[PATCH v2 2/7] target/arm: Implement v8.3 QARMA3 PAC cipher

[Aaron Lindsay <aaron@os.amperecomputing.com>]

Signed-off-by: Aaron Lindsay <aaron@os.amperecomputing.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/pauth_helper.c | 50 +++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 10 deletions(-)

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index e5206453f6..f525ef7fad 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -96,6 +96,21 @@ static uint64_t pac_sub(uint64_t i)
     return o;
 }
 
+static uint64_t pac_sub1(uint64_t i)
+{
+    static const uint8_t sub1[16] = {
+        0xa, 0xd, 0xe, 0x6, 0xf, 0x7, 0x3, 0x5,
+        0x9, 0x8, 0x0, 0xc, 0xb, 0x1, 0x2, 0x4,
+    };
+    uint64_t o = 0;
+    int b;
+
+    for (b = 0; b < 64; b += 4) {
+        o |= (uint64_t)sub1[(i >> b) & 0xf] << b;
+    }
+    return o;
+}
+
 static uint64_t pac_inv_sub(uint64_t i)
 {
     static const uint8_t inv_sub[16] = {
@@ -209,7 +224,7 @@ static uint64_t tweak_inv_shuffle(uint64_t i)
 }
 
 static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
-                                             ARMPACKey key)
+                                             ARMPACKey key, bool isqarma3)
 {
     static const uint64_t RC[5] = {
         0x0000000000000000ull,
@@ -219,6 +234,7 @@ static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
         0x452821E638D01377ull,
     };
     const uint64_t alpha = 0xC0AC29B7C97C50DDull;
+    int iterations = isqarma3 ? 2 : 4;
     /*
      * Note that in the ARM pseudocode, key0 contains bits <127:64>
      * and key1 contains bits <63:0> of the 128-bit key.
@@ -231,7 +247,7 @@ static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
     runningmod = modifier;
     workingval = data ^ key0;
 
-    for (i = 0; i <= 4; ++i) {
+    for (i = 0; i <= iterations; ++i) {
         roundkey = key1 ^ runningmod;
         workingval ^= roundkey;
         workingval ^= RC[i];
@@ -239,32 +255,44 @@ static uint64_t pauth_computepac_architected(uint64_t data, uint64_t modifier,
             workingval = pac_cell_shuffle(workingval);
             workingval = pac_mult(workingval);
         }
-        workingval = pac_sub(workingval);
+        if (isqarma3)
+            workingval = pac_sub1(workingval);
+        else
+            workingval = pac_sub(workingval);
         runningmod = tweak_shuffle(runningmod);
     }
     roundkey = modk0 ^ runningmod;
     workingval ^= roundkey;
     workingval = pac_cell_shuffle(workingval);
     workingval = pac_mult(workingval);
-    workingval = pac_sub(workingval);
+    if (isqarma3)
+        workingval = pac_sub1(workingval);
+    else
+        workingval = pac_sub(workingval);
     workingval = pac_cell_shuffle(workingval);
     workingval = pac_mult(workingval);
     workingval ^= key1;
     workingval = pac_cell_inv_shuffle(workingval);
-    workingval = pac_inv_sub(workingval);
+    if (isqarma3)
+        workingval = pac_sub1(workingval);
+    else
+        workingval = pac_inv_sub(workingval);
     workingval = pac_mult(workingval);
     workingval = pac_cell_inv_shuffle(workingval);
     workingval ^= key0;
     workingval ^= runningmod;
-    for (i = 0; i <= 4; ++i) {
-        workingval = pac_inv_sub(workingval);
-        if (i < 4) {
+    for (i = 0; i <= iterations; ++i) {
+        if (isqarma3)
+            workingval = pac_sub1(workingval);
+        else
+            workingval = pac_inv_sub(workingval);
+        if (i < iterations) {
             workingval = pac_mult(workingval);
             workingval = pac_cell_inv_shuffle(workingval);
         }
         runningmod = tweak_inv_shuffle(runningmod);
         roundkey = key1 ^ runningmod;
-        workingval ^= RC[4 - i];
+        workingval ^= RC[iterations - i];
         workingval ^= roundkey;
         workingval ^= alpha;
     }
@@ -283,7 +311,9 @@ static uint64_t pauth_computepac(CPUARMState *env, uint64_t data,
                                  uint64_t modifier, ARMPACKey key)
 {
     if (cpu_isar_feature(aa64_pauth_arch_qarma5, env_archcpu(env))) {
-        return pauth_computepac_architected(data, modifier, key);
+        return pauth_computepac_architected(data, modifier, key, false);
+    } else if (cpu_isar_feature(aa64_pauth_arch_qarma3, env_archcpu(env))) {
+        return pauth_computepac_architected(data, modifier, key, true);
     } else {
         return pauth_computepac_impdef(data, modifier, key);
     }
-- 
2.25.1