#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>

#include "symbol.h"
#include "debug.h"

#ifndef HAVE_ELF_GETPHDRNUM
static int elf_getphdrnum(Elf *elf, size_t *dst)
{
        GElf_Ehdr gehdr;
        GElf_Ehdr *ehdr;

        ehdr = gelf_getehdr(elf, &gehdr);
        if (!ehdr)
                return -1;

        *dst = ehdr->e_phnum;

        return 0;
}
#endif

#ifndef NT_GNU_BUILD_ID
#define NT_GNU_BUILD_ID 3
#endif

/**
 * elf_symtab__for_each_symbol - iterate thru all the symbols
 *
 * @syms: struct elf_symtab instance to iterate
 * @idx: uint32_t idx
 * @sym: GElf_Sym iterator
 */
#define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
        for (idx = 0, gelf_getsym(syms, idx, &sym);\
             idx < nr_syms; \
             idx++, gelf_getsym(syms, idx, &sym))

static inline uint8_t elf_sym__type(const GElf_Sym *sym)
{
        return GELF_ST_TYPE(sym->st_info);
}

static inline int elf_sym__is_function(const GElf_Sym *sym)
{
        return elf_sym__type(sym) == STT_FUNC &&
               sym->st_name != 0 &&
               sym->st_shndx != SHN_UNDEF;
}

static inline bool elf_sym__is_object(const GElf_Sym *sym)
{
        return elf_sym__type(sym) == STT_OBJECT &&
                sym->st_name != 0 &&
                sym->st_shndx != SHN_UNDEF;
}

static inline int elf_sym__is_label(const GElf_Sym *sym)
{
        return elf_sym__type(sym) == STT_NOTYPE &&
                sym->st_name != 0 &&
                sym->st_shndx != SHN_UNDEF &&
                sym->st_shndx != SHN_ABS;
}

static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type)
{
        switch (type) {
        case MAP__FUNCTION:
                return elf_sym__is_function(sym);
        case MAP__VARIABLE:
                return elf_sym__is_object(sym);
        default:
                return false;
        }
}

static inline const char *elf_sym__name(const GElf_Sym *sym,
                                        const Elf_Data *symstrs)
{
        return symstrs->d_buf + sym->st_name;
}

static inline const char *elf_sec__name(const GElf_Shdr *shdr,
                                        const Elf_Data *secstrs)
{
        return secstrs->d_buf + shdr->sh_name;
}

static inline int elf_sec__is_text(const GElf_Shdr *shdr,
                                        const Elf_Data *secstrs)
{
        return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
}

static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
                                    const Elf_Data *secstrs)
{
        return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
}

static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs,
                          enum map_type type)
{
        switch (type) {
        case MAP__FUNCTION:
                return elf_sec__is_text(shdr, secstrs);
        case MAP__VARIABLE:
                return elf_sec__is_data(shdr, secstrs);
        default:
                return false;
        }
}

static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
{
        Elf_Scn *sec = NULL;
        GElf_Shdr shdr;
        size_t cnt = 1;

        while ((sec = elf_nextscn(elf, sec)) != NULL) {
                gelf_getshdr(sec, &shdr);

                if ((addr >= shdr.sh_addr) &&
                    (addr < (shdr.sh_addr + shdr.sh_size)))
                        return cnt;

                ++cnt;
        }

        return -1;
}

static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
                                    GElf_Shdr *shp, const char *name,
                                    size_t *idx)
{
        Elf_Scn *sec = NULL;
        size_t cnt = 1;

        /* Elf is corrupted/truncated, avoid calling elf_strptr. */
        if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
                return NULL;

        while ((sec = elf_nextscn(elf, sec)) != NULL) {
                char *str;

                gelf_getshdr(sec, shp);
                str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
                if (!strcmp(name, str)) {
                        if (idx)
                                *idx = cnt;
                        break;
                }
                ++cnt;
        }

        return sec;
}

#define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
        for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
             idx < nr_entries; \
             ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))

#define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
        for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
             idx < nr_entries; \
             ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))

/*
 * We need to check if we have a .dynsym, so that we can handle the
 * .plt, synthesizing its symbols, that aren't on the symtabs (be it
 * .dynsym or .symtab).
 * And always look at the original dso, not at debuginfo packages, that
 * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
 */
int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map,
                                symbol_filter_t filter)
{
        uint32_t nr_rel_entries, idx;
        GElf_Sym sym;
        u64 plt_offset;
        GElf_Shdr shdr_plt;
        struct symbol *f;
        GElf_Shdr shdr_rel_plt, shdr_dynsym;
        Elf_Data *reldata, *syms, *symstrs;
        Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
        size_t dynsym_idx;
        GElf_Ehdr ehdr;
        char sympltname[1024];
        Elf *elf;
        int nr = 0, symidx, err = 0;

        if (!ss->dynsym)
                return 0;

        elf = ss->elf;
        ehdr = ss->ehdr;

        scn_dynsym = ss->dynsym;
        shdr_dynsym = ss->dynshdr;
        dynsym_idx = ss->dynsym_idx;

        if (scn_dynsym == NULL)
                goto out_elf_end;

        scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
                                          ".rela.plt", NULL);
        if (scn_plt_rel == NULL) {
                scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
                                                  ".rel.plt", NULL);
                if (scn_plt_rel == NULL)
                        goto out_elf_end;
        }

        err = -1;

        if (shdr_rel_plt.sh_link != dynsym_idx)
                goto out_elf_end;

        if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL)
                goto out_elf_end;

        /*
         * Fetch the relocation section to find the idxes to the GOT
         * and the symbols in the .dynsym they refer to.
         */
        reldata = elf_getdata(scn_plt_rel, NULL);
        if (reldata == NULL)
                goto out_elf_end;

        syms = elf_getdata(scn_dynsym, NULL);
        if (syms == NULL)
                goto out_elf_end;

        scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
        if (scn_symstrs == NULL)
                goto out_elf_end;

        symstrs = elf_getdata(scn_symstrs, NULL);
        if (symstrs == NULL)
                goto out_elf_end;

        if (symstrs->d_size == 0)
                goto out_elf_end;

        nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
        plt_offset = shdr_plt.sh_offset;

        if (shdr_rel_plt.sh_type == SHT_RELA) {
                GElf_Rela pos_mem, *pos;

                elf_section__for_each_rela(reldata, pos, pos_mem, idx,
                                           nr_rel_entries) {
                        symidx = GELF_R_SYM(pos->r_info);
                        plt_offset += shdr_plt.sh_entsize;
                        gelf_getsym(syms, symidx, &sym);
                        snprintf(sympltname, sizeof(sympltname),
                                 "%s@plt", elf_sym__name(&sym, symstrs));

                        f = symbol__new(plt_offset, shdr_plt.sh_entsize,
                                        STB_GLOBAL, sympltname);
                        if (!f)
                                goto out_elf_end;

                        if (filter && filter(map, f))
                                symbol__delete(f);
                        else {
                                symbols__insert(&dso->symbols[map->type], f);
                                ++nr;
                        }
                }
        } else if (shdr_rel_plt.sh_type == SHT_REL) {
                GElf_Rel pos_mem, *pos;
                elf_section__for_each_rel(reldata, pos, pos_mem, idx,
                                          nr_rel_entries) {
                        symidx = GELF_R_SYM(pos->r_info);
                        plt_offset += shdr_plt.sh_entsize;
                        gelf_getsym(syms, symidx, &sym);
                        snprintf(sympltname, sizeof(sympltname),
                                 "%s@plt", elf_sym__name(&sym, symstrs));

                        f = symbol__new(plt_offset, shdr_plt.sh_entsize,
                                        STB_GLOBAL, sympltname);
                        if (!f)
                                goto out_elf_end;

                        if (filter && filter(map, f))
                                symbol__delete(f);
                        else {
                                symbols__insert(&dso->symbols[map->type], f);
                                ++nr;
                        }
                }
        }

        err = 0;
out_elf_end:
        if (err == 0)
                return nr;
        pr_debug("%s: problems reading %s PLT info.\n",
                 __func__, dso->long_name);
        return 0;
}

/*
 * Align offset to 4 bytes as needed for note name and descriptor data.
 */
#define NOTE_ALIGN(n) (((n) + 3) & -4U)

static int elf_read_build_id(Elf *elf, void *bf, size_t size)
{
        int err = -1;
        GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        Elf_Data *data;
        Elf_Scn *sec;
        Elf_Kind ek;
        void *ptr;

        if (size < BUILD_ID_SIZE)
                goto out;

        ek = elf_kind(elf);
        if (ek != ELF_K_ELF)
                goto out;

        if (gelf_getehdr(elf, &ehdr) == NULL) {
                pr_err("%s: cannot get elf header.\n", __func__);
                goto out;
        }

        /*
         * Check following sections for notes:
         *   '.note.gnu.build-id'
         *   '.notes'
         *   '.note' (VDSO specific)
         */
        do {
                sec = elf_section_by_name(elf, &ehdr, &shdr,
                                          ".note.gnu.build-id", NULL);
                if (sec)
                        break;

                sec = elf_section_by_name(elf, &ehdr, &shdr,
                                          ".notes", NULL);
                if (sec)
                        break;

                sec = elf_section_by_name(elf, &ehdr, &shdr,
                                          ".note", NULL);
                if (sec)
                        break;

                return err;

        } while (0);

        data = elf_getdata(sec, NULL);
        if (data == NULL)
                goto out;

        ptr = data->d_buf;
        while (ptr < (data->d_buf + data->d_size)) {
                GElf_Nhdr *nhdr = ptr;
                size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
                       descsz = NOTE_ALIGN(nhdr->n_descsz);
                const char *name;

                ptr += sizeof(*nhdr);
                name = ptr;
                ptr += namesz;
                if (nhdr->n_type == NT_GNU_BUILD_ID &&
                    nhdr->n_namesz == sizeof("GNU")) {
                        if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
                                size_t sz = min(size, descsz);
                                memcpy(bf, ptr, sz);
                                memset(bf + sz, 0, size - sz);
                                err = descsz;
                                break;
                        }
                }
                ptr += descsz;
        }

out:
        return err;
}

int filename__read_build_id(const char *filename, void *bf, size_t size)
{
        int fd, err = -1;
        Elf *elf;

        if (size < BUILD_ID_SIZE)
                goto out;

        fd = open(filename, O_RDONLY);
        if (fd < 0)
                goto out;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (elf == NULL) {
                pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
                goto out_close;
        }

        err = elf_read_build_id(elf, bf, size);

        elf_end(elf);
out_close:
        close(fd);
out:
        return err;
}

int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
{
        int fd, err = -1;

        if (size < BUILD_ID_SIZE)
                goto out;

        fd = open(filename, O_RDONLY);
        if (fd < 0)
                goto out;

        while (1) {
                char bf[BUFSIZ];
                GElf_Nhdr nhdr;
                size_t namesz, descsz;

                if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
                        break;

                namesz = NOTE_ALIGN(nhdr.n_namesz);
                descsz = NOTE_ALIGN(nhdr.n_descsz);
                if (nhdr.n_type == NT_GNU_BUILD_ID &&
                    nhdr.n_namesz == sizeof("GNU")) {
                        if (read(fd, bf, namesz) != (ssize_t)namesz)
                                break;
                        if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
                                size_t sz = min(descsz, size);
                                if (read(fd, build_id, sz) == (ssize_t)sz) {
                                        memset(build_id + sz, 0, size - sz);
                                        err = 0;
                                        break;
                                }
                        } else if (read(fd, bf, descsz) != (ssize_t)descsz)
                                break;
                } else {
                        int n = namesz + descsz;
                        if (read(fd, bf, n) != n)
                                break;
                }
        }
        close(fd);
out:
        return err;
}

int filename__read_debuglink(const char *filename, char *debuglink,
                             size_t size)
{
        int fd, err = -1;
        Elf *elf;
        GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        Elf_Data *data;
        Elf_Scn *sec;
        Elf_Kind ek;

        fd = open(filename, O_RDONLY);
        if (fd < 0)
                goto out;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (elf == NULL) {
                pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
                goto out_close;
        }

        ek = elf_kind(elf);
        if (ek != ELF_K_ELF)
                goto out_close;

        if (gelf_getehdr(elf, &ehdr) == NULL) {
                pr_err("%s: cannot get elf header.\n", __func__);
                goto out_close;
        }

        sec = elf_section_by_name(elf, &ehdr, &shdr,
                                  ".gnu_debuglink", NULL);
        if (sec == NULL)
                goto out_close;

        data = elf_getdata(sec, NULL);
        if (data == NULL)
                goto out_close;

        /* the start of this section is a zero-terminated string */
        strncpy(debuglink, data->d_buf, size);

        elf_end(elf);

out_close:
        close(fd);
out:
        return err;
}

static int dso__swap_init(struct dso *dso, unsigned char eidata)
{
        static unsigned int const endian = 1;

        dso->needs_swap = DSO_SWAP__NO;

        switch (eidata) {
        case ELFDATA2LSB:
                /* We are big endian, DSO is little endian. */
                if (*(unsigned char const *)&endian != 1)
                        dso->needs_swap = DSO_SWAP__YES;
                break;

        case ELFDATA2MSB:
                /* We are little endian, DSO is big endian. */
                if (*(unsigned char const *)&endian != 0)
                        dso->needs_swap = DSO_SWAP__YES;
                break;

        default:
                pr_err("unrecognized DSO data encoding %d\n", eidata);
                return -EINVAL;
        }

        return 0;
}

bool symsrc__possibly_runtime(struct symsrc *ss)
{
        return ss->dynsym || ss->opdsec;
}

bool symsrc__has_symtab(struct symsrc *ss)
{
        return ss->symtab != NULL;
}

void symsrc__destroy(struct symsrc *ss)
{
        free(ss->name);
        elf_end(ss->elf);
        close(ss->fd);
}

int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
                 enum dso_binary_type type)
{
        int err = -1;
        GElf_Ehdr ehdr;
        Elf *elf;
        int fd;

        fd = open(name, O_RDONLY);
        if (fd < 0)
                return -1;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (elf == NULL) {
                pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
                goto out_close;
        }

        if (gelf_getehdr(elf, &ehdr) == NULL) {
                pr_debug("%s: cannot get elf header.\n", __func__);
                goto out_elf_end;
        }

        if (dso__swap_init(dso, ehdr.e_ident[EI_DATA]))
                goto out_elf_end;

        /* Always reject images with a mismatched build-id: */
        if (dso->has_build_id) {
                u8 build_id[BUILD_ID_SIZE];

                if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0)
                        goto out_elf_end;

                if (!dso__build_id_equal(dso, build_id))
                        goto out_elf_end;
        }

        ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
                        NULL);
        if (ss->symshdr.sh_type != SHT_SYMTAB)
                ss->symtab = NULL;

        ss->dynsym_idx = 0;
        ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
                        &ss->dynsym_idx);
        if (ss->dynshdr.sh_type != SHT_DYNSYM)
                ss->dynsym = NULL;

        ss->opdidx = 0;
        ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
                        &ss->opdidx);
        if (ss->opdshdr.sh_type != SHT_PROGBITS)
                ss->opdsec = NULL;

        if (dso->kernel == DSO_TYPE_USER) {
                GElf_Shdr shdr;
                ss->adjust_symbols = (ehdr.e_type == ET_EXEC ||
                                ehdr.e_type == ET_REL ||
                                elf_section_by_name(elf, &ehdr, &shdr,
                                                     ".gnu.prelink_undo",
                                                     NULL) != NULL);
        } else {
                ss->adjust_symbols = ehdr.e_type == ET_EXEC ||
                                     ehdr.e_type == ET_REL;
        }

        ss->name   = strdup(name);
        if (!ss->name)
                goto out_elf_end;

        ss->elf    = elf;
        ss->fd     = fd;
        ss->ehdr   = ehdr;
        ss->type   = type;

        return 0;

out_elf_end:
        elf_end(elf);
out_close:
        close(fd);
        return err;
}

/**
 * ref_reloc_sym_not_found - has kernel relocation symbol been found.
 * @kmap: kernel maps and relocation reference symbol
 *
 * This function returns %true if we are dealing with the kernel maps and the
 * relocation reference symbol has not yet been found.  Otherwise %false is
 * returned.
 */
static bool ref_reloc_sym_not_found(struct kmap *kmap)
{
        return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
               !kmap->ref_reloc_sym->unrelocated_addr;
}

/**
 * ref_reloc - kernel relocation offset.
 * @kmap: kernel maps and relocation reference symbol
 *
 * This function returns the offset of kernel addresses as determined by using
 * the relocation reference symbol i.e. if the kernel has not been relocated
 * then the return value is zero.
 */
static u64 ref_reloc(struct kmap *kmap)
{
        if (kmap && kmap->ref_reloc_sym &&
            kmap->ref_reloc_sym->unrelocated_addr)
                return kmap->ref_reloc_sym->addr -
                       kmap->ref_reloc_sym->unrelocated_addr;
        return 0;
}

int dso__load_sym(struct dso *dso, struct map *map,
                  struct symsrc *syms_ss, struct symsrc *runtime_ss,
                  symbol_filter_t filter, int kmodule)
{
        struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
        struct map *curr_map = map;
        struct dso *curr_dso = dso;
        Elf_Data *symstrs, *secstrs;
        uint32_t nr_syms;
        int err = -1;
        uint32_t idx;
        GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        Elf_Data *syms, *opddata = NULL;
        GElf_Sym sym;
        Elf_Scn *sec, *sec_strndx;
        Elf *elf;
        int nr = 0;
        bool remap_kernel = false, adjust_kernel_syms = false;

        dso->symtab_type = syms_ss->type;
        dso->rel = syms_ss->ehdr.e_type == ET_REL;

        /*
         * Modules may already have symbols from kallsyms, but those symbols
         * have the wrong values for the dso maps, so remove them.
         */
        if (kmodule && syms_ss->symtab)
                symbols__delete(&dso->symbols[map->type]);

        if (!syms_ss->symtab) {
                syms_ss->symtab  = syms_ss->dynsym;
                syms_ss->symshdr = syms_ss->dynshdr;
        }

        elf = syms_ss->elf;
        ehdr = syms_ss->ehdr;
        sec = syms_ss->symtab;
        shdr = syms_ss->symshdr;

        if (runtime_ss->opdsec)
                opddata = elf_rawdata(runtime_ss->opdsec, NULL);

        syms = elf_getdata(sec, NULL);
        if (syms == NULL)
                goto out_elf_end;

        sec = elf_getscn(elf, shdr.sh_link);
        if (sec == NULL)
                goto out_elf_end;

        symstrs = elf_getdata(sec, NULL);
        if (symstrs == NULL)
                goto out_elf_end;

        sec_strndx = elf_getscn(elf, ehdr.e_shstrndx);
        if (sec_strndx == NULL)
                goto out_elf_end;

        secstrs = elf_getdata(sec_strndx, NULL);
        if (secstrs == NULL)
                goto out_elf_end;

        nr_syms = shdr.sh_size / shdr.sh_entsize;

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

        /*
         * The kernel relocation symbol is needed in advance in order to adjust
         * kernel maps correctly.
         */
        if (ref_reloc_sym_not_found(kmap)) {
                elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
                        const char *elf_name = elf_sym__name(&sym, symstrs);

                        if (strcmp(elf_name, kmap->ref_reloc_sym->name))
                                continue;
                        kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
                        break;
                }
        }

        dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
        /*
         * Initial kernel and module mappings do not map to the dso.  For
         * function mappings, flag the fixups.
         */
        if (map->type == MAP__FUNCTION && (dso->kernel || kmodule)) {
                remap_kernel = true;
                adjust_kernel_syms = dso->adjust_symbols;
        }
        elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
                struct symbol *f;
                const char *elf_name = elf_sym__name(&sym, symstrs);
                char *demangled = NULL;
                int is_label = elf_sym__is_label(&sym);
                const char *section_name;
                bool used_opd = false;

                if (!is_label && !elf_sym__is_a(&sym, map->type))
                        continue;

                /* Reject ARM ELF "mapping symbols": these aren't unique and
                 * don't identify functions, so will confuse the profile
                 * output: */
                if (ehdr.e_machine == EM_ARM) {
                        if (!strcmp(elf_name, "$a") ||
                            !strcmp(elf_name, "$d") ||
                            !strcmp(elf_name, "$t"))
                                continue;
                }

                if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
                        u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
                        u64 *opd = opddata->d_buf + offset;
                        sym.st_value = DSO__SWAP(dso, u64, *opd);
                        sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
                                        sym.st_value);
                        used_opd = true;
                }
                /*
                 * When loading symbols in a data mapping, ABS symbols (which
                 * has a value of SHN_ABS in its st_shndx) failed at
                 * elf_getscn().  And it marks the loading as a failure so
                 * already loaded symbols cannot be fixed up.
                 *
                 * I'm not sure what should be done. Just ignore them for now.
                 * - Namhyung Kim
                 */
                if (sym.st_shndx == SHN_ABS)
                        continue;

                sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
                if (!sec)
                        goto out_elf_end;

                gelf_getshdr(sec, &shdr);

                if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
                        continue;

                section_name = elf_sec__name(&shdr, secstrs);

                /* On ARM, symbols for thumb functions have 1 added to
                 * the symbol address as a flag - remove it */
                if ((ehdr.e_machine == EM_ARM) &&
                    (map->type == MAP__FUNCTION) &&
                    (sym.st_value & 1))
                        --sym.st_value;

                if (dso->kernel || kmodule) {
                        char dso_name[PATH_MAX];

                        /* Adjust symbol to map to file offset */
                        if (adjust_kernel_syms)
                                sym.st_value -= shdr.sh_addr - shdr.sh_offset;

                        if (strcmp(section_name,
                                   (curr_dso->short_name +
                                    dso->short_name_len)) == 0)
                                goto new_symbol;

                        if (strcmp(section_name, ".text") == 0) {
                                /*
                                 * The initial kernel mapping is based on
                                 * kallsyms and identity maps.  Overwrite it to
                                 * map to the kernel dso.
                                 */
                                if (remap_kernel && dso->kernel) {
                                        remap_kernel = false;
                                        map->start = shdr.sh_addr +
                                                     ref_reloc(kmap);
                                        map->end = map->start + shdr.sh_size;
                                        map->pgoff = shdr.sh_offset;
                                        map->map_ip = map__map_ip;
                                        map->unmap_ip = map__unmap_ip;
                                        /* Ensure maps are correctly ordered */
                                        map_groups__remove(kmap->kmaps, map);
                                        map_groups__insert(kmap->kmaps, map);
                                }

                                /*
                                 * The initial module mapping is based on
                                 * /proc/modules mapped to offset zero.
                                 * Overwrite it to map to the module dso.
                                 */
                                if (remap_kernel && kmodule) {
                                        remap_kernel = false;
                                        map->pgoff = shdr.sh_offset;
                                }

                                curr_map = map;
                                curr_dso = dso;
                                goto new_symbol;
                        }

                        if (!kmap)
                                goto new_symbol;

                        snprintf(dso_name, sizeof(dso_name),
                                 "%s%s", dso->short_name, section_name);

                        curr_map = map_groups__find_by_name(kmap->kmaps, map->type, dso_name);
                        if (curr_map == NULL) {
                                u64 start = sym.st_value;

                                if (kmodule)
                                        start += map->start + shdr.sh_offset;

                                curr_dso = dso__new(dso_name);
                                if (curr_dso == NULL)
                                        goto out_elf_end;
                                curr_dso->kernel = dso->kernel;
                                curr_dso->long_name = dso->long_name;
                                curr_dso->long_name_len = dso->long_name_len;
                                curr_map = map__new2(start, curr_dso,
                                                     map->type);
                                if (curr_map == NULL) {
                                        dso__delete(curr_dso);
                                        goto out_elf_end;
                                }
                                if (adjust_kernel_syms) {
                                        curr_map->start = shdr.sh_addr +
                                                          ref_reloc(kmap);
                                        curr_map->end = curr_map->start +
                                                        shdr.sh_size;
                                        curr_map->pgoff = shdr.sh_offset;
                                } else {
                                        curr_map->map_ip = identity__map_ip;
                                        curr_map->unmap_ip = identity__map_ip;
                                }
                                curr_dso->symtab_type = dso->symtab_type;
                                map_groups__insert(kmap->kmaps, curr_map);
                                dsos__add(&dso->node, curr_dso);
                                dso__set_loaded(curr_dso, map->type);
                        } else
                                curr_dso = curr_map->dso;

                        goto new_symbol;
                }

                if ((used_opd && runtime_ss->adjust_symbols)
                                || (!used_opd && syms_ss->adjust_symbols)) {
                        pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
                                  "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
                                  (u64)sym.st_value, (u64)shdr.sh_addr,
                                  (u64)shdr.sh_offset);
                        sym.st_value -= shdr.sh_addr - shdr.sh_offset;
                }
                /*
                 * We need to figure out if the object was created from C++ sources
                 * DWARF DW_compile_unit has this, but we don't always have access
                 * to it...
                 */
                if (symbol_conf.demangle) {
                        demangled = bfd_demangle(NULL, elf_name,
                                                 DMGL_PARAMS | DMGL_ANSI);
                        if (demangled != NULL)
                                elf_name = demangled;
                }
new_symbol:
                f = symbol__new(sym.st_value, sym.st_size,
                                GELF_ST_BIND(sym.st_info), elf_name);
                free(demangled);
                if (!f)
                        goto out_elf_end;

                if (filter && filter(curr_map, f))
                        symbol__delete(f);
                else {
                        symbols__insert(&curr_dso->symbols[curr_map->type], f);
                        nr++;
                }
        }

        /*
         * For misannotated, zeroed, ASM function sizes.
         */
        if (nr > 0) {
                symbols__fixup_duplicate(&dso->symbols[map->type]);
                symbols__fixup_end(&dso->symbols[map->type]);
                if (kmap) {
                        /*
                         * We need to fixup this here too because we create new
                         * maps here, for things like vsyscall sections.
                         */
                        __map_groups__fixup_end(kmap->kmaps, map->type);
                }
        }
        err = nr;
out_elf_end:
        return err;
}

static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
{
        GElf_Phdr phdr;
        size_t i, phdrnum;
        int err;
        u64 sz;

        if (elf_getphdrnum(elf, &phdrnum))
                return -1;

        for (i = 0; i < phdrnum; i++) {
                if (gelf_getphdr(elf, i, &phdr) == NULL)
                        return -1;
                if (phdr.p_type != PT_LOAD)
                        continue;
                if (exe) {
                        if (!(phdr.p_flags & PF_X))
                                continue;
                } else {
                        if (!(phdr.p_flags & PF_R))
                                continue;
                }
                sz = min(phdr.p_memsz, phdr.p_filesz);
                if (!sz)
                        continue;
                err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
                if (err)
                        return err;
        }
        return 0;
}

int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
                    bool *is_64_bit)
{
        int err;
        Elf *elf;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (elf == NULL)
                return -1;

        if (is_64_bit)
                *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);

        err = elf_read_maps(elf, exe, mapfn, data);

        elf_end(elf);
        return err;
}

void symbol__elf_init(void)
{
        elf_version(EV_CURRENT);
}