[PATCH 6/7] target/arm: Implement v8.3 FPAC and FPACCOMBINE

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

Signed-off-by: Aaron Lindsay <aaron@os.amperecomputing.com>
---
 target/arm/pauth_helper.c | 26 ++++++++++++++++++++++++++
 target/arm/syndrome.h     |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index 66dc90a289..3a2772de0e 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -385,6 +385,21 @@ static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
     return deposit64(ptr, bot_pac_bit, top_pac_bit - bot_pac_bit, extfield);
 }
 
+static G_NORETURN
+void pauth_fail_exception(CPUARMState *env, int error_code)
+{
+    int target_el = arm_current_el(env);
+    if (target_el == 0) {
+        uint64_t hcr = arm_hcr_el2_eff(env);
+        if (arm_is_el2_enabled(env) && (hcr & HCR_TGE))
+            target_el = 2;
+        else
+            target_el = 1;
+    }
+
+    raise_exception_ra(env, EXCP_UDEF, syn_pacfail(error_code), target_el, GETPC());
+}
+
 static uint64_t pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t modifier,
                            ARMPACKey *key, bool data, int keynumber,
                            bool is_combined)
@@ -403,6 +418,17 @@ static uint64_t pauth_auth(CPUARMState *env, uint64_t ptr, uint64_t modifier,
         uint64_t xor_mask = MAKE_64BIT_MASK(bot_bit, top_bit - bot_bit + 1) &
             ~MAKE_64BIT_MASK(55, 1);
         result = ((ptr ^ pac) & xor_mask) | (ptr & ~xor_mask);
+        if (cpu_isar_feature(aa64_fpac_combine, env_archcpu(env)) ||
+                (cpu_isar_feature(aa64_fpac, env_archcpu(env)) &&
+                 !is_combined)) {
+            int fpac_top = param.tbi ? 55 : 64;
+            uint64_t fpac_mask = MAKE_64BIT_MASK(bot_bit, fpac_top - bot_bit);
+            test = (result ^ sextract64(result, 55, 1)) & fpac_mask;
+            if (unlikely(test)) {
+                int error_code = ((data ? 1 : 0) << 1) | (keynumber);
+                pauth_fail_exception(env, error_code);
+            }
+        }
     } else {
         test = (pac ^ ptr) & ~MAKE_64BIT_MASK(55, 1);
         if (unlikely(extract64(test, bot_bit, top_bit - bot_bit))) {
diff --git a/target/arm/syndrome.h b/target/arm/syndrome.h
index 73df5e3793..885a85735c 100644
--- a/target/arm/syndrome.h
+++ b/target/arm/syndrome.h
@@ -48,6 +48,7 @@ enum arm_exception_class {
     EC_AA64_SMC               = 0x17,
     EC_SYSTEMREGISTERTRAP     = 0x18,
     EC_SVEACCESSTRAP          = 0x19,
+    EC_PACFAIL                = 0x1c,
     EC_SMETRAP                = 0x1d,
     EC_INSNABORT              = 0x20,
     EC_INSNABORT_SAME_EL      = 0x21,
@@ -221,6 +222,11 @@ static inline uint32_t syn_smetrap(SMEExceptionType etype, bool is_16bit)
         | (is_16bit ? 0 : ARM_EL_IL) | etype;
 }
 
+static inline uint32_t syn_pacfail(int error_code)
+{
+    return (EC_PACFAIL << ARM_EL_EC_SHIFT) | error_code;
+}
+
 static inline uint32_t syn_pactrap(void)
 {
     return EC_PACTRAP << ARM_EL_EC_SHIFT;
-- 
2.25.1