PLT generation fix
This commit is contained in:
bellard
parent
d6819c2c36
commit
c2e6daafc1
1 changed files with 68 additions and 46 deletions
110
tccelf.c
110
tccelf.c
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@ -433,7 +433,7 @@ static void relocate_syms(TCCState *s1, int do_resolve)
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}
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}
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}
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}
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/* relocate a given section (CPU dependant) */
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/* relocate a given section (CPU dependent) */
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static void relocate_section(TCCState *s1, Section *s)
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static void relocate_section(TCCState *s1, Section *s)
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{
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{
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Section *sr;
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Section *sr;
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@ -581,7 +581,7 @@ static void put_got_offset(TCCState *s1, int index, unsigned long val)
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}
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}
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/* XXX: suppress that */
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/* XXX: suppress that */
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static void put32(unsigned char *p, unsigned int val)
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static void put32(unsigned char *p, uint32_t val)
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{
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{
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p[0] = val;
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p[0] = val;
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p[1] = val >> 8;
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p[1] = val >> 8;
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@ -589,6 +589,11 @@ static void put32(unsigned char *p, unsigned int val)
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p[3] = val >> 24;
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p[3] = val >> 24;
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}
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}
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static uint32_t get32(unsigned char *p)
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{
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return p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
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}
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static void build_got(TCCState *s1)
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static void build_got(TCCState *s1)
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{
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{
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unsigned char *ptr;
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unsigned char *ptr;
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@ -632,10 +637,43 @@ static void put_got_entry(TCCState *s1,
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sym = &((Elf32_Sym *)symtab_section->data)[sym_index];
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sym = &((Elf32_Sym *)symtab_section->data)[sym_index];
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name = symtab_section->link->data + sym->st_name;
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name = symtab_section->link->data + sym->st_name;
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offset = sym->st_value;
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offset = sym->st_value;
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/* NOTE: we put temporarily the got offset */
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if (reloc_type == R_386_JMP_SLOT) {
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if (reloc_type == R_386_JMP_SLOT) {
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s1->nb_plt_entries++;
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Section *plt;
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offset = s1->got->data_offset;
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uint8_t *p;
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int modrm;
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/* if we build a DLL, we add a %ebx offset */
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if (s1->output_type == TCC_OUTPUT_DLL)
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modrm = 0xa3;
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else
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modrm = 0x25;
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/* add a PLT entry */
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plt = s1->plt;
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if (plt->data_offset == 0) {
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/* first plt entry */
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p = section_ptr_add(plt, 16);
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p[0] = 0xff; /* pushl got + 4 */
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p[1] = modrm + 0x10;
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put32(p + 2, 4);
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p[6] = 0xff; /* jmp *(got + 8) */
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p[7] = modrm;
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put32(p + 8, 8);
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}
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p = section_ptr_add(plt, 16);
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p[0] = 0xff; /* jmp *(got + x) */
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p[1] = modrm;
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put32(p + 2, s1->got->data_offset);
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p[6] = 0x68; /* push $xxx */
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put32(p + 7, (plt->data_offset - 32) >> 1);
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p[11] = 0xe9; /* jmp plt_start */
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put32(p + 12, -(plt->data_offset));
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/* the symbol is modified so that it will be relocated to
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the PLT */
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if (s1->output_type == TCC_OUTPUT_EXE)
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offset = plt->data_offset - 16;
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}
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}
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index = put_elf_sym(s1->dynsym, offset,
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index = put_elf_sym(s1->dynsym, offset,
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size, info, 0, sym->st_shndx, name);
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size, info, 0, sym->st_shndx, name);
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@ -847,7 +885,7 @@ int tcc_output_file(TCCState *s1, const char *filename)
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Section *strsec, *s;
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Section *strsec, *s;
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Elf32_Shdr shdr, *sh;
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Elf32_Shdr shdr, *sh;
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Elf32_Phdr *phdr, *ph;
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Elf32_Phdr *phdr, *ph;
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Section *interp, *plt, *dynamic, *dynstr;
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Section *interp, *dynamic, *dynstr;
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unsigned long saved_dynamic_data_offset;
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unsigned long saved_dynamic_data_offset;
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Elf32_Sym *sym;
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Elf32_Sym *sym;
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int type, file_type;
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int type, file_type;
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@ -863,7 +901,6 @@ int tcc_output_file(TCCState *s1, const char *filename)
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section_order = NULL;
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section_order = NULL;
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interp = NULL;
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interp = NULL;
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dynamic = NULL;
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dynamic = NULL;
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plt = NULL; /* avoid warning */
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dynstr = NULL; /* avoid warning */
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dynstr = NULL; /* avoid warning */
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saved_dynamic_data_offset = 0; /* avoid warning */
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saved_dynamic_data_offset = 0; /* avoid warning */
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@ -898,8 +935,9 @@ int tcc_output_file(TCCState *s1, const char *filename)
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dynamic->sh_entsize = sizeof(Elf32_Dyn);
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dynamic->sh_entsize = sizeof(Elf32_Dyn);
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/* add PLT */
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/* add PLT */
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plt = new_section(s1, ".plt", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR);
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s1->plt = new_section(s1, ".plt", SHT_PROGBITS,
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plt->sh_entsize = 4;
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SHF_ALLOC | SHF_EXECINSTR);
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s1->plt->sh_entsize = 4;
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build_got(s1);
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build_got(s1);
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@ -998,9 +1036,6 @@ int tcc_output_file(TCCState *s1, const char *filename)
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build_got_entries(s1);
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build_got_entries(s1);
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/* update PLT/GOT sizes so that we can allocate their space */
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plt->data_offset += 16 * (s1->nb_plt_entries + 1);
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/* add a list of needed dlls */
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/* add a list of needed dlls */
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for(i = 0; i < s1->nb_loaded_dlls; i++) {
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for(i = 0; i < s1->nb_loaded_dlls; i++) {
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DLLReference *dllref = s1->loaded_dlls[i];
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DLLReference *dllref = s1->loaded_dlls[i];
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@ -1191,8 +1226,6 @@ int tcc_output_file(TCCState *s1, const char *filename)
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/* if dynamic section, then add corresponing program header */
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/* if dynamic section, then add corresponing program header */
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if (dynamic) {
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if (dynamic) {
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int plt_offset;
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unsigned char *p;
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Elf32_Sym *sym_end;
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Elf32_Sym *sym_end;
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ph = &phdr[phnum - 1];
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ph = &phdr[phnum - 1];
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@ -1209,49 +1242,38 @@ int tcc_output_file(TCCState *s1, const char *filename)
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/* put GOT dynamic section address */
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/* put GOT dynamic section address */
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put32(s1->got->data, dynamic->sh_addr);
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put32(s1->got->data, dynamic->sh_addr);
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/* compute the PLT */
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/* relocate the PLT */
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plt->data_offset = 0;
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if (file_type == TCC_OUTPUT_EXE) {
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uint8_t *p, *p_end;
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/* first plt entry */
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p = s1->plt->data;
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p = section_ptr_add(plt, 16);
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p_end = p + s1->plt->data_offset;
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p[0] = 0xff; /* pushl got + 4 */
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put32(p + 2, get32(p + 2) + s1->got->sh_addr);
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p[1] = 0x35;
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put32(p + 8, get32(p + 8) + s1->got->sh_addr);
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put32(p + 2, s1->got->sh_addr + 4);
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p += 16;
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p[6] = 0xff; /* jmp *(got + 8) */
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while (p < p_end) {
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p[7] = 0x25;
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put32(p + 2, get32(p + 2) + s1->got->sh_addr);
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put32(p + 8, s1->got->sh_addr + 8);
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p += 16;
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}
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}
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/* relocation symbols in .dynsym and build PLT. */
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/* relocate symbols in .dynsym */
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plt_offset = 0;
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sym_end = (Elf32_Sym *)(s1->dynsym->data + s1->dynsym->data_offset);
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sym_end = (Elf32_Sym *)(s1->dynsym->data + s1->dynsym->data_offset);
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for(sym = (Elf32_Sym *)s1->dynsym->data + 1;
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for(sym = (Elf32_Sym *)s1->dynsym->data + 1;
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sym < sym_end;
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sym < sym_end;
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sym++) {
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sym++) {
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type = ELF32_ST_TYPE(sym->st_info);
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if (sym->st_shndx == SHN_UNDEF) {
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if (sym->st_shndx == SHN_UNDEF) {
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if (type == STT_FUNC) {
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/* relocate to the PLT if the symbol corresponds
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/* one more entry in PLT */
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to a PLT entry */
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p = section_ptr_add(plt, 16);
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if (sym->st_value)
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p[0] = 0xff; /* jmp *(got + x) */
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sym->st_value += s1->plt->sh_addr;
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p[1] = 0x25;
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put32(p + 2, s1->got->sh_addr + sym->st_value);
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p[6] = 0x68; /* push $xxx */
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put32(p + 7, plt_offset);
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p[11] = 0xe9; /* jmp plt_start */
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put32(p + 12, -(plt->data_offset));
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/* patch symbol value to point to plt */
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sym->st_value = plt->sh_addr + p - plt->data;
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plt_offset += 8;
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}
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} else if (sym->st_shndx < SHN_LORESERVE) {
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} else if (sym->st_shndx < SHN_LORESERVE) {
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/* do symbol relocation */
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/* do symbol relocation */
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sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
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sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
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}
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}
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}
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}
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/* put dynamic section entries */
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/* put dynamic section entries */
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dynamic->data_offset = saved_dynamic_data_offset;
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dynamic->data_offset = saved_dynamic_data_offset;
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put_dt(dynamic, DT_HASH, s1->dynsym->hash->sh_addr);
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put_dt(dynamic, DT_HASH, s1->dynsym->hash->sh_addr);
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put_dt(dynamic, DT_STRTAB, dynstr->sh_addr);
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put_dt(dynamic, DT_STRTAB, dynstr->sh_addr);
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