Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/cpregs.h            |  1 +
 target/arm/cpregs-gcs.c        |  3 +++
 target/arm/tcg/translate-a64.c | 35 ++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/target/arm/cpregs.h b/target/arm/cpregs.h
index 3d76afd20b..084ea00e51 100644
--- a/target/arm/cpregs.h
+++ b/target/arm/cpregs.h
@@ -50,6 +50,7 @@ enum {
     ARM_CP_GCSPUSHM              = 0x0008,
     ARM_CP_GCSPOPM               = 0x0009,
     ARM_CP_GCSPUSHX              = 0x000a,
+    ARM_CP_GCSPOPX               = 0x000b,
 
     /* Flag: reads produce resetvalue; writes ignored. */
     ARM_CP_CONST                 = 1 << 4,
diff --git a/target/arm/cpregs-gcs.c b/target/arm/cpregs-gcs.c
index c688d0c391..2d39b17188 100644
--- a/target/arm/cpregs-gcs.c
+++ b/target/arm/cpregs-gcs.c
@@ -116,6 +116,9 @@ static const ARMCPRegInfo gcs_reginfo[] = {
       .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 7, .opc2 = 4,
       .access = PL1_W, .accessfn = access_gcspushx, .fgt = FGT_NGCSEPP,
       .type = ARM_CP_GCSPUSHX },
+    { .name = "GCSPOPX", .state = ARM_CP_STATE_AA64,
+      .opc0 = 1, .opc1 = 0, .crn = 7, .crm = 7, .opc2 = 6,
+      .access = PL1_W, .type = ARM_CP_GCSPOPX },
 };
 
 void define_gcs_cpregs(ARMCPU *cpu)
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
index e5d9a6e837..b0a1a62a91 100644
--- a/target/arm/tcg/translate-a64.c
+++ b/target/arm/tcg/translate-a64.c
@@ -2560,6 +2560,33 @@ static void gen_gcspushx(DisasContext *s)
     clear_pstate_bits(PSTATE_EXLOCK);
 }
 
+static void gen_gcspopx(DisasContext *s)
+{
+    TCGv_i64 gcspr = cpu_gcspr[s->current_el];
+    int mmuidx = core_gcs_mem_index(s->mmu_idx);
+    MemOp mop = finalize_memop(s, MO_64 | MO_ALIGN);
+    TCGv_i64 addr = tcg_temp_new_i64();
+    TCGv_i64 tmp = tcg_temp_new_i64();
+    TCGLabel *fail_label =
+        delay_exception(s, EXCP_UDEF, syn_gcs_data_check(GCS_IT_GCSPOPX, 31));
+
+    /* The value at top-of-stack must be an exception token. */
+    tcg_gen_qemu_ld_i64(tmp, gcspr, mmuidx, mop);
+    tcg_gen_brcondi_i64(TCG_COND_NE, tmp, 0b1001, fail_label);
+
+    /*
+     * The other three values in the exception return record
+     * are ignored, but are loaded anyway to raise faults.
+     */
+    tcg_gen_addi_i64(addr, gcspr, 8);
+    tcg_gen_qemu_ld_i64(tmp, addr, mmuidx, mop);
+    tcg_gen_addi_i64(addr, addr, 8);
+    tcg_gen_qemu_ld_i64(tmp, addr, mmuidx, mop);
+    tcg_gen_addi_i64(addr, addr, 8);
+    tcg_gen_qemu_ld_i64(tmp, addr, mmuidx, mop);
+    tcg_gen_addi_i64(gcspr, addr, 8);
+}
+
 /* MRS - move from system register
  * MSR (register) - move to system register
  * SYS
@@ -2855,6 +2882,14 @@ static void handle_sys(DisasContext *s, bool isread,
             gen_gcspushx(s);
         }
         return;
+    case ARM_CP_GCSPOPX:
+        /* Choose the CONSTRAINED UNPREDICTABLE for UNDEF. */
+        if (rt != 31) {
+            unallocated_encoding(s);
+        } else if (s->gcs_en) {
+            gen_gcspopx(s);
+        }
+        return;
     default:
         g_assert_not_reached();
     }
-- 
2.43.0