Hi Arnd,
On Mon, Jun 17, 2019 at 01:59:08PM +0200, Arnd Bergmann wrote:
> The same bug that gcc hit in the past is apparently now showing
> up with clang, which decides to inline __serpent_setkey_sbox:
>
> crypto/serpent_generic.c:268:5: error: stack frame size of 2112 bytes in function '__serpent_setkey' [-Werror,-Wframe-larger-than=]
>
> Marking it 'noinline' reduces the stack usage from 2112 bytes to
> 192 and 96 bytes, respectively, and seems to generate more
> useful object code.
>
> Fixes: c871c10e4ea7 ("crypto: serpent - improve __serpent_setkey with UBSAN")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> crypto/serpent_generic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/crypto/serpent_generic.c b/crypto/serpent_generic.c
> index e57757904677..183661faf420 100644
> --- a/crypto/serpent_generic.c
> +++ b/crypto/serpent_generic.c
> @@ -225,7 +225,7 @@
> x4 ^= x2; \
> })
>
> -static void __serpent_setkey_sbox(u32 r0, u32 r1, u32 r2, u32 r3, u32 r4, u32 *k)
> +static void noinline __serpent_setkey_sbox(u32 r0, u32 r1, u32 r2, u32 r3, u32 r4, u32 *k)
> {
> k += 100;
> S3(r3, r4, r0, r1, r2); store_and_load_keys(r1, r2, r4, r3, 28, 24);
> --
> 2.20.0
>
A few nits: 'static noinline void' seems to be the much more common order,
presumably to match 'static inline void'. Line breaking at 80 characters would
also be nice. Finally, a brief comment explaining the purpose of 'noinline'
might be helpful for people working with this code later.
- Eric
