Messages in this thread Patch in this message | | | Date | Tue, 21 Apr 2020 15:08:43 -0700 | Subject | [PATCH v2 2/2] objtool: optimize add_dead_ends for split sections | From | Sami Tolvanen <> |
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Instead of iterating through all instructions to find the last instruction each time .rela.discard.(un)reachable points beyond the section, use find_insn to locate the last instruction by looking at the last bytes of the section instead.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- tools/objtool/check.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4b170fd08a28..4f1d405420a4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -303,6 +303,19 @@ static int decode_instructions(struct objtool_file *file) return ret; } +static struct instruction *find_last_insn(struct objtool_file *file, + struct section *sec) +{ + struct instruction *insn = NULL; + unsigned int offset; + unsigned int end = (sec->len > 10) ? sec->len - 10 : 0; + + for (offset = sec->len - 1; offset >= end && !insn; offset--) + insn = find_insn(file, sec, offset); + + return insn; +} + /* * Mark "ud2" instructions and manually annotated dead ends. */ @@ -311,7 +324,6 @@ 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 @@ -337,15 +349,8 @@ 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; - } - } - - if (!found) { + insn = find_last_insn(file, rela->sym->sec); + if (!insn) { WARN("can't find unreachable insn at %s+0x%x", rela->sym->sec->name, rela->addend); return -1; @@ -379,15 +384,8 @@ 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; - } - } - - if (!found) { + insn = find_last_insn(file, rela->sym->sec); + if (!insn) { WARN("can't find reachable insn at %s+0x%x", rela->sym->sec->name, rela->addend); return -1; -- 2.26.1.301.g55bc3eb7cb9-goog
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