| Date | Tue, 08 Mar 2022 16:30:49 +0100 | From | Peter Zijlstra <> | Subject | [PATCH v4 38/45] objtool: Rework ASM_REACHABLE |
| |
Currently ASM_REACHABLE only works for UD2 instructions; reorder things to also allow over-riding dead_end_function().
To that end:
- Mark INSN_BUG instructions in decode_instructions(), this saves having to iterate all instructions yet again.
- Have add_call_destinations() set insn->dead_end for dead_end_function() calls.
- Move add_dead_ends() *after* add_call_destinations() such that ASM_REACHABLE can clear the ->dead_end mark.
- have validate_branch() only check ->dead_end.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- tools/objtool/check.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-)
--- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -394,6 +394,14 @@ static int decode_instructions(struct ob if (ret) goto err; + /* + * By default, "ud2" is a dead end unless otherwise + * annotated, because GCC 7 inserts it for certain + * divide-by-zero cases. + */ + if (insn->type == INSN_BUG) + insn->dead_end = true; + hash_add(file->insn_hash, &insn->hash, sec_offset_hash(sec, insn->offset)); list_add_tail(&insn->list, &file->insn_list); nr_insns++; @@ -532,14 +541,6 @@ static int add_dead_ends(struct objtool_ struct instruction *insn; /* - * By default, "ud2" is a dead end unless otherwise annotated, because - * GCC 7 inserts it for certain divide-by-zero cases. - */ - for_each_insn(file, insn) - if (insn->type == INSN_BUG) - insn->dead_end = true; - - /* * Check for manually annotated dead ends. */ sec = find_section_by_name(file->elf, ".rela.discard.unreachable"); @@ -1174,6 +1175,9 @@ static void annotate_call_site(struct ob list_add_tail(&insn->call_node, &file->mcount_loc_list); return; } + + if (!sibling && dead_end_function(file, sym)) + insn->dead_end = true; } static void add_call_dest(struct objtool_file *file, struct instruction *insn, @@ -2198,10 +2202,6 @@ static int decode_sections(struct objtoo if (ret) return ret; - ret = add_dead_ends(file); - if (ret) - return ret; - add_ignores(file); add_uaccess_safe(file); @@ -2247,6 +2247,14 @@ static int decode_sections(struct objtoo if (ret) return ret; + /* + * Must be after add_call_destinations() such that it can override + * dead_end_function() marks. + */ + ret = add_dead_ends(file); + if (ret) + return ret; + ret = add_jump_table_alts(file); if (ret) return ret; @@ -3363,7 +3371,7 @@ static int validate_branch(struct objtoo return 1; } - if (dead_end_function(file, insn->call_dest)) + if (insn->dead_end) return 0; break;
|