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- /* Run an ELF binary on a linux system.
- Copyright (C) 1993, Eric Youngdale.
- This program 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 2, or (at your option)
- any later version.
- This program 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, write to the Free Software
- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
- #ifndef VERBOSE_DLINKER
- #define VERBOSE_DLINKER
- #endif
- #ifdef VERBOSE_DLINKER
- static char *_dl_reltypes[] =
- { "R_ARM_NONE", "R_ARM_PC24", "R_ARM_ABS32", "R_ARM_REL32",
- "R_ARM_PC13", "R_ARM_ABS16", "R_ARM_ABS12", "R_ARM_THM_ABS5",
- "R_ARM_ABS8", "R_ARM_SBREL32", "R_ARM_THM_PC22", "R_ARM_THM_PC8",
- "R_ARM_AMP_VCALL9", "R_ARM_SWI24", "R_ARM_THM_SWI8", "R_ARM_XPC25",
- "R_ARM_THM_XPC22", "R_ARM_COPY", "R_ARM_GLOB_DAT", "R_ARM_JUMP_SLOT",
- "R_ARM_RELATIVE", "R_ARM_GOTOFF", "R_ARM_GOTPC", "R_ARM_GOT32",
- "R_ARM_PLT32", "R_ARM_ALU_PCREL_7_0", "R_ARM_ALU_PCREL_15_8",
- "R_ARM_ALU_PCREL_23_15", "R_ARM_LDR_SBREL_11_0", "R_ARM_ALU_SBREL_19_12",
- "R_ARM_ALU_SBREL_27_20", "R_ARM_GNU_VTENTRY", "R_ARM_GNU_VTINHERIT",
- "R_ARM_THM_PC11", "R_ARM_THM_PC9", "R_ARM_RXPC25", "R_ARM_RSBREL32",
- "R_ARM_THM_RPC22", "R_ARM_RREL32", "R_ARM_RABS22", "R_ARM_RPC24",
- "R_ARM_RBASE", "R_ARM_NUM"
- };
- #endif
- /* Program to load an ELF binary on a linux system, and run it.
- References to symbols in sharable libraries can be resolved by either
- an ELF sharable library or a linux style of shared library. */
- /* Disclaimer: I have never seen any AT&T source code for SVr4, nor have
- I ever taken any courses on internals. This program was developed using
- information available through the book "UNIX SYSTEM V RELEASE 4,
- Programmers guide: Ansi C and Programming Support Tools", which did
- a more than adequate job of explaining everything required to get this
- working. */
- #include <sys/types.h>
- #include <errno.h>
- #include "elf.h"
- #include "hash.h"
- #include "syscall.h"
- #include "string.h"
- #include "sysdep.h"
- extern char *_dl_progname;
- extern int _dl_linux_resolve(void);
- unsigned long _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
- {
- int reloc_type;
- Elf32_Rel *this_reloc;
- char *strtab;
- Elf32_Sym *symtab;
- Elf32_Rel *rel_addr;
- int symtab_index;
- char *new_addr;
- char **got_addr;
- unsigned long instr_addr;
- rel_addr = (Elf32_Rel *) (tpnt->dynamic_info[DT_JMPREL] + tpnt->loadaddr);
- this_reloc = rel_addr + (reloc_entry >> 3);
- reloc_type = ELF32_R_TYPE(this_reloc->r_info);
- symtab_index = ELF32_R_SYM(this_reloc->r_info);
- symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
- strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
- if (reloc_type != R_ARM_JUMP_SLOT) {
- _dl_fdprintf(2, "%s: Incorrect relocation type in jump relocations\n",
- _dl_progname);
- _dl_exit(1);
- };
-
- /* Address of jump instruction to fix up */
- instr_addr = ((unsigned long) this_reloc->r_offset +
- (unsigned long) tpnt->loadaddr);
- got_addr = (char **) instr_addr;
- #ifdef DL_DEBUG
- _dl_fdprintf(2, "Resolving symbol %s\n",
- strtab + symtab[symtab_index].st_name);
- #endif
- /* Get the address of the GOT entry */
- new_addr = _dl_find_hash(strtab + symtab[symtab_index].st_name,
- tpnt->symbol_scope, (unsigned long) got_addr, tpnt, 0);
- if (!new_addr) {
- _dl_fdprintf(2, "%s: can't resolve symbol '%s'\n",
- _dl_progname, strtab + symtab[symtab_index].st_name);
- _dl_exit(1);
- };
- #ifdef DL_DEBUG
- if ((unsigned long) got_addr < 0x40000000) {
- _dl_fdprintf(2, "Calling library function: %s\n",
- strtab + symtab[symtab_index].st_name);
- } else {
- *got_addr = new_addr;
- }
- #else
- *got_addr = new_addr;
- #endif
- return (unsigned long) new_addr;
- }
- void _dl_parse_lazy_relocation_information(struct elf_resolve *tpnt,
- unsigned long rel_addr, unsigned long rel_size, int type)
- {
- int i;
- char *strtab;
- int reloc_type;
- int symtab_index;
- Elf32_Sym *symtab;
- Elf32_Rel *rpnt;
- unsigned long *reloc_addr;
- /* Now parse the relocation information */
- rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
- rel_size = rel_size / sizeof(Elf32_Rel);
- symtab =
- (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
- strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
- for (i = 0; i < rel_size; i++, rpnt++) {
- reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
- reloc_type = ELF32_R_TYPE(rpnt->r_info);
- symtab_index = ELF32_R_SYM(rpnt->r_info);
- /* When the dynamic linker bootstrapped itself, it resolved some symbols.
- Make sure we do not do them again */
- if (!symtab_index && tpnt->libtype == program_interpreter)
- continue;
- if (symtab_index && tpnt->libtype == program_interpreter &&
- _dl_symbol(strtab + symtab[symtab_index].st_name))
- continue;
- switch (reloc_type) {
- case R_ARM_NONE:
- break;
- case R_ARM_JUMP_SLOT:
- *reloc_addr += (unsigned long) tpnt->loadaddr;
- break;
- default:
- _dl_fdprintf(2, "%s: (LAZY) can't handle reloc type ",
- _dl_progname);
- #ifdef VERBOSE_DLINKER
- _dl_fdprintf(2, "%s ", _dl_reltypes[reloc_type]);
- #endif
- if (symtab_index)
- _dl_fdprintf(2, "'%s'\n", strtab + symtab[symtab_index].st_name);
- _dl_exit(1);
- };
- };
- }
- static unsigned long
- fix_bad_pc24 (unsigned long *const reloc_addr, unsigned long value)
- {
- static void *fix_page;
- static unsigned int fix_offset;
- unsigned int *fix_address;
- if (! fix_page)
- {
- fix_page = _dl_mmap (NULL, 4096 , PROT_READ | PROT_WRITE | PROT_EXEC,
- MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
- fix_offset = 0;
- }
- fix_address = (unsigned int *)(fix_page + fix_offset);
- fix_address[0] = 0xe51ff004; /* ldr pc, [pc, #-4] */
- fix_address[1] = value;
- fix_offset += 8;
- if (fix_offset >= 4096)
- fix_page = NULL;
- return (unsigned long)fix_address;
- }
- int _dl_parse_relocation_information(struct elf_resolve *tpnt,
- unsigned long rel_addr, unsigned long rel_size, int type)
- {
- int i;
- char *strtab;
- int reloc_type;
- int goof = 0;
- Elf32_Sym *symtab;
- Elf32_Rel *rpnt;
- unsigned long *reloc_addr;
- unsigned long symbol_addr;
- int symtab_index;
- /* Now parse the relocation information */
- rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
- rel_size = rel_size / sizeof(Elf32_Rel);
- symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
- strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
- for (i = 0; i < rel_size; i++, rpnt++) {
- reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
- reloc_type = ELF32_R_TYPE(rpnt->r_info);
- symtab_index = ELF32_R_SYM(rpnt->r_info);
- symbol_addr = 0;
- if (!symtab_index && tpnt->libtype == program_interpreter)
- continue;
- if (symtab_index) {
- if (tpnt->libtype == program_interpreter &&
- _dl_symbol(strtab + symtab[symtab_index].st_name))
- continue;
- symbol_addr = (unsigned long) _dl_find_hash(strtab + symtab[symtab_index].st_name,
- tpnt->symbol_scope, (unsigned long) reloc_addr,
- (reloc_type == R_ARM_JUMP_SLOT ? tpnt : NULL), 0);
- /*
- * We want to allow undefined references to weak symbols - this might
- * have been intentional. We should not be linking local symbols
- * here, so all bases should be covered.
- */
- if (!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) == STB_GLOBAL) {
- _dl_fdprintf(2, "%s: can't resolve symbol '%s'\n",
- _dl_progname, strtab + symtab[symtab_index].st_name);
- goof++;
- }
- }
- switch (reloc_type) {
- case R_ARM_NONE:
- break;
- case R_ARM_ABS32:
- *reloc_addr += symbol_addr;
- break;
- case R_ARM_PC24:
- {
- unsigned long addend;
- long newvalue, topbits;
- addend = *reloc_addr & 0x00ffffff;
- if (addend & 0x00800000) addend |= 0xff000000;
- newvalue = symbol_addr - (unsigned long)reloc_addr + (addend << 2);
- topbits = newvalue & 0xfe000000;
- if (topbits != 0xfe000000 && topbits != 0x00000000)
- {
- newvalue = fix_bad_pc24(reloc_addr, symbol_addr)
- - (unsigned long)reloc_addr + (addend << 2);
- topbits = newvalue & 0xfe000000;
- if (topbits != 0xfe000000 && topbits != 0x00000000)
- {
- _dl_fdprintf(2, "R_ARM_PC24 relocation out of range ");
- _dl_exit(1);
- }
- }
- newvalue >>= 2;
- symbol_addr = (*reloc_addr & 0xff000000) | (newvalue & 0x00ffffff);
- *reloc_addr = symbol_addr;
- break;
- }
- case R_ARM_GLOB_DAT:
- case R_ARM_JUMP_SLOT:
- *reloc_addr = symbol_addr;
- break;
- case R_ARM_RELATIVE:
- *reloc_addr += (unsigned long) tpnt->loadaddr;
- break;
- case R_ARM_COPY:
- #if 0
- /* Do this later */
- _dl_fdprintf(2, "Doing copy for symbol ");
- if (symtab_index) _dl_fdprintf(2, strtab + symtab[symtab_index].st_name);
- _dl_fdprintf(2, "\n");
- _dl_memcpy((void *) symtab[symtab_index].st_value,
- (void *) symbol_addr, symtab[symtab_index].st_size);
- #endif
- break;
- default:
- _dl_fdprintf(2, "%s: can't handle reloc type ", _dl_progname);
- #ifdef VERBOSE_DLINKER
- _dl_fdprintf(2, "%s ", _dl_reltypes[reloc_type]);
- #endif
- if (symtab_index)
- _dl_fdprintf(2, "'%s'\n", strtab + symtab[symtab_index].st_name);
- _dl_exit(1);
- };
- };
- return goof;
- }
- /* This is done as a separate step, because there are cases where
- information is first copied and later initialized. This results in
- the wrong information being copied. Someone at Sun was complaining about
- a bug in the handling of _COPY by SVr4, and this may in fact be what he
- was talking about. Sigh. */
- /* No, there are cases where the SVr4 linker fails to emit COPY relocs
- at all */
- int _dl_parse_copy_information(struct dyn_elf *xpnt, unsigned long rel_addr,
- unsigned long rel_size, int type)
- {
- int i;
- char *strtab;
- int reloc_type;
- int goof = 0;
- Elf32_Sym *symtab;
- Elf32_Rel *rpnt;
- unsigned long *reloc_addr;
- unsigned long symbol_addr;
- struct elf_resolve *tpnt;
- int symtab_index;
- /* Now parse the relocation information */
- tpnt = xpnt->dyn;
- rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
- rel_size = rel_size / sizeof(Elf32_Rel);
- symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
- strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
- for (i = 0; i < rel_size; i++, rpnt++) {
- reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
- reloc_type = ELF32_R_TYPE(rpnt->r_info);
- if (reloc_type != R_ARM_COPY)
- continue;
- symtab_index = ELF32_R_SYM(rpnt->r_info);
- symbol_addr = 0;
- if (!symtab_index && tpnt->libtype == program_interpreter)
- continue;
- if (symtab_index) {
- if (tpnt->libtype == program_interpreter &&
- _dl_symbol(strtab + symtab[symtab_index].st_name))
- continue;
- symbol_addr = (unsigned long) _dl_find_hash(strtab +
- symtab[symtab_index].st_name, xpnt->next,
- (unsigned long) reloc_addr, NULL, 1);
- if (!symbol_addr) {
- _dl_fdprintf(2, "%s: can't resolve symbol '%s'\n",
- _dl_progname, strtab + symtab[symtab_index].st_name);
- goof++;
- };
- };
- if (!goof) {
- _dl_memcpy((char *) symtab[symtab_index].st_value,
- (char *) symbol_addr, symtab[symtab_index].st_size);
- }
- };
- return goof;
- }
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