Messages in this thread Patch in this message | | | Date | Thu, 13 Apr 2023 10:48:01 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2 8/9] objtool: Detect missing __noreturn annotations |
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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) ?
--- tools/objtool/Makefile | 1 + tools/objtool/check.c | 27 +-------------------------- tools/objtool/noreturns | 26 ++++++++++++++++++++++++++ tools/objtool/noreturns.sh | 7 +++++++ 4 files changed, 35 insertions(+), 26 deletions(-)
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile index 83b100c1e7f6..50b6cd241571 100644 --- a/tools/objtool/Makefile +++ b/tools/objtool/Makefile @@ -63,6 +63,7 @@ include $(srctree)/tools/build/Makefile.include $(OBJTOOL_IN): fixdep $(LIBSUBCMD) FORCE $(Q)$(CONFIG_SHELL) ./sync-check.sh + $(Q)$(CONFIG_SHELL) ./noreturns.sh $(Q)$(MAKE) $(build)=objtool $(HOST_OVERRIDES) CFLAGS="$(OBJTOOL_CFLAGS)" \ LDFLAGS="$(OBJTOOL_LDFLAGS)" diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f937be1afe65..f558730c27b6 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -197,32 +197,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, * attribute isn't provided in ELF data. Keep 'em sorted. */ static const char * const global_noreturns[] = { - "__invalid_creds", - "__module_put_and_kthread_exit", - "__reiserfs_panic", - "__stack_chk_fail", - "__ubsan_handle_builtin_unreachable", - "cpu_bringup_and_idle", - "cpu_startup_entry", - "do_exit", - "do_group_exit", - "do_task_dead", - "ex_handler_msr_mce", - "fortify_panic", - "kthread_complete_and_exit", - "kthread_exit", - "kunit_try_catch_throw", - "lbug_with_loc", - "machine_real_restart", - "make_task_dead", - "panic", - "rewind_stack_and_make_dead", - "sev_es_terminate", - "snp_abort", - "stop_this_cpu", - "usercopy_abort", - "xen_cpu_bringup_again", - "xen_start_kernel", +#include "noreturns.h" }; if (!func) diff --git a/tools/objtool/noreturns b/tools/objtool/noreturns new file mode 100644 index 000000000000..75f35fbb34d1 --- /dev/null +++ b/tools/objtool/noreturns @@ -0,0 +1,26 @@ +__invalid_creds +__module_put_and_kthread_exit +__reiserfs_panic +__stack_chk_fail +__ubsan_handle_builtin_unreachable +cpu_bringup_and_idle +cpu_startup_entry +do_exit +do_group_exit +do_task_dead +ex_handler_msr_mce +fortify_panic +kthread_complete_and_exit +kthread_exit +kunit_try_catch_throw +lbug_with_loc +machine_real_restart +make_task_dead +panic +rewind_stack_and_make_dead +sev_es_terminate +snp_abort +stop_this_cpu +usercopy_abort +xen_cpu_bringup_again +xen_start_kernel diff --git a/tools/objtool/noreturns.sh b/tools/objtool/noreturns.sh new file mode 100755 index 000000000000..f728cb61e665 --- /dev/null +++ b/tools/objtool/noreturns.sh @@ -0,0 +1,7 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +cat noreturns | while read func +do + echo \"${func}\", +done > noreturns.h
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