| /* Copyright (C) 2001, 2002, 2003, 2004, 2005 Red Hat, Inc. |
| Written by Ulrich Drepper <drepper@redhat.com>, 2001. |
| |
| This program is Open Source software; you can redistribute it and/or |
| modify it under the terms of the Open Software License version 1.0 as |
| published by the Open Source Initiative. |
| |
| You should have received a copy of the Open Software License along |
| with this program; if not, you may obtain a copy of the Open Software |
| License version 1.0 from http://www.opensource.org/licenses/osl.php or |
| by writing the Open Source Initiative c/o Lawrence Rosen, Esq., |
| 3001 King Ranch Road, Ukiah, CA 95482. */ |
| |
| #ifdef HAVE_CONFIG_H |
| # include <config.h> |
| #endif |
| |
| #include <assert.h> |
| #include <error.h> |
| #include <libintl.h> |
| #include <stdlib.h> |
| #include <string.h> |
| |
| // XXX For debugging |
| #include <stdio.h> |
| |
| #include <system.h> |
| #include "ld.h" |
| #include "list.h" |
| /* x86 is little endian. */ |
| #define UNALIGNED_ACCESS_CLASS LITTLE_ENDIAN |
| #include "unaligned.h" |
| #include "xelf.h" |
| |
| |
| /* The old callbacks. */ |
| static int (*old_open_outfile) (struct ld_state *, int, int, int); |
| |
| |
| static int |
| elf_i386_open_outfile (struct ld_state *statep, |
| int machine __attribute__ ((unused)), |
| int klass __attribute__ ((unused)), |
| int data __attribute__ ((unused))) |
| { |
| /* This backend only handles 32-bit object files. */ |
| /* XXX For now just use the generic backend. */ |
| return old_open_outfile (statep, EM_386, ELFCLASS32, ELFDATA2LSB); |
| } |
| |
| |
| /* Process relocations for the output in a relocatable file. This |
| only means adjusting offset and symbol indices. */ |
| static void |
| elf_i386_relocate_section (struct ld_state *statep __attribute__ ((unused)), |
| Elf_Scn *outscn, struct scninfo *firstp, |
| const Elf32_Word *dblindirect) |
| { |
| struct scninfo *runp; |
| Elf_Data *data; |
| |
| /* Iterate over all the input sections. Appropriate data buffers in the |
| output sections were already created. I get them iteratively, too. */ |
| runp = firstp; |
| data = NULL; |
| do |
| { |
| Elf_Data *reltgtdata; |
| Elf_Data *insymdata; |
| Elf_Data *inxndxdata = NULL; |
| size_t maxcnt; |
| size_t cnt; |
| const Elf32_Word *symindirect; |
| struct symbol **symref; |
| struct usedfiles *file = runp->fileinfo; |
| XElf_Shdr *shdr = &SCNINFO_SHDR (runp->shdr); |
| |
| /* Get the output section data buffer for this input section. */ |
| data = elf_getdata (outscn, data); |
| assert (data != NULL); |
| |
| /* Get the data for section in the input file this relocation |
| section is relocating. Since these buffers are reused in the |
| output modifying these buffers has the correct result. */ |
| reltgtdata = elf_getdata (file->scninfo[shdr->sh_info].scn, NULL); |
| |
| /* Get the data for the input section symbol table for this |
| relocation section. */ |
| insymdata = elf_getdata (file->scninfo[shdr->sh_link].scn, NULL); |
| assert (insymdata != NULL); |
| |
| /* And the extended section index table. */ |
| inxndxdata = runp->fileinfo->xndxdata; |
| |
| /* Number of relocations. */ |
| maxcnt = shdr->sh_size / shdr->sh_entsize; |
| |
| /* Array directing local symbol table offsets to output symbol |
| table offsets. */ |
| symindirect = file->symindirect; |
| |
| /* References to the symbol records. */ |
| symref = file->symref; |
| |
| /* Iterate over all the relocations in the section. */ |
| for (cnt = 0; cnt < maxcnt; ++cnt) |
| { |
| XElf_Rel_vardef (rel); |
| Elf32_Word si; |
| XElf_Sym_vardef (sym); |
| Elf32_Word xndx; |
| |
| /* Get the relocation data itself. x86 uses Rel |
| relocations. In case we have to handle Rela as well the |
| whole loop probably should be duplicated. */ |
| xelf_getrel (data, cnt, rel); |
| assert (rel != NULL); |
| |
| /* Compute the symbol index in the output file. */ |
| si = symindirect[XELF_R_SYM (rel->r_info)]; |
| if (si == 0) |
| { |
| /* This happens if the symbol is locally undefined or |
| superceded by some other definition. */ |
| assert (symref[XELF_R_SYM (rel->r_info)] != NULL); |
| si = symref[XELF_R_SYM (rel->r_info)]->outsymidx; |
| } |
| /* Take reordering performed to sort the symbol table into |
| account. */ |
| si = dblindirect[si]; |
| |
| /* Get the symbol table entry. */ |
| xelf_getsymshndx (insymdata, inxndxdata, XELF_R_SYM (rel->r_info), |
| sym, xndx); |
| if (sym->st_shndx != SHN_XINDEX) |
| xndx = sym->st_shndx; |
| assert (xndx < SHN_LORESERVE || xndx > SHN_HIRESERVE); |
| |
| /* We fortunately don't have to do much. The relocations |
| mostly get only updates of the offset. Only is a |
| relocation referred to a section do we have to do |
| something. In this case the reference to the sections |
| has no direct equivalent since the part the input section |
| contributes need not start at the same offset as in the |
| input file. Therefore we have to adjust the addend which |
| in the case of Rel relocations is in the target section |
| itself. */ |
| if (XELF_ST_TYPE (sym->st_info) == STT_SECTION) |
| { |
| Elf32_Word toadd; |
| |
| /* We expect here on R_386_32 relocations. */ |
| assert (XELF_R_TYPE (rel->r_info) == R_386_32); |
| |
| /* Avoid writing to the section memory if this is |
| effectively a no-op since it might save a |
| copy-on-write operation. */ |
| toadd = file->scninfo[xndx].offset; |
| if (toadd != 0) |
| add_4ubyte_unaligned (reltgtdata->d_buf + rel->r_offset, |
| toadd); |
| } |
| |
| /* Adjust the offset for the position of the input section |
| content in the output section. */ |
| rel->r_offset += file->scninfo[shdr->sh_info].offset; |
| |
| /* And finally adjust the index of the symbol in the output |
| symbol table. */ |
| rel->r_info = XELF_R_INFO (si, XELF_R_TYPE (rel->r_info)); |
| |
| /* Store the result. */ |
| (void) xelf_update_rel (data, cnt, rel); |
| } |
| |
| runp = runp->next; |
| } |
| while (runp != firstp); |
| } |
| |
| |
| /* Each PLT entry has 16 bytes. We need one entry as overhead for |
| the code to set up the call into the runtime relocation. */ |
| #define PLT_ENTRY_SIZE 16 |
| |
| static void |
| elf_i386_initialize_plt (struct ld_state *statep, Elf_Scn *scn) |
| { |
| Elf_Data *data; |
| XElf_Shdr_vardef (shdr); |
| |
| /* Change the entry size in the section header. */ |
| xelf_getshdr (scn, shdr); |
| assert (shdr != NULL); |
| shdr->sh_entsize = PLT_ENTRY_SIZE; |
| (void) xelf_update_shdr (scn, shdr); |
| |
| data = elf_newdata (scn); |
| if (data == NULL) |
| error (EXIT_FAILURE, 0, gettext ("cannot allocate PLT section: %s"), |
| elf_errmsg (-1)); |
| |
| /* We need one special PLT entry (performing the jump to the runtime |
| relocation routines) and one for each function we call in a DSO. */ |
| data->d_size = (1 + statep->nplt) * PLT_ENTRY_SIZE; |
| data->d_buf = xcalloc (1, data->d_size); |
| data->d_align = 8; |
| data->d_off = 0; |
| |
| statep->nplt_used = 1; |
| } |
| |
| |
| static void |
| elf_i386_initialize_pltrel (struct ld_state *statep, Elf_Scn *scn) |
| { |
| Elf_Data *data; |
| |
| data = elf_newdata (scn); |
| if (data == NULL) |
| error (EXIT_FAILURE, 0, gettext ("cannot allocate PLTREL section: %s"), |
| elf_errmsg (-1)); |
| |
| /* One relocation per PLT entry. */ |
| data->d_size = statep->nplt * sizeof (Elf32_Rel); |
| data->d_buf = xcalloc (1, data->d_size); |
| data->d_type = ELF_T_REL; |
| data->d_align = 4; |
| data->d_off = 0; |
| } |
| |
| |
| static void |
| elf_i386_initialize_got (struct ld_state *statep, Elf_Scn *scn) |
| { |
| Elf_Data *data; |
| |
| /* If we have no .plt we don't need the special entries we normally |
| create for it. The other contents is created later. */ |
| if (statep->ngot + statep->nplt == 0) |
| return; |
| |
| data = elf_newdata (scn); |
| if (data == NULL) |
| error (EXIT_FAILURE, 0, gettext ("cannot allocate GOT section: %s"), |
| elf_errmsg (-1)); |
| |
| /* We construct the .got section in pieces. Here we only add the data |
| structures which are used by the PLT. This includes three reserved |
| entries at the beginning (the first will contain a pointer to the |
| .dynamic section), and one word for each PLT entry. */ |
| data->d_size = (3 + statep->ngot + statep->nplt) * sizeof (Elf32_Addr); |
| data->d_buf = xcalloc (1, data->d_size); |
| data->d_align = sizeof (Elf32_Addr); |
| data->d_off = 0; |
| } |
| |
| |
| /* The first entry in an absolute procedure linkage table looks like |
| this. See the SVR4 ABI i386 supplement to see how this works. */ |
| static const unsigned char elf_i386_plt0_entry[PLT_ENTRY_SIZE] = |
| { |
| 0xff, 0x35, /* pushl contents of address */ |
| 0, 0, 0, 0, /* replaced with address of .got + 4. */ |
| 0xff, 0x25, /* jmp indirect */ |
| 0, 0, 0, 0, /* replaced with address of .got + 8. */ |
| 0, 0, 0, 0 /* pad out to 16 bytes. */ |
| }; |
| |
| /* Type describing the first PLT entry in non-PIC. */ |
| struct plt0_entry |
| { |
| /* First a 'push' of the second GOT entry. */ |
| unsigned char push_instr[2]; |
| uint32_t gotp4_addr; |
| /* Second, a 'jmp indirect' to the third GOT entry. */ |
| unsigned char jmp_instr[2]; |
| uint32_t gotp8_addr; |
| /* Padding. */ |
| unsigned char padding[4]; |
| } __attribute__ ((packed)); |
| |
| /* The first entry in a PIC procedure linkage table look like this. */ |
| static const unsigned char elf_i386_pic_plt0_entry[PLT_ENTRY_SIZE] = |
| { |
| 0xff, 0xb3, 4, 0, 0, 0, /* pushl 4(%ebx) */ |
| 0xff, 0xa3, 8, 0, 0, 0, /* jmp *8(%ebx) */ |
| 0, 0, 0, 0 /* pad out to 16 bytes. */ |
| }; |
| |
| /* Contents of all but the first PLT entry in executable. */ |
| static const unsigned char elf_i386_plt_entry[PLT_ENTRY_SIZE] = |
| { |
| 0xff, 0x25, /* jmp indirect */ |
| 0, 0, 0, 0, /* replaced with address of this symbol in .got. */ |
| 0x68, /* pushl immediate */ |
| 0, 0, 0, 0, /* replaced with offset into relocation table. */ |
| 0xe9, /* jmp relative */ |
| 0, 0, 0, 0 /* replaced with offset to start of .plt. */ |
| }; |
| |
| /* Contents of all but the first PLT entry in DSOs. */ |
| static const unsigned char elf_i386_pic_plt_entry[PLT_ENTRY_SIZE] = |
| { |
| 0xff, 0xa3, /* jmp *offset(%ebx) */ |
| 0, 0, 0, 0, /* replaced with offset of this symbol in .got. */ |
| 0x68, /* pushl immediate */ |
| 0, 0, 0, 0, /* replaced with offset into relocation table. */ |
| 0xe9, /* jmp relative */ |
| 0, 0, 0, 0 /* replaced with offset to start of .plt. */ |
| }; |
| |
| /* Type describing a PLT entry. */ |
| struct plt_entry |
| { |
| /* The first instruction is 'jmp indirect' or 'jmp *offset(%ebs)'. */ |
| unsigned char jmp_instr[2]; |
| uint32_t offset_got; |
| /* The second instruction is 'push immediate'. */ |
| unsigned char push_instr; |
| uint32_t push_imm; |
| /* Finally a 'jmp relative'. */ |
| unsigned char jmp_instr2; |
| uint32_t plt0_offset; |
| } __attribute__ ((packed)); |
| |
| |
| static void |
| elf_i386_finalize_plt (struct ld_state *statep, size_t nsym, |
| size_t nsym_dyn __attribute__ ((unused))) |
| { |
| Elf_Scn *scn; |
| XElf_Shdr_vardef (shdr); |
| Elf_Data *data; |
| Elf_Data *symdata = NULL; |
| Elf_Data *dynsymdata; |
| size_t cnt; |
| const bool build_dso = statep->file_type == dso_file_type; |
| |
| if (unlikely (statep->nplt + statep->ngot == 0)) |
| /* Nothing to be done. */ |
| return; |
| |
| /* Get the address of the got section. */ |
| scn = elf_getscn (statep->outelf, statep->gotscnidx); |
| xelf_getshdr (scn, shdr); |
| data = elf_getdata (scn, NULL); |
| assert (shdr != NULL && data != NULL); |
| Elf32_Addr gotaddr = shdr->sh_addr; |
| |
| /* Now create the initial values for the .got section. The first |
| word contains the address of the .dynamic section. */ |
| xelf_getshdr (elf_getscn (statep->outelf, statep->dynamicscnidx), shdr); |
| assert (shdr != NULL); |
| ((Elf32_Word *) data->d_buf)[0] = shdr->sh_addr; |
| |
| /* The second and third entry are left empty for use by the dynamic |
| linker. The following entries are pointers to the instructions |
| following the initial jmp instruction in the corresponding PLT |
| entry. Since the first PLT entry is special the first used one |
| has the index 1. */ |
| scn = elf_getscn (statep->outelf, statep->pltscnidx); |
| xelf_getshdr (scn, shdr); |
| assert (shdr != NULL); |
| |
| dynsymdata = elf_getdata (elf_getscn (statep->outelf, statep->dynsymscnidx), |
| NULL); |
| assert (dynsymdata != NULL); |
| |
| if (statep->symscnidx != 0) |
| { |
| symdata = elf_getdata (elf_getscn (statep->outelf, statep->symscnidx), |
| NULL); |
| assert (symdata != NULL); |
| } |
| |
| for (cnt = 0; cnt < statep->nplt; ++cnt) |
| { |
| assert ((4 + cnt) * sizeof (Elf32_Word) <= data->d_size); |
| |
| /* Address in the PLT. */ |
| Elf32_Addr pltentryaddr = shdr->sh_addr + (1 + cnt) * PLT_ENTRY_SIZE; |
| |
| /* Point the GOT entry at the PLT entry, after the initial jmp. */ |
| ((Elf32_Word *) data->d_buf)[3 + cnt] = pltentryaddr + 6; |
| |
| /* The value of the symbol is the address of the corresponding PLT |
| entry. Store the address, also for the normal symbol table if |
| this is necessary. */ |
| ((Elf32_Sym *) dynsymdata->d_buf)[1 + cnt].st_value = pltentryaddr; |
| |
| if (symdata != NULL) |
| ((Elf32_Sym *) symdata->d_buf)[nsym - statep->nplt + cnt].st_value |
| = pltentryaddr; |
| } |
| |
| /* Create the .plt section. */ |
| scn = elf_getscn (statep->outelf, statep->pltscnidx); |
| data = elf_getdata (scn, NULL); |
| assert (data != NULL); |
| |
| /* Create the first entry. */ |
| assert (data->d_size >= PLT_ENTRY_SIZE); |
| if (build_dso) |
| /* Copy the entry. It's complete, no relocation needed. */ |
| memcpy (data->d_buf, elf_i386_pic_plt0_entry, PLT_ENTRY_SIZE); |
| else |
| { |
| /* Copy the skeleton. */ |
| memcpy (data->d_buf, elf_i386_plt0_entry, PLT_ENTRY_SIZE); |
| |
| /* And fill in the addresses. */ |
| struct plt0_entry *addr = (struct plt0_entry *) data->d_buf; |
| addr->gotp4_addr = target_bswap_32 (gotaddr + 4); |
| addr->gotp8_addr = target_bswap_32 (gotaddr + 8); |
| } |
| |
| /* For DSOs we need GOT offsets, otherwise the GOT address. */ |
| Elf32_Addr gotaddr_off = build_dso ? 0 : gotaddr; |
| |
| /* Create the remaining entries. */ |
| const unsigned char *plt_template |
| = build_dso ? elf_i386_pic_plt_entry : elf_i386_plt_entry; |
| |
| for (cnt = 0; cnt < statep->nplt; ++cnt) |
| { |
| struct plt_entry *addr; |
| |
| /* Copy the template. */ |
| assert (data->d_size >= (2 + cnt) * PLT_ENTRY_SIZE); |
| addr = (struct plt_entry *) ((char *) data->d_buf |
| + (1 + cnt) * PLT_ENTRY_SIZE); |
| memcpy (addr, plt_template, PLT_ENTRY_SIZE); |
| |
| /* And once more, fill in the addresses. First the address of |
| this symbol in .got. */ |
| addr->offset_got = target_bswap_32 (gotaddr_off |
| + (3 + cnt) * sizeof (Elf32_Addr)); |
| /* Offset into relocation table. */ |
| addr->push_imm = target_bswap_32 (cnt * sizeof (Elf32_Rel)); |
| /* Offset to start of .plt. */ |
| addr->plt0_offset = target_bswap_32 (-(2 + cnt) * PLT_ENTRY_SIZE); |
| } |
| |
| /* Create the .rel.plt section data. It simply means relocations |
| addressing the corresponding entry in the .got section. The |
| section name is misleading. */ |
| scn = elf_getscn (statep->outelf, statep->pltrelscnidx); |
| xelf_getshdr (scn, shdr); |
| data = elf_getdata (scn, NULL); |
| assert (shdr != NULL && data != NULL); |
| |
| /* Update the sh_link to point to the section being modified. We |
| point it here (correctly) to the .got section. Some linkers |
| (e.g., the GNU binutils linker) point to the .plt section. This |
| is wrong since the .plt section isn't modified even though the |
| name .rel.plt suggests that this is correct. */ |
| shdr->sh_link = statep->dynsymscnidx; |
| shdr->sh_info = statep->gotscnidx; |
| (void) xelf_update_shdr (scn, shdr); |
| |
| for (cnt = 0; cnt < statep->nplt; ++cnt) |
| { |
| XElf_Rel_vardef (rel); |
| |
| assert ((1 + cnt) * sizeof (Elf32_Rel) <= data->d_size); |
| xelf_getrel_ptr (data, cnt, rel); |
| rel->r_offset = gotaddr + (3 + cnt) * sizeof (Elf32_Addr); |
| /* The symbol table entries for the functions from DSOs are at |
| the end of the symbol table. */ |
| rel->r_info = XELF_R_INFO (1 + cnt, R_386_JMP_SLOT); |
| (void) xelf_update_rel (data, cnt, rel); |
| } |
| } |
| |
| |
| static int |
| elf_i386_rel_type (struct ld_state *statep __attribute__ ((__unused__))) |
| { |
| /* ELF/i386 uses REL. */ |
| return DT_REL; |
| } |
| |
| |
| static void |
| elf_i386_count_relocations (struct ld_state *statep, struct scninfo *scninfo) |
| { |
| /* We go through the list of input sections and count those relocations |
| which are not handled by the linker. At the same time we have to |
| see how many GOT entries we need and how much .bss space is needed |
| for copy relocations. */ |
| Elf_Data *data = elf_getdata (scninfo->scn, NULL); |
| XElf_Shdr *shdr = &SCNINFO_SHDR (scninfo->shdr); |
| size_t maxcnt = shdr->sh_size / shdr->sh_entsize; |
| size_t relsize = 0; |
| size_t cnt; |
| struct symbol *sym; |
| |
| assert (shdr->sh_type == SHT_REL); |
| |
| for (cnt = 0; cnt < maxcnt; ++cnt) |
| { |
| XElf_Rel_vardef (rel); |
| |
| xelf_getrel (data, cnt, rel); |
| /* XXX Should we complain about failing accesses? */ |
| if (rel != NULL) |
| { |
| Elf32_Word r_sym = XELF_R_SYM (rel->r_info); |
| |
| switch (XELF_R_TYPE (rel->r_info)) |
| { |
| case R_386_GOT32: |
| if (! scninfo->fileinfo->symref[r_sym]->defined) |
| relsize += sizeof (Elf32_Rel); |
| |
| /* This relocation is not emitted in the output file but |
| requires a GOT entry. */ |
| ++statep->ngot; |
| ++statep->nrel_got; |
| |
| /* FALLTHROUGH */ |
| |
| case R_386_GOTOFF: |
| case R_386_GOTPC: |
| statep->need_got = true; |
| break; |
| |
| case R_386_32: |
| case R_386_PC32: |
| /* These relocations cause text relocations in DSOs. */ |
| if (linked_from_dso_p (scninfo, r_sym)) |
| { |
| if (statep->file_type == dso_file_type) |
| { |
| relsize += sizeof (Elf32_Rel); |
| statep->dt_flags |= DF_TEXTREL; |
| } |
| else |
| { |
| /* Non-function objects from a DSO need to get a |
| copy relocation. */ |
| sym = scninfo->fileinfo->symref[r_sym]; |
| |
| /* Only do this if we have not requested a copy |
| relocation already. */ |
| if (unlikely (sym->type != STT_FUNC) && ! sym->need_copy) |
| { |
| sym->need_copy = 1; |
| ++statep->ncopy; |
| relsize += sizeof (Elf32_Rel); |
| } |
| } |
| } |
| else if (statep->file_type == dso_file_type |
| && r_sym >= SCNINFO_SHDR (scninfo->fileinfo->scninfo[shdr->sh_link].shdr).sh_info |
| && scninfo->fileinfo->symref[r_sym]->outdynsymidx != 0 |
| && XELF_R_TYPE (rel->r_info) == R_386_32) |
| relsize += sizeof (Elf32_Rel); |
| break; |
| |
| case R_386_PLT32: |
| /* We might need a PLT entry. But we cannot say for sure |
| here since one of the symbols might turn up being |
| defined in the executable (if we create such a thing). |
| If a DSO is created we still might use a local |
| definition. |
| |
| If the symbol is not defined and we are not creating |
| a statically linked binary, then we need in any case |
| a PLT entry. */ |
| if (! scninfo->fileinfo->symref[r_sym]->defined) |
| { |
| assert (!statep->statically); |
| |
| sym = scninfo->fileinfo->symref[r_sym]; |
| sym->type = STT_FUNC; |
| sym->in_dso = 1; |
| sym->defined = 1; |
| |
| /* Remove from the list of unresolved symbols. */ |
| --statep->nunresolved; |
| if (! sym->weak) |
| --statep->nunresolved_nonweak; |
| CDBL_LIST_DEL (statep->unresolved, sym); |
| |
| /* Add to the list of symbols we expect from a DSO. */ |
| ++statep->nplt; |
| ++statep->nfrom_dso; |
| CDBL_LIST_ADD_REAR (statep->from_dso, sym); |
| } |
| break; |
| |
| case R_386_TLS_GD: |
| case R_386_TLS_LDM: |
| case R_386_TLS_GD_32: |
| case R_386_TLS_GD_PUSH: |
| case R_386_TLS_GD_CALL: |
| case R_386_TLS_GD_POP: |
| case R_386_TLS_LDM_32: |
| case R_386_TLS_LDM_PUSH: |
| case R_386_TLS_LDM_CALL: |
| case R_386_TLS_LDM_POP: |
| case R_386_TLS_LDO_32: |
| case R_386_TLS_IE_32: |
| case R_386_TLS_LE_32: |
| /* XXX */ |
| abort (); |
| break; |
| |
| case R_386_NONE: |
| /* Nothing to be done. */ |
| break; |
| |
| /* These relocation should never be generated by an |
| assembler. */ |
| case R_386_COPY: |
| case R_386_GLOB_DAT: |
| case R_386_JMP_SLOT: |
| case R_386_RELATIVE: |
| case R_386_TLS_DTPMOD32: |
| case R_386_TLS_DTPOFF32: |
| case R_386_TLS_TPOFF32: |
| /* Unknown relocation. */ |
| default: |
| abort (); |
| } |
| } |
| } |
| |
| scninfo->relsize = relsize; |
| } |
| |
| |
| static void |
| elf_i386_create_relocations (struct ld_state *statep, |
| const Elf32_Word *dblindirect __attribute__ ((unused))) |
| { |
| /* Get the address of the got section. */ |
| Elf_Scn *pltscn = elf_getscn (statep->outelf, statep->pltscnidx); |
| Elf32_Shdr *shdr = elf32_getshdr (pltscn); |
| assert (shdr != NULL); |
| Elf32_Addr pltaddr = shdr->sh_addr; |
| |
| Elf_Scn *gotscn = elf_getscn (statep->outelf, statep->gotscnidx); |
| shdr = elf32_getshdr (gotscn); |
| assert (shdr != NULL); |
| Elf32_Addr gotaddr = shdr->sh_addr; |
| |
| Elf_Scn *reldynscn = elf_getscn (statep->outelf, statep->reldynscnidx); |
| Elf_Data *reldyndata = elf_getdata (reldynscn, NULL); |
| |
| size_t nreldyn = 0; |
| #define ngot_used (3 + statep->nplt + nreldyn) |
| |
| struct scninfo *first = statep->rellist->next; |
| struct scninfo *runp = first; |
| do |
| { |
| XElf_Shdr *rshdr = &SCNINFO_SHDR (runp->shdr); |
| Elf_Data *reldata = elf_getdata (runp->scn, NULL); |
| int nrels = rshdr->sh_size / rshdr->sh_entsize; |
| |
| /* We will need the following vlaues a couple of times. Help |
| the compiler and improve readability. */ |
| struct symbol **symref = runp->fileinfo->symref; |
| struct scninfo *scninfo = runp->fileinfo->scninfo; |
| |
| /* This is the offset of the input section we are looking at in |
| the output file. */ |
| XElf_Addr inscnoffset = scninfo[rshdr->sh_info].offset; |
| |
| /* The target section. We use the data from the input file. */ |
| Elf_Data *data = elf_getdata (scninfo[rshdr->sh_info].scn, NULL); |
| |
| /* We cannot handle relocations against merge-able sections. */ |
| assert ((SCNINFO_SHDR (scninfo[rshdr->sh_link].shdr).sh_flags |
| & SHF_MERGE) == 0); |
| |
| /* Cache the access to the symbol table data. */ |
| Elf_Data *symdata = elf_getdata (scninfo[rshdr->sh_link].scn, NULL); |
| |
| int cnt; |
| for (cnt = 0; cnt < nrels; ++cnt) |
| { |
| XElf_Rel_vardef (rel); |
| XElf_Rel *rel2; |
| xelf_getrel (reldata, cnt, rel); |
| assert (rel != NULL); |
| XElf_Addr reladdr = inscnoffset + rel->r_offset; |
| XElf_Addr value; |
| |
| size_t idx = XELF_R_SYM (rel->r_info); |
| if (idx < runp->fileinfo->nlocalsymbols) |
| { |
| XElf_Sym_vardef (sym); |
| xelf_getsym (symdata, idx, sym); |
| |
| /* The value just depends on the position of the referenced |
| section in the output file and the addend. */ |
| value = scninfo[sym->st_shndx].offset + sym->st_value; |
| } |
| else if (symref[idx]->in_dso) |
| { |
| /* MERGE.VALUE contains the PLT index. We have to add 1 since |
| there is this one special PLT entry at the beginning. */ |
| assert (symref[idx]->merge.value != 0 |
| || symref[idx]->type != STT_FUNC); |
| value = pltaddr + symref[idx]->merge.value * PLT_ENTRY_SIZE; |
| } |
| else |
| value = symref[idx]->merge.value; |
| |
| /* Address of the relocated memory in the data buffer. */ |
| void *relloc = (char *) data->d_buf + rel->r_offset; |
| |
| switch (XELF_R_TYPE (rel->r_info)) |
| { |
| /* These three cases can be handled together since the |
| symbol associated with the R_386_GOTPC relocation is |
| _GLOBAL_OFFSET_TABLE_ which has a value corresponding |
| to the address of the GOT and the address of the PLT |
| entry required for R_386_PLT32 is computed above. */ |
| case R_386_PC32: |
| case R_386_GOTPC: |
| case R_386_PLT32: |
| value -= reladdr; |
| /* FALLTHROUGH */ |
| |
| case R_386_32: |
| if (linked_from_dso_p (scninfo, idx) |
| && statep->file_type != dso_file_type |
| && symref[idx]->type != STT_FUNC) |
| { |
| value = (ld_state.copy_section->offset |
| + symref[idx]->merge.value); |
| |
| if (unlikely (symref[idx]->need_copy)) |
| { |
| /* Add a relocation to initialize the GOT entry. */ |
| assert (symref[idx]->outdynsymidx != 0); |
| #if NATIVE_ELF != 0 |
| xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| #else |
| rel2 = &rel_mem; |
| #endif |
| rel2->r_offset = value; |
| rel2->r_info |
| = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_COPY); |
| (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| ++nreldyn; |
| |
| /* Update the symbol table record for the new |
| address. */ |
| Elf32_Word symidx = symref[idx]->outdynsymidx; |
| Elf_Scn *symscn = elf_getscn (statep->outelf, |
| statep->dynsymscnidx); |
| Elf_Data *outsymdata = elf_getdata (symscn, NULL); |
| assert (outsymdata != NULL); |
| XElf_Sym_vardef (sym); |
| xelf_getsym (outsymdata, symidx, sym); |
| sym->st_value = value; |
| sym->st_shndx = statep->copy_section->outscnndx; |
| (void) xelf_update_sym (outsymdata, symidx, sym); |
| |
| symidx = symref[idx]->outsymidx; |
| if (symidx != 0) |
| { |
| symidx = statep->dblindirect[symidx]; |
| symscn = elf_getscn (statep->outelf, |
| statep->symscnidx); |
| outsymdata = elf_getdata (symscn, NULL); |
| assert (outsymdata != NULL); |
| xelf_getsym (outsymdata, symidx, sym); |
| sym->st_value = value; |
| sym->st_shndx = statep->copy_section->outscnndx; |
| (void) xelf_update_sym (outsymdata, symidx, sym); |
| } |
| |
| /* Remember that we set up the copy relocation. */ |
| symref[idx]->need_copy = 0; |
| } |
| } |
| else if (statep->file_type == dso_file_type |
| && idx >= SCNINFO_SHDR (scninfo[rshdr->sh_link].shdr).sh_info |
| && symref[idx]->outdynsymidx != 0) |
| { |
| #if NATIVE_ELF != 0 |
| xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| #else |
| rel2 = &rel_mem; |
| #endif |
| rel2->r_offset = value; |
| rel2->r_info |
| = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_32); |
| (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| ++nreldyn; |
| |
| value = 0; |
| } |
| add_4ubyte_unaligned (relloc, value); |
| break; |
| |
| case R_386_GOT32: |
| store_4ubyte_unaligned (relloc, ngot_used * sizeof (Elf32_Addr)); |
| |
| /* Add a relocation to initialize the GOT entry. */ |
| #if NATIVE_ELF != 0 |
| xelf_getrel_ptr (reldyndata, nreldyn, rel2); |
| #else |
| rel2 = &rel_mem; |
| #endif |
| rel2->r_offset = gotaddr + ngot_used * sizeof (Elf32_Addr); |
| rel2->r_info |
| = XELF_R_INFO (symref[idx]->outdynsymidx, R_386_GLOB_DAT); |
| (void) xelf_update_rel (reldyndata, nreldyn, rel2); |
| ++nreldyn; |
| break; |
| |
| case R_386_GOTOFF: |
| add_4ubyte_unaligned (relloc, value - gotaddr); |
| break; |
| |
| case R_386_32PLT: |
| case R_386_TLS_TPOFF: |
| case R_386_TLS_IE: |
| case R_386_TLS_GOTIE: |
| case R_386_TLS_LE: |
| case R_386_TLS_GD: |
| case R_386_TLS_LDM: |
| case R_386_16: |
| case R_386_PC16: |
| case R_386_8: |
| case R_386_PC8: |
| case R_386_TLS_GD_32: |
| case R_386_TLS_GD_PUSH: |
| case R_386_TLS_GD_CALL: |
| case R_386_TLS_GD_POP: |
| case R_386_TLS_LDM_32: |
| case R_386_TLS_LDM_PUSH: |
| case R_386_TLS_LDM_CALL: |
| case R_386_TLS_LDM_POP: |
| case R_386_TLS_LDO_32: |
| case R_386_TLS_IE_32: |
| case R_386_TLS_LE_32: |
| // XXX For now fall through |
| printf("ignored relocation %d\n", (int) XELF_R_TYPE (rel->r_info)); |
| break; |
| |
| case R_386_NONE: |
| /* Nothing to do. */ |
| break; |
| |
| case R_386_COPY: |
| case R_386_JMP_SLOT: |
| case R_386_RELATIVE: |
| case R_386_GLOB_DAT: |
| case R_386_TLS_DTPMOD32: |
| case R_386_TLS_DTPOFF32: |
| case R_386_TLS_TPOFF32: |
| default: |
| /* Should not happen. */ |
| abort (); |
| } |
| } |
| } |
| while ((runp = runp->next) != first); |
| } |
| |
| |
| int |
| elf_i386_ld_init (struct ld_state *statep) |
| { |
| /* We have a few callbacks available. */ |
| old_open_outfile = statep->callbacks.open_outfile; |
| statep->callbacks.open_outfile = elf_i386_open_outfile; |
| |
| statep->callbacks.relocate_section = elf_i386_relocate_section; |
| |
| statep->callbacks.initialize_plt = elf_i386_initialize_plt; |
| statep->callbacks.initialize_pltrel = elf_i386_initialize_pltrel; |
| |
| statep->callbacks.initialize_got = elf_i386_initialize_got; |
| |
| statep->callbacks.finalize_plt = elf_i386_finalize_plt; |
| |
| statep->callbacks.rel_type = elf_i386_rel_type; |
| |
| statep->callbacks.count_relocations = elf_i386_count_relocations; |
| |
| statep->callbacks.create_relocations = elf_i386_create_relocations; |
| |
| return 0; |
| } |