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680e84fe42
local symbols can be resolved statically, they don't have to be done dynamically, so this is a slight speedup at load time for produced executables and shared libs. The musl libc also rejects any STB_LOCAL symbols for dynamic symbol resolution, so there it also fixes use of shared libs created by tcc.
251 lines
7.3 KiB
C
251 lines
7.3 KiB
C
#ifdef TARGET_DEFS_ONLY
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#define EM_TCC_TARGET EM_X86_64
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/* relocation type for 32 bit data relocation */
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#define R_DATA_32 R_X86_64_32S
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#define R_DATA_PTR R_X86_64_64
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#define R_JMP_SLOT R_X86_64_JUMP_SLOT
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#define R_GLOB_DAT R_X86_64_GLOB_DAT
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#define R_COPY R_X86_64_COPY
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#define R_RELATIVE R_X86_64_RELATIVE
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#define R_NUM R_X86_64_NUM
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#define ELF_START_ADDR 0x400000
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#define ELF_PAGE_SIZE 0x200000
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#define PCRELATIVE_DLLPLT 1
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#define RELOCATE_DLLPLT 1
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#else /* !TARGET_DEFS_ONLY */
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#include "tcc.h"
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/* Returns 1 for a code relocation, 0 for a data relocation. For unknown
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relocations, returns -1. */
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int code_reloc (int reloc_type)
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{
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switch (reloc_type) {
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case R_X86_64_32:
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case R_X86_64_32S:
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case R_X86_64_64:
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case R_X86_64_GOTPCREL:
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case R_X86_64_GOTPCRELX:
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case R_X86_64_REX_GOTPCRELX:
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case R_X86_64_GOTTPOFF:
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case R_X86_64_GOT32:
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case R_X86_64_GLOB_DAT:
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case R_X86_64_COPY:
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case R_X86_64_RELATIVE:
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return 0;
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case R_X86_64_PC32:
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case R_X86_64_PLT32:
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case R_X86_64_JUMP_SLOT:
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return 1;
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}
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tcc_error ("Unknown relocation type: %d", reloc_type);
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return -1;
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}
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/* Returns an enumerator to describe wether and when the relocation needs a
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GOT and/or PLT entry to be created. See tcc.h for a description of the
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different values. */
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int gotplt_entry_type (int reloc_type)
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{
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switch (reloc_type) {
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case R_X86_64_GLOB_DAT:
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case R_X86_64_JUMP_SLOT:
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case R_X86_64_COPY:
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case R_X86_64_RELATIVE:
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return NO_GOTPLT_ENTRY;
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/* The following relocs wouldn't normally need GOT or PLT
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slots, but we need them for simplicity in the link
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editor part. See our caller for comments. */
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case R_X86_64_32:
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case R_X86_64_32S:
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case R_X86_64_64:
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case R_X86_64_PC32:
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return AUTO_GOTPLT_ENTRY;
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case R_X86_64_GOTTPOFF:
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return BUILD_GOT_ONLY;
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case R_X86_64_GOT32:
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case R_X86_64_GOTPCREL:
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case R_X86_64_GOTPCRELX:
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case R_X86_64_REX_GOTPCRELX:
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case R_X86_64_PLT32:
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return ALWAYS_GOTPLT_ENTRY;
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}
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tcc_error ("Unknown relocation type: %d", reloc_type);
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return -1;
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}
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ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
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{
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Section *plt = s1->plt;
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uint8_t *p;
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int modrm;
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unsigned plt_offset, relofs;
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modrm = 0x25;
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/* empty PLT: create PLT0 entry that pushes the library indentifier
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(GOT + PTR_SIZE) and jumps to ld.so resolution routine
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(GOT + 2 * PTR_SIZE) */
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if (plt->data_offset == 0) {
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p = section_ptr_add(plt, 16);
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p[0] = 0xff; /* pushl got + PTR_SIZE */
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p[1] = modrm + 0x10;
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write32le(p + 2, PTR_SIZE);
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p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
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p[7] = modrm;
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write32le(p + 8, PTR_SIZE * 2);
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}
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plt_offset = plt->data_offset;
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/* The PLT slot refers to the relocation entry it needs via offset.
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The reloc entry is created below, so its offset is the current
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data_offset */
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relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0;
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/* Jump to GOT entry where ld.so initially put the address of ip + 4 */
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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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write32le(p + 2, got_offset);
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p[6] = 0x68; /* push $xxx */
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/* On x86-64, the relocation is referred to by _index_ */
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write32le(p + 7, relofs / sizeof (ElfW_Rel));
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p[11] = 0xe9; /* jmp plt_start */
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write32le(p + 12, -(plt->data_offset));
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return plt_offset;
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}
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/* relocate the PLT: compute addresses and offsets in the PLT now that final
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address for PLT and GOT are known (see fill_program_header) */
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ST_FUNC void relocate_plt(TCCState *s1)
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{
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uint8_t *p, *p_end;
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if (!s1->plt)
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return;
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p = s1->plt->data;
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p_end = p + s1->plt->data_offset;
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if (p < p_end) {
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int x = s1->got->sh_addr - s1->plt->sh_addr - 6;
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add32le(p + 2, x);
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add32le(p + 8, x - 6);
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p += 16;
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while (p < p_end) {
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add32le(p + 2, x + s1->plt->data - p);
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p += 16;
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}
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}
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}
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static ElfW_Rel *qrel; /* ptr to next reloc entry reused */
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void relocate_init(Section *sr)
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{
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qrel = (ElfW_Rel *) sr->data;
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}
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void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
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{
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int sym_index, esym_index;
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sym_index = ELFW(R_SYM)(rel->r_info);
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switch (type) {
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case R_X86_64_64:
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if (s1->output_type == TCC_OUTPUT_DLL) {
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esym_index = s1->sym_attrs[sym_index].dyn_index;
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qrel->r_offset = rel->r_offset;
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if (esym_index) {
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qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64);
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qrel->r_addend = rel->r_addend;
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qrel++;
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break;
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} else {
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qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
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qrel->r_addend = read64le(ptr) + val;
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qrel++;
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}
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}
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add64le(ptr, val);
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break;
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case R_X86_64_32:
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case R_X86_64_32S:
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if (s1->output_type == TCC_OUTPUT_DLL) {
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/* XXX: this logic may depend on TCC's codegen
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now TCC uses R_X86_64_32 even for a 64bit pointer */
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qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
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/* Use sign extension! */
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qrel->r_addend = (int)read32le(ptr) + val;
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qrel++;
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}
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add32le(ptr, val);
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break;
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case R_X86_64_PC32:
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if (s1->output_type == TCC_OUTPUT_DLL) {
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/* DLL relocation */
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esym_index = s1->sym_attrs[sym_index].dyn_index;
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if (esym_index) {
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qrel->r_offset = rel->r_offset;
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qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
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/* Use sign extension! */
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qrel->r_addend = (int)read32le(ptr) + rel->r_addend;
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qrel++;
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break;
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}
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}
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goto plt32pc32;
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case R_X86_64_PLT32:
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/* fallthrough: val already holds the PLT slot address */
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plt32pc32:
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{
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long long diff;
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diff = (long long)val - addr;
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if (diff < -2147483648LL || diff > 2147483647LL) {
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tcc_error("internal error: relocation failed");
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}
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add32le(ptr, diff);
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}
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break;
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case R_X86_64_GLOB_DAT:
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case R_X86_64_JUMP_SLOT:
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/* They don't need addend */
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write64le(ptr, val - rel->r_addend);
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break;
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case R_X86_64_GOTPCREL:
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case R_X86_64_GOTPCRELX:
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case R_X86_64_REX_GOTPCRELX:
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add32le(ptr, s1->got->sh_addr - addr +
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s1->sym_attrs[sym_index].got_offset - 4);
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break;
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case R_X86_64_GOTTPOFF:
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add32le(ptr, val - s1->got->sh_addr);
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break;
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case R_X86_64_GOT32:
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/* we load the got offset */
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add32le(ptr, s1->sym_attrs[sym_index].got_offset);
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break;
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case R_X86_64_RELATIVE:
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/* do nothing */
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break;
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}
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}
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#endif /* !TARGET_DEFS_ONLY */
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