Messages in this thread Patch in this message | | | From | Josh Poimboeuf <> | Subject | [PATCH 5/5] objtool: Add "missing __noreturn" warning | Date | Mon, 27 Mar 2023 09:00:48 -0700 |
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Most "unreachable instruction" warnings these days seem to actually be the result of a missing __noreturn annotation. Add an explicit check for that.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- tools/objtool/Documentation/objtool.txt | 7 +++++++ tools/objtool/check.c | 16 ++++++++++++++-- 2 files changed, 21 insertions(+), 2 deletions(-)
diff --git a/tools/objtool/Documentation/objtool.txt b/tools/objtool/Documentation/objtool.txt index ec6f82fb414c..e04d16490c3b 100644 --- a/tools/objtool/Documentation/objtool.txt +++ b/tools/objtool/Documentation/objtool.txt @@ -423,6 +423,13 @@ the objtool maintainers. names and does not use module_init() / module_exit() macros to create them. +13. file.o: warning: func(): missing __noreturn + + Objtool has detected that the function doesn't return, but is missing + the __noreturn annotation. NOTE: In addition to adding the + __noreturn annotation, the function name also needs to be added to + 'global_noreturns' in tools/objtool/check.c. + If the error doesn't seem to make sense, it could be a bug in objtool. Feel free to ask the objtool maintainer for help. diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 67a684225702..1ed3024af2b1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -4548,7 +4548,8 @@ static int validate_sls(struct objtool_file *file) static int validate_reachable_instructions(struct objtool_file *file) { - struct instruction *insn; + struct instruction *insn, *prev_insn; + struct symbol *call_dest; if (file->ignore_unreachables) return 0; @@ -4561,8 +4562,19 @@ static int validate_reachable_instructions(struct objtool_file *file) continue; insn->sym->warned = 1; + prev_insn = prev_insn_same_sec(file, insn); + if (prev_insn) + call_dest = insn_call_dest(prev_insn); + if (prev_insn && prev_insn->dead_end && call_dest) { + if (call_dest->warned) + continue; + call_dest->warned = 1; + + WARN("%s(): missing __noreturn", call_dest->name); + continue; + } + WARN_FUNC("unreachable instruction", insn->sec, insn->offset); - return 1; } return 0; -- 2.39.2
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