diff options
Diffstat (limited to 'tools/objtool/orc_gen.c')
| -rw-r--r-- | tools/objtool/orc_gen.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c new file mode 100644 index 000000000..dd3c64af9 --- /dev/null +++ b/tools/objtool/orc_gen.c @@ -0,0 +1,245 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Josh Poimboeuf <jpoimboe@redhat.com> + */ + +#include <stdlib.h> +#include <string.h> + +#include <linux/objtool.h> +#include <asm/orc_types.h> + +#include <objtool/check.h> +#include <objtool/warn.h> +#include <objtool/endianness.h> + +static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi, + struct instruction *insn) +{ + struct cfi_reg *bp = &cfi->regs[CFI_BP]; + + memset(orc, 0, sizeof(*orc)); + + if (!cfi) { + orc->end = 0; + orc->sp_reg = ORC_REG_UNDEFINED; + return 0; + } + + orc->end = cfi->end; + + if (cfi->cfa.base == CFI_UNDEFINED) { + orc->sp_reg = ORC_REG_UNDEFINED; + return 0; + } + + switch (cfi->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, cfi->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 = cfi->cfa.offset; + orc->bp_offset = bp->offset; + orc->type = cfi->type; + + return 0; +} + +static int write_orc_entry(struct elf *elf, struct section *orc_sec, + struct section *ip_sec, unsigned int idx, + struct section *insn_sec, unsigned long insn_off, + struct orc_entry *o) +{ + struct orc_entry *orc; + + /* populate ORC data */ + orc = (struct orc_entry *)orc_sec->data->d_buf + idx; + memcpy(orc, o, sizeof(*orc)); + orc->sp_offset = bswap_if_needed(orc->sp_offset); + orc->bp_offset = bswap_if_needed(orc->bp_offset); + + /* populate reloc for ip */ + if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32, + insn_sec, insn_off)) + return -1; + + return 0; +} + +struct orc_list_entry { + struct list_head list; + struct orc_entry orc; + struct section *insn_sec; + unsigned long insn_off; +}; + +static int orc_list_add(struct list_head *orc_list, struct orc_entry *orc, + struct section *sec, unsigned long offset) +{ + struct orc_list_entry *entry = malloc(sizeof(*entry)); + + if (!entry) { + WARN("malloc failed"); + return -1; + } + + entry->orc = *orc; + entry->insn_sec = sec; + entry->insn_off = offset; + + list_add_tail(&entry->list, orc_list); + return 0; +} + +static unsigned long alt_group_len(struct alt_group *alt_group) +{ + return alt_group->last_insn->offset + + alt_group->last_insn->len - + alt_group->first_insn->offset; +} + +int orc_create(struct objtool_file *file) +{ + struct section *sec, *orc_sec; + unsigned int nr = 0, idx = 0; + struct orc_list_entry *entry; + struct list_head orc_list; + + struct orc_entry null = { + .sp_reg = ORC_REG_UNDEFINED, + .bp_reg = ORC_REG_UNDEFINED, + .type = UNWIND_HINT_TYPE_CALL, + }; + + /* Build a deduplicated list of ORC entries: */ + INIT_LIST_HEAD(&orc_list); + for_each_sec(file, sec) { + struct orc_entry orc, prev_orc = {0}; + struct instruction *insn; + bool empty = true; + + if (!sec->text) + continue; + + sec_for_each_insn(file, sec, insn) { + struct alt_group *alt_group = insn->alt_group; + int i; + + if (!alt_group) { + if (init_orc_entry(&orc, insn->cfi, insn)) + return -1; + if (!memcmp(&prev_orc, &orc, sizeof(orc))) + continue; + if (orc_list_add(&orc_list, &orc, sec, + insn->offset)) + return -1; + nr++; + prev_orc = orc; + empty = false; + continue; + } + + /* + * Alternatives can have different stack layout + * possibilities (but they shouldn't conflict). + * Instead of traversing the instructions, use the + * alt_group's flattened byte-offset-addressed CFI + * array. + */ + for (i = 0; i < alt_group_len(alt_group); i++) { + struct cfi_state *cfi = alt_group->cfi[i]; + if (!cfi) + continue; + /* errors are reported on the original insn */ + if (init_orc_entry(&orc, cfi, insn)) + return -1; + if (!memcmp(&prev_orc, &orc, sizeof(orc))) + continue; + if (orc_list_add(&orc_list, &orc, insn->sec, + insn->offset + i)) + return -1; + nr++; + prev_orc = orc; + empty = false; + } + + /* Skip to the end of the alt_group */ + insn = alt_group->last_insn; + } + + /* Add a section terminator */ + if (!empty) { + orc_list_add(&orc_list, &null, sec, sec->sh.sh_size); + nr++; + } + } + if (!nr) + return 0; + + /* Create .orc_unwind, .orc_unwind_ip and .rela.orc_unwind_ip sections: */ + sec = find_section_by_name(file->elf, ".orc_unwind"); + if (sec) { + WARN("file already has .orc_unwind section, skipping"); + return -1; + } + orc_sec = elf_create_section(file->elf, ".orc_unwind", 0, + sizeof(struct orc_entry), nr); + if (!orc_sec) + return -1; + + sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr); + if (!sec) + return -1; + + /* Write ORC entries to sections: */ + list_for_each_entry(entry, &orc_list, list) { + if (write_orc_entry(file->elf, orc_sec, sec, idx++, + entry->insn_sec, entry->insn_off, + &entry->orc)) + return -1; + } + + return 0; +} |