From: Alexander Graf <agraf@suse.de>
Date: Tue, 17 Dec 2013 19:42:33 +0000 (+0000)
Subject: target-arm: A64: add support for BR, BLR and RET insns
X-Git-Tag: qemu-xen-4.5.0-rc1~284^2~28
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=b001c8c3d6855b0b52fc0fdd63b5a93fd326bf0c;p=qemu-upstream-4.6-testing.git

target-arm: A64: add support for BR, BLR and RET insns

Implement BR, BLR and RET. This is all of the 'unconditional
branch (register)' instruction category except for ERET
and DPRS (which are system mode only).

Signed-off-by: Alexander Graf <agraf@suse.de>
[claudio: reimplemented on top of new decoder structure]
Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
---

diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index ead5658d4..b69466585 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -384,10 +384,49 @@ static void disas_exc(DisasContext *s, uint32_t insn)
     unsupported_encoding(s, insn);
 }
 
-/* Unconditional branch (register) */
+/* C3.2.7 Unconditional branch (register)
+ *  31           25 24   21 20   16 15   10 9    5 4     0
+ * +---------------+-------+-------+-------+------+-------+
+ * | 1 1 0 1 0 1 1 |  opc  |  op2  |  op3  |  Rn  |  op4  |
+ * +---------------+-------+-------+-------+------+-------+
+ */
 static void disas_uncond_b_reg(DisasContext *s, uint32_t insn)
 {
-    unsupported_encoding(s, insn);
+    unsigned int opc, op2, op3, rn, op4;
+
+    opc = extract32(insn, 21, 4);
+    op2 = extract32(insn, 16, 5);
+    op3 = extract32(insn, 10, 6);
+    rn = extract32(insn, 5, 5);
+    op4 = extract32(insn, 0, 5);
+
+    if (op4 != 0x0 || op3 != 0x0 || op2 != 0x1f) {
+        unallocated_encoding(s);
+        return;
+    }
+
+    switch (opc) {
+    case 0: /* BR */
+    case 2: /* RET */
+        break;
+    case 1: /* BLR */
+        tcg_gen_movi_i64(cpu_reg(s, 30), s->pc);
+        break;
+    case 4: /* ERET */
+    case 5: /* DRPS */
+        if (rn != 0x1f) {
+            unallocated_encoding(s);
+        } else {
+            unsupported_encoding(s, insn);
+        }
+        return;
+    default:
+        unallocated_encoding(s);
+        return;
+    }
+
+    tcg_gen_mov_i64(cpu_pc, cpu_reg(s, rn));
+    s->is_jmp = DISAS_JUMP;
 }
 
 /* C3.2 Branches, exception generating and system instructions */