Messages in this thread Patch in this message | | | Date | Thu, 13 Apr 2023 08:19:36 -0700 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2 8/9] objtool: Detect missing __noreturn annotations |
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On Thu, Apr 13, 2023 at 10:48:01AM +0200, Peter Zijlstra wrote: > On Wed, Apr 12, 2023 at 12:03:23PM -0700, Josh Poimboeuf wrote: > > 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 | 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 5a69c207a10e..2cd1fa16ed08 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. > > Do we want something like the below (except perhaps less horrible) ?
Yeah, maybe. Another possible way to do it:
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index cae6ac6ff246..a4e8ff9dabf1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -192,39 +192,16 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, struct instruction *insn; bool empty = true; +#define NORETURN(func) "\"" __stringify(func) "\"", + /* * Unfortunately these have to be hard coded because the noreturn * attribute isn't provided in ELF data. Keep 'em sorted. */ static const char * const global_noreturns[] = { - "__invalid_creds", - "__module_put_and_kthread_exit", - "__reiserfs_panic", - "__stack_chk_fail", - "__ubsan_handle_builtin_unreachable", - "arch_cpu_idle_dead", - "cpu_bringup_and_idle", - "cpu_startup_entry", - "do_exit", - "do_group_exit", - "do_task_dead", - "ex_handler_msr_mce", - "fortify_panic", - "kthread_complete_and_exit", - "kthread_exit", - "kunit_try_catch_throw", - "lbug_with_loc", - "machine_real_restart", - "make_task_dead", - "panic", - "rewind_stack_and_make_dead", - "sev_es_terminate", - "snp_abort", - "stop_this_cpu", - "usercopy_abort", - "xen_cpu_bringup_again", - "xen_start_kernel", +#include "noreturns.h" }; +#undef NORETURN if (!func) return false; diff --git a/tools/objtool/noreturns.h b/tools/objtool/noreturns.h new file mode 100644 index 000000000000..0f5e53fd9e7a --- /dev/null +++ b/tools/objtool/noreturns.h @@ -0,0 +1,27 @@ +NORETURN(__invalid_creds) +NORETURN(__module_put_and_kthread_exit) +NORETURN(__reiserfs_panic) +NORETURN(__stack_chk_fail) +NORETURN(__ubsan_handle_builtin_unreachable) +NORETURN(arch_cpu_idle_dead) +NORETURN(cpu_bringup_and_idle) +NORETURN(cpu_startup_entry) +NORETURN(do_exit) +NORETURN(do_group_exit) +NORETURN(do_task_dead) +NORETURN(ex_handler_msr_mce) +NORETURN(fortify_panic) +NORETURN(kthread_complete_and_exit) +NORETURN(kthread_exit) +NORETURN(kunit_try_catch_throw) +NORETURN(lbug_with_loc) +NORETURN(machine_real_restart) +NORETURN(make_task_dead) +NORETURN(panic) +NORETURN(rewind_stack_and_make_dead) +NORETURN(sev_es_terminate) +NORETURN(snp_abort) +NORETURN(stop_this_cpu) +NORETURN(usercopy_abort) +NORETURN(xen_cpu_bringup_again) +NORETURN(xen_start_kernel)
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