On Sat, Jul 26, 2025 at 02:26:19PM -0700, Kees Cook wrote: > Once CONFIG_KSTACK_ERASE is enabled with Clang on i386, the build warns: > > kernel/kstack_erase.c:168:2: warning: function with attribute > 'no_caller_saved_registers' should only call a function with attribute > 'no_caller_saved_registers' or be compiled with '-mgeneral-regs-only' > [-Wexcessive-regsave] > > Add -mgeneral-regs-only for the kstack_erase handler, to make Clang feel > better (it is effectively a no-op flag for the kernel). No binary > changes encountered. > > Build & boot tested with Clang 21 on x86_64, and i386. > Build tested with GCC 14.2.0 on x86_64, i386, arm64, and arm. > > Reported-by: Nathan Chancellor <nat...@kernel.org> > Closes: https://lore.kernel.org/all/20250726004313.GA3650901@ax162 > Signed-off-by: Kees Cook <k...@kernel.org>
Tested-by: Nathan Chancellor <nat...@kernel.org> > --- > kernel/Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/Makefile b/kernel/Makefile > index e4f01f1d4d0c..0ee9afd8b7cf 100644 > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -140,6 +140,7 @@ obj-$(CONFIG_RESOURCE_KUNIT_TEST) += resource_kunit.o > obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o > > CFLAGS_kstack_erase.o += $(DISABLE_KSTACK_ERASE) > +CFLAGS_kstack_erase.o += $(call cc-option,-mgeneral-regs-only) > obj-$(CONFIG_KSTACK_ERASE) += kstack_erase.o > KASAN_SANITIZE_kstack_erase.o := n > KCSAN_SANITIZE_kstack_erase.o := n > -- > 2.34.1 >
