From 627fce14809ba5610b0cb476cd0186d3fcedecfc Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 11 Jul 2017 10:33:42 -0500 Subject: objtool: Add ORC unwind table generation Now that objtool knows the states of all registers on the stack for each instruction, it's straightforward to generate debuginfo for an unwinder to use. Instead of generating DWARF, generate a new format called ORC, which is more suitable for an in-kernel unwinder. See Documentation/x86/orc-unwinder.txt for a more detailed description of this new debuginfo format and why it's preferable to DWARF. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jiri Slaby Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/c9b9f01ba6c5ed2bdc9bb0957b78167fdbf9632e.1499786555.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/orc_dump.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 tools/objtool/orc_dump.c (limited to 'tools/objtool/orc_dump.c') diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c new file mode 100644 index 000000000000..36c5bf6a2675 --- /dev/null +++ b/tools/objtool/orc_dump.c @@ -0,0 +1,212 @@ +/* + * Copyright (C) 2017 Josh Poimboeuf + * + * 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 . + */ + +#include +#include "orc.h" +#include "warn.h" + +static const char *reg_name(unsigned int reg) +{ + switch (reg) { + case ORC_REG_PREV_SP: + return "prevsp"; + case ORC_REG_DX: + return "dx"; + case ORC_REG_DI: + return "di"; + case ORC_REG_BP: + return "bp"; + case ORC_REG_SP: + return "sp"; + case ORC_REG_R10: + return "r10"; + case ORC_REG_R13: + return "r13"; + case ORC_REG_BP_INDIRECT: + return "bp(ind)"; + case ORC_REG_SP_INDIRECT: + return "sp(ind)"; + default: + return "?"; + } +} + +static const char *orc_type_name(unsigned int type) +{ + switch (type) { + case ORC_TYPE_CALL: + return "call"; + case ORC_TYPE_REGS: + return "regs"; + case ORC_TYPE_REGS_IRET: + return "iret"; + default: + return "?"; + } +} + +static void print_reg(unsigned int reg, int offset) +{ + if (reg == ORC_REG_BP_INDIRECT) + printf("(bp%+d)", offset); + else if (reg == ORC_REG_SP_INDIRECT) + printf("(sp%+d)", offset); + else if (reg == ORC_REG_UNDEFINED) + printf("(und)"); + else + printf("%s%+d", reg_name(reg), offset); +} + +int orc_dump(const char *_objname) +{ + int fd, nr_entries, i, *orc_ip = NULL, orc_size = 0; + struct orc_entry *orc = NULL; + char *name; + unsigned long nr_sections, orc_ip_addr = 0; + size_t shstrtab_idx; + Elf *elf; + Elf_Scn *scn; + GElf_Shdr sh; + GElf_Rela rela; + GElf_Sym sym; + Elf_Data *data, *symtab = NULL, *rela_orc_ip = NULL; + + + objname = _objname; + + elf_version(EV_CURRENT); + + fd = open(objname, O_RDONLY); + if (fd == -1) { + perror("open"); + return -1; + } + + elf = elf_begin(fd, ELF_C_READ_MMAP, NULL); + if (!elf) { + WARN_ELF("elf_begin"); + return -1; + } + + if (elf_getshdrnum(elf, &nr_sections)) { + WARN_ELF("elf_getshdrnum"); + return -1; + } + + if (elf_getshdrstrndx(elf, &shstrtab_idx)) { + WARN_ELF("elf_getshdrstrndx"); + return -1; + } + + for (i = 0; i < nr_sections; i++) { + scn = elf_getscn(elf, i); + if (!scn) { + WARN_ELF("elf_getscn"); + return -1; + } + + if (!gelf_getshdr(scn, &sh)) { + WARN_ELF("gelf_getshdr"); + return -1; + } + + name = elf_strptr(elf, shstrtab_idx, sh.sh_name); + if (!name) { + WARN_ELF("elf_strptr"); + return -1; + } + + data = elf_getdata(scn, NULL); + if (!data) { + WARN_ELF("elf_getdata"); + return -1; + } + + if (!strcmp(name, ".symtab")) { + symtab = data; + } else if (!strcmp(name, ".orc_unwind")) { + orc = data->d_buf; + orc_size = sh.sh_size; + } else if (!strcmp(name, ".orc_unwind_ip")) { + orc_ip = data->d_buf; + orc_ip_addr = sh.sh_addr; + } else if (!strcmp(name, ".rela.orc_unwind_ip")) { + rela_orc_ip = data; + } + } + + if (!symtab || !orc || !orc_ip) + return 0; + + if (orc_size % sizeof(*orc) != 0) { + WARN("bad .orc_unwind section size"); + return -1; + } + + nr_entries = orc_size / sizeof(*orc); + for (i = 0; i < nr_entries; i++) { + if (rela_orc_ip) { + if (!gelf_getrela(rela_orc_ip, i, &rela)) { + WARN_ELF("gelf_getrela"); + return -1; + } + + if (!gelf_getsym(symtab, GELF_R_SYM(rela.r_info), &sym)) { + WARN_ELF("gelf_getsym"); + return -1; + } + + scn = elf_getscn(elf, sym.st_shndx); + if (!scn) { + WARN_ELF("elf_getscn"); + return -1; + } + + if (!gelf_getshdr(scn, &sh)) { + WARN_ELF("gelf_getshdr"); + return -1; + } + + name = elf_strptr(elf, shstrtab_idx, sh.sh_name); + if (!name || !*name) { + WARN_ELF("elf_strptr"); + return -1; + } + + printf("%s+%lx:", name, rela.r_addend); + + } else { + printf("%lx:", orc_ip_addr + (i * sizeof(int)) + orc_ip[i]); + } + + + printf(" sp:"); + + print_reg(orc[i].sp_reg, orc[i].sp_offset); + + printf(" bp:"); + + print_reg(orc[i].bp_reg, orc[i].bp_offset); + + printf(" type:%s\n", orc_type_name(orc[i].type)); + } + + elf_end(elf); + close(fd); + + return 0; +} -- cgit v1.2.3