Messages in this thread Patch in this message | | | Date | Tue, 21 Apr 2020 11:07:24 -0700 | Subject | [PATCH 3/3] objtool: optimize add_dead_ends for split sections | From | Sami Tolvanen <> |
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When running objtool on vmlinux.o compiled with -ffunction-sections, .rela.discard.(un)reachable often contains relocations that point to a different section. Instead of iterating through the list of all instructions each time, store a pointer to the last instruction of each section when decoding instructions.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- tools/objtool/check.c | 43 ++++++++++++++++++++++++++----------------- tools/objtool/check.h | 4 ++++ tools/objtool/elf.h | 1 + 3 files changed, 31 insertions(+), 17 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4770fb07b365..7d4104de0a5e 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -237,6 +237,7 @@ static void clear_insn_state(struct insn_state *state) static int decode_instructions(struct objtool_file *file) { struct section *sec; + struct section_info *sec_info = NULL; struct symbol *func; unsigned long offset; struct instruction *insn; @@ -253,6 +254,8 @@ static int decode_instructions(struct objtool_file *file) strncmp(sec->name, ".discard.", 9)) sec->text = true; + insn = NULL; + for (offset = 0; offset < sec->len; offset += insn->len) { insn = malloc(sizeof(*insn)); if (!insn) { @@ -279,6 +282,17 @@ static int decode_instructions(struct objtool_file *file) nr_insns++; } + if (insn) { + sec_info = malloc(sizeof(*sec_info)); + if (!sec_info) { + WARN("malloc failed"); + return -1; + } + + sec_info->last_insn = insn; + sec->section_info = sec_info; + } + list_for_each_entry(func, &sec->symbol_list, list) { if (func->type != STT_FUNC || func->alias != func) continue; @@ -312,7 +326,6 @@ static int add_dead_ends(struct objtool_file *file) struct section *sec; struct rela *rela; struct instruction *insn; - bool found; /* * By default, "ud2" is a dead end unless otherwise annotated, because @@ -338,15 +351,13 @@ static int add_dead_ends(struct objtool_file *file) if (insn) insn = list_prev_entry(insn, list); else if (rela->addend == rela->sym->sec->len) { - found = false; - list_for_each_entry_reverse(insn, &file->insn_list, list) { - if (insn->sec == rela->sym->sec) { - found = true; - break; - } - } + struct section_info *sec_info = (struct section_info *) + rela->sym->sec->section_info; + + if (sec_info) + insn = sec_info->last_insn; - if (!found) { + if (!insn) { WARN("can't find unreachable insn at %s+0x%x", rela->sym->sec->name, rela->addend); return -1; @@ -380,15 +391,13 @@ static int add_dead_ends(struct objtool_file *file) if (insn) insn = list_prev_entry(insn, list); else if (rela->addend == rela->sym->sec->len) { - found = false; - list_for_each_entry_reverse(insn, &file->insn_list, list) { - if (insn->sec == rela->sym->sec) { - found = true; - break; - } - } + struct section_info *sec_info = (struct section_info *) + rela->sym->sec->section_info; + + if (sec_info) + insn = sec_info->last_insn; - if (!found) { + if (!insn) { WARN("can't find reachable insn at %s+0x%x", rela->sym->sec->name, rela->addend); return -1; diff --git a/tools/objtool/check.h b/tools/objtool/check.h index bc78eca7982e..353677ec85d4 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -47,6 +47,10 @@ struct instruction { struct orc_entry orc; }; +struct section_info { + struct instruction *last_insn; +}; + struct objtool_file { struct elf *elf; struct list_head insn_list; diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index ebbb10c61e24..98f2b41d18e4 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -40,6 +40,7 @@ struct section { int idx; unsigned int len; bool changed, text, rodata; + void *section_info; }; struct symbol { -- 2.26.1.301.g55bc3eb7cb9-goog
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