diff options
Diffstat (limited to 'tinyc/x86_64-link.c')
| -rw-r--r-- | tinyc/x86_64-link.c | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/tinyc/x86_64-link.c b/tinyc/x86_64-link.c new file mode 100644 index 000000000..c0c5e13bf --- /dev/null +++ b/tinyc/x86_64-link.c @@ -0,0 +1,295 @@ +#ifdef TARGET_DEFS_ONLY + +#define EM_TCC_TARGET EM_X86_64 + +/* relocation type for 32 bit data relocation */ +#define R_DATA_32 R_X86_64_32S +#define R_DATA_PTR R_X86_64_64 +#define R_JMP_SLOT R_X86_64_JUMP_SLOT +#define R_GLOB_DAT R_X86_64_GLOB_DAT +#define R_COPY R_X86_64_COPY +#define R_RELATIVE R_X86_64_RELATIVE + +#define R_NUM R_X86_64_NUM + +#define ELF_START_ADDR 0x400000 +#define ELF_PAGE_SIZE 0x200000 + +#define PCRELATIVE_DLLPLT 1 +#define RELOCATE_DLLPLT 1 + +#else /* !TARGET_DEFS_ONLY */ + +#include "tcc.h" + +/* Returns 1 for a code relocation, 0 for a data relocation. For unknown + relocations, returns -1. */ +int code_reloc (int reloc_type) +{ + switch (reloc_type) { + case R_X86_64_32: + case R_X86_64_32S: + case R_X86_64_64: + case R_X86_64_GOTPC32: + case R_X86_64_GOTPC64: + case R_X86_64_GOTPCREL: + case R_X86_64_GOTPCRELX: + case R_X86_64_REX_GOTPCRELX: + case R_X86_64_GOTTPOFF: + case R_X86_64_GOT32: + case R_X86_64_GOT64: + case R_X86_64_GLOB_DAT: + case R_X86_64_COPY: + case R_X86_64_RELATIVE: + case R_X86_64_GOTOFF64: + return 0; + + case R_X86_64_PC32: + case R_X86_64_PC64: + case R_X86_64_PLT32: + case R_X86_64_PLTOFF64: + case R_X86_64_JUMP_SLOT: + return 1; + } + + tcc_error ("Unknown relocation type: %d", reloc_type); + return -1; +} + +/* Returns an enumerator to describe whether and when the relocation needs a + GOT and/or PLT entry to be created. See tcc.h for a description of the + different values. */ +int gotplt_entry_type (int reloc_type) +{ + switch (reloc_type) { + case R_X86_64_GLOB_DAT: + case R_X86_64_JUMP_SLOT: + case R_X86_64_COPY: + case R_X86_64_RELATIVE: + return NO_GOTPLT_ENTRY; + + /* The following relocs wouldn't normally need GOT or PLT + slots, but we need them for simplicity in the link + editor part. See our caller for comments. */ + case R_X86_64_32: + case R_X86_64_32S: + case R_X86_64_64: + case R_X86_64_PC32: + case R_X86_64_PC64: + return AUTO_GOTPLT_ENTRY; + + case R_X86_64_GOTTPOFF: + return BUILD_GOT_ONLY; + + case R_X86_64_GOT32: + case R_X86_64_GOT64: + case R_X86_64_GOTPC32: + case R_X86_64_GOTPC64: + case R_X86_64_GOTOFF64: + case R_X86_64_GOTPCREL: + case R_X86_64_GOTPCRELX: + case R_X86_64_REX_GOTPCRELX: + case R_X86_64_PLT32: + case R_X86_64_PLTOFF64: + return ALWAYS_GOTPLT_ENTRY; + } + + tcc_error ("Unknown relocation type: %d", reloc_type); + return -1; +} + +ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr) +{ + Section *plt = s1->plt; + uint8_t *p; + int modrm; + unsigned plt_offset, relofs; + + modrm = 0x25; + + /* empty PLT: create PLT0 entry that pushes the library identifier + (GOT + PTR_SIZE) and jumps to ld.so resolution routine + (GOT + 2 * PTR_SIZE) */ + if (plt->data_offset == 0) { + p = section_ptr_add(plt, 16); + p[0] = 0xff; /* pushl got + PTR_SIZE */ + p[1] = modrm + 0x10; + write32le(p + 2, PTR_SIZE); + p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */ + p[7] = modrm; + write32le(p + 8, PTR_SIZE * 2); + } + plt_offset = plt->data_offset; + + /* The PLT slot refers to the relocation entry it needs via offset. + The reloc entry is created below, so its offset is the current + data_offset */ + relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0; + + /* Jump to GOT entry where ld.so initially put the address of ip + 4 */ + p = section_ptr_add(plt, 16); + p[0] = 0xff; /* jmp *(got + x) */ + p[1] = modrm; + write32le(p + 2, got_offset); + p[6] = 0x68; /* push $xxx */ + /* On x86-64, the relocation is referred to by _index_ */ + write32le(p + 7, relofs / sizeof (ElfW_Rel)); + p[11] = 0xe9; /* jmp plt_start */ + write32le(p + 12, -(plt->data_offset)); + return plt_offset; +} + +/* relocate the PLT: compute addresses and offsets in the PLT now that final + address for PLT and GOT are known (see fill_program_header) */ +ST_FUNC void relocate_plt(TCCState *s1) +{ + uint8_t *p, *p_end; + + if (!s1->plt) + return; + + p = s1->plt->data; + p_end = p + s1->plt->data_offset; + + if (p < p_end) { + int x = s1->got->sh_addr - s1->plt->sh_addr - 6; + add32le(p + 2, x); + add32le(p + 8, x - 6); + p += 16; + while (p < p_end) { + add32le(p + 2, x + s1->plt->data - p); + p += 16; + } + } +} + +static ElfW_Rel *qrel; /* ptr to next reloc entry reused */ + +void relocate_init(Section *sr) +{ + qrel = (ElfW_Rel *) sr->data; +} + +void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val) +{ + int sym_index, esym_index; + + sym_index = ELFW(R_SYM)(rel->r_info); + + switch (type) { + case R_X86_64_64: + if (s1->output_type == TCC_OUTPUT_DLL) { + esym_index = s1->sym_attrs[sym_index].dyn_index; + qrel->r_offset = rel->r_offset; + if (esym_index) { + qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64); + qrel->r_addend = rel->r_addend; + qrel++; + break; + } else { + qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE); + qrel->r_addend = read64le(ptr) + val; + qrel++; + } + } + add64le(ptr, val); + break; + case R_X86_64_32: + case R_X86_64_32S: + if (s1->output_type == TCC_OUTPUT_DLL) { + /* XXX: this logic may depend on TCC's codegen + now TCC uses R_X86_64_32 even for a 64bit pointer */ + qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE); + /* Use sign extension! */ + qrel->r_addend = (int)read32le(ptr) + val; + qrel++; + } + add32le(ptr, val); + break; + + case R_X86_64_PC32: + if (s1->output_type == TCC_OUTPUT_DLL) { + /* DLL relocation */ + esym_index = s1->sym_attrs[sym_index].dyn_index; + if (esym_index) { + qrel->r_offset = rel->r_offset; + qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32); + /* Use sign extension! */ + qrel->r_addend = (int)read32le(ptr) + rel->r_addend; + qrel++; + break; + } + } + goto plt32pc32; + + case R_X86_64_PLT32: + /* fallthrough: val already holds the PLT slot address */ + + plt32pc32: + { + long long diff; + diff = (long long)val - addr; + if (diff < -2147483648LL || diff > 2147483647LL) { + tcc_error("internal error: relocation failed"); + } + add32le(ptr, diff); + } + break; + + case R_X86_64_PLTOFF64: + add64le(ptr, val - s1->got->sh_addr + rel->r_addend); + break; + + case R_X86_64_PC64: + if (s1->output_type == TCC_OUTPUT_DLL) { + /* DLL relocation */ + esym_index = s1->sym_attrs[sym_index].dyn_index; + if (esym_index) { + qrel->r_offset = rel->r_offset; + qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC64); + qrel->r_addend = read64le(ptr) + rel->r_addend; + qrel++; + break; + } + } + add64le(ptr, val - addr); + break; + + case R_X86_64_GLOB_DAT: + case R_X86_64_JUMP_SLOT: + /* They don't need addend */ + write64le(ptr, val - rel->r_addend); + break; + case R_X86_64_GOTPCREL: + case R_X86_64_GOTPCRELX: + case R_X86_64_REX_GOTPCRELX: + add32le(ptr, s1->got->sh_addr - addr + + s1->sym_attrs[sym_index].got_offset - 4); + break; + case R_X86_64_GOTPC32: + add32le(ptr, s1->got->sh_addr - addr + rel->r_addend); + break; + case R_X86_64_GOTPC64: + add64le(ptr, s1->got->sh_addr - addr + rel->r_addend); + break; + case R_X86_64_GOTTPOFF: + add32le(ptr, val - s1->got->sh_addr); + break; + case R_X86_64_GOT32: + /* we load the got offset */ + add32le(ptr, s1->sym_attrs[sym_index].got_offset); + break; + case R_X86_64_GOT64: + /* we load the got offset */ + add64le(ptr, s1->sym_attrs[sym_index].got_offset); + break; + case R_X86_64_GOTOFF64: + add64le(ptr, val - s1->got->sh_addr); + break; + case R_X86_64_RELATIVE: + /* do nothing */ + break; + } +} + +#endif /* !TARGET_DEFS_ONLY */ |