* [PATCH] crypto: serpent - mark __serpent_setkey_sbox noinline
@ 2019-06-17 11:59 Arnd Bergmann
2019-06-18 3:19 ` Eric Biggers
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2019-06-17 11:59 UTC (permalink / raw)
To: Herbert Xu, David S. Miller
Cc: Arnd Bergmann, Eric Biggers, linux-crypto, linux-kernel
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@arndb.de>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] crypto: serpent - mark __serpent_setkey_sbox noinline
2019-06-17 11:59 [PATCH] crypto: serpent - mark __serpent_setkey_sbox noinline Arnd Bergmann
@ 2019-06-18 3:19 ` Eric Biggers
0 siblings, 0 replies; 2+ messages in thread
From: Eric Biggers @ 2019-06-18 3:19 UTC (permalink / raw)
To: Arnd Bergmann; +Cc: Herbert Xu, David S. Miller, linux-crypto, linux-kernel
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@arndb.de>
> ---
> 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
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-06-17 11:59 [PATCH] crypto: serpent - mark __serpent_setkey_sbox noinline Arnd Bergmann
2019-06-18 3:19 ` Eric Biggers
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