From 0e4cc77316732e67cff33e493eff2aa7feed4587 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 23 Jul 2021 08:03:21 +0200
Subject: x86: express unduly set rounding control bits in disassembly

While EVEX.L'L are indeed ignored when EVEX.b stands for just SAE,
EVEX.b itself is not ignored when an insn permits neither rounding
control nor SAE.

While changing this aspect of EVEX.b handling, also alter unduly set
embedded broadcast: Don't call BadOp(), screwing up subsequent
disassembly, but emit "{bad}" instead.
---
 opcodes/i386-dis.c | 90 ++++++++++++++++++++++++++++++++----------------------
 1 file changed, 53 insertions(+), 37 deletions(-)

(limited to 'opcodes')

diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 521d689..b25a9f3 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -159,6 +159,11 @@ static int rex_used;
    current instruction.  */
 static int used_prefixes;
 
+/* Flags for EVEX bits which we somehow handled when printing the
+   current instruction.  */
+#define EVEX_b_used 1
+static int evex_used;
+
 /* Flags stored in PREFIXES.  */
 #define PREFIX_REPZ 1
 #define PREFIX_REPNZ 2
@@ -2524,12 +2529,12 @@ static const char *att_names_mask[] = {
   "%k0", "%k1", "%k2", "%k3", "%k4", "%k5", "%k6", "%k7"
 };
 
-static const char *names_rounding[] =
+static const char *const names_rounding[] =
 {
-  "{rn-sae}",
-  "{rd-sae}",
-  "{ru-sae}",
-  "{rz-sae}"
+  "{rn-",
+  "{rd-",
+  "{ru-",
+  "{rz-"
 };
 
 static const struct dis386 reg_table[][8] = {
@@ -8578,6 +8583,7 @@ ckprefix (void)
   prefixes = 0;
   used_prefixes = 0;
   rex_used = 0;
+  evex_used = 0;
   last_lock_prefix = -1;
   last_repz_prefix = -1;
   last_repnz_prefix = -1;
@@ -9661,6 +9667,21 @@ print_insn (bfd_vma pc, disassemble_info *info)
 		    oappend ("/(bad)");
 		}
 	    }
+
+	  /* Check whether rounding control was enabled for an insn not
+	     supporting it.  */
+	  if (modrm.mod == 3 && vex.b && !(evex_used & EVEX_b_used))
+	    {
+	      for (i = 0; i < MAX_OPERANDS; ++i)
+		{
+		  obufp = op_out[i];
+		  if (*obufp)
+		    continue;
+		  oappend (names_rounding[vex.ll]);
+		  oappend ("bad}");
+		  break;
+		}
+	    }
 	}
     }
 
@@ -11316,14 +11337,6 @@ OP_E_memory (int bytemode, int sizeflag)
 
   if (vex.evex)
     {
-      /* In EVEX, if operand doesn't allow broadcast, vex.b should be 0.  */
-      if (vex.b
-	  && bytemode != x_mode
-	  && bytemode != evex_half_bcst_xmmq_mode)
-	{
-	  BadOp ();
-	  return;
-	}
       switch (bytemode)
 	{
 	case dw_mode:
@@ -11764,10 +11777,9 @@ OP_E_memory (int bytemode, int sizeflag)
 	  oappend (scratchbuf);
 	}
     }
-  if (vex.b
-      && (bytemode == x_mode
-	  || bytemode == evex_half_bcst_xmmq_mode))
+  if (vex.b)
     {
+      evex_used |= EVEX_b_used;
       if (vex.w
 	  || bytemode == evex_half_bcst_xmmq_mode)
 	{
@@ -11786,7 +11798,7 @@ OP_E_memory (int bytemode, int sizeflag)
 	      abort ();
 	    }
 	}
-      else
+      else if (bytemode == x_mode)
 	{
 	  switch (vex.length)
 	    {
@@ -11803,6 +11815,9 @@ OP_E_memory (int bytemode, int sizeflag)
 	      abort ();
 	    }
 	}
+      else
+	/* If operand doesn't allow broadcast, vex.b should be 0.  */
+	oappend ("{bad}");
     }
 }
 
@@ -13495,24 +13510,25 @@ MOVSXD_Fixup (int bytemode, int sizeflag)
 static void
 OP_Rounding (int bytemode, int sizeflag ATTRIBUTE_UNUSED)
 {
-  if (modrm.mod == 3 && vex.b)
-    switch (bytemode)
-      {
-      case evex_rounding_64_mode:
-	if (address_mode != mode_64bit || !vex.w)
-	  {
-	    oappend ("(bad)");
-	    break;
-	  }
-	/* Fall through.  */
-      case evex_rounding_mode:
-	oappend (names_rounding[vex.ll]);
-	break;
-      case evex_sae_mode:
-	oappend ("{sae}");
-	break;
-      default:
-	abort ();
-	break;
-      }
+  if (modrm.mod != 3 || !vex.b)
+    return;
+
+  switch (bytemode)
+    {
+    case evex_rounding_64_mode:
+      if (address_mode != mode_64bit || !vex.w)
+        return;
+      /* Fall through.  */
+    case evex_rounding_mode:
+      evex_used |= EVEX_b_used;
+      oappend (names_rounding[vex.ll]);
+      break;
+    case evex_sae_mode:
+      evex_used |= EVEX_b_used;
+      oappend ("{");
+      break;
+    default:
+      abort ();
+    }
+  oappend ("sae}");
 }
-- 
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