The following commit has been merged into the objtool/core branch of tip:
Commit-ID: fedb724c3db5490234ddde0103811c28c2fedae0
Gitweb: https://git.kernel.org/tip/fedb724c3db5490234ddde0103811c28c2fedae0
Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Tue, 18 Apr 2023 14:27:50 -07:00
Committer: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Tue, 16 May 2023 06:31:53 -07:00
objtool: Detect missing __noreturn annotations
Most "unreachable instruction" warnings these days seem to actually be
the result of a missing __noreturn annotation. Add an explicit check
for that.
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Link: https://lore.kernel.org/r/6e2b93d8c65eaed6c4166a358269dc0ef01f890c.1681853186.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
tools/objtool/Documentation/objtool.txt | 6 ++++++
tools/objtool/check.c | 14 +++++++++++++-
2 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/tools/objtool/Documentation/objtool.txt b/tools/objtool/Documentation/objtool.txt
index 9ec8cbf..f9345e0 100644
--- a/tools/objtool/Documentation/objtool.txt
+++ b/tools/objtool/Documentation/objtool.txt
@@ -303,6 +303,12 @@ the objtool maintainers.
If it's not actually in a callable function (e.g. kernel entry code),
change ENDPROC to END.
+3. file.o: warning: objtool: foo+0x48c: bar() is missing a __noreturn annotation
+
+ The call from foo() to bar() doesn't return, but bar() 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.
4. file.o: warning: objtool: func(): can't find starting instruction
or
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 71985f3..8d1b422 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4507,7 +4507,8 @@ 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;
int warnings = 0;
if (file->ignore_unreachables)
@@ -4517,6 +4518,17 @@ static int validate_reachable_instructions(struct objtool_file *file)
if (insn->visited || ignore_unreachable_insn(file, insn))
continue;
+ prev_insn = prev_insn_same_sec(file, insn);
+ if (prev_insn && prev_insn->dead_end) {
+ call_dest = insn_call_dest(prev_insn);
+ if (call_dest) {
+ WARN_INSN(insn, "%s() is missing a __noreturn annotation",
+ call_dest->name);
+ warnings++;
+ continue;
+ }
+ }
+
WARN_INSN(insn, "unreachable instruction");
warnings++;
}
|