[PATCH v4 3/9] target/arm: Add feature detection for FEAT_Pauth2 and extensions

[Richard Henderson <richard.henderson@linaro.org>]

From: Aaron Lindsay <aaron@os.amperecomputing.com>

Rename isar_feature_aa64_pauth_arch to isar_feature_aa64_pauth_qarma5
to distinguish the other architectural algorithm qarma3.

Add ARMPauthFeature and isar_feature_pauth_feature to cover the
other pauth conditions.

Signed-off-by: Aaron Lindsay <aaron@os.amperecomputing.com>
Message-Id: <20230609172324.982888-3-aaron@os.amperecomputing.com>
[rth: Add ARMPauthFeature and eliminate most other predicates]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpu.h              | 49 +++++++++++++++++++++++++++++------
 target/arm/tcg/pauth_helper.c |  2 +-
 2 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index fbdbf2df7f..e9fe268453 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -3794,28 +3794,61 @@ static inline bool isar_feature_aa64_fcma(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, FCMA) != 0;
 }
 
+/*
+ * These are the values from APA/API/APA3.
+ *
+ * They must be compared '>=', except EPAC should use '=='.
+ * In the ARM pseudocode, EPAC is treated as not being implemented
+ * by larger values.
+ */
+typedef enum {
+    PauthFeat_None         = 0,
+    PauthFeat_1            = 1,
+    PauthFeat_EPAC         = 2,
+    PauthFeat_2            = 3,
+    PauthFeat_FPAC         = 4,
+    PauthFeat_FPACCOMBINED = 5,
+} ARMPauthFeature;
+
+static inline ARMPauthFeature
+isar_feature_pauth_feature(const ARMISARegisters *id)
+{
+    /*
+     * Architecturally, only one of {APA,API,APA3} may be active (non-zero)
+     * and the other two must be zero.  Thus we may avoid conditionals.
+     */
+    return (FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, APA) |
+            FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, API) |
+            FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, APA3));
+}
+
 static inline bool isar_feature_aa64_pauth(const ARMISARegisters *id)
 {
     /*
      * Return true if any form of pauth is enabled, as this
      * predicate controls migration of the 128-bit keys.
      */
-    return (id->id_aa64isar1 &
-            (FIELD_DP64(0, ID_AA64ISAR1, APA, 0xf) |
-             FIELD_DP64(0, ID_AA64ISAR1, API, 0xf) |
-             FIELD_DP64(0, ID_AA64ISAR1, GPA, 0xf) |
-             FIELD_DP64(0, ID_AA64ISAR1, GPI, 0xf))) != 0;
+    return isar_feature_pauth_feature(id) != PauthFeat_None;
 }
 
-static inline bool isar_feature_aa64_pauth_arch(const ARMISARegisters *id)
+static inline bool isar_feature_aa64_pauth_qarma5(const ARMISARegisters *id)
 {
     /*
-     * Return true if pauth is enabled with the architected QARMA algorithm.
-     * QEMU will always set APA+GPA to the same value.
+     * Return true if pauth is enabled with the architected QARMA5 algorithm.
+     * QEMU will always enable or disable both APA and GPA.
      */
     return FIELD_EX64(id->id_aa64isar1, ID_AA64ISAR1, APA) != 0;
 }
 
+static inline bool isar_feature_aa64_pauth_qarma3(const ARMISARegisters *id)
+{
+    /*
+     * Return true if pauth is enabled with the architected QARMA3 algorithm.
+     * QEMU will always enable or disable both APA3 and GPA3.
+     */
+    return FIELD_EX64(id->id_aa64isar2, ID_AA64ISAR2, APA3) != 0;
+}
+
 static inline bool isar_feature_aa64_tlbirange(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64isar0, ID_AA64ISAR0, TLB) == 2;
diff --git a/target/arm/tcg/pauth_helper.c b/target/arm/tcg/pauth_helper.c
index 62af569341..6271a84ec9 100644
--- a/target/arm/tcg/pauth_helper.c
+++ b/target/arm/tcg/pauth_helper.c
@@ -282,7 +282,7 @@ static uint64_t pauth_computepac_impdef(uint64_t data, uint64_t modifier,
 static uint64_t pauth_computepac(CPUARMState *env, uint64_t data,
                                  uint64_t modifier, ARMPACKey key)
 {
-    if (cpu_isar_feature(aa64_pauth_arch, env_archcpu(env))) {
+    if (cpu_isar_feature(aa64_pauth_qarma5, env_archcpu(env))) {
         return pauth_computepac_architected(data, modifier, key);
     } else {
         return pauth_computepac_impdef(data, modifier, key);
-- 
2.34.1