[PATCH] arm: crypto: Add NEON optimized SHA-256

[Ard Biesheuvel]

On 16 March 2015 at 17:23, Sami Tolvanen <samitolvanen at google.com> wrote:
> On Mon, Mar 16, 2015 at 05:08:03PM +0100, Ard Biesheuvel wrote:
>> Have you tested this code with the tcrypt.ko module?
>
> I have not, but I can look into it.
>
>> Did you talk to Andy about the license? I don't think this is
>> permissible for the kernel as-is.
>
> Unless I have misunderstood something, the license at the Cryptogams
> website includes an option to license the code under the GNU GPL.
>
> However, I can certainly contact Andy to clarify his intentions.
>
>> This is broken on thumb-2, use adr instead
>
>> You can also implement SHA-224 using the same core transform, it's
>> just some trivial glue code.
>
>> Could you please rebase this onto Herbert's cryptodev tree and move
>> this to arch/arm/crypto/Kconfig?
>
> Thanks for the comments, I will submit a second version once we have
> a clarification on the license.
>

I have tested your code with a Thumb2 kernel. With this patch folded,
it builds and passes the tcrypt.ko test for me

--- a/arch/arm/crypto/sha256-armv7-neon.S
+++ b/arch/arm/crypto/sha256-armv7-neon.S
@@ -10,7 +10,6 @@
 #include <linux/linkage.h>

 .text
-.code   32
 .fpu neon

 .type  K256,%object
@@ -44,15 +43,15 @@ ENTRY(sha256_transform_neon)
         *      %r1: data
         *      %r2: nblks
         */
-       sub     r3,pc,#8                @ sha256_transform_neon
        add     r2,r1,r2,lsl#6  @ len to point at the end of inp

        stmdb   sp!,{r4-r12,lr}

        mov     r12,sp
-       sub     sp,sp,#16*4+16          @ alloca
-       sub     r14,r3,#256+32  @ K256
-       bic     sp,sp,#15               @ align for 128-bit stores
+       sub     r14,sp,#16*4+16         @ alloca
+       bic     r14,r14,#15             @ align for 128-bit stores
+       mov     sp,r14
+       adr     r14,K256

        vld1.8          {q0},[r1]!
        vld1.8          {q1},[r1]!