// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2017 Josh Poimboeuf */ #include #include #include "check.h" #include "warn.h" int create_orc(struct objtool_file *file) { struct instruction *insn; for_each_insn(file, insn) { struct orc_entry *orc = &insn->orc; struct cfi_reg *cfa = &insn->cfi.cfa; struct cfi_reg *bp = &insn->cfi.regs[CFI_BP]; orc->end = insn->cfi.end; if (cfa->base == CFI_UNDEFINED) { orc->sp_reg = ORC_REG_UNDEFINED; continue; } switch (cfa->base) { case CFI_SP: orc->sp_reg = ORC_REG_SP; break; case CFI_SP_INDIRECT: orc->sp_reg = ORC_REG_SP_INDIRECT; break; case CFI_BP: orc->sp_reg = ORC_REG_BP; break; case CFI_BP_INDIRECT: orc->sp_reg = ORC_REG_BP_INDIRECT; break; case CFI_R10: orc->sp_reg = ORC_REG_R10; break; case CFI_R13: orc->sp_reg = ORC_REG_R13; break; case CFI_DI: orc->sp_reg = ORC_REG_DI; break; case CFI_DX: orc->sp_reg = ORC_REG_DX; break; default: WARN_FUNC("unknown CFA base reg %d", insn->sec, insn->offset, cfa->base); return -1; } switch(bp->base) { case CFI_UNDEFINED: orc->bp_reg = ORC_REG_UNDEFINED; break; case CFI_CFA: orc->bp_reg = ORC_REG_PREV_SP; break; case CFI_BP: orc->bp_reg = ORC_REG_BP; break; default: WARN_FUNC("unknown BP base reg %d", insn->sec, insn->offset, bp->base); return -1; } orc->sp_offset = cfa->offset; orc->bp_offset = bp->offset; orc->type = insn->cfi.type; } return 0; } static int create_orc_entry(struct elf *elf, struct section *u_sec, struct section *ip_relocsec, unsigned int idx, struct section *insn_sec, unsigned long insn_off, struct orc_entry *o) { struct orc_entry *orc; struct reloc *reloc; /* populate ORC data */ orc = (struct orc_entry *)u_sec->data->d_buf + idx; memcpy(orc, o, sizeof(*orc)); /* populate reloc for ip */ reloc = malloc(sizeof(*reloc)); if (!reloc) { perror("malloc"); return -1; } memset(reloc, 0, sizeof(*reloc)); if (insn_sec->sym) { reloc->sym = insn_sec->sym; reloc->addend = insn_off; } else { /* * The Clang assembler doesn't produce section symbols, so we * have to reference the function symbol instead: */ reloc->sym = find_symbol_containing(insn_sec, insn_off); if (!reloc->sym) { /* * Hack alert. This happens when we need to reference * the NOP pad insn immediately after the function. */ reloc->sym = find_symbol_containing(insn_sec, insn_off - 1); } if (!reloc->sym) { WARN("missing symbol for insn at offset 0x%lx\n", insn_off); return -1; } reloc->addend = insn_off - reloc->sym->offset; } reloc->type = R_X86_64_PC32; reloc->offset = idx * sizeof(int); reloc->sec = ip_relocsec; elf_add_reloc(elf, reloc); return 0; } int create_orc_sections(struct objtool_file *file) { struct instruction *insn, *prev_insn; struct section *sec, *u_sec, *ip_relocsec; unsigned int idx; struct orc_entry empty = { .sp_reg = ORC_REG_UNDEFINED, .bp_reg = ORC_REG_UNDEFINED, .type = ORC_TYPE_CALL, }; sec = find_section_by_name(file->elf, ".orc_unwind"); if (sec) { WARN("file already has .orc_unwind section, skipping"); return -1; } /* count the number of needed orcs */ idx = 0; for_each_sec(file, sec) { if (!sec->text) continue; prev_insn = NULL; sec_for_each_insn(file, sec, insn) { if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc, sizeof(struct orc_entry))) { idx++; } prev_insn = insn; } /* section terminator */ if (prev_insn) idx++; } if (!idx) return -1; /* create .orc_unwind_ip and .rela.orc_unwind_ip sections */ sec = elf_create_section(file->elf, ".orc_unwind_ip", sizeof(int), idx); if (!sec) return -1; ip_relocsec = elf_create_reloc_section(file->elf, sec, SHT_RELA); if (!ip_relocsec) return -1; /* create .orc_unwind section */ u_sec = elf_create_section(file->elf, ".orc_unwind", sizeof(struct orc_entry), idx); /* populate sections */ idx = 0; for_each_sec(file, sec) { if (!sec->text) continue; prev_insn = NULL; sec_for_each_insn(file, sec, insn) { if (!prev_insn || memcmp(&insn->orc, &prev_insn->orc, sizeof(struct orc_entry))) { if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx, insn->sec, insn->offset, &insn->orc)) return -1; idx++; } prev_insn = insn; } /* section terminator */ if (prev_insn) { if (create_orc_entry(file->elf, u_sec, ip_relocsec, idx, prev_insn->sec, prev_insn->offset + prev_insn->len, &empty)) return -1; idx++; } } if (elf_rebuild_reloc_section(ip_relocsec)) return -1; return 0; }