[PATCH v2 7/7] x86: move bad-use-of-TLS-reloc check

Jan Beulich jbeulich@suse.com
Fri Aug 26 10:33:44 GMT 2022


Having it in match_template() is unhelpful. Neither does looking for the
next template to possibly match make any sense in that case, nor is the
resulting diagnostic making clear what the problem is.

While moving the check, also generalize it to include all SIMD and VEX-
encoded insns. This way an existing conditional can be re-used in
md_assemble(). Note though that this still leaves a lof of insns which
are also wrong to use with these relocations.

Further fold the remaining check (BFD_RELOC_386_GOT32) with the XRELEASE
related one a few lines down. This again allows re-using an existing
conditional.
---
Is the set of relocations enumerated here actually complete?
---
v2: New.

--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -5116,14 +5116,30 @@ md_assemble (char *line)
       return;
     }
 
-  /* Check for data size prefix on VEX/XOP/EVEX encoded and SIMD insns.  */
-  if (i.prefix[DATA_PREFIX]
-      && (is_any_vex_encoding (&i.tm)
-	  || i.tm.operand_types[i.imm_operands].bitfield.class >= RegMMX
-	  || i.tm.operand_types[i.imm_operands + 1].bitfield.class >= RegMMX))
+  if (is_any_vex_encoding (&i.tm)
+      || i.tm.operand_types[i.imm_operands].bitfield.class >= RegMMX
+      || i.tm.operand_types[i.imm_operands + 1].bitfield.class >= RegMMX)
     {
-      as_bad (_("data size prefix invalid with `%s'"), i.tm.name);
-      return;
+      /* Check for data size prefix on VEX/XOP/EVEX encoded and SIMD insns.  */
+      if (i.prefix[DATA_PREFIX])
+	{
+	  as_bad (_("data size prefix invalid with `%s'"), i.tm.name);
+	  return;
+	}
+
+      /* Don't allow e.g. KMOV in TLS code sequences.  */
+      for (j = i.imm_operands; j < i.operands; ++j)
+	switch (i.reloc[j])
+	  {
+	  case BFD_RELOC_386_TLS_GOTIE:
+	  case BFD_RELOC_386_TLS_LE_32:
+	  case BFD_RELOC_X86_64_GOTTPOFF:
+	  case BFD_RELOC_X86_64_TLSLD:
+	    as_bad (_("TLS relocation cannot be used with `%s'"), i.tm.name);
+	    return;
+	  default:
+	    break;
+	  }
     }
 
   /* Check if HLE prefix is OK.  */
@@ -6765,26 +6781,6 @@ match_template (char mnem_suffix)
 	    }
 	}
 
-      switch (i.reloc[0])
-	{
-	case BFD_RELOC_386_GOT32:
-	  /* Force 0x8b encoding for "mov foo@GOT, %eax".  */
-	  if (t->base_opcode == 0xa0
-	      && t->opcode_modifier.opcodespace == SPACE_BASE)
-	    continue;
-	  break;
-	case BFD_RELOC_386_TLS_GOTIE:
-	case BFD_RELOC_386_TLS_LE_32:
-	case BFD_RELOC_X86_64_GOTTPOFF:
-	case BFD_RELOC_X86_64_TLSLD:
-	  /* Don't allow KMOV in TLS code sequences.  */
-	  if (t->opcode_modifier.vex)
-	    continue;
-	  break;
-	default:
-	  break;
-	}
-
       /* We check register size if needed.  */
       if (t->opcode_modifier.checkregsize)
 	{
@@ -6815,12 +6811,19 @@ match_template (char mnem_suffix)
 	      && i.types[1].bitfield.instance == Accum
 	      && i.types[1].bitfield.dword)
 	    continue;
-	  /* xrelease mov %eax, <disp> is another special case. It must not
-	     match the accumulator-only encoding of mov.  */
-	  if (i.hle_prefix
-	      && t->base_opcode == 0xa0
+
+	  if (t->base_opcode == MOV_AX_DISP32
 	      && t->opcode_modifier.opcodespace == SPACE_BASE)
-	    continue;
+	    {
+	      /* Force 0x8b encoding for "mov foo@GOT, %eax".  */
+	      if (i.reloc[0] == BFD_RELOC_386_GOT32)
+		continue;
+
+	      /* xrelease mov %eax, <disp> is another special case. It must not
+		 match the accumulator-only encoding of mov.  */
+	      if (i.hle_prefix)
+		continue;
+	    }
 	  /* Fall through.  */
 
 	case 3:



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