/*      $NetBSD: libdwarf_reloc.c,v 1.7 2024/03/31 03:20:38 christos Exp $      */

/*-
* Copyright (c) 2010 Kai Wang
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include "_libdwarf.h"

__RCSID("$NetBSD: libdwarf_reloc.c,v 1.7 2024/03/31 03:20:38 christos Exp $");
ELFTC_VCSID("Id: libdwarf_reloc.c 3741 2019-06-07 06:32:01Z jkoshy");

Dwarf_Unsigned
_dwarf_get_reloc_type(Dwarf_P_Debug dbg, int is64)
{

       assert(dbg != NULL);

       switch (dbg->dbgp_isa) {
       case DW_ISA_AARCH64:
               return (is64 ? R_AARCH64_ABS64 : R_AARCH64_ABS32);
       case DW_ISA_X86:
               return (R_386_32);
       case DW_ISA_X86_64:
               return (is64 ? R_X86_64_64 : R_X86_64_32);
       case DW_ISA_SPARC:
               return (is64 ? R_SPARC_UA64 : R_SPARC_UA32);
       case DW_ISA_PPC:
               return (is64 ? R_PPC64_ADDR64 : R_PPC_ADDR32);
       case DW_ISA_ARM:
               return (R_ARM_ABS32);
       case DW_ISA_MIPS:
               return (is64 ? R_MIPS_64 : R_MIPS_32);
       case DW_ISA_RISCV:
               return (is64 ? R_RISCV_64 : R_RISCV_32);
       case DW_ISA_IA64:
               return (is64 ? R_IA_64_DIR64LSB : R_IA_64_DIR32LSB);
       default:
               break;
       }
       return (0);             /* NOT REACHED */
}

int
_dwarf_get_reloc_size(Dwarf_Debug dbg, Dwarf_Unsigned rel_type)
{

       switch (dbg->dbg_machine) {
       case EM_NONE:
               break;
       case EM_AARCH64:
               if (rel_type == R_AARCH64_ABS32)
                       return (4);
               else if (rel_type == R_AARCH64_ABS64)
                       return (8);
               break;
       case EM_ARM:
               if (rel_type == R_ARM_ABS32)
                       return (4);
               break;
       case EM_386:
       case EM_IAMCU:
               if (rel_type == R_386_32)
                       return (4);
               break;
       case EM_X86_64:
               if (rel_type == R_X86_64_32)
                       return (4);
               else if (rel_type == R_X86_64_64)
                       return (8);
               break;
       case EM_SPARC:
               if (rel_type == R_SPARC_UA32)
                       return (4);
               else if (rel_type == R_SPARC_UA64)
                       return (8);
               break;
       case EM_PPC:
               if (rel_type == R_PPC_ADDR32)
                       return (4);
               break;
       case EM_PPC64:
               if (rel_type == R_PPC_ADDR32)
                       return (4);
               else if (rel_type == R_PPC64_ADDR64)
                       return (8);
               break;
       case EM_MIPS:
               if (rel_type == R_MIPS_32)
                       return (4);
               else if (rel_type == R_MIPS_64)
                       return (8);
               break;
       case EM_RISCV:
               if (rel_type == R_RISCV_32)
                       return (4);
               else if (rel_type == R_RISCV_64)
                       return (8);
               break;
       case EM_IA_64:
               if (rel_type == R_IA_64_SECREL32LSB)
                       return (4);
               else if (rel_type == R_IA_64_DIR64LSB)
                       return (8);
               break;
       default:
               break;
       }

       /* unknown relocation. */
       return (0);
}

int
_dwarf_reloc_section_init(Dwarf_P_Debug dbg, Dwarf_Rel_Section *drsp,
   Dwarf_P_Section ref, Dwarf_Error *error)
{
       Dwarf_Rel_Section drs;
       char name[128];
       int pseudo;

       assert(dbg != NULL && drsp != NULL && ref != NULL);

       if ((drs = calloc(1, sizeof(struct _Dwarf_Rel_Section))) == NULL) {
               DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
               return (DW_DLE_MEMORY);
       }

       drs->drs_ref = ref;

       /*
        * FIXME The logic here is most likely wrong. It should
        * be the ISA that determines relocation type.
        */
       if (dbg->dbgp_flags & DW_DLC_SIZE_64)
               drs->drs_addend = 1;
       else
               drs->drs_addend = 0;

       if (dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS)
               pseudo = 1;
       else
               pseudo = 0;

       snprintf(name, sizeof(name), "%s%s",
           drs->drs_addend ? ".rela" : ".rel", ref->ds_name);
       if (_dwarf_section_init(dbg, &drs->drs_ds, name, pseudo, error) !=
           DW_DLE_NONE) {
               free(drs);
               DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
               return (DW_DLE_MEMORY);
       }

       STAILQ_INIT(&drs->drs_dre);
       STAILQ_INSERT_TAIL(&dbg->dbgp_drslist, drs, drs_next);
       dbg->dbgp_drscnt++;
       *drsp = drs;

       return (DW_DLE_NONE);
}

void
_dwarf_reloc_section_free(Dwarf_P_Debug dbg, Dwarf_Rel_Section *drsp)
{
       Dwarf_Rel_Section drs, tdrs;
       Dwarf_Rel_Entry dre, tdre;

       assert(dbg != NULL && drsp != NULL);

       if (*drsp == NULL)
               return;

       STAILQ_FOREACH_SAFE(drs, &dbg->dbgp_drslist, drs_next, tdrs) {
               if (drs != *drsp)
                       continue;
               STAILQ_REMOVE(&dbg->dbgp_drslist, drs, _Dwarf_Rel_Section,
                   drs_next);
               STAILQ_FOREACH_SAFE(dre, &drs->drs_dre, dre_next, tdre) {
                       STAILQ_REMOVE(&drs->drs_dre, dre, _Dwarf_Rel_Entry,
                           dre_next);
                       free(dre);
               }
               if ((dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) == 0)
                       _dwarf_section_free(dbg, &drs->drs_ds);
               else {
                       if (drs->drs_ds->ds_name)
                               free(drs->drs_ds->ds_name);
                       free(drs->drs_ds);
               }
               free(drs);
               *drsp = NULL;
               dbg->dbgp_drscnt--;
               break;
       }
}

int
_dwarf_reloc_entry_add(Dwarf_P_Debug dbg, Dwarf_Rel_Section drs,
   Dwarf_P_Section ds, unsigned char type, unsigned char length,
   Dwarf_Unsigned offset, Dwarf_Unsigned symndx, Dwarf_Unsigned addend,
   const char *secname, Dwarf_Error *error)
{
       Dwarf_Rel_Entry dre;
       Dwarf_Unsigned reloff;
       int ret;

       assert(drs != NULL);
       assert(offset <= ds->ds_size);
       reloff = offset;

       /*
        * If the DW_DLC_SYMBOLIC_RELOCATIONS flag is set or ElfXX_Rel
        * is used instead of ELfXX_Rela, we need to write the addend
        * in the storage unit to be relocated. Otherwise write 0 in the
        * storage unit and the addend will be written into relocation
        * section later.
        */
       if ((dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) ||
           drs->drs_addend == 0)
               ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap, &offset,
                   addend, length, error);
       else
               ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap, &offset,
                   0, length, error);
       if (ret != DW_DLE_NONE)
               return (ret);
       if (offset > ds->ds_size)
               ds->ds_size = offset;

       if ((dre = calloc(1, sizeof(struct _Dwarf_Rel_Entry))) == NULL) {
               DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
               return (DW_DLE_MEMORY);
       }
       STAILQ_INSERT_TAIL(&drs->drs_dre, dre, dre_next);
       dre->dre_type = type;
       dre->dre_length = length;
       dre->dre_offset = reloff;
       dre->dre_symndx = symndx;
       dre->dre_addend = addend;
       dre->dre_secname = secname;
       drs->drs_drecnt++;

       return (DW_DLE_NONE);
}

int
_dwarf_reloc_entry_add_pair(Dwarf_P_Debug dbg, Dwarf_Rel_Section drs,
   Dwarf_P_Section ds, unsigned char length, Dwarf_Unsigned offset,
   Dwarf_Unsigned symndx, Dwarf_Unsigned esymndx, Dwarf_Unsigned symoff,
   Dwarf_Unsigned esymoff, Dwarf_Error *error)
{
       Dwarf_Rel_Entry dre;
       Dwarf_Unsigned reloff;
       int ret;

       assert(drs != NULL);
       assert(offset <= ds->ds_size);
       assert(dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS);
       reloff = offset;

       /* Write net offset into section stream. */
       ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap, &offset,
           esymoff - symoff, length, error);
       if (ret != DW_DLE_NONE)
               return (ret);
       if (offset > ds->ds_size)
               ds->ds_size = offset;

       if ((dre = calloc(2, sizeof(struct _Dwarf_Rel_Entry))) == NULL) {
               DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
               return (DW_DLE_MEMORY);
       }
       STAILQ_INSERT_TAIL(&drs->drs_dre, &dre[0], dre_next);
       STAILQ_INSERT_TAIL(&drs->drs_dre, &dre[1], dre_next);
       dre[0].dre_type = dwarf_drt_first_of_length_pair;
       dre[0].dre_length = length;
       dre[0].dre_offset = reloff;
       dre[0].dre_symndx = symndx;
       dre[0].dre_addend = 0;
       dre[0].dre_secname = NULL;
       dre[1].dre_type = dwarf_drt_second_of_length_pair;
       dre[1].dre_length = length;
       dre[1].dre_offset = reloff;
       dre[1].dre_symndx = esymndx;
       dre[1].dre_addend = 0;
       dre[1].dre_secname = NULL;
       drs->drs_drecnt += 2;

       return (DW_DLE_NONE);
}

int
_dwarf_reloc_section_finalize(Dwarf_P_Debug dbg, Dwarf_Rel_Section drs,
   Dwarf_Error *error)
{
       Dwarf_P_Section ds;
       Dwarf_Unsigned unit;
       int ret, size;

       assert(dbg != NULL && drs != NULL && drs->drs_ds != NULL &&
           drs->drs_ref != NULL);

       ds = drs->drs_ds;

       /*
        * Calculate the size (in bytes) of the relocation section.
        */
       if (dbg->dbgp_flags & DW_DLC_SIZE_64)
               unit = drs->drs_addend ? sizeof(Elf64_Rela) : sizeof(Elf64_Rel);
       else
               unit = drs->drs_addend ? sizeof(Elf32_Rela) : sizeof(Elf32_Rel);
       assert(ds->ds_size == 0);
       size = drs->drs_drecnt * unit;

       /*
        * Discard this relocation section if there is no entry in it.
        */
       if (size == 0) {
               _dwarf_reloc_section_free(dbg, &drs);
               return (DW_DLE_NONE);
       }

       /*
        * If we are under stream mode, realloc the section data block to
        * this size.
        */
       if ((dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) == 0) {
               ds->ds_cap = size;
               if ((ds->ds_data = realloc(ds->ds_data, (size_t) ds->ds_cap)) ==
                   NULL) {
                       DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
                       return (DW_DLE_MEMORY);
               }
       }

       /*
        * Notify the application the creation of this relocation section.
        * Note that the section link here should point to the .symtab
        * section, we set it to 0 since we have no way to know .symtab
        * section index.
        */
       ret = _dwarf_pro_callback(dbg, ds->ds_name, size,
           drs->drs_addend ? SHT_RELA : SHT_REL, 0, 0, drs->drs_ref->ds_ndx,
           &ds->ds_symndx, NULL);
       if (ret < 0) {
               DWARF_SET_ERROR(dbg, error, DW_DLE_ELF_SECT_ERR);
               return (DW_DLE_ELF_SECT_ERR);
       }
       ds->ds_ndx = ret;

       return (DW_DLE_NONE);
}

int
_dwarf_reloc_section_gen(Dwarf_P_Debug dbg, Dwarf_Rel_Section drs,
   Dwarf_Error *error)
{
       Dwarf_Rel_Entry dre;
       Dwarf_P_Section ds;
       Dwarf_Unsigned type;
       int ret;

       assert((dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) == 0);
       assert(drs->drs_ds != NULL && drs->drs_ds->ds_size == 0);
       assert(!STAILQ_EMPTY(&drs->drs_dre));
       ds = drs->drs_ds;

       STAILQ_FOREACH(dre, &drs->drs_dre, dre_next) {
               assert(dre->dre_length == 4 || dre->dre_length == 8);
               type = _dwarf_get_reloc_type(dbg, dre->dre_length == 8);
               if (dbg->dbgp_flags & DW_DLC_SIZE_64) {
                       /* Write r_offset (8 bytes) */
                       ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap,
                           &ds->ds_size, dre->dre_offset, 8, error);
                       if (ret != DW_DLE_NONE)
                               return (ret);
                       /* Write r_info (8 bytes) */
                       ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap,
                           &ds->ds_size, ELF64_R_INFO(dre->dre_symndx, type),
                           8, error);
                       if (ret != DW_DLE_NONE)
                               return (ret);
                       /* Write r_addend (8 bytes) */
                       if (drs->drs_addend) {
                               ret = dbg->write_alloc(&ds->ds_data,
                                   &ds->ds_cap, &ds->ds_size, dre->dre_addend,
                                   8, error);
                               if (ret != DW_DLE_NONE)
                                       return (ret);
                       }
               } else {
                       /* Write r_offset (4 bytes) */
                       ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap,
                           &ds->ds_size, dre->dre_offset, 4, error);
                       if (ret != DW_DLE_NONE)
                               return (ret);
                       /* Write r_info (4 bytes) */
                       ret = dbg->write_alloc(&ds->ds_data, &ds->ds_cap,
                           &ds->ds_size, ELF32_R_INFO(dre->dre_symndx, type),
                           4, error);
                       if (ret != DW_DLE_NONE)
                               return (ret);
                       /* Write r_addend (4 bytes) */
                       if (drs->drs_addend) {
                               ret = dbg->write_alloc(&ds->ds_data,
                                   &ds->ds_cap, &ds->ds_size, dre->dre_addend,
                                   4, error);
                               if (ret != DW_DLE_NONE)
                                       return (ret);
                       }
               }
       }
       assert(ds->ds_size == ds->ds_cap);

       return (DW_DLE_NONE);
}

int
_dwarf_reloc_gen(Dwarf_P_Debug dbg, Dwarf_Error *error)
{
       Dwarf_Rel_Section drs;
       Dwarf_Rel_Entry dre;
       Dwarf_P_Section ds;
       int ret;

       STAILQ_FOREACH(drs, &dbg->dbgp_drslist, drs_next) {
               /*
                * Update relocation entries: translate any section name
                * reference to section symbol index.
                */
               STAILQ_FOREACH(dre, &drs->drs_dre, dre_next) {
                       if (dre->dre_secname == NULL)
                               continue;
                       ds = _dwarf_pro_find_section(dbg, dre->dre_secname);
                       assert(ds != NULL && ds->ds_symndx != 0);
                       dre->dre_symndx = ds->ds_symndx;
               }

               /*
                * Generate ELF relocation section if we are under stream
                * mode.
                */
               if ((dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) == 0) {
                       ret = _dwarf_reloc_section_gen(dbg, drs, error);
                       if (ret != DW_DLE_NONE)
                               return (ret);
               }
       }

       return (DW_DLE_NONE);
}

void
_dwarf_reloc_cleanup(Dwarf_P_Debug dbg)
{
       Dwarf_Rel_Section drs, tdrs;
       Dwarf_Rel_Entry dre, tdre;

       assert(dbg != NULL && dbg->dbg_mode == DW_DLC_WRITE);

       STAILQ_FOREACH_SAFE(drs, &dbg->dbgp_drslist, drs_next, tdrs) {
               STAILQ_REMOVE(&dbg->dbgp_drslist, drs, _Dwarf_Rel_Section,
                   drs_next);
               free(drs->drs_drd);
               STAILQ_FOREACH_SAFE(dre, &drs->drs_dre, dre_next, tdre) {
                       STAILQ_REMOVE(&drs->drs_dre, dre, _Dwarf_Rel_Entry,
                           dre_next);
                       free(dre);
               }
               if (dbg->dbgp_flags & DW_DLC_SYMBOLIC_RELOCATIONS) {
                       if (drs->drs_ds) {
                               if (drs->drs_ds->ds_name)
                                       free(drs->drs_ds->ds_name);
                               free(drs->drs_ds);
                       }
               }
               free(drs);
       }
       dbg->dbgp_drscnt = 0;
       dbg->dbgp_drspos = NULL;
}

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