#ifdef TARGET_DEFS_ONLY #define EM_TCC_TARGET EM_ARM /* relocation type for 32 bit data relocation */ #define R_DATA_32 R_ARM_ABS32 #define R_DATA_PTR R_ARM_ABS32 #define R_JMP_SLOT R_ARM_JUMP_SLOT #define R_GLOB_DAT R_ARM_GLOB_DAT #define R_COPY R_ARM_COPY #define R_RELATIVE R_ARM_RELATIVE #define R_NUM R_ARM_NUM #define ELF_START_ADDR 0x00008000 #define ELF_PAGE_SIZE 0x1000 #define PCRELATIVE_DLLPLT 1 #define RELOCATE_DLLPLT 0 enum float_abi { ARM_SOFTFP_FLOAT, ARM_HARD_FLOAT, }; #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_ARM_MOVT_ABS: case R_ARM_MOVW_ABS_NC: case R_ARM_THM_MOVT_ABS: case R_ARM_THM_MOVW_ABS_NC: case R_ARM_ABS32: case R_ARM_REL32: case R_ARM_GOTPC: case R_ARM_GOTOFF: case R_ARM_GOT32: case R_ARM_COPY: case R_ARM_GLOB_DAT: case R_ARM_NONE: return 0; case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: case R_ARM_PLT32: case R_ARM_THM_PC22: case R_ARM_THM_JUMP24: case R_ARM_PREL31: case R_ARM_V4BX: case R_ARM_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_ARM_NONE: case R_ARM_COPY: case R_ARM_GLOB_DAT: case R_ARM_JUMP_SLOT: return NO_GOTPLT_ENTRY; case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: case R_ARM_PLT32: case R_ARM_THM_PC22: case R_ARM_THM_JUMP24: case R_ARM_MOVT_ABS: case R_ARM_MOVW_ABS_NC: case R_ARM_THM_MOVT_ABS: case R_ARM_THM_MOVW_ABS_NC: case R_ARM_PREL31: case R_ARM_ABS32: case R_ARM_REL32: case R_ARM_V4BX: return AUTO_GOTPLT_ENTRY; case R_ARM_GOTPC: case R_ARM_GOTOFF: return BUILD_GOT_ONLY; case R_ARM_GOT32: 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; unsigned plt_offset; /* when building a DLL, GOT entry accesses must be done relative to start of GOT (see x86_64 example above) */ if (s1->output_type == TCC_OUTPUT_DLL) tcc_error("DLLs unimplemented!"); /* empty PLT: create PLT0 entry that push address of call site and jump to ld.so resolution routine (GOT + 8) */ if (plt->data_offset == 0) { p = section_ptr_add(plt, 20); write32le(p, 0xe52de004); /* push {lr} */ write32le(p+4, 0xe59fe004); /* ldr lr, [pc, #4] */ write32le(p+8, 0xe08fe00e); /* add lr, pc, lr */ write32le(p+12, 0xe5bef008); /* ldr pc, [lr, #8]! */ /* p+16 is set in relocate_plt */ } plt_offset = plt->data_offset; if (attr->plt_thumb_stub) { p = section_ptr_add(plt, 4); write32le(p, 0x4778); /* bx pc */ write32le(p+2, 0x46c0); /* nop */ } p = section_ptr_add(plt, 16); /* Jump to GOT entry where ld.so initially put address of PLT0 */ write32le(p, 0xe59fc004); /* ldr ip, [pc, #4] */ write32le(p+4, 0xe08fc00c); /* add ip, pc, ip */ write32le(p+8, 0xe59cf000); /* ldr pc, [ip] */ /* p + 12 contains offset to GOT entry once patched by relocate_plt */ write32le(p+12, got_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 - 12; write32le(s1->plt->data + 16, x - 16); p += 20; while (p < p_end) { if (read32le(p) == 0x46c04778) /* PLT Thumb stub present */ p += 4; add32le(p + 12, x + s1->plt->data - p); p += 16; } } } void relocate_init(Section *sr) {} void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val) { ElfW(Sym) *sym; int sym_index; sym_index = ELFW(R_SYM)(rel->r_info); sym = &((ElfW(Sym) *)symtab_section->data)[sym_index]; switch(type) { case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: case R_ARM_PLT32: { int x, is_thumb, is_call, h, blx_avail, is_bl, th_ko; x = (*(int *) ptr) & 0xffffff; #ifdef DEBUG_RELOC printf ("reloc %d: x=0x%x val=0x%x ", type, x, val); #endif (*(int *)ptr) &= 0xff000000; if (x & 0x800000) x -= 0x1000000; x <<= 2; blx_avail = (TCC_CPU_VERSION >= 5); is_thumb = val & 1; is_bl = (*(unsigned *) ptr) >> 24 == 0xeb; is_call = (type == R_ARM_CALL || (type == R_ARM_PC24 && is_bl)); x += val - addr; #ifdef DEBUG_RELOC printf (" newx=0x%x name=%s\n", x, (char *) symtab_section->link->data + sym->st_name); #endif h = x & 2; th_ko = (x & 3) && (!blx_avail || !is_call); if (th_ko || x >= 0x2000000 || x < -0x2000000) tcc_error("can't relocate value at %x,%d",addr, type); x >>= 2; x &= 0xffffff; /* Only reached if blx is avail and it is a call */ if (is_thumb) { x |= h << 24; (*(int *)ptr) = 0xfa << 24; /* bl -> blx */ } (*(int *) ptr) |= x; } return; /* Since these relocations only concern Thumb-2 and blx instruction was introduced before Thumb-2, we can assume blx is available and not guard its use */ case R_ARM_THM_PC22: case R_ARM_THM_JUMP24: { int x, hi, lo, s, j1, j2, i1, i2, imm10, imm11; int to_thumb, is_call, to_plt, blx_bit = 1 << 12; Section *plt; /* weak reference */ if (sym->st_shndx == SHN_UNDEF && ELFW(ST_BIND)(sym->st_info) == STB_WEAK) return; /* Get initial offset */ hi = (*(uint16_t *)ptr); lo = (*(uint16_t *)(ptr+2)); s = (hi >> 10) & 1; j1 = (lo >> 13) & 1; j2 = (lo >> 11) & 1; i1 = (j1 ^ s) ^ 1; i2 = (j2 ^ s) ^ 1; imm10 = hi & 0x3ff; imm11 = lo & 0x7ff; x = (s << 24) | (i1 << 23) | (i2 << 22) | (imm10 << 12) | (imm11 << 1); if (x & 0x01000000) x -= 0x02000000; /* Relocation infos */ to_thumb = val & 1; plt = s1->plt; to_plt = (val >= plt->sh_addr) && (val < plt->sh_addr + plt->data_offset); is_call = (type == R_ARM_THM_PC22); if (!to_thumb && !to_plt && !is_call) { int index; uint8_t *p; char *name, buf[1024]; Section *text_section; name = (char *) symtab_section->link->data + sym->st_name; text_section = s1->sections[sym->st_shndx]; /* Modify reloc to target a thumb stub to switch to ARM */ snprintf(buf, sizeof(buf), "%s_from_thumb", name); index = put_elf_sym(symtab_section, text_section->data_offset + 1, sym->st_size, sym->st_info, 0, sym->st_shndx, buf); to_thumb = 1; val = text_section->data_offset + 1; rel->r_info = ELFW(R_INFO)(index, type); /* Create a thumb stub function to switch to ARM mode */ put_elf_reloc(symtab_section, text_section, text_section->data_offset + 4, R_ARM_JUMP24, sym_index); p = section_ptr_add(text_section, 8); write32le(p, 0x4778); /* bx pc */ write32le(p+2, 0x46c0); /* nop */ write32le(p+4, 0xeafffffe); /* b $sym */ } /* Compute final offset */ x += val - addr; if (!to_thumb && is_call) { blx_bit = 0; /* bl -> blx */ x = (x + 3) & -4; /* Compute offset from aligned PC */ } /* Check that relocation is possible * offset must not be out of range * if target is to be entered in arm mode: - bit 1 must not set - instruction must be a call (bl) or a jump to PLT */ if (!to_thumb || x >= 0x1000000 || x < -0x1000000) if (to_thumb || (val & 2) || (!is_call && !to_plt)) tcc_error("can't relocate value at %x,%d",addr, type); /* Compute and store final offset */ s = (x >> 24) & 1; i1 = (x >> 23) & 1; i2 = (x >> 22) & 1; j1 = s ^ (i1 ^ 1); j2 = s ^ (i2 ^ 1); imm10 = (x >> 12) & 0x3ff; imm11 = (x >> 1) & 0x7ff; (*(uint16_t *)ptr) = (uint16_t) ((hi & 0xf800) | (s << 10) | imm10); (*(uint16_t *)(ptr+2)) = (uint16_t) ((lo & 0xc000) | (j1 << 13) | blx_bit | (j2 << 11) | imm11); } return; case R_ARM_MOVT_ABS: case R_ARM_MOVW_ABS_NC: { int x, imm4, imm12; if (type == R_ARM_MOVT_ABS) val >>= 16; imm12 = val & 0xfff; imm4 = (val >> 12) & 0xf; x = (imm4 << 16) | imm12; if (type == R_ARM_THM_MOVT_ABS) *(int *)ptr |= x; else *(int *)ptr += x; } return; case R_ARM_THM_MOVT_ABS: case R_ARM_THM_MOVW_ABS_NC: { int x, i, imm4, imm3, imm8; if (type == R_ARM_THM_MOVT_ABS) val >>= 16; imm8 = val & 0xff; imm3 = (val >> 8) & 0x7; i = (val >> 11) & 1; imm4 = (val >> 12) & 0xf; x = (imm3 << 28) | (imm8 << 16) | (i << 10) | imm4; if (type == R_ARM_THM_MOVT_ABS) *(int *)ptr |= x; else *(int *)ptr += x; } return; case R_ARM_PREL31: { int x; x = (*(int *)ptr) & 0x7fffffff; (*(int *)ptr) &= 0x80000000; x = (x * 2) / 2; x += val - addr; if((x^(x>>1))&0x40000000) tcc_error("can't relocate value at %x,%d",addr, type); (*(int *)ptr) |= x & 0x7fffffff; } case R_ARM_ABS32: *(int *)ptr += val; return; case R_ARM_REL32: *(int *)ptr += val - addr; return; case R_ARM_GOTPC: *(int *)ptr += s1->got->sh_addr - addr; return; case R_ARM_GOTOFF: *(int *)ptr += val - s1->got->sh_addr; return; case R_ARM_GOT32: /* we load the got offset */ *(int *)ptr += s1->sym_attrs[sym_index].got_offset; return; case R_ARM_COPY: return; case R_ARM_V4BX: /* trade Thumb support for ARMv4 support */ if ((0x0ffffff0 & *(int*)ptr) == 0x012FFF10) *(int*)ptr ^= 0xE12FFF10 ^ 0xE1A0F000; /* BX Rm -> MOV PC, Rm */ return; case R_ARM_GLOB_DAT: case R_ARM_JUMP_SLOT: *(addr_t *)ptr = val; return; case R_ARM_NONE: /* Nothing to do. Normally used to indicate a dependency on a certain symbol (like for exception handling under EABI). */ return; case R_ARM_RELATIVE: #ifdef TCC_TARGET_PE add32le(ptr, val - s1->pe_imagebase); #endif /* do nothing */ return; default: fprintf(stderr,"FIXME: handle reloc type %x at %x [%p] to %x\n", type, (unsigned)addr, ptr, (unsigned)val); return; } } #endif /* !TARGET_DEFS_ONLY */