The following commit has been merged into the x86/core branch of tip: Commit-ID: 0d5b64134b49881d62029a1a9923c604507e973b Gitweb: https://git.kernel.org/tip/0d5b64134b49881d62029a1a9923c604507e973b Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Tue, 08 Mar 2022 16:30:49 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Tue, 08 Mar 2022 23:53:37 +01:00 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@xxxxxxxxxxxxx> Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220308154319.410010807@xxxxxxxxxxxxx --- tools/objtool/check.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 9896562..aee6246 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -394,6 +394,14 @@ static int decode_instructions(struct objtool_file *file) 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++; @@ -523,14 +531,6 @@ static int add_dead_ends(struct objtool_file *file) 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"); @@ -1113,6 +1113,9 @@ static void annotate_call_site(struct objtool_file *file, 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, @@ -2088,10 +2091,6 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; - ret = add_dead_ends(file); - if (ret) - return ret; - add_ignores(file); add_uaccess_safe(file); @@ -2130,6 +2129,14 @@ static int decode_sections(struct objtool_file *file) 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; @@ -3137,7 +3144,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 1; } - if (dead_end_function(file, insn->call_dest)) + if (insn->dead_end) return 0; break;
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