target-arm: Break the TB after ISB to execute self-modified code correctly

If any store instruction writes the code inside the same TB
after this store insn, the execution of the TB must be stopped
to execute new code correctly.
As described in ARMv8 manual D3.4.6 self-modifying code must do an
IC invalidation to be valid, and an ISB after it. So it's enough to end
the TB after ISB instruction on the code translation.
Also this TB break is necessary to take any pending interrupts immediately
after an ISB (as required by ARMv8 ARM D1.14.4).

Signed-off-by: Sergey Sorokin <afarallax@yandex.ru>
[PMM: tweaked commit message and comments slightly]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/target-arm/helper.c b/target-arm/helper.c
index 584f6df80ddb6ab47a05c065ad885756ee9dc25d..b4986705c4458a7ffc8c9b6c852835b360f88e13 100644 (file)
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -657,8 +657,12 @@ static const ARMCPRegInfo v6_cp_reginfo[] = {
     { .name = "MVA_prefetch",
       .cp = 15, .crn = 7, .crm = 13, .opc1 = 0, .opc2 = 1,
       .access = PL1_W, .type = ARM_CP_NOP },
+    /* We need to break the TB after ISB to execute self-modifying code
+     * correctly and also to take any pending interrupts immediately.
+     * So use arm_cp_write_ignore() function instead of ARM_CP_NOP flag.
+     */
     { .name = "ISB", .cp = 15, .crn = 7, .crm = 5, .opc1 = 0, .opc2 = 4,
-      .access = PL0_W, .type = ARM_CP_NOP },
+      .access = PL0_W, .type = ARM_CP_NO_RAW, .writefn = arm_cp_write_ignore },
     { .name = "DSB", .cp = 15, .crn = 7, .crm = 10, .opc1 = 0, .opc2 = 4,
       .access = PL0_W, .type = ARM_CP_NOP },
     { .name = "DMB", .cp = 15, .crn = 7, .crm = 10, .opc1 = 0, .opc2 = 5,

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index e65e309535a84442b2aa07a4a2178fbdcee59bd4..a4580c07a62472aef6d9d1dcc5284857a34c9c4f 100644 (file)
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -1230,9 +1230,15 @@ static void handle_sync(DisasContext *s, uint32_t insn,
         return;
     case 4: /* DSB */
     case 5: /* DMB */
-    case 6: /* ISB */
         /* We don't emulate caches so barriers are no-ops */
         return;
+    case 6: /* ISB */
+        /* We need to break the TB after this insn to execute
+         * a self-modified code correctly and also to take
+         * any pending interrupts immediately.
+         */
+        s->is_jmp = DISAS_UPDATE;
+        return;
     default:
         unallocated_encoding(s);
         return;

diff --git a/target-arm/translate.c b/target-arm/translate.c
index 22c35877e53bfc9b1aaea231a8ab92f94d6915c8..127300007f9eb7d92f3de119696402a8eb2bbada 100644 (file)
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -7720,10 +7720,16 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
                 return;
             case 4: /* dsb */
             case 5: /* dmb */
-            case 6: /* isb */
                 ARCH(7);
                 /* We don't emulate caches so these are a no-op.  */
                 return;
+            case 6: /* isb */
+                /* We need to break the TB after this insn to execute
+                 * self-modifying code correctly and also to take
+                 * any pending interrupts immediately.
+                 */
+                gen_lookup_tb(s);
+                return;
             default:
                 goto illegal_op;
             }
@@ -10030,9 +10036,16 @@ static int disas_thumb2_insn(CPUARMState *env, DisasContext *s, uint16_t insn_hw
                             break;
                         case 4: /* dsb */
                         case 5: /* dmb */
-                        case 6: /* isb */
                             /* These execute as NOPs.  */
                             break;
+                        case 6: /* isb */
+                            /* We need to break the TB after this insn
+                             * to execute self-modifying code correctly
+                             * and also to take any pending interrupts
+                             * immediately.
+                             */
+                            gen_lookup_tb(s);
+                            break;
                         default:
                             goto illegal_op;
                         }