Hi Ard, On Sat, Jul 13, 2024 at 12:23:24PM +0200, Ard Biesheuvel wrote: > On Fri, 12 Jul 2024 at 13:37, <flyingpenghao@xxxxxxxxx> wrote: > > > > From: Peng Hao <flyingpeng@xxxxxxxxxxx> > > > > When building kernel with clang, which will typically > > have sanitizers enabled, there is a warning about a large stack frame. > > > > crypto/ecc.c:1129:13: error: stack frame size (2136) exceeds limit (2048) in 'ecc_point_double_jacobian' [-Werror,-Wframe-larger-than] > > static void ecc_point_double_jacobian(u64 *x1, u64 *y1, u64 *z1, > > ^ > > > > Since many arrays are defined in ecc_point_double_jacobian, they occupy a > > lot of stack space, but are difficult to adjust. just increase the limit > > for configurations that have KASAN or KCSAN enabled. > > > > Signed-off-by: Peng Hao <flyingpeng@xxxxxxxxxxx> > > --- > > crypto/Makefile | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/crypto/Makefile b/crypto/Makefile > > index edbbaa3ffef5..ab7bebaa7218 100644 > > --- a/crypto/Makefile > > +++ b/crypto/Makefile > > @@ -190,6 +190,12 @@ obj-$(CONFIG_CRYPTO_ECC) += ecc.o > > obj-$(CONFIG_CRYPTO_ESSIV) += essiv.o > > obj-$(CONFIG_CRYPTO_CURVE25519) += curve25519-generic.o > > > > +ifneq ($(CONFIG_FRAME_WARN),0) > > +ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)),y) > > +CFLAGS_ecc.o = -Wframe-larger-than=2776 > > +endif > > +endif > > + > > I don't think this is an acceptable workaround - this applies to all > functions in the file, which call into each other as well. Agreed, as I stated on a review of another patch this same submitter sent for a similar warning in infiniband: https://lore.kernel.org/20240709212608.GA1649561@thelio-3990X/ Unfortunately, this appears to be getting copy and pasted from AMDGPU, which needed it for their horrible DCN code that comes from some other upstream source. > It would be better if we could figure out why the stack blows up like > this on clang, which could be related to inlining behavior or other > compiler heuristics that prevent stack allocations from being reused. I asked for further details like configuration in my second message in that thread and it never materialized: https://lore.kernel.org/20240709212608.GA1649561@thelio-3990X/ I suspect this might just be a KASAN_STACK warning, which is known to generate high stack usage warnings (as noted in the Kconfig text),we will have to wait for confirmation: https://github.com/ClangBuiltLinux/linux/issues/39 Cheers, Nathan
