sortextable.h

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/*
 * sortextable.h
 *
 * Copyright 2011 - 2012 Cavium, Inc.
 *
 * Some of this code was taken out of recordmcount.h written by:
 *
 * Copyright 2009 John F. Reiser <[email protected]>.  All rights reserved.
 * Copyright 2010 Steven Rostedt <[email protected]>, Red Hat Inc.
 *
 *
 * Licensed under the GNU General Public License, version 2 (GPLv2).
 */

#undef extable_ent_size
#undef compare_extable
#undef do_func
#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
#undef Elf_Sym
#undef ELF_R_SYM
#undef Elf_r_sym
#undef ELF_R_INFO
#undef Elf_r_info
#undef ELF_ST_BIND
#undef ELF_ST_TYPE
#undef fn_ELF_R_SYM
#undef fn_ELF_R_INFO
#undef uint_t
#undef _r
#undef _w

#ifdef SORTEXTABLE_64
# define extable_ent_size   16
# define compare_extable    compare_extable_64
# define do_func        do64
# define Elf_Addr       Elf64_Addr
# define Elf_Ehdr       Elf64_Ehdr
# define Elf_Shdr       Elf64_Shdr
# define Elf_Rel        Elf64_Rel
# define Elf_Rela       Elf64_Rela
# define Elf_Sym        Elf64_Sym
# define ELF_R_SYM      ELF64_R_SYM
# define Elf_r_sym      Elf64_r_sym
# define ELF_R_INFO     ELF64_R_INFO
# define Elf_r_info     Elf64_r_info
# define ELF_ST_BIND        ELF64_ST_BIND
# define ELF_ST_TYPE        ELF64_ST_TYPE
# define fn_ELF_R_SYM       fn_ELF64_R_SYM
# define fn_ELF_R_INFO      fn_ELF64_R_INFO
# define uint_t         uint64_t
# define _r         r8
# define _w         w8
#else
# define extable_ent_size   8
# define compare_extable    compare_extable_32
# define do_func        do32
# define Elf_Addr       Elf32_Addr
# define Elf_Ehdr       Elf32_Ehdr
# define Elf_Shdr       Elf32_Shdr
# define Elf_Rel        Elf32_Rel
# define Elf_Rela       Elf32_Rela
# define Elf_Sym        Elf32_Sym
# define ELF_R_SYM      ELF32_R_SYM
# define Elf_r_sym      Elf32_r_sym
# define ELF_R_INFO     ELF32_R_INFO
# define Elf_r_info     Elf32_r_info
# define ELF_ST_BIND        ELF32_ST_BIND
# define ELF_ST_TYPE        ELF32_ST_TYPE
# define fn_ELF_R_SYM       fn_ELF32_R_SYM
# define fn_ELF_R_INFO      fn_ELF32_R_INFO
# define uint_t         uint32_t
# define _r         r
# define _w         w
#endif

static int compare_extable(const void *a, const void *b)
{
    Elf_Addr av = _r(a);
    Elf_Addr bv = _r(b);

    if (av < bv)
        return -1;
    if (av > bv)
        return 1;
    return 0;
}

static void
do_func(Elf_Ehdr *ehdr, char const *const fname, table_sort_t custom_sort)
{
    Elf_Shdr *shdr;
    Elf_Shdr *shstrtab_sec;
    Elf_Shdr *strtab_sec = NULL;
    Elf_Shdr *symtab_sec = NULL;
    Elf_Shdr *extab_sec = NULL;
    Elf_Sym *sym;
    Elf_Sym *sort_needed_sym;
    Elf_Shdr *sort_needed_sec;
    Elf_Rel *relocs = NULL;
    int relocs_size;
    uint32_t *sort_done_location;
    const char *secstrtab;
    const char *strtab;
    char *extab_image;
    int extab_index = 0;
    int i;
    int idx;

    shdr = (Elf_Shdr *)((char *)ehdr + _r(&ehdr->e_shoff));
    shstrtab_sec = shdr + r2(&ehdr->e_shstrndx);
    secstrtab = (const char *)ehdr + _r(&shstrtab_sec->sh_offset);
    for (i = 0; i < r2(&ehdr->e_shnum); i++) {
        idx = r(&shdr[i].sh_name);
        if (strcmp(secstrtab + idx, "__ex_table") == 0) {
            extab_sec = shdr + i;
            extab_index = i;
        }
        if ((r(&shdr[i].sh_type) == SHT_REL ||
             r(&shdr[i].sh_type) == SHT_RELA) &&
            r(&shdr[i].sh_info) == extab_index) {
            relocs = (void *)ehdr + _r(&shdr[i].sh_offset);
            relocs_size = _r(&shdr[i].sh_size);
        }
        if (strcmp(secstrtab + idx, ".symtab") == 0)
            symtab_sec = shdr + i;
        if (strcmp(secstrtab + idx, ".strtab") == 0)
            strtab_sec = shdr + i;
    }
    if (strtab_sec == NULL) {
        fprintf(stderr, "no .strtab in  file: %s\n", fname);
        fail_file();
    }
    if (symtab_sec == NULL) {
        fprintf(stderr, "no .symtab in  file: %s\n", fname);
        fail_file();
    }
    if (extab_sec == NULL) {
        fprintf(stderr, "no __ex_table in  file: %s\n", fname);
        fail_file();
    }
    strtab = (const char *)ehdr + _r(&strtab_sec->sh_offset);

    extab_image = (void *)ehdr + _r(&extab_sec->sh_offset);

    if (custom_sort) {
        custom_sort(extab_image, _r(&extab_sec->sh_size));
    } else {
        int num_entries = _r(&extab_sec->sh_size) / extable_ent_size;
        qsort(extab_image, num_entries,
              extable_ent_size, compare_extable);
    }
    /* If there were relocations, we no longer need them. */
    if (relocs)
        memset(relocs, 0, relocs_size);

    /* find main_extable_sort_needed */
    sort_needed_sym = NULL;
    for (i = 0; i < _r(&symtab_sec->sh_size) / sizeof(Elf_Sym); i++) {
        sym = (void *)ehdr + _r(&symtab_sec->sh_offset);
        sym += i;
        if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT)
            continue;
        idx = r(&sym->st_name);
        if (strcmp(strtab + idx, "main_extable_sort_needed") == 0) {
            sort_needed_sym = sym;
            break;
        }
    }
    if (sort_needed_sym == NULL) {
        fprintf(stderr,
            "no main_extable_sort_needed symbol in  file: %s\n",
            fname);
        fail_file();
    }
    sort_needed_sec = &shdr[r2(&sort_needed_sym->st_shndx)];
    sort_done_location = (void *)ehdr +
        _r(&sort_needed_sec->sh_offset) +
        _r(&sort_needed_sym->st_value) -
        _r(&sort_needed_sec->sh_addr);

#if 1
    printf("sort done marker at %lx\n",
           (unsigned long)((char *)sort_done_location - (char *)ehdr));
#endif
    /* We sorted it, clear the flag. */
    w(0, sort_done_location);
}