| Message ID | ede3460d63f4a65d282c86f1175bd2662c2286ba.1681342859.git.jpoimboe@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Sprinkle more __noreturn | expand |
On Wed, 12 Apr 2023, Josh Poimboeuf wrote: > If a global function doesn't return, and its prototype has the > __noreturn attribute, its weak counterpart must also not return so that > it matches the prototype and meets call site expectations. > > To properly follow the compiled control flow at the call sites, change > the global_noreturns check to include both global and weak functions. > > On the other hand, if a weak function isn't in global_noreturns, assume > the prototype doesn't have __noreturn. Even if the weak function > doesn't return, call sites treat it like a returnable function. > > Fixes the following warning: > > kernel/sched/build_policy.o: warning: objtool: do_idle() falls through to next function play_idle_precise() > > Reported-by: kernel test robot <lkp@intel.com> > Link: https://lore.kernel.org/oe-kbuild-all/202304090346.erhqxnlt-lkp@intel.com/ > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Reviewed-by: Miroslav Benes <mbenes@suse.cz> The rest of the patch set looks good to me too. M
diff --git a/tools/objtool/check.c b/tools/objtool/check.c index ed42717463f9..94c16436d990 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -236,14 +236,14 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, if (!func) return false; - if (func->bind == STB_WEAK) - return false; - - if (func->bind == STB_GLOBAL) + if (func->bind == STB_GLOBAL || func->bind == STB_WEAK) for (i = 0; i < ARRAY_SIZE(global_noreturns); i++) if (!strcmp(func->name, global_noreturns[i])) return true; + if (func->bind == STB_WEAK) + return false; + if (!func->len) return false;
If a global function doesn't return, and its prototype has the __noreturn attribute, its weak counterpart must also not return so that it matches the prototype and meets call site expectations. To properly follow the compiled control flow at the call sites, change the global_noreturns check to include both global and weak functions. On the other hand, if a weak function isn't in global_noreturns, assume the prototype doesn't have __noreturn. Even if the weak function doesn't return, call sites treat it like a returnable function. Fixes the following warning: kernel/sched/build_policy.o: warning: objtool: do_idle() falls through to next function play_idle_precise() Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202304090346.erhqxnlt-lkp@intel.com/ Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> --- tools/objtool/check.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)