[Qemu-devel] [PATCH v3 04/28] target/arm: Add MTE_ACTIVE to tb_flags

[Richard Henderson]

When MTE is fully enabled, i.e. access to tags are enabled and
tag checks affect the PE, then arrange to perform the check
while stripping the TBI.

The check is not yet implemented, just the plumbing to that point.

Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
v2: Clean TBI bits exactly.
    Fix license to lgpl 2.1.
v3: Remove stub helper_mte_check; moved to a later patch.
---
 target/arm/cpu.h           | 12 +++++++++
 target/arm/internals.h     | 18 ++++++++++++++
 target/arm/translate.h     |  2 ++
 target/arm/helper.c        | 51 ++++++++++++++++++++++++++++++--------
 target/arm/translate-a64.c |  1 +
 5 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 20be9fb53a..2776df6981 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -1215,6 +1215,7 @@ void pmu_init(ARMCPU *cpu);
 #define PSTATE_BTYPE (3U << 10)
 #define PSTATE_IL (1U << 20)
 #define PSTATE_SS (1U << 21)
+#define PSTATE_TCO (1U << 25)
 #define PSTATE_V (1U << 28)
 #define PSTATE_C (1U << 29)
 #define PSTATE_Z (1U << 30)
@@ -3071,6 +3072,7 @@ FIELD(TBFLAG_A64, PAUTH_ACTIVE, 8, 1)
 FIELD(TBFLAG_A64, BT, 9, 1)
 FIELD(TBFLAG_A64, BTYPE, 10, 2)
 FIELD(TBFLAG_A64, TBID, 12, 2)
+FIELD(TBFLAG_A64, MTE_ACTIVE, 14, 1)
 
 static inline bool bswap_code(bool sctlr_b)
 {
@@ -3361,6 +3363,16 @@ static inline bool isar_feature_aa64_bti(const 
ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, BT) != 0;
 }
 
+static inline bool isar_feature_aa64_mte_insn_reg(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, MTE) != 0;
+}
+
+static inline bool isar_feature_aa64_mte(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64pfr1, ID_AA64PFR1, MTE) >= 2;
+}
+
 /*
  * Forward to the above feature tests given an ARMCPU pointer.
  */
diff --git a/target/arm/internals.h b/target/arm/internals.h
index 587a1ddf58..6c018e773c 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -983,4 +983,22 @@ static inline int exception_target_el(CPUARMState *env)
     return target_el;
 }
 
+/* Determine if allocation tags are available.  */
+static inline bool allocation_tag_access_enabled(CPUARMState *env, int el,
+                                                 uint64_t sctlr)
+{
+    if (el < 3
+        && arm_feature(env, ARM_FEATURE_EL3)
+        && !(env->cp15.scr_el3 & SCR_ATA)) {
+        return false;
+    }
+    if (el < 2
+        && arm_feature(env, ARM_FEATURE_EL2)
+        && !(arm_hcr_el2_eff(env) & HCR_ATA)) {
+        return false;
+    }
+    sctlr &= (el == 0 ? SCTLR_ATA0 : SCTLR_ATA);
+    return sctlr != 0;
+}
+
 #endif
diff --git a/target/arm/translate.h b/target/arm/translate.h
index 33af50a13f..5a101e1c6d 100644
--- a/target/arm/translate.h
+++ b/target/arm/translate.h
@@ -70,6 +70,8 @@ typedef struct DisasContext {
     bool ss_same_el;
     /* True if v8.3-PAuth is active.  */
     bool pauth_active;
+    /* True if v8.5-MTE tag checks affect the PE.  */
+    bool mte_active;
     /* True with v8.5-BTI and SCTLR_ELx.BT* set.  */
     bool bt;
     /*
diff --git a/target/arm/helper.c b/target/arm/helper.c
index d4abbb5076..e73bdbf041 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -1862,6 +1862,9 @@ static void scr_write(CPUARMState *env, const 
ARMCPRegInfo *ri, uint64_t value)
     if (cpu_isar_feature(aa64_pauth, cpu)) {
         valid_mask |= SCR_API | SCR_APK;
     }
+    if (cpu_isar_feature(aa64_mte, cpu)) {
+        valid_mask |= SCR_ATA;
+    }
 
     /* Clear all-context RES0 bits.  */
     value &= valid_mask;
@@ -4056,22 +4059,31 @@ static void sctlr_write(CPUARMState *env, const 
ARMCPRegInfo *ri,
 {
     ARMCPU *cpu = arm_env_get_cpu(env);
 
-    if (raw_read(env, ri) == value) {
-        /* Skip the TLB flush if nothing actually changed; Linux likes
-         * to do a lot of pointless SCTLR writes.
-         */
-        return;
-    }
-
     if (arm_feature(env, ARM_FEATURE_PMSA) && !cpu->has_mpu) {
         /* M bit is RAZ/WI for PMSA with no MPU implemented */
         value &= ~SCTLR_M;
     }
 
-    raw_write(env, ri, value);
+    if (!cpu_isar_feature(aa64_mte, cpu)) {
+        if (ri->opc1 == 6) { /* SCTLR_EL3 */
+            value &= ~(SCTLR_ITFSB | SCTLR_TCF | SCTLR_ATA);
+        } else {
+            value &= ~(SCTLR_ITFSB | SCTLR_TCF0 | SCTLR_TCF |
+                       SCTLR_ATA0 | SCTLR_ATA);
+        }
+    }
+
     /* ??? Lots of these bits are not implemented.  */
-    /* This may enable/disable the MMU, so do a TLB flush.  */
-    tlb_flush(CPU(cpu));
+
+    if (raw_read(env, ri) != value) {
+        /*
+         * This may enable/disable the MMU, so do a TLB flush.
+         * Skip the TLB flush if nothing actually changed;
+         * Linux likes to do a lot of pointless SCTLR writes.
+         */
+        raw_write(env, ri, value);
+        tlb_flush(CPU(cpu));
+    }
 }
 
 static CPAccessResult fpexc32_access(CPUARMState *env, const ARMCPRegInfo *ri,
@@ -4564,6 +4576,9 @@ static void hcr_write(CPUARMState *env, const 
ARMCPRegInfo *ri, uint64_t value)
     if (cpu_isar_feature(aa64_pauth, cpu)) {
         valid_mask |= HCR_API | HCR_APK;
     }
+    if (cpu_isar_feature(aa64_mte, cpu)) {
+        valid_mask |= HCR_ATA;
+    }
 
     /* Clear RES0 bits.  */
     value &= valid_mask;
@@ -13756,6 +13771,7 @@ void cpu_get_tb_cpu_state(CPUARMState *env, 
target_ulong *pc,
     if (is_a64(env)) {
         ARMCPU *cpu = arm_env_get_cpu(env);
         uint64_t sctlr;
+        int tbid;
 
         *pc = env->pc;
         flags = FIELD_DP32(flags, TBFLAG_ANY, AARCH64_STATE, 1);
@@ -13764,7 +13780,7 @@ void cpu_get_tb_cpu_state(CPUARMState *env, 
target_ulong *pc,
         {
             ARMMMUIdx stage1 = stage_1_mmu_idx(mmu_idx);
             ARMVAParameters p0 = aa64_va_parameters_both(env, 0, stage1);
-            int tbii, tbid;
+            int tbii;
 
             /* FIXME: ARMv8.1-VHE S2 translation regime.  */
             if (regime_el(env, stage1) < 2) {
@@ -13817,6 +13833,19 @@ void cpu_get_tb_cpu_state(CPUARMState *env, 
target_ulong *pc,
             }
             flags = FIELD_DP32(flags, TBFLAG_A64, BTYPE, env->btype);
         }
+
+        /*
+         * If MTE is enabled, and tag checks affect the PE,
+         * then we check the tag as we strip the TBI field.
+         * Note that if TBI is disabled, all accesses are unchecked.
+         */
+        if (tbid
+            && cpu_isar_feature(aa64_mte, cpu)
+            && allocation_tag_access_enabled(env, current_el, sctlr)
+            && !(env->pstate & PSTATE_TCO)
+            && (sctlr & (current_el == 0 ? SCTLR_TCF0 : SCTLR_TCF))) {
+            flags = FIELD_DP32(flags, TBFLAG_A64, MTE_ACTIVE, 1);
+        }
     } else {
         *pc = env->regs[15];
         flags = FIELD_DP32(flags, TBFLAG_A32, THUMB, env->thumb);
diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index ba139bba26..3950067b79 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -14041,6 +14041,7 @@ static void 
aarch64_tr_init_disas_context(DisasContextBase *dcbase,
     dc->pauth_active = FIELD_EX32(tb_flags, TBFLAG_A64, PAUTH_ACTIVE);
     dc->bt = FIELD_EX32(tb_flags, TBFLAG_A64, BT);
     dc->btype = FIELD_EX32(tb_flags, TBFLAG_A64, BTYPE);
+    dc->mte_active = FIELD_EX32(tb_flags, TBFLAG_A64, MTE_ACTIVE);
     dc->vec_len = 0;
     dc->vec_stride = 0;
     dc->cp_regs = arm_cpu->cp_regs;
-- 
2.17.2