From 7927f3cff5d19e4edbb0959edfe5961d7f653408 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Tue, 18 Dec 2018 05:33:59 -0500
Subject: [PATCH] tcg/s390x: Return false on failure from patch_reloc

This does require an extra two checks within the slow paths
to replace the assert that we're moving. Also add two checks
within existing functions that lacked any kind of assert for
out of range branch.

Backports commit 55dfd8fedceb1311d9cdded1a0f94b2da91a387d from qemu
---
 qemu/tcg/s390/tcg-target.inc.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/qemu/tcg/s390/tcg-target.inc.c b/qemu/tcg/s390/tcg-target.inc.c
index 838869d8..2fbc310b 100644
--- a/qemu/tcg/s390/tcg-target.inc.c
+++ b/qemu/tcg/s390/tcg-target.inc.c
@@ -383,23 +383,29 @@ static bool patch_reloc(tcg_insn_unit *code_ptr, int type,
 
     switch (type) {
     case R_390_PC16DBL:
-        assert(pcrel2 == (int16_t)pcrel2);
-        tcg_patch16(code_ptr, pcrel2);
+        if (pcrel2 == (int16_t)pcrel2) {
+            tcg_patch16(code_ptr, pcrel2);
+            return true;
+        }
         break;
     case R_390_PC32DBL:
-        assert(pcrel2 == (int32_t)pcrel2);
-        tcg_patch32(code_ptr, pcrel2);
+        if (pcrel2 == (int32_t)pcrel2) {
+            tcg_patch32(code_ptr, pcrel2);
+            return true;
+        }
         break;
     case R_390_20:
-        assert(value == sextract64(value, 0, 20));
-        old = *(uint32_t *)code_ptr & 0xf00000ff;
-        old |= ((value & 0xfff) << 16) | ((value & 0xff000) >> 4);
-        tcg_patch32(code_ptr, old);
+        if (value == sextract64(value, 0, 20)) {
+            old = *(uint32_t *)code_ptr & 0xf00000ff;
+            old |= ((value & 0xfff) << 16) | ((value & 0xff000) >> 4);
+            tcg_patch32(code_ptr, old);
+            return true;
+        }
         break;
     default:
         g_assert_not_reached();
     }
-    return true;
+    return false;
 }
 
 /* parse target specific constraints */
@@ -1339,6 +1345,7 @@ static void tgen_compare_branch(TCGContext *s, S390Opcode opc, int cc,
 
     if (l->has_value) {
         off = l->u.value_ptr - s->code_ptr;
+        tcg_debug_assert(off == (int16_t)off);
     } else {
         tcg_out_reloc(s, s->code_ptr + 1, R_390_PC16DBL, l, 2);
     }
@@ -1355,6 +1362,7 @@ static void tgen_compare_imm_branch(TCGContext *s, S390Opcode opc, int cc,
 
     if (l->has_value) {
         off = l->u.value_ptr - s->code_ptr;
+        tcg_debug_assert(off == (int16_t)off);
     } else {
         tcg_out_reloc(s, s->code_ptr + 1, R_390_PC16DBL, l, 2);
     }
@@ -1621,7 +1629,9 @@ static void tcg_out_qemu_ld_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOpIdx oi = lb->oi;
     TCGMemOp opc = get_memop(oi);
 
-    patch_reloc(lb->label_ptr[0], R_390_PC16DBL, (intptr_t)s->code_ptr, 2);
+    bool ok = patch_reloc(lb->label_ptr[0], R_390_PC16DBL,
+                          (intptr_t)s->code_ptr, 2);
+    tcg_debug_assert(ok);
 
     tcg_out_mov(s, TCG_TYPE_PTR, TCG_REG_R2, TCG_AREG0);
     if (TARGET_LONG_BITS == 64) {
@@ -1642,7 +1652,9 @@ static void tcg_out_qemu_st_slow_path(TCGContext *s, TCGLabelQemuLdst *lb)
     TCGMemOpIdx oi = lb->oi;
     TCGMemOp opc = get_memop(oi);
 
-    patch_reloc(lb->label_ptr[0], R_390_PC16DBL, (intptr_t)s->code_ptr, 2);
+    bool ok = patch_reloc(lb->label_ptr[0], R_390_PC16DBL,
+                          (intptr_t)s->code_ptr, 2);
+    tcg_debug_assert(ok);
 
     tcg_out_mov(s, TCG_TYPE_PTR, TCG_REG_R2, TCG_AREG0);
     if (TARGET_LONG_BITS == 64) {