target/arm: Fix cpu_get_tb_cpu_state() for non-SVE CPUs

Not only are the sve-related tb_flags fields unused when SVE is
disabled, but not all of the cpu registers are initialized properly
for computing same.  This can corrupt other fields by ORing in -1,
which might result in QEMU crashing.

This bug was not present in 3.0, but this patch is cc'd to
stable because adf92eab90e3f5f34c285 where the bug was
introduced was marked for stable.

Fixes: adf92eab90e3f5f34c285
Cc: qemu-stable@nongnu.org (3.0.1)
Signed-off-by: Richard Henderson <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 e79b445d896deb61909be52b61b87c98a9ed96f7)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 991b077e8fbd9da6a1fc0bb9c887e861288f1e55..7ee614c04f04278b4002e46c02cecead49451d3a 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -12401,36 +12401,39 @@ void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
     uint32_t flags;
 
     if (is_a64(env)) {
-        int sve_el = sve_exception_el(env);
-        uint32_t zcr_len;
-
         *pc = env->pc;
         flags = ARM_TBFLAG_AARCH64_STATE_MASK;
         /* Get control bits for tagged addresses */
         flags |= (arm_regime_tbi0(env, mmu_idx) << ARM_TBFLAG_TBI0_SHIFT);
         flags |= (arm_regime_tbi1(env, mmu_idx) << ARM_TBFLAG_TBI1_SHIFT);
-        flags |= sve_el << ARM_TBFLAG_SVEEXC_EL_SHIFT;
 
-        /* If SVE is disabled, but FP is enabled,
-           then the effective len is 0.  */
-        if (sve_el != 0 && fp_el == 0) {
-            zcr_len = 0;
-        } else {
-            int current_el = arm_current_el(env);
-            ARMCPU *cpu = arm_env_get_cpu(env);
+        if (arm_feature(env, ARM_FEATURE_SVE)) {
+            int sve_el = sve_exception_el(env);
+            uint32_t zcr_len;
 
-            zcr_len = cpu->sve_max_vq - 1;
-            if (current_el <= 1) {
-                zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[1]);
-            }
-            if (current_el < 2 && arm_feature(env, ARM_FEATURE_EL2)) {
-                zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[2]);
-            }
-            if (current_el < 3 && arm_feature(env, ARM_FEATURE_EL3)) {
-                zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[3]);
+            /* If SVE is disabled, but FP is enabled,
+             * then the effective len is 0.
+             */
+            if (sve_el != 0 && fp_el == 0) {
+                zcr_len = 0;
+            } else {
+                int current_el = arm_current_el(env);
+                ARMCPU *cpu = arm_env_get_cpu(env);
+
+                zcr_len = cpu->sve_max_vq - 1;
+                if (current_el <= 1) {
+                    zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[1]);
+                }
+                if (current_el < 2 && arm_feature(env, ARM_FEATURE_EL2)) {
+                    zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[2]);
+                }
+                if (current_el < 3 && arm_feature(env, ARM_FEATURE_EL3)) {
+                    zcr_len = MIN(zcr_len, 0xf & (uint32_t)env->vfp.zcr_el[3]);
+                }
             }
+            flags |= sve_el << ARM_TBFLAG_SVEEXC_EL_SHIFT;
+            flags |= zcr_len << ARM_TBFLAG_ZCR_LEN_SHIFT;
         }
-        flags |= zcr_len << ARM_TBFLAG_ZCR_LEN_SHIFT;
     } else {
         *pc = env->regs[15];
         flags = (env->thumb << ARM_TBFLAG_THUMB_SHIFT)