RAWIO to read and access
         * can't check it.
         */
        if (filename__readable("/proc/kcore") &&
            !validate_kcore_addresses("/proc/kallsyms", map))
            goto proc_kallsyms;
    }

    build_id__sprintf(dso->build_id, sizeof(dso->build_id), sbuild_id);

    /* Find kallsyms in build-id cache with kcore */
    scnprintf(path, sizeof(path), "%s/%s/%s",
          buildid_dir, DSO__NAME_KCORE, sbuild_id);

    if (!find_matching_kcore(map, path, sizeof(path)))
        return strdup(path);

    /* Use current /proc/kallsyms if possible */
    if (is_host) {
proc_kallsyms:
        return strdup("/proc/kallsyms");
    }

    /* Finally, find a cache of kallsyms */
    if (!build_id_cache__kallsyms_path(sbuild_id, path, sizeof(path))) {
        pr_err("No kallsyms or vmlinux with build-id %s was found\n",
               sbuild_id);
        return NULL;
    }

    return strdup(path);
}

static int dso__load_kernel_sym(struct dso *dso, struct map *map)
{
    int err;
    const char *kallsyms_filename = NULL;
    char *kallsyms_allocated_filename = NULL;
    /*
     * Step 1: if the user specified a kallsyms or vmlinux filename, use
     * it and only it, reporting errors to the user if it cannot be used.
     *
     * For instance, try to analyse an ARM perf.data file _without_ a
     * build-id, or if the user specifies the wrong path to the right
     * vmlinux file, obviously we can't fallback to another vmlinux (a
     * x86_86 one, on the machine where analysis is being performed, say),
     * or worse, /proc/kallsyms.
     *
     * If the specified file _has_ a build-id and there is a build-id
     * section in the perf.data file, we will still do the expected
     * validation in dso__load_vmlinux and will bail out if they don't
     * match.
     */
    if (symbol_conf.kallsyms_name != NULL) {
        kallsyms_filename = symbol_conf.kallsyms_name;
        goto do_kallsyms;
    }

    if (!symbol_conf.ignore_vmlinux && symbol_conf.vmlinux_name != NULL) {
        return dso__load_vmlinux(dso, map, symbol_conf.vmlinux_name, false);
    }

    if (!symbol_conf.ignore_vmlinux && vmlinux_path != NULL) {
        err = dso__load_vmlinux_path(dso, map);
        if (err > 0)
            return err;
    }

    /* do not try local files if a symfs was given */
    if (symbol_conf.symfs[0] != 0)
        return -1;

    kallsyms_allocated_filename = dso__find_kallsyms(dso, map);
    if (!kallsyms_allocated_filename)
        return -1;

    kallsyms_filename = kallsyms_allocated_filename;

do_kallsyms:
    err = dso__load_kallsyms(dso, kallsyms_filename, map);
    if (err > 0)
        pr_debug("Using %s for symbols\n", kallsyms_filename);
    free(kallsyms_allocated_filename);

    if (err > 0 && !dso__is_kcore(dso)) {
        dso->binary_type = DSO_BINARY_TYPE__KALLSYMS;
        dso__set_long_name(dso, DSO__NAME_KALLSYMS, false);
        map__fixup_start(map);
        map__fixup_end(map);
    }

    return err;
}

static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map)
{
    int err;
    const char *kallsyms_filename = NULL;
    struct machine *machine;
    char path[PATH_MAX];

    if (!map->groups) {
        pr_debug("Guest kernel map hasn't the point to groups\n");
        return -1;
    }
    machine = map->groups->machine;

    if (machine__is_default_guest(machine)) {
        /*
         * if the user specified a vmlinux filename, use it and only
         * it, reporting errors to the user if it cannot be used.
         * Or use file guest_kallsyms inputted by user on commandline
         */
        if (symbol_conf.default_guest_vmlinux_name != NULL) {
            err = dso__load_vmlinux(dso, map,
                        symbol_conf.default_guest_vmlinux_name,
                        false);
            return err;
        }

        kallsyms_filename = symbol_conf.default_guest_kallsyms;
        if (!kallsyms_filename)
            return -1;
    } else {
        sprintf(path, "%s/proc/kallsyms", machine->root_dir);
        kallsyms_filename = path;
    }

    err = dso__load_kallsyms(dso, kallsyms_filename, map);
    if (err > 0)
        pr_debug("Using %s for symbols\n", kallsyms_filename);
    if (err > 0 && !dso__is_kcore(dso)) {
        dso->binary_type = DSO_BINARY_TYPE__GUEST_KALLSYMS;
        dso__set_long_name(dso, machine->mmap_name, false);
        map__fixup_start(map);
        map__fixup_end(map);
    }

    return err;
}

static void vmlinux_path__exit(void)
{
    while (--vmlinux_path__nr_entries >= 0)
        zfree(&vmlinux_path[vmlinux_path__nr_entries]);
    vmlinux_path__nr_entries = 0;

    zfree(&vmlinux_path);
}

static const char * const vmlinux_paths[] = {
    "vmlinux",
    "/boot/vmlinux"
};

static const char * const vmlinux_paths_upd[] = {
    "/boot/vmlinux-%s",
    "/usr/lib/debug/boot/vmlinux-%s",
    "/lib/modules/%s/build/vmlinux",
    "/usr/lib/debug/lib/modules/%s/vmlinux",
    "/usr/lib/debug/boot/vmlinux-%s.debug"
};

static int vmlinux_path__add(const char *new_entry)
{
    vmlinux_path[vmlinux_path__nr_entries] = strdup(new_entry);
    if (vmlinux_path[vmlinux_path__nr_entries] == NULL)
        return -1;
    ++vmlinux_path__nr_entries;

    return 0;
}

static int vmlinux_path__init(struct perf_env *env)
{
    struct utsname uts;
    char bf[PATH_MAX];
    char *kernel_version;
    unsigned int i;

    vmlinux_path = malloc(sizeof(char *) * (ARRAY_SIZE(vmlinux_paths) +
                  ARRAY_SIZE(vmlinux_paths_upd)));
    if (vmlinux_path == NULL)
        return -1;

    for (i = 0; i < ARRAY_SIZE(vmlinux_paths); i++)
        if (vmlinux_path__add(vmlinux_paths[i]) < 0)
            goto out_fail;

    /* only try kernel version if no symfs was given */
    if (symbol_conf.symfs[0] != 0)
        return 0;

    if (env) {
        kernel_version = env->os_release;
    } else {
        if (uname(&uts) < 0)
            goto out_fail;

        kernel_version = uts.release;
    }

    for (i = 0; i < ARRAY_SIZE(vmlinux_paths_upd); i++) {
        snprintf(bf, sizeof(bf), vmlinux_paths_upd[i], kernel_version);
        if (vmlinux_path__add(bf) < 0)
            goto out_fail;
    }

    return 0;

out_fail:
    vmlinux_path__exit();
    return -1;
}

int setup_list(struct strlist **list, const char *list_str,
              const char *list_name)
{
    if (list_str == NULL)
        return 0;

    *list = strlist__new(list_str, NULL);
    if (!*list) {
        pr_err("problems parsing %s list\n", list_name);
        return -1;
    }

    symbol_conf.has_filter = true;
    return 0;
}

int setup_intlist(struct intlist **list, const char *list_str,
          const char *list_name)
{
    if (list_str == NULL)
        return 0;

    *list = intlist__new(list_str);
    if (!*list) {
        pr_err("problems parsing %s list\n", list_name);
        return -1;
    }
    return 0;
}

static bool symbol__read_kptr_restrict(void)
{
    bool value = false;
    FILE *fp = fopen("/proc/sys/kernel/kptr_restrict", "r");

    if (fp != NULL) {
        char line[8];

        if (fgets(line, sizeof(line), fp) != NULL)
            value = ((geteuid() != 0) || (getuid() != 0)) ?
                    (atoi(line) != 0) :
                    (atoi(line) == 2);

        fclose(fp);
    }

    return value;
}

int symbol__annotation_init(void)
{
    if (symbol_conf.init_annotation)
        return 0;

    if (symbol_conf.initialized) {
        pr_err("Annotation needs to be init before symbol__init()\n");
        return -1;
    }

    symbol_conf.priv_size += sizeof(struct annotation);
    symbol_conf.init_annotation = true;
    return 0;
}

int symbol__init(struct perf_env *env)
{
    const char *symfs;

    if (symbol_conf.initialized)
        return 0;

    symbol_conf.priv_size = PERF_ALIGN(symbol_conf.priv_size, sizeof(u64));

    symbol__elf_init();

    if (symbol_conf.sort_by_name)
        symbol_conf.priv_size += (sizeof(struct symbol_name_rb_node) -
                      sizeof(struct symbol));

    if (symbol_conf.try_vmlinux_path && vmlinux_path__init(env) < 0)
        return -1;

    if (symbol_conf.field_sep && *symbol_conf.field_sep == '.') {
        pr_err("'.' is the only non valid --field-separator argument\n");
        return -1;
    }

    if (setup_list(&symbol_conf.dso_list,
               symbol_conf.dso_list_str, "dso") < 0)
        return -1;

    if (setup_list(&symbol_conf.comm_list,
               symbol_conf.comm_list_str, "comm") < 0)
        goto out_free_dso_list;

    if (setup_intlist(&symbol_conf.pid_list,
               symbol_conf.pid_list_str, "pid") < 0)
        goto out_free_comm_list;

    if (setup_intlist(&symbol_conf.tid_list,
               symbol_conf.tid_list_str, "tid") < 0)
        goto out_free_pid_list;

    if (setup_list(&symbol_conf.sym_list,
               symbol_conf.sym_list_str, "symbol") < 0)
        goto out_free_tid_list;

    if (setup_list(&symbol_conf.bt_stop_list,
               symbol_conf.bt_stop_list_str, "symbol") < 0)
        goto out_free_sym_list;

    /*
     * A path to symbols of "/" is identical to ""
     * reset here for simplicity.
     */
    symfs = realpath(symbol_conf.symfs, NULL);
    if (symfs == NULL)
        symfs = symbol_conf.symfs;
    if (strcmp(symfs, "/") == 0)
        symbol_conf.symfs = "";
    if (symfs != symbol_conf.symfs)
        free((void *)symfs);

    symbol_conf.kptr_restrict = symbol__read_kptr_restrict();

    symbol_conf.initialized = true;
    return 0;

out_free_sym_list:
    strlist__delete(symbol_conf.sym_list);
out_free_tid_list:
    intlist__delete(symbol_conf.tid_list);
out_free_pid_list:
    intlist__delete(symbol_conf.pid_list);
out_free_comm_list:
    strlist__delete(symbol_conf.comm_list);
out_free_dso_list:
    strlist__delete(symbol_conf.dso_list);
    return -1;
}

void symbol__exit(void)
{
    if (!symbol_conf.initialized)
        return;
    strlist__delete(symbol_conf.bt_stop_list);
    strlist__delete(symbol_conf.sym_list);
    strlist__delete(symbol_conf.dso_list);
    strlist__delete(symbol_conf.comm_list);
    intlist__delete(symbol_conf.tid_list);
    intlist__delete(symbol_conf.pid_list);
    vmlinux_path__exit();
    symbol_conf.sym_list = symbol_conf.dso_list = symbol_conf.comm_list = NULL;
    symbol_conf.bt_stop_list = NULL;
    symbol_conf.initialized = false;
}

int symbol__config_symfs(const struct option *opt __maybe_unused,
             const char *dir, int unset __maybe_unused)
{
    char *bf = NULL;
    int ret;

    symbol_conf.symfs = strdup(dir);
    if (symbol_conf.symfs == NULL)
        return -ENOMEM;

    /* skip the locally configured cache if a symfs is given, and
     * config buildid dir to symfs/.debug
     */
    ret = asprintf(&bf, "%s/%s", dir, ".debug");
    if (ret < 0)
        return -ENOMEM;

    set_buildid_dir(bf);

    free(bf);
    return 0;
}

struct mem_info *mem_info__get(struct mem_info *mi)
{
    if (mi)
        refcount_inc(&mi->refcnt);
    return mi;
}

void mem_info__put(struct mem_info *mi)
{
    if (mi && refcount_dec_and_test(&mi->refcnt))
        free(mi);
}

struct mem_info *mem_info__new(void)
{
    struct mem_info *mi = zalloc(sizeof(*mi));

    if (mi)
        refcount_set(&mi->refcnt, 1);
    return mi;
}