// SPDX-License-Identifier: GPL-2.0
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <inttypes.h>

#include "dso.h"
#include "map.h"
#include "maps.h"
#include "symbol.h"
#include "symsrc.h"
#include "demangle-ocaml.h"
#include "demangle-java.h"
#include "demangle-rust.h"
#include "machine.h"
#include "vdso.h"
#include "debug.h"
#include "util/copyfile.h"
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/zalloc.h>
#include <symbol/kallsyms.h>
#include <internal/lib.h>

#ifndef EM_AARCH64
#define EM_AARCH64      183  /* ARM 64 bit */
#endif

#ifndef ELF32_ST_VISIBILITY
#define ELF32_ST_VISIBILITY(o)  ((o) & 0x03)
#endif

/* For ELF64 the definitions are the same.  */
#ifndef ELF64_ST_VISIBILITY
#define ELF64_ST_VISIBILITY(o)  ELF32_ST_VISIBILITY (o)
#endif

/* How to extract information held in the st_other field.  */
#ifndef GELF_ST_VISIBILITY
#define GELF_ST_VISIBILITY(val) ELF64_ST_VISIBILITY (val)
#endif

typedef Elf64_Nhdr GElf_Nhdr;

#ifndef DMGL_PARAMS
#define DMGL_NO_OPTS     0              /* For readability... */
#define DMGL_PARAMS      (1 << 0)       /* Include function args */
#define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */
#endif

#ifdef HAVE_LIBBFD_SUPPORT
#define PACKAGE 'perf'
#include <bfd.h>
#else
#ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
extern char *cplus_demangle(const char *, int);

static inline char *bfd_demangle(void __maybe_unused *v, const char *c, int i)
{
        return cplus_demangle(c, i);
}
#else
#ifdef NO_DEMANGLE
static inline char *bfd_demangle(void __maybe_unused *v,
                                 const char __maybe_unused *c,
                                 int __maybe_unused i)
{
        return NULL;
}
#endif
#endif
#endif

#ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
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 HAVE_ELF_GETSHDRSTRNDX_SUPPORT
static int elf_getshdrstrndx(Elf *elf __maybe_unused, size_t *dst __maybe_unused)
{
        pr_err("%s: update your libelf to > 0.140, this one lacks elf_getshdrstrndx().\n", __func__);
        return -1;
}
#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 uint8_t elf_sym__visibility(const GElf_Sym *sym)
{
        return GELF_ST_VISIBILITY(sym->st_other);
}

#ifndef STT_GNU_IFUNC
#define STT_GNU_IFUNC 10
#endif

static inline int elf_sym__is_function(const GElf_Sym *sym)
{
        return (elf_sym__type(sym) == STT_FUNC ||
                elf_sym__type(sym) == STT_GNU_IFUNC) &&
               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 &&
                elf_sym__visibility(sym) != STV_HIDDEN &&
                elf_sym__visibility(sym) != STV_INTERNAL;
}

static bool elf_sym__filter(GElf_Sym *sym)
{
        return elf_sym__is_function(sym) || elf_sym__is_object(sym);
}

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__filter(GElf_Shdr *shdr, Elf_Data *secstrs)
{
        return elf_sec__is_text(shdr, secstrs) || 
               elf_sec__is_data(shdr, secstrs);
}

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;
}

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 (str && !strcmp(name, str)) {
                        if (idx)
                                *idx = cnt;
                        return sec;
                }
                ++cnt;
        }

        return NULL;
}

static bool want_demangle(bool is_kernel_sym)
{
        return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
}

static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
{
        int demangle_flags = verbose > 0 ? (DMGL_PARAMS | DMGL_ANSI) : DMGL_NO_OPTS;
        char *demangled = NULL;

        /*
         * 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 (!want_demangle(dso->kernel || kmodule))
            return demangled;

        demangled = bfd_demangle(NULL, elf_name, demangle_flags);
        if (demangled == NULL) {
                demangled = ocaml_demangle_sym(elf_name);
                if (demangled == NULL) {
                        demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
                }
        }
        else if (rust_is_mangled(demangled))
                /*
                    * Input to Rust demangling is the BFD-demangled
                    * name which it Rust-demangles in place.
                    */
                rust_demangle_sym(demangled);

        return demangled;
}

#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)
{
        uint32_t nr_rel_entries, idx;
        GElf_Sym sym;
        u64 plt_offset, plt_header_size, plt_entry_size;
        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;
        switch (ehdr.e_machine) {
                case EM_ARM:
                        plt_header_size = 20;
                        plt_entry_size = 12;
                        break;

                case EM_AARCH64:
                        plt_header_size = 32;
                        plt_entry_size = 16;
                        break;

                case EM_SPARC:
                        plt_header_size = 48;
                        plt_entry_size = 12;
                        break;

                case EM_SPARCV9:
                        plt_header_size = 128;
                        plt_entry_size = 32;
                        break;

                default: /* FIXME: s390/alpha/mips/parisc/poperpc/sh/xtensa need to be checked */
                        plt_header_size = shdr_plt.sh_entsize;
                        plt_entry_size = shdr_plt.sh_entsize;
                        break;
        }
        plt_offset += plt_header_size;

        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) {
                        const char *elf_name = NULL;
                        char *demangled = NULL;
                        symidx = GELF_R_SYM(pos->r_info);
                        gelf_getsym(syms, symidx, &sym);

                        elf_name = elf_sym__name(&sym, symstrs);
                        demangled = demangle_sym(dso, 0, elf_name);
                        if (demangled != NULL)
                                elf_name = demangled;
                        snprintf(sympltname, sizeof(sympltname),
                                 "%s@plt", elf_name);
                        free(demangled);

                        f = symbol__new(plt_offset, plt_entry_size,
                                        STB_GLOBAL, STT_FUNC, sympltname);
                        if (!f)
                                goto out_elf_end;

                        plt_offset += plt_entry_size;
                        symbols__insert(&dso->symbols, 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) {
                        const char *elf_name = NULL;
                        char *demangled = NULL;
                        symidx = GELF_R_SYM(pos->r_info);
                        gelf_getsym(syms, symidx, &sym);

                        elf_name = elf_sym__name(&sym, symstrs);
                        demangled = demangle_sym(dso, 0, elf_name);
                        if (demangled != NULL)
                                elf_name = demangled;
                        snprintf(sympltname, sizeof(sympltname),
                                 "%s@plt", elf_name);
                        free(demangled);

                        f = symbol__new(plt_offset, plt_entry_size,
                                        STB_GLOBAL, STT_FUNC, sympltname);
                        if (!f)
                                goto out_elf_end;

                        plt_offset += plt_entry_size;
                        symbols__insert(&dso->symbols, 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;
}

char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
{
        return demangle_sym(dso, kmodule, elf_name);
}

/*
 * 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;
}

#ifdef HAVE_LIBBFD_BUILDID_SUPPORT

static int read_build_id(const char *filename, struct build_id *bid)
{
        size_t size = sizeof(bid->data);
        int err = -1;
        bfd *abfd;

        abfd = bfd_openr(filename, NULL);
        if (!abfd)
                return -1;

        if (!bfd_check_format(abfd, bfd_object)) {
                pr_debug2("%s: cannot read %s bfd file.\n", __func__, filename);
                goto out_close;
        }

        if (!abfd->build_id || abfd->build_id->size > size)
                goto out_close;

        memcpy(bid->data, abfd->build_id->data, abfd->build_id->size);
        memset(bid->data + abfd->build_id->size, 0, size - abfd->build_id->size);
        err = bid->size = abfd->build_id->size;

out_close:
        bfd_close(abfd);
        return err;
}

#else // HAVE_LIBBFD_BUILDID_SUPPORT

static int read_build_id(const char *filename, struct build_id *bid)
{
        size_t size = sizeof(bid->data);
        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, bid->data, size);
        if (err > 0)
                bid->size = err;

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

#endif // HAVE_LIBBFD_BUILDID_SUPPORT

int filename__read_build_id(const char *filename, struct build_id *bid)
{
        struct kmod_path m = { .name = NULL, };
        char path[PATH_MAX];
        int err;

        if (!filename)
                return -EFAULT;

        err = kmod_path__parse(&m, filename);
        if (err)
                return -1;

        if (m.comp) {
                int error = 0, fd;

                fd = filename__decompress(filename, path, sizeof(path), m.comp, &error);
                if (fd < 0) {
                        pr_debug("Failed to decompress (error %d) %s\n",
                                 error, filename);
                        return -1;
                }
                close(fd);
                filename = path;
        }

        err = read_build_id(filename, bid);

        if (m.comp)
                unlink(filename);
        return err;
}

int sysfs__read_build_id(const char *filename, struct build_id *bid)
{
        size_t size = sizeof(bid->data);
        int fd, err = -1;

        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, bid->data, sz) == (ssize_t)sz) {
                                        memset(bid->data + sz, 0, size - sz);
                                        bid->size = sz;
                                        err = 0;
                                        break;
                                }
                        } else if (read(fd, bf, descsz) != (ssize_t)descsz)
                                break;
                } else {
                        int n = namesz + descsz;

                        if (n > (int)sizeof(bf)) {
                                n = sizeof(bf);
                                pr_debug("%s: truncating reading of build id in sysfs file %s: n_namesz=%u, n_descsz=%u.\n",
                                         __func__, filename, nhdr.n_namesz, nhdr.n_descsz);
                        }
                        if (read(fd, bf, n) != n)
                                break;
                }
        }
        close(fd);
out:
        return err;
}

#ifdef HAVE_LIBBFD_SUPPORT

int filename__read_debuglink(const char *filename, char *debuglink,
                             size_t size)
{
        int err = -1;
        asection *section;
        bfd *abfd;

        abfd = bfd_openr(filename, NULL);
        if (!abfd)
                return -1;

        if (!bfd_check_format(abfd, bfd_object)) {
                pr_debug2("%s: cannot read %s bfd file.\n", __func__, filename);
                goto out_close;
        }

        section = bfd_get_section_by_name(abfd, ".gnu_debuglink");
        if (!section)
                goto out_close;

        if (section->size > size)
                goto out_close;

        if (!bfd_get_section_contents(abfd, section, debuglink, 0,
                                      section->size))
                goto out_close;

        err = 0;

out_close:
        bfd_close(abfd);
        return err;
}

#else

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_elf_end;

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

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

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

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

        err = 0;

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

#endif

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)
{
        zfree(&ss->name);
        elf_end(ss->elf);
        close(ss->fd);
}

bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
{
        /*
         * Usually vmlinux is an ELF file with type ET_EXEC for most
         * architectures; except Arm64 kernel is linked with option
         * '-share', so need to check type ET_DYN.
         */
        return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL ||
               ehdr.e_type == ET_DYN;
}

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

        if (dso__needs_decompress(dso)) {
                fd = dso__decompress_kmodule_fd(dso, name);
                if (fd < 0)
                        return -1;

                type = dso->symtab_type;
        } else {
                fd = open(name, O_RDONLY);
                if (fd < 0) {
                        dso->load_errno = errno;
                        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);
                dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
                goto out_close;
        }

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

        if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) {
                dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR;
                goto out_elf_end;
        }

        /* Always reject images with a mismatched build-id: */
        if (dso->has_build_id && !symbol_conf.ignore_vmlinux_buildid) {
                u8 build_id[BUILD_ID_SIZE];
                struct build_id bid;
                int size;

                size = elf_read_build_id(elf, build_id, BUILD_ID_SIZE);
                if (size <= 0) {
                        dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID;
                        goto out_elf_end;
                }

                build_id__init(&bid, build_id, size);
                if (!dso__build_id_equal(dso, &bid)) {
                        pr_debug("%s: build id mismatch for %s.\n", __func__, name);
                        dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID;
                        goto out_elf_end;
                }
        }

        ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64);

        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_SPACE__USER)
                ss->adjust_symbols = true;
        else
                ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);

        ss->name   = strdup(name);
        if (!ss->name) {
                dso->load_errno = errno;
                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 -1;
}

/**
 * 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;
}

void __weak arch__sym_update(struct symbol *s __maybe_unused,
                GElf_Sym *sym __maybe_unused) { }

static int dso__process_kernel_symbol(struct dso *dso, struct map *map,
                                      GElf_Sym *sym, GElf_Shdr *shdr,
                                      struct maps *kmaps, struct kmap *kmap,
                                      struct dso **curr_dsop, struct map **curr_mapp,
                                      const char *section_name,
                                      bool adjust_kernel_syms, bool kmodule, bool *remap_kernel)
{
        struct dso *curr_dso = *curr_dsop;
        struct map *curr_map;
        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)
                return 0;

        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 && !kmodule) {
                        *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 */
                        if (kmaps) {
                                map__get(map);
                                maps__remove(kmaps, map);
                                maps__insert(kmaps, map);
                                map__put(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_mapp = map;
                *curr_dsop = dso;
                return 0;
        }

        if (!kmap)
                return 0;

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

        curr_map = maps__find_by_name(kmaps, 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)
                        return -1;
                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);
                dso__put(curr_dso);
                if (curr_map == NULL)
                        return -1;

                if (curr_dso->kernel)
                        map__kmap(curr_map)->kmaps = kmaps;

                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 = curr_map->unmap_ip = identity__map_ip;
                }
                curr_dso->symtab_type = dso->symtab_type;
                maps__insert(kmaps, curr_map);
                /*
                 * Add it before we drop the reference to curr_map, i.e. while
                 * we still are sure to have a reference to this DSO via
                 * *curr_map->dso.
                 */
                dsos__add(&kmaps->machine->dsos, curr_dso);
                /* kmaps already got it */
                map__put(curr_map);
                dso__set_loaded(curr_dso);
                *curr_mapp = curr_map;
                *curr_dsop = curr_dso;
        } else
                *curr_dsop = curr_map->dso;

        return 0;
}

static int
dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
                       struct symsrc *runtime_ss, int kmodule, int dynsym)
{
        struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
        struct maps *kmaps = kmap ? map__kmaps(map) : NULL;
        struct map *curr_map = map;
        struct dso *curr_dso = dso;
        Elf_Data *symstrs, *secstrs, *secstrs_run, *secstrs_sym;
        uint32_t nr_syms;
        int err = -1;
        uint32_t idx;
        GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        GElf_Shdr tshdr;
        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;

        if (kmap && !kmaps)
                return -1;

        elf = syms_ss->elf;
        ehdr = syms_ss->ehdr;
        if (dynsym) {
                sec  = syms_ss->dynsym;
                shdr = syms_ss->dynshdr;
        } else {
                sec =  syms_ss->symtab;
                shdr = syms_ss->symshdr;
        }

        if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr,
                                ".text", NULL))
                dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;

        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(runtime_ss->elf, runtime_ss->ehdr.e_shstrndx);
        if (sec_strndx == NULL)
                goto out_elf_end;

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

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

        secstrs_sym = elf_getdata(sec_strndx, NULL);
        if (secstrs_sym == 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;
                        map->reloc = kmap->ref_reloc_sym->addr -
                                     kmap->ref_reloc_sym->unrelocated_addr;
                        break;
                }
        }

        /*
         * Handle any relocation of vdso necessary because older kernels
         * attempted to prelink vdso to its virtual address.
         */
        if (dso__is_vdso(dso))
                map->reloc = map->start - dso->text_offset;

        dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
        /*
         * Initial kernel and module mappings do not map to the dso.
         * Flag the fixups.
         */
        if (dso->kernel) {
                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__filter(&sym))
                        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 || ehdr.e_machine == EM_AARCH64) {
                        if (elf_name[0] == '$' && strchr("adtx", elf_name[1])
                            && (elf_name[2] == '\0' || elf_name[2] == '.'))
                                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(syms_ss->elf, sym.st_shndx);
                if (!sec)
                        goto out_elf_end;

                gelf_getshdr(sec, &shdr);

                secstrs = secstrs_sym;

                /*
                 * We have to fallback to runtime when syms' section header has
                 * NOBITS set. NOBITS results in file offset (sh_offset) not
                 * being incremented. So sh_offset used below has different
                 * values for syms (invalid) and runtime (valid).
                 */
                if (shdr.sh_type == SHT_NOBITS) {
                        sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
                        if (!sec)
                                goto out_elf_end;

                        gelf_getshdr(sec, &shdr);
                        secstrs = secstrs_run;
                }

                if (is_label && !elf_sec__filter(&shdr, secstrs))
                        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) &&
                    (GELF_ST_TYPE(sym.st_info) == STT_FUNC) &&
                    (sym.st_value & 1))
                        --sym.st_value;

                if (dso->kernel) {
                        if (dso__process_kernel_symbol(dso, map, &sym, &shdr, kmaps, kmap, &curr_dso, &curr_map,
                                                       section_name, adjust_kernel_syms, kmodule, &remap_kernel))
                                goto out_elf_end;
                } else 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;
                }

                demangled = demangle_sym(dso, kmodule, elf_name);
                if (demangled != NULL)
                        elf_name = demangled;

                f = symbol__new(sym.st_value, sym.st_size,
                                GELF_ST_BIND(sym.st_info),
                                GELF_ST_TYPE(sym.st_info), elf_name);
                free(demangled);
                if (!f)
                        goto out_elf_end;

                arch__sym_update(f, &sym);

                __symbols__insert(&curr_dso->symbols, f, dso->kernel);
                nr++;
        }

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

int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss,
                  struct symsrc *runtime_ss, int kmodule)
{
        int nr = 0;
        int err = -1;

        dso->symtab_type = syms_ss->type;
        dso->is_64_bit = syms_ss->is_64_bit;
        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);

        if (!syms_ss->symtab) {
                /*
                 * If the vmlinux is stripped, fail so we will fall back
                 * to using kallsyms. The vmlinux runtime symbols aren't
                 * of much use.
                 */
                if (dso->kernel)
                        return err;
        } else  {
                err = dso__load_sym_internal(dso, map, syms_ss, runtime_ss,
                                             kmodule, 0);
                if (err < 0)
                        return err;
                nr = err;
        }

        if (syms_ss->dynsym) {
                err = dso__load_sym_internal(dso, map, syms_ss, runtime_ss,
                                             kmodule, 1);
                if (err < 0)
                        return err;
                err += nr;
        }

        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;
}

enum dso_type dso__type_fd(int fd)
{
        enum dso_type dso_type = DSO__TYPE_UNKNOWN;
        GElf_Ehdr ehdr;
        Elf_Kind ek;
        Elf *elf;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (elf == NULL)
                goto out;

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

        if (gelf_getclass(elf) == ELFCLASS64) {
                dso_type = DSO__TYPE_64BIT;
                goto out_end;
        }

        if (gelf_getehdr(elf, &ehdr) == NULL)
                goto out_end;

        if (ehdr.e_machine == EM_X86_64)
                dso_type = DSO__TYPE_X32BIT;
        else
                dso_type = DSO__TYPE_32BIT;
out_end:
        elf_end(elf);
out:
        return dso_type;
}

static int copy_bytes(int from, off_t from_offs, int to, off_t to_offs, u64 len)
{
        ssize_t r;
        size_t n;
        int err = -1;
        char *buf = malloc(page_size);

        if (buf == NULL)
                return -1;

        if (lseek(to, to_offs, SEEK_SET) != to_offs)
                goto out;

        if (lseek(from, from_offs, SEEK_SET) != from_offs)
                goto out;

        while (len) {
                n = page_size;
                if (len < n)
                        n = len;
                /* Use read because mmap won't work on proc files */
                r = read(from, buf, n);
                if (r < 0)
                        goto out;
                if (!r)
                        break;
                n = r;
                r = write(to, buf, n);
                if (r < 0)
                        goto out;
                if ((size_t)r != n)
                        goto out;
                len -= n;
        }

        err = 0;
out:
        free(buf);
        return err;
}

struct kcore {
        int fd;
        int elfclass;
        Elf *elf;
        GElf_Ehdr ehdr;
};

static int kcore__open(struct kcore *kcore, const char *filename)
{
        GElf_Ehdr *ehdr;

        kcore->fd = open(filename, O_RDONLY);
        if (kcore->fd == -1)
                return -1;

        kcore->elf = elf_begin(kcore->fd, ELF_C_READ, NULL);
        if (!kcore->elf)
                goto out_close;

        kcore->elfclass = gelf_getclass(kcore->elf);
        if (kcore->elfclass == ELFCLASSNONE)
                goto out_end;

        ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);
        if (!ehdr)
                goto out_end;

        return 0;

out_end:
        elf_end(kcore->elf);
out_close:
        close(kcore->fd);
        return -1;
}

static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
                       bool temp)
{
        kcore->elfclass = elfclass;

        if (temp)
                kcore->fd = mkstemp(filename);
        else
                kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);
        if (kcore->fd == -1)
                return -1;

        kcore->elf = elf_begin(kcore->fd, ELF_C_WRITE, NULL);
        if (!kcore->elf)
                goto out_close;

        if (!gelf_newehdr(kcore->elf, elfclass))
                goto out_end;

        memset(&kcore->ehdr, 0, sizeof(GElf_Ehdr));

        return 0;

out_end:
        elf_end(kcore->elf);
out_close:
        close(kcore->fd);
        unlink(filename);
        return -1;
}

static void kcore__close(struct kcore *kcore)
{
        elf_end(kcore->elf);
        close(kcore->fd);
}

static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)
{
        GElf_Ehdr *ehdr = &to->ehdr;
        GElf_Ehdr *kehdr = &from->ehdr;

        memcpy(ehdr->e_ident, kehdr->e_ident, EI_NIDENT);
        ehdr->e_type      = kehdr->e_type;
        ehdr->e_machine   = kehdr->e_machine;
        ehdr->e_version   = kehdr->e_version;
        ehdr->e_entry     = 0;
        ehdr->e_shoff     = 0;
        ehdr->e_flags     = kehdr->e_flags;
        ehdr->e_phnum     = count;
        ehdr->e_shentsize = 0;
        ehdr->e_shnum     = 0;
        ehdr->e_shstrndx  = 0;

        if (from->elfclass == ELFCLASS32) {
                ehdr->e_phoff     = sizeof(Elf32_Ehdr);
                ehdr->e_ehsize    = sizeof(Elf32_Ehdr);
                ehdr->e_phentsize = sizeof(Elf32_Phdr);
        } else {
                ehdr->e_phoff     = sizeof(Elf64_Ehdr);
                ehdr->e_ehsize    = sizeof(Elf64_Ehdr);
                ehdr->e_phentsize = sizeof(Elf64_Phdr);
        }

        if (!gelf_update_ehdr(to->elf, ehdr))
                return -1;

        if (!gelf_newphdr(to->elf, count))
                return -1;

        return 0;
}

static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,
                           u64 addr, u64 len)
{
        GElf_Phdr phdr = {
                .p_type         = PT_LOAD,
                .p_flags        = PF_R | PF_W | PF_X,
                .p_offset       = offset,
                .p_vaddr        = addr,
                .p_paddr        = 0,
                .p_filesz       = len,
                .p_memsz        = len,
                .p_align        = page_size,
        };

        if (!gelf_update_phdr(kcore->elf, idx, &phdr))
                return -1;

        return 0;
}

static off_t kcore__write(struct kcore *kcore)
{
        return elf_update(kcore->elf, ELF_C_WRITE);
}

struct phdr_data {
        off_t offset;
        off_t rel;
        u64 addr;
        u64 len;
        struct list_head node;
        struct phdr_data *remaps;
};

struct sym_data {
        u64 addr;
        struct list_head node;
};

struct kcore_copy_info {
        u64 stext;
        u64 etext;
        u64 first_symbol;
        u64 last_symbol;
        u64 first_module;
        u64 first_module_symbol;
        u64 last_module_symbol;
        size_t phnum;
        struct list_head phdrs;
        struct list_head syms;
};

#define kcore_copy__for_each_phdr(k, p) \
        list_for_each_entry((p), &(k)->phdrs, node)

static struct phdr_data *phdr_data__new(u64 addr, u64 len, off_t offset)
{
        struct phdr_data *p = zalloc(sizeof(*p));

        if (p) {
                p->addr   = addr;
                p->len    = len;
                p->offset = offset;
        }

        return p;
}

static struct phdr_data *kcore_copy_info__addnew(struct kcore_copy_info *kci,
                                                 u64 addr, u64 len,
                                                 off_t offset)
{
        struct phdr_data *p = phdr_data__new(addr, len, offset);

        if (p)
                list_add_tail(&p->node, &kci->phdrs);

        return p;
}

static void kcore_copy__free_phdrs(struct kcore_copy_info *kci)
{
        struct phdr_data *p, *tmp;

        list_for_each_entry_safe(p, tmp, &kci->phdrs, node) {
                list_del_init(&p->node);
                free(p);
        }
}

static struct sym_data *kcore_copy__new_sym(struct kcore_copy_info *kci,
                                            u64 addr)
{
        struct sym_data *s = zalloc(sizeof(*s));

        if (s) {
                s->addr = addr;
                list_add_tail(&s->node, &kci->syms);
        }

        return s;
}

static void kcore_copy__free_syms(struct kcore_copy_info *kci)
{
        struct sym_data *s, *tmp;

        list_for_each_entry_safe(s, tmp, &kci->syms, node) {
                list_del_init(&s->node);
                free(s);
        }
}

static int kcore_copy__process_kallsyms(void *arg, const char *name, char type,
                                        u64 start)
{
        struct kcore_copy_info *kci = arg;

        if (!kallsyms__is_function(type))
                return 0;

        if (strchr(name, '[')) {
                if (!kci->first_module_symbol || start < kci->first_module_symbol)
                        kci->first_module_symbol = start;
                if (start > kci->last_module_symbol)
                        kci->last_module_symbol = start;
                return 0;
        }

        if (!kci->first_symbol || start < kci->first_symbol)
                kci->first_symbol = start;

        if (!kci->last_symbol || start > kci->last_symbol)
                kci->last_symbol = start;

        if (!strcmp(name, "_stext")) {
                kci->stext = start;
                return 0;
        }

        if (!strcmp(name, "_etext")) {
                kci->etext = start;
                return 0;
        }

        if (is_entry_trampoline(name) && !kcore_copy__new_sym(kci, start))
                return -1;

        return 0;
}

static int kcore_copy__parse_kallsyms(struct kcore_copy_info *kci,
                                      const char *dir)
{
        char kallsyms_filename[PATH_MAX];

        scnprintf(kallsyms_filename, PATH_MAX, "%s/kallsyms", dir);

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

        if (kallsyms__parse(kallsyms_filename, kci,
                            kcore_copy__process_kallsyms) < 0)
                return -1;

        return 0;
}

static int kcore_copy__process_modules(void *arg,
                                       const char *name __maybe_unused,
                                       u64 start, u64 size __maybe_unused)
{
        struct kcore_copy_info *kci = arg;

        if (!kci->first_module || start < kci->first_module)
                kci->first_module = start;

        return 0;
}

static int kcore_copy__parse_modules(struct kcore_copy_info *kci,
                                     const char *dir)
{
        char modules_filename[PATH_MAX];

        scnprintf(modules_filename, PATH_MAX, "%s/modules", dir);

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

        if (modules__parse(modules_filename, kci,
                           kcore_copy__process_modules) < 0)
                return -1;

        return 0;
}

static int kcore_copy__map(struct kcore_copy_info *kci, u64 start, u64 end,
                           u64 pgoff, u64 s, u64 e)
{
        u64 len, offset;

        if (s < start || s >= end)
                return 0;

        offset = (s - start) + pgoff;
        len = e < end ? e - s : end - s;

        return kcore_copy_info__addnew(kci, s, len, offset) ? 0 : -1;
}

static int kcore_copy__read_map(u64 start, u64 len, u64 pgoff, void *data)
{
        struct kcore_copy_info *kci = data;
        u64 end = start + len;
        struct sym_data *sdat;

        if (kcore_copy__map(kci, start, end, pgoff, kci->stext, kci->etext))
                return -1;

        if (kcore_copy__map(kci, start, end, pgoff, kci->first_module,
                            kci->last_module_symbol))
                return -1;

        list_for_each_entry(sdat, &kci->syms, node) {
                u64 s = round_down(sdat->addr, page_size);

                if (kcore_copy__map(kci, start, end, pgoff, s, s + len))
                        return -1;
        }

        return 0;
}

static int kcore_copy__read_maps(struct kcore_copy_info *kci, Elf *elf)
{
        if (elf_read_maps(elf, true, kcore_copy__read_map, kci) < 0)
                return -1;

        return 0;
}

static void kcore_copy__find_remaps(struct kcore_copy_info *kci)
{
        struct phdr_data *p, *k = NULL;
        u64 kend;

        if (!kci->stext)
                return;

        /* Find phdr that corresponds to the kernel map (contains stext) */
        kcore_copy__for_each_phdr(kci, p) {
                u64 pend = p->addr + p->len - 1;

                if (p->addr <= kci->stext && pend >= kci->stext) {
                        k = p;
                        break;
                }
        }

        if (!k)
                return;

        kend = k->offset + k->len;

        /* Find phdrs that remap the kernel */
        kcore_copy__for_each_phdr(kci, p) {
                u64 pend = p->offset + p->len;

                if (p == k)
                        continue;

                if (p->offset >= k->offset && pend <= kend)
                        p->remaps = k;
        }
}

static void kcore_copy__layout(struct kcore_copy_info *kci)
{
        struct phdr_data *p;
        off_t rel = 0;

        kcore_copy__find_remaps(kci);

        kcore_copy__for_each_phdr(kci, p) {
                if (!p->remaps) {
                        p->rel = rel;
                        rel += p->len;
                }
                kci->phnum += 1;
        }

        kcore_copy__for_each_phdr(kci, p) {
                struct phdr_data *k = p->remaps;

                if (k)
                        p->rel = p->offset - k->offset + k->rel;
        }
}

static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
                                 Elf *elf)
{
        if (kcore_copy__parse_kallsyms(kci, dir))
                return -1;

        if (kcore_copy__parse_modules(kci, dir))
                return -1;

        if (kci->stext)
                kci->stext = round_down(kci->stext, page_size);
        else
                kci->stext = round_down(kci->first_symbol, page_size);

        if (kci->etext) {
                kci->etext = round_up(kci->etext, page_size);
        } else if (kci->last_symbol) {
                kci->etext = round_up(kci->last_symbol, page_size);
                kci->etext += page_size;
        }

        if (kci->first_module_symbol &&
            (!kci->first_module || kci->first_module_symbol < kci->first_module))
                kci->first_module = kci->first_module_symbol;

        kci->first_module = round_down(kci->first_module, page_size);

        if (kci->last_module_symbol) {
                kci->last_module_symbol = round_up(kci->last_module_symbol,
                                                   page_size);
                kci->last_module_symbol += page_size;
        }

        if (!kci->stext || !kci->etext)
                return -1;

        if (kci->first_module && !kci->last_module_symbol)
                return -1;

        if (kcore_copy__read_maps(kci, elf))
                return -1;

        kcore_copy__layout(kci);

        return 0;
}

static int kcore_copy__copy_file(const char *from_dir, const char *to_dir,
                                 const char *name)
{
        char from_filename[PATH_MAX];
        char to_filename[PATH_MAX];

        scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
        scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);

        return copyfile_mode(from_filename, to_filename, 0400);
}

static int kcore_copy__unlink(const char *dir, const char *name)
{
        char filename[PATH_MAX];

        scnprintf(filename, PATH_MAX, "%s/%s", dir, name);

        return unlink(filename);
}

static int kcore_copy__compare_fds(int from, int to)
{
        char *buf_from;
        char *buf_to;
        ssize_t ret;
        size_t len;
        int err = -1;

        buf_from = malloc(page_size);
        buf_to = malloc(page_size);
        if (!buf_from || !buf_to)
                goto out;

        while (1) {
                /* Use read because mmap won't work on proc files */
                ret = read(from, buf_from, page_size);
                if (ret < 0)
                        goto out;

                if (!ret)
                        break;

                len = ret;

                if (readn(to, buf_to, len) != (int)len)
                        goto out;

                if (memcmp(buf_from, buf_to, len))
                        goto out;
        }

        err = 0;
out:
        free(buf_to);
        free(buf_from);
        return err;
}

static int kcore_copy__compare_files(const char *from_filename,
                                     const char *to_filename)
{
        int from, to, err = -1;

        from = open(from_filename, O_RDONLY);
        if (from < 0)
                return -1;

        to = open(to_filename, O_RDONLY);
        if (to < 0)
                goto out_close_from;

        err = kcore_copy__compare_fds(from, to);

        close(to);
out_close_from:
        close(from);
        return err;
}

static int kcore_copy__compare_file(const char *from_dir, const char *to_dir,
                                    const char *name)
{
        char from_filename[PATH_MAX];
        char to_filename[PATH_MAX];

        scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
        scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);

        return kcore_copy__compare_files(from_filename, to_filename);
}

/**
 * kcore_copy - copy kallsyms, modules and kcore from one directory to another.
 * @from_dir: from directory
 * @to_dir: to directory
 *
 * This function copies kallsyms, modules and kcore files from one directory to
 * another.  kallsyms and modules are copied entirely.  Only code segments are
 * copied from kcore.  It is assumed that two segments suffice: one for the
 * kernel proper and one for all the modules.  The code segments are determined
 * from kallsyms and modules files.  The kernel map starts at _stext or the
 * lowest function symbol, and ends at _etext or the highest function symbol.
 * The module map starts at the lowest module address and ends at the highest
 * module symbol.  Start addresses are rounded down to the nearest page.  End
 * addresses are rounded up to the nearest page.  An extra page is added to the
 * highest kernel symbol and highest module symbol to, hopefully, encompass that
 * symbol too.  Because it contains only code sections, the resulting kcore is
 * unusual.  One significant peculiarity is that the mapping (start -> pgoff)
 * is not the same for the kernel map and the modules map.  That happens because
 * the data is copied adjacently whereas the original kcore has gaps.  Finally,
 * kallsyms and modules files are compared with their copies to check that
 * modules have not been loaded or unloaded while the copies were taking place.
 *
 * Return: %0 on success, %-1 on failure.
 */
int kcore_copy(const char *from_dir, const char *to_dir)
{
        struct kcore kcore;
        struct kcore extract;
        int idx = 0, err = -1;
        off_t offset, sz;
        struct kcore_copy_info kci = { .stext = 0, };
        char kcore_filename[PATH_MAX];
        char extract_filename[PATH_MAX];
        struct phdr_data *p;

        INIT_LIST_HEAD(&kci.phdrs);
        INIT_LIST_HEAD(&kci.syms);

        if (kcore_copy__copy_file(from_dir, to_dir, "kallsyms"))
                return -1;

        if (kcore_copy__copy_file(from_dir, to_dir, "modules"))
                goto out_unlink_kallsyms;

        scnprintf(kcore_filename, PATH_MAX, "%s/kcore", from_dir);
        scnprintf(extract_filename, PATH_MAX, "%s/kcore", to_dir);

        if (kcore__open(&kcore, kcore_filename))
                goto out_unlink_modules;

        if (kcore_copy__calc_maps(&kci, from_dir, kcore.elf))
                goto out_kcore_close;

        if (kcore__init(&extract, extract_filename, kcore.elfclass, false))
                goto out_kcore_close;

        if (kcore__copy_hdr(&kcore, &extract, kci.phnum))
                goto out_extract_close;

        offset = gelf_fsize(extract.elf, ELF_T_EHDR, 1, EV_CURRENT) +
                 gelf_fsize(extract.elf, ELF_T_PHDR, kci.phnum, EV_CURRENT);
        offset = round_up(offset, page_size);

        kcore_copy__for_each_phdr(&kci, p) {
                off_t offs = p->rel + offset;

                if (kcore__add_phdr(&extract, idx++, offs, p->addr, p->len))
                        goto out_extract_close;
        }

        sz = kcore__write(&extract);
        if (sz < 0 || sz > offset)
                goto out_extract_close;

        kcore_copy__for_each_phdr(&kci, p) {
                off_t offs = p->rel + offset;

                if (p->remaps)
                        continue;
                if (copy_bytes(kcore.fd, p->offset, extract.fd, offs, p->len))
                        goto out_extract_close;
        }

        if (kcore_copy__compare_file(from_dir, to_dir, "modules"))
                goto out_extract_close;

        if (kcore_copy__compare_file(from_dir, to_dir, "kallsyms"))
                goto out_extract_close;

        err = 0;

out_extract_close:
        kcore__close(&extract);
        if (err)
                unlink(extract_filename);
out_kcore_close:
        kcore__close(&kcore);
out_unlink_modules:
        if (err)
                kcore_copy__unlink(to_dir, "modules");
out_unlink_kallsyms:
        if (err)
                kcore_copy__unlink(to_dir, "kallsyms");

        kcore_copy__free_phdrs(&kci);
        kcore_copy__free_syms(&kci);

        return err;
}

int kcore_extract__create(struct kcore_extract *kce)
{
        struct kcore kcore;
        struct kcore extract;
        size_t count = 1;
        int idx = 0, err = -1;
        off_t offset = page_size, sz;

        if (kcore__open(&kcore, kce->kcore_filename))
                return -1;

        strcpy(kce->extract_filename, PERF_KCORE_EXTRACT);
        if (kcore__init(&extract, kce->extract_filename, kcore.elfclass, true))
                goto out_kcore_close;

        if (kcore__copy_hdr(&kcore, &extract, count))
                goto out_extract_close;

        if (kcore__add_phdr(&extract, idx, offset, kce->addr, kce->len))
                goto out_extract_close;

        sz = kcore__write(&extract);
        if (sz < 0 || sz > offset)
                goto out_extract_close;

        if (copy_bytes(kcore.fd, kce->offs, extract.fd, offset, kce->len))
                goto out_extract_close;

        err = 0;

out_extract_close:
        kcore__close(&extract);
        if (err)
                unlink(kce->extract_filename);
out_kcore_close:
        kcore__close(&kcore);

        return err;
}

void kcore_extract__delete(struct kcore_extract *kce)
{
        unlink(kce->extract_filename);
}

#ifdef HAVE_GELF_GETNOTE_SUPPORT

static void sdt_adjust_loc(struct sdt_note *tmp, GElf_Addr base_off)
{
        if (!base_off)
                return;

        if (tmp->bit32)
                tmp->addr.a32[SDT_NOTE_IDX_LOC] =
                        tmp->addr.a32[SDT_NOTE_IDX_LOC] + base_off -
                        tmp->addr.a32[SDT_NOTE_IDX_BASE];
        else
                tmp->addr.a64[SDT_NOTE_IDX_LOC] =
                        tmp->addr.a64[SDT_NOTE_IDX_LOC] + base_off -
                        tmp->addr.a64[SDT_NOTE_IDX_BASE];
}

static void sdt_adjust_refctr(struct sdt_note *tmp, GElf_Addr base_addr,
                              GElf_Addr base_off)
{
        if (!base_off)
                return;

        if (tmp->bit32 && tmp->addr.a32[SDT_NOTE_IDX_REFCTR])
                tmp->addr.a32[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
        else if (tmp->addr.a64[SDT_NOTE_IDX_REFCTR])
                tmp->addr.a64[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
}

/**
 * populate_sdt_note : Parse raw data and identify SDT note
 * @elf: elf of the opened file
 * @data: raw data of a section with description offset applied
 * @len: note description size
 * @type: type of the note
 * @sdt_notes: List to add the SDT note
 *
 * Responsible for parsing the @data in section .note.stapsdt in @elf and
 * if its an SDT note, it appends to @sdt_notes list.
 */
static int populate_sdt_note(Elf **elf, const char *data, size_t len,
                             struct list_head *sdt_notes)
{
        const char *provider, *name, *args;
        struct sdt_note *tmp = NULL;
        GElf_Ehdr ehdr;
        GElf_Shdr shdr;
        int ret = -EINVAL;

        union {
                Elf64_Addr a64[NR_ADDR];
                Elf32_Addr a32[NR_ADDR];
        } buf;

        Elf_Data dst = {
                .d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,
                .d_size = gelf_fsize((*elf), ELF_T_ADDR, NR_ADDR, EV_CURRENT),
                .d_off = 0, .d_align = 0
        };
        Elf_Data src = {
                .d_buf = (void *) data, .d_type = ELF_T_ADDR,
                .d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0,
                .d_align = 0
        };

        tmp = (struct sdt_note *)calloc(1, sizeof(struct sdt_note));
        if (!tmp) {
                ret = -ENOMEM;
                goto out_err;
        }

        INIT_LIST_HEAD(&tmp->note_list);

        if (len < dst.d_size + 3)
                goto out_free_note;

        /* Translation from file representation to memory representation */
        if (gelf_xlatetom(*elf, &dst, &src,
                          elf_getident(*elf, NULL)[EI_DATA]) == NULL) {
                pr_err("gelf_xlatetom : %s\n", elf_errmsg(-1));
                goto out_free_note;
        }

        /* Populate the fields of sdt_note */
        provider = data + dst.d_size;

        name = (const char *)memchr(provider, '\0', data + len - provider);
        if (name++ == NULL)
                goto out_free_note;

        tmp->provider = strdup(provider);
        if (!tmp->provider) {
                ret = -ENOMEM;
                goto out_free_note;
        }
        tmp->name = strdup(name);
        if (!tmp->name) {
                ret = -ENOMEM;
                goto out_free_prov;
        }

        args = memchr(name, '\0', data + len - name);

        /*
         * There is no argument if:
         * - We reached the end of the note;
         * - There is not enough room to hold a potential string;
         * - The argument string is empty or just contains ':'.
         */
        if (args == NULL || data + len - args < 2 ||
                args[1] == ':' || args[1] == '\0')
                tmp->args = NULL;
        else {
                tmp->args = strdup(++args);
                if (!tmp->args) {
                        ret = -ENOMEM;
                        goto out_free_name;
                }
        }

        if (gelf_getclass(*elf) == ELFCLASS32) {
                memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
                tmp->bit32 = true;
        } else {
                memcpy(&tmp->addr, &buf, 3 * sizeof(Elf64_Addr));
                tmp->bit32 = false;
        }

        if (!gelf_getehdr(*elf, &ehdr)) {
                pr_debug("%s : cannot get elf header.\n", __func__);
                ret = -EBADF;
                goto out_free_args;
        }

        /* Adjust the prelink effect :
         * Find out the .stapsdt.base section.
         * This scn will help us to handle prelinking (if present).
         * Compare the retrieved file offset of the base section with the
         * base address in the description of the SDT note. If its different,
         * then accordingly, adjust the note location.
         */
        if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL))
                sdt_adjust_loc(tmp, shdr.sh_offset);

        /* Adjust reference counter offset */
        if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_PROBES_SCN, NULL))
                sdt_adjust_refctr(tmp, shdr.sh_addr, shdr.sh_offset);

        list_add_tail(&tmp->note_list, sdt_notes);
        return 0;

out_free_args:
        zfree(&tmp->args);
out_free_name:
        zfree(&tmp->name);
out_free_prov:
        zfree(&tmp->provider);
out_free_note:
        free(tmp);
out_err:
        return ret;
}

/**
 * construct_sdt_notes_list : constructs a list of SDT notes
 * @elf : elf to look into
 * @sdt_notes : empty list_head
 *
 * Scans the sections in 'elf' for the section
 * .note.stapsdt. It, then calls populate_sdt_note to find
 * out the SDT events and populates the 'sdt_notes'.
 */
static int construct_sdt_notes_list(Elf *elf, struct list_head *sdt_notes)
{
        GElf_Ehdr ehdr;
        Elf_Scn *scn = NULL;
        Elf_Data *data;
        GElf_Shdr shdr;
        size_t shstrndx, next;
        GElf_Nhdr nhdr;
        size_t name_off, desc_off, offset;
        int ret = 0;

        if (gelf_getehdr(elf, &ehdr) == NULL) {
                ret = -EBADF;
                goto out_ret;
        }
        if (elf_getshdrstrndx(elf, &shstrndx) != 0) {
                ret = -EBADF;
                goto out_ret;
        }

        /* Look for the required section */
        scn = elf_section_by_name(elf, &ehdr, &shdr, SDT_NOTE_SCN, NULL);
        if (!scn) {
                ret = -ENOENT;
                goto out_ret;
        }

        if ((shdr.sh_type != SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC)) {
                ret = -ENOENT;
                goto out_ret;
        }

        data = elf_getdata(scn, NULL);

        /* Get the SDT notes */
        for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off,
                                              &desc_off)) > 0; offset = next) {
                if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) &&
                    !memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
                            sizeof(SDT_NOTE_NAME))) {
                        /* Check the type of the note */
                        if (nhdr.n_type != SDT_NOTE_TYPE)
                                goto out_ret;

                        ret = populate_sdt_note(&elf, ((data->d_buf) + desc_off),
                                                nhdr.n_descsz, sdt_notes);
                        if (ret < 0)
                                goto out_ret;
                }
        }
        if (list_empty(sdt_notes))
                ret = -ENOENT;

out_ret:
        return ret;
}

/**
 * get_sdt_note_list : Wrapper to construct a list of sdt notes
 * @head : empty list_head
 * @target : file to find SDT notes from
 *
 * This opens the file, initializes
 * the ELF and then calls construct_sdt_notes_list.
 */
int get_sdt_note_list(struct list_head *head, const char *target)
{
        Elf *elf;
        int fd, ret;

        fd = open(target, O_RDONLY);
        if (fd < 0)
                return -EBADF;

        elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
        if (!elf) {
                ret = -EBADF;
                goto out_close;
        }
        ret = construct_sdt_notes_list(elf, head);
        elf_end(elf);
out_close:
        close(fd);
        return ret;
}

/**
 * cleanup_sdt_note_list : free the sdt notes' list
 * @sdt_notes: sdt notes' list
 *
 * Free up the SDT notes in @sdt_notes.
 * Returns the number of SDT notes free'd.
 */
int cleanup_sdt_note_list(struct list_head *sdt_notes)
{
        struct sdt_note *tmp, *pos;
        int nr_free = 0;

        list_for_each_entry_safe(pos, tmp, sdt_notes, note_list) {
                list_del_init(&pos->note_list);
                zfree(&pos->args);
                zfree(&pos->name);
                zfree(&pos->provider);
                free(pos);
                nr_free++;
        }
        return nr_free;
}

/**
 * sdt_notes__get_count: Counts the number of sdt events
 * @start: list_head to sdt_notes list
 *
 * Returns the number of SDT notes in a list
 */
int sdt_notes__get_count(struct list_head *start)
{
        struct sdt_note *sdt_ptr;
        int count = 0;

        list_for_each_entry(sdt_ptr, start, note_list)
                count++;
        return count;
}
#endif

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