eresi_Addr elfops_add(elf_bf_exec_t *ee, eresi_Addr delta)
{
elf_bf_link_map_t *l = &(ee->ee_lm);
eresi_Addr start = l->lm_next_reloc;
//we assume that correct value is in scratch space, just do addition
set_next_reloc(l, R_X86_64_64, symtab_get_index(ee->ee_tape_ptr),
symtab_get_value_addr(ee->ee_tape_ptr), delta);
eresi_Addr setupi, copyi;
elf_bf_Rela setup, copy;
//update tape
setupi = set_next_reloc(l, 0, 0, 0, 0);
//copy new value back to tape
copyi = set_next_reloc(l, R_X86_64_COPY, symtab_get_index(ee->ee_tape_copy),
0, 0);
//go back at actually setup first entry
reloc_get_reloc_entry(l, setupi, &setup);
reloc_get_reloc_entry(l, copyi, ©);
//setup next entry so it knows where tape pointer is
reloc_set_rela(&setup, R_X86_64_64, symtab_get_index(ee->ee_ptr_tape_ptr),
reloc_get_offset_addr(©), 0);
return l->lm_next_reloc - start;
}
eresi_Addr set_next_reloc(elf_bf_link_map_t *l, Elf64_Word type, Elf64_Word sym, Elf64_Addr off, Elf64_Addr val)
{
if(l->lm_allocated) {
elf_bf_Rela r;
reloc_get_reloc_entry(l, l->lm_next_reloc, &r);
reloc_set_rela(&r, type, sym, off, val);
} //otherwise just count
l->lm_next_reloc++;
return l->lm_next_reloc - 1;
}
eresi_Addr elfops_branch_start(elf_bf_exec_t *ee)
{
elf_bf_link_map_t *l = &(ee->ee_lm);
eresi_Addr start = l->lm_next_reloc;
elfops_prepare_branch(ee);
eresi_Addr firsti;
elf_bf_Rela first, next;
//setup relocation entry that fixes dt_rela to jump past unconditional branch
//we don't know address of next yet, so don't actually set it yet
firsti = set_next_reloc(l, 0, 0, 0, 0);
//setup relocation entry that fixes dt_relasz assuming unconditional branch
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_relasz, ee->ee_dt_relasz_value - (l->lm_next_reloc*sizeof(Elf64_Rela)));
//sets symbol's link addr to (value on tape)
set_next_reloc(l, R_X86_64_COPY, symtab_get_index(ee->ee_tape_copy),
symtab_get_link_addr(ee->ee_lm.lm_ifunc), 0);
//sets end to zero or ifunc, depending on link value of sym1 set earlier
set_next_reloc(l, R_X86_64_64, symtab_get_index(ee->ee_lm.lm_ifunc),
ee->ee_reloc_end,0);
//unconditional branch past ] (if tape is zero)
//update dt_rela (addend to be filled in once ] is known)
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_rela, 0);
//update dt_relasz (addend to be filled in once ] is known)
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_relasz, 0);
//set end to zero to force immediate branch
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_reloc_end, 0);
//fix first entry to it points to last entry
reloc_get_reloc_entry(l, firsti, &first);
reloc_get_reloc_entry(l, l->lm_next_reloc, &next);
reloc_set_rela(&first, R_X86_64_RELATIVE, 0, ee->ee_dt_rela,
reloc_get_addr(&next));
return l->lm_next_reloc - start;
}
eresi_Addr elfops_exit(elf_bf_exec_t *ee)
{
eresi_Addr start;
elf_bf_link_map_t *l = &(ee->ee_lm);
start = l->lm_next_reloc;
//this will end up causing the loader to divide by zero
//if (l->lm_allocated) {
// reloc_set_rela(&r0, R_X86_64_TLSDESC, 0, 0, 0);
// l->lm_next_reloc = index;
//}
// force a branch to run original relocation entrires
// restore PLT stuff
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_jmprel, ee->ee_dt_jmprel_value);
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_pltrelsz, ee->ee_dt_pltrelsz_value);
elfops_prepare_branch(ee);
//restore RELA to point to entry after branch
eresi_Addr relai, bucketi;
elf_bf_Rela rela, bucket;
//don't know all the information we need to set in this yet
relai = set_next_reloc(l, 0, 0, 0, 0);
//fix RELACOUNT accordingly
// should probably calculate the 6
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_relasz,
ee->ee_relasz_orig + 6*sizeof(Elf64_Rela));
//force immediate branch so that we finally process PLT entries
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_reloc_end, 0);
// restore l_buckets
bucketi = set_next_reloc(l, R_X86_64_RELATIVE, 0, get_l_buckets(l->lm_l_s),
ee->ee_dt_gnu_hash);
// now go back at steup relai
reloc_get_reloc_entry(l, relai, &rela);
reloc_get_reloc_entry(l, bucketi, &bucket);
reloc_set_rela(&rela, R_X86_64_RELATIVE, 0, ee->ee_dt_rela,
reloc_get_addr(&bucket));
//restore l->libname->next
set_next_reloc(l, R_X86_64_RELATIVE, 0, get_l_libname_next(l->lm_l_s), 0);
//restore l_direct_opencount
set_next_reloc(l, R_X86_64_RELATIVE, 0, get_l_direct_opencount(l->lm_l_s), 1);
//restore l_prev
set_next_reloc(l, R_X86_64_RELATIVE, 0, get_l_prev(l->lm_l_s), 0);
//restore symtable size to original value TODO
//reloc_set_rela(&r, R_X86_64_RELATIVE, 0, 0, 0);
//restore RELA to point to original dynrel
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_rela,ee->ee_rela_orig);
//restore RELACOUNT or whatever to original value
set_next_reloc(l, R_X86_64_RELATIVE, 0, ee->ee_dt_relasz, ee->ee_relasz_orig);
return l->lm_next_reloc - start;
}
