graphene/LibOS/shim/src/elf/do-rel.h

/* -*- mode:c; c-file-style:"k&r"; c-basic-offset: 4; tab-width:4; indent-tabs-mode:nil; mode:auto-fill; fill-column:78; -*- */
/* vim: set ts=4 sw=4 et tw=78 fo=cqt wm=0: */

/* Copyright (C) 2014 OSCAR lab, Stony Brook University
   This file is part of Graphene Library OS.

   Graphene Library OS is free software: you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   Graphene Library OS is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/*
 * do-rel.c
 *
 * This file contains architecture-independent codes for relocating ELF
 * binaries.
 * Most of the source codes are imported from GNU C library.
 */

#include "dl-machine-x86_64.h"

#define elf_dynamic_do_rel          elf_dynamic_do_rela
#define RELCOUNT_IDX                VERSYMIDX (DT_RELACOUNT)
#define Rel                         Rela
#define elf_machine_rel             elf_machine_rela
#define elf_machine_rel_relative    elf_machine_rela_relative

#ifndef DO_ELF_MACHINE_REL_RELATIVE
# define DO_ELF_MACHINE_REL_RELATIVE(l, relative)           \
    elf_machine_rel_relative (l, relative,                  \
                              (void *) (l->l_addr + relative->r_offset))
#endif

#ifndef VERSYMIDX
# define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
#endif

#ifndef VALIDX
# define VALIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM    \
                      + DT_EXTRANUM + DT_VALTAGIDX (tag))
#endif

#define elf_dynamic_copy_rel        elf_dynamic_copy_rela
#define dt_reloc                    DT_RELA
#define dt_reloc_sz                 DT_RELASZ

/* Perform the relocations in MAP on the running program image as specified
   by RELTAG, SZTAG.  If LAZY is nonzero, this is the first pass on PLT
   relocations; they should be set up to call _dl_runtime_resolve, rather
   than fully resolved now.  */
static void __attribute__((unused))
elf_dynamic_do_rel (struct link_map * l, ElfW(Addr) reladdr, int relsize)
{
    ElfW(Sym) * symtab = (void *) D_PTR (l->l_info[DT_SYMTAB]);
    ElfW(Rel) * r = (void *) reladdr;
    ElfW(Rel) * end = (void *) (reladdr + relsize);
    ElfW(Word) nrelative = l->l_info[RELCOUNT_IDX] == NULL
                           ? 0 : l->l_info[RELCOUNT_IDX]->d_un.d_val;
    /* ElfW(Rel) * relative = r; */
    int nrelsize = relsize / sizeof (ElfW(Rel));
    r = r + (nrelative < nrelsize ? nrelative : nrelsize);

    for (; r < end; ++r)
        elf_machine_rel(l, r, &symtab[ELFW(R_SYM) (r->r_info)],
                        (void *) (l->l_addr + r->r_offset));
}

static void inline elf_copy_rel (struct link_map * l1, struct link_map * l2,
                                 int reloc, int reloc_sz)
{
    if (!l1->l_info[reloc] || !l2->l_info[reloc])
        return;

    ElfW(Sym) *  symtab1 = (void *) D_PTR (l1->l_info[DT_SYMTAB]);
    const char * strtab1 = (void *) D_PTR (l1->l_info[DT_STRTAB]);
    ElfW(Sym) *  symtab2 = (void *) D_PTR (l2->l_info[DT_SYMTAB]);
    const char * strtab2 = (void *) D_PTR (l2->l_info[DT_STRTAB]);

    ElfW(Rel) * r1, * r2, * end1, * end2;

    r1 = (ElfW(Rel) *) D_PTR (l1->l_info[reloc]);
    end1 = ((void *) r1 + l1->l_info[reloc_sz]->d_un.d_val);
    r1 += l1->l_info[RELCOUNT_IDX] ? l1->l_info[RELCOUNT_IDX]->d_un.d_val : 0;

    r2 = (ElfW(Rel) *) D_PTR (l2->l_info[reloc]);
    end2 = ((void *) r2 + l2->l_info[reloc_sz]->d_un.d_val);
    r2 += l2->l_info[RELCOUNT_IDX] ? l2->l_info[RELCOUNT_IDX]->d_un.d_val : 0;

    for (; r1 < end1 && r2 < end2; ++r1, ++r2) {
        debug("copy %s from %s\n",
              strtab1 + symtab1[ELFW(R_SYM) (r1->r_info)].st_name,
              strtab2 + symtab2[ELFW(R_SYM) (r2->r_info)].st_name);

        r1->r_info = r2->r_info;

        ElfW(Addr) * reladdr1 = (void *) l1->l_addr + r1->r_offset;
        ElfW(Addr) * reladdr2 = (void *) l2->l_addr + r2->r_offset;

        if (*reladdr1 != *reladdr2)
            *reladdr1 = *reladdr2;
    }
}

/* copy the relocation done by PAL */
static void __attribute__((unused))
elf_dynamic_copy_rel (struct link_map * l1, struct link_map * l2)
{
    elf_copy_rel(l1, l2, dt_reloc, dt_reloc_sz);
    elf_copy_rel(l1, l2, DT_JMPREL, DT_PLTRELSZ);
}

#undef elf_dynamic_do_rel
#undef Rel
#undef elf_machine_rel
#undef elf_machine_rel_relative
#undef DO_ELF_MACHINE_REL_RELATIVE
#undef RELCOUNT_IDX
#undef elf_dynamic_copy_rel
#undef dt_reloc
#undef dt_reloc_sz