target/arm: Fix PAuth sbox functions

In the PAC computation, sbox was applied over wrong bits.
As this is a 4-bit sbox, bit index should be incremented by 4 instead of 16.

Test vector from QARMA paper (https://eprint.iacr.org/2016/444.pdf) was
used to verify one computation of the pauth_computepac() function which
uses sbox2.

Launchpad: https://bugs.launchpad.net/bugs/1859713
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Vincent DEHORS <vincent.dehors@smile.fr>
Signed-off-by: Adrien GRASSEIN <adrien.grassein@smile.fr>
Message-id: 20200116230809.19078-2-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry picked from commit de0b1bae6461f67243282555475f88b2384a1eb9)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index d3194f2..0a5f41e 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -89,7 +89,7 @@ static uint64_t pac_sub(uint64_t i)
     uint64_t o = 0;
     int b;
 
-    for (b = 0; b < 64; b += 16) {
+    for (b = 0; b < 64; b += 4) {
         o |= (uint64_t)sub[(i >> b) & 0xf] << b;
     }
     return o;
@@ -104,7 +104,7 @@ static uint64_t pac_inv_sub(uint64_t i)
     uint64_t o = 0;
     int b;
 
-    for (b = 0; b < 64; b += 16) {
+    for (b = 0; b < 64; b += 4) {
         o |= (uint64_t)inv_sub[(i >> b) & 0xf] << b;
     }
     return o;