diff options
Diffstat (limited to 'tools/objtool/orc_gen.c')
| -rw-r--r-- | tools/objtool/orc_gen.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c new file mode 100644 index 000000000..0b1ba8e7d --- /dev/null +++ b/tools/objtool/orc_gen.c @@ -0,0 +1,242 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <stdlib.h> +#include <string.h> + +#include "orc.h" +#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->state.cfa; + struct cfi_reg *bp = &insn->state.regs[CFI_BP]; + + orc->end = insn->state.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->state.type; + } + + return 0; +} + +static int create_orc_entry(struct section *u_sec, struct section *ip_relasec, + unsigned int idx, struct section *insn_sec, + unsigned long insn_off, struct orc_entry *o) +{ + struct orc_entry *orc; + struct rela *rela; + + /* populate ORC data */ + orc = (struct orc_entry *)u_sec->data->d_buf + idx; + memcpy(orc, o, sizeof(*orc)); + + /* populate rela for ip */ + rela = malloc(sizeof(*rela)); + if (!rela) { + perror("malloc"); + return -1; + } + memset(rela, 0, sizeof(*rela)); + + if (insn_sec->sym) { + rela->sym = insn_sec->sym; + rela->addend = insn_off; + } else { + /* + * The Clang assembler doesn't produce section symbols, so we + * have to reference the function symbol instead: + */ + rela->sym = find_symbol_containing(insn_sec, insn_off); + if (!rela->sym) { + /* + * Hack alert. This happens when we need to reference + * the NOP pad insn immediately after the function. + */ + rela->sym = find_symbol_containing(insn_sec, + insn_off - 1); + } + if (!rela->sym) { + WARN("missing symbol for insn at offset 0x%lx\n", + insn_off); + return -1; + } + + rela->addend = insn_off - rela->sym->offset; + } + + rela->type = R_X86_64_PC32; + rela->offset = idx * sizeof(int); + + list_add_tail(&rela->list, &ip_relasec->rela_list); + hash_add(ip_relasec->rela_hash, &rela->hash, rela->offset); + + return 0; +} + +int create_orc_sections(struct objtool_file *file) +{ + struct instruction *insn, *prev_insn; + struct section *sec, *u_sec, *ip_relasec; + 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_relasec = elf_create_rela_section(file->elf, sec); + if (!ip_relasec) + 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(u_sec, ip_relasec, idx, + insn->sec, insn->offset, + &insn->orc)) + return -1; + + idx++; + } + prev_insn = insn; + } + + /* section terminator */ + if (prev_insn) { + if (create_orc_entry(u_sec, ip_relasec, idx, + prev_insn->sec, + prev_insn->offset + prev_insn->len, + &empty)) + return -1; + + idx++; + } + } + + if (elf_rebuild_rela_section(ip_relasec)) + return -1; + + return 0; +} |