x86: Properly handle PLT expression in directive

For PLT expressions, we should subtract the PLT relocation size only for
jump instructions.  Since PLT relocations are PC relative, we only allow
"symbol@PLT" in PLT expression.

gas/

	PR gas/23997
	* config/tc-i386.c (x86_cons): Check for invalid PLT expression.
	(md_apply_fix): Subtract the PLT relocation size only for jump
	instructions.
	* testsuite/gas/i386/reloc32.s: Add test for invalid PLT
	expression.
	* testsuite/gas/i386/reloc64.s: Likewise.
	* testsuite/gas/i386/ilp32/reloc64.s: Likewise.
	* testsuite/gas/i386/reloc32.l: Updated.
	* testsuite/gas/i386/reloc64.l: Likewise.
	* testsuite/gas/i386/ilp32/reloc64.l: Likewise.

ld/

	PR gas/23997
	* testsuite/ld-i386/i386.exp: Run PR gas/23997 test.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/pr23997a.s: New file.
	* testsuite/ld-x86-64/pr23997b.c: Likewise.
	* testsuite/ld-x86-64/pr23997c.c: Likewise.

8 files changed, 34 insertions, 3 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 0015920..b21680a 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,17 @@
+2018-12-19  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR gas/23997
+	* config/tc-i386.c (x86_cons): Check for invalid PLT expression.
+	(md_apply_fix): Subtract the PLT relocation size only for jump
+	instructions.
+	* testsuite/gas/i386/reloc32.s: Add test for invalid PLT
+	expression.
+	* testsuite/gas/i386/reloc64.s: Likewise.
+	* testsuite/gas/i386/ilp32/reloc64.s: Likewise.
+	* testsuite/gas/i386/reloc32.l: Updated.
+	* testsuite/gas/i386/reloc64.l: Likewise.
+	* testsuite/gas/i386/ilp32/reloc64.l: Likewise.
+
 2018-12-14  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR ld/23900
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 8e25e6c..7640631 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -8919,6 +8919,15 @@ x86_cons (expressionS *exp, int size)
 	      as_bad (_("missing or invalid expression `%s'"), save);
 	      *input_line_pointer = c;
 	    }
+	  else if ((got_reloc == BFD_RELOC_386_PLT32
+		    || got_reloc == BFD_RELOC_X86_64_PLT32)
+		   && exp->X_op != O_symbol)
+	    {
+	      char c = *input_line_pointer;
+	      *input_line_pointer = 0;
+	      as_bad (_("invalid PLT expression `%s'"), save);
+	      *input_line_pointer = c;
+	    }
 	}
     }
   else
@@ -10533,9 +10542,11 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
       {
       case BFD_RELOC_386_PLT32:
       case BFD_RELOC_X86_64_PLT32:
-	/* Make the jump instruction point to the address of the operand.  At
-	   runtime we merely add the offset to the actual PLT entry.  */
-	value = -4;
+	/* Make the jump instruction point to the address of the operand.
+	   At runtime we merely add the offset to the actual PLT entry.
+	   NB: Subtract the offset size only for jump instructions.  */
+	if (fixP->fx_pcrel)
+	  value = -4;
 	break;
 
       case BFD_RELOC_386_TLS_GD:
diff --git a/gas/testsuite/gas/i386/ilp32/reloc64.l b/gas/testsuite/gas/i386/ilp32/reloc64.l
index ff49194..7a1808e 100644
--- a/gas/testsuite/gas/i386/ilp32/reloc64.l
+++ b/gas/testsuite/gas/i386/ilp32/reloc64.l
@@ -51,3 +51,4 @@
 .*:175: Error: .*
 .*:176: Error: .*
 .*:177: Error: .*
+.*:189: Error: .*
diff --git a/gas/testsuite/gas/i386/ilp32/reloc64.s b/gas/testsuite/gas/i386/ilp32/reloc64.s
index 77764b3..3ab25ef 100644
--- a/gas/testsuite/gas/i386/ilp32/reloc64.s
+++ b/gas/testsuite/gas/i386/ilp32/reloc64.s
@@ -186,3 +186,4 @@ bad	.byte	xtrn@tpoff
 	.quad	xtrn - 0x80000000
 	.long	xtrn@got - 4
 	.long	xtrn@got + 4
+bad	.long	xtrn@plt - .
diff --git a/gas/testsuite/gas/i386/reloc32.l b/gas/testsuite/gas/i386/reloc32.l
index 9299445..3fb3255 100644
--- a/gas/testsuite/gas/i386/reloc32.l
+++ b/gas/testsuite/gas/i386/reloc32.l
@@ -65,4 +65,5 @@
 .*:159: Error: .*
 .*:160: Error: .*
 .*:161: Error: .*
+.*:164: Error: .*
 #pass
diff --git a/gas/testsuite/gas/i386/reloc32.s b/gas/testsuite/gas/i386/reloc32.s
index 855dcf5..e766a3d 100644
--- a/gas/testsuite/gas/i386/reloc32.s
+++ b/gas/testsuite/gas/i386/reloc32.s
@@ -161,3 +161,4 @@ bad	.byte	xtrn@ntpoff
 bad	.byte	xtrn@tpoff
 	.long	xtrn@got + 4
 	.long	xtrn@got - 4
+bad	.long	xtrn@plt - .
diff --git a/gas/testsuite/gas/i386/reloc64.l b/gas/testsuite/gas/i386/reloc64.l
index 5e970cb..6d7a3c7 100644
--- a/gas/testsuite/gas/i386/reloc64.l
+++ b/gas/testsuite/gas/i386/reloc64.l
@@ -81,3 +81,4 @@
 .*:218: Error: .*
 .*:219: Error: .*
 .*:220: Error: .*
+.*:227: Error: .*
diff --git a/gas/testsuite/gas/i386/reloc64.s b/gas/testsuite/gas/i386/reloc64.s
index 0f9c51e..bc6f0fa 100644
--- a/gas/testsuite/gas/i386/reloc64.s
+++ b/gas/testsuite/gas/i386/reloc64.s
@@ -224,3 +224,4 @@ bad	.byte	xtrn@gotplt
 	mov	xtrn(,%ebx), %eax
 	vgatherdps %xmm2, xtrn(,%xmm1), %xmm0
 	addr32 vgatherdps %xmm2, xtrn(,%xmm1), %xmm0
+bad	.long	xtrn@plt - .