x86: Disallow instructions with length > 15 bytes

It is a hard error when an instruction length exceeds the limit of 15
bytes:

[hjl@gnu-cfl-3 tmp]$ cat x.s
	.text
	xacquire lock addq $0x11223344, %fs:(,%eax)
[hjl@gnu-cfl-3 tmp]$ gcc -c x.s
x.s: Assembler messages:
x.s:2: Warning: instruction length of 16 bytes exceeds the limit of 15
[hjl@gnu-cfl-3 tmp]$ objdump -dw x.o

x.o:     file format elf64-x86-64

Disassembly of section .text:

0000000000000000 <.text>:
   0:	64 67 f2 f0 48 81 04 05 00 00 00 00 44 33 22 	xacquire lock (bad)
   f:	11                   	.byte 0x11
[hjl@gnu-cfl-3 tmp]$

and

[hjl@gnu-cfl-3 tmp]$ cat z.s
	addq $0xe0, %fs:0, %rdx
[hjl@gnu-cfl-3 tmp]$ as -o z.o z.s
z.s: Assembler messages:
z.s:1: Warning: instruction length of 16 bytes exceeds the limit of 15
[hjl@gnu-cfl-3 tmp]$ objdump -dw z.o

z.o:     file format elf64-x86-64

Disassembly of section .text:

0000000000000000 <.text>:
   0:	64 62 f4 ec 18 81 04 25 00 00 00 00 e0 00 00 	(bad)
	...
[hjl@gnu-cfl-3 pr31323]$

Instructions with length > 15 bytes are always invalid.  It is quite easy
to generate invalid instructions with AVX now.  We should issue an error
when instruction length exceeds the limit of 15 bytes.

	PR gas/31323
	* config/tc-i386.c (output_insn): Issue an error when instruction
	length exceeds the limit of 15 bytes.
	* testsuite/gas/i386/oversized16.l: Updated.
	* testsuite/gas/i386/oversized64.l: Likewise.
	* testsuite/gas/i386/x86-64-apx-inval.l: New file.
	* testsuite/gas/i386/x86-64-apx-inval.s: Likewise.

gas/config/tc-i386.c

@@ -11780,8 +11780,8 @@ output_insn (const struct last_insn *last_insn)
 	{
 	  j = encoding_length (insn_start_frag, insn_start_off, frag_more (0));
 	  if (j > 15)
-	    as_warn (_("instruction length of %u bytes exceeds the limit of 15"),
-		     j);
+	    as_bad (_("instruction length of %u bytes exceeds the limit of 15"),
+		    j);
 	  else if (fragP)
 	    {
 	      /* NB: Don't add prefix with GOTPC relocation since

gas/testsuite/gas/i386/oversized16.l

@@ -1,9 +1,9 @@
 .*: Assembler messages:
-.*:6: Warning: instruction length.*
-.*:7: Warning: instruction length.*
-.*:8: Warning: instruction length.*
-.*:10: Warning: instruction length.*
-.*:11: Warning: instruction length.*
+.*:6: Error: instruction length.*
+.*:7: Error: instruction length.*
+.*:8: Error: instruction length.*
+.*:10: Error: instruction length.*
+.*:11: Error: instruction length.*
 GAS LISTING .*
 
 
@@ -12,29 +12,29 @@ GAS LISTING .*
 [ 	]*3[ 	]+\.code16
 [ 	]*4[ 	]+
 [ 	]*5[ 	]+long16:
-[ 	]*6[ 	]+0000 26678FEA[ 	]+lwpins	eax, es:\[eax\*8\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*6[ 	]+\?\?\?\? 26678FEA[ 	]+lwpins	eax, es:\[eax\*8\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*6[ 	]+781204C5[ 	]*
 [ 	]*6[ 	]+00000000[ 	]*
 [ 	]*6[ 	]+44332211[ 	]*
-[ 	]*7[ 	]+0010 26678FEA[ 	]+lwpval	eax, es:\[eax\*4\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*7[ 	]+\?\?\?\? 26678FEA[ 	]+lwpval	eax, es:\[eax\*4\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*7[ 	]+78120C85[ 	]*
 [ 	]*7[ 	]+00000000[ 	]*
 [ 	]*7[ 	]+44332211[ 	]*
-[ 	]*8[ 	]+0020 26678FEA[ 	]+bextr	eax, es:\[eax\*2\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*8[ 	]+\?\?\?\? 26678FEA[ 	]+bextr	eax, es:\[eax\*2\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*8[ 	]+78100445[ 	]*
 [ 	]*8[ 	]+00000000[ 	]*
 [ 	]*8[ 	]+44332211[ 	]*
 [ 	]*9[ 	]+
-[ 	]*10[ 	]+0030 266766F2[ 	]+xacquire lock add dword ptr es:\[eax\*2\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*10[ 	]+\?\?\?\? 266766F2[ 	]+xacquire lock add dword ptr es:\[eax\*2\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*10[ 	]+F0810445[ 	]*
 [ 	]*10[ 	]+00000000[ 	]*
 [ 	]*10[ 	]+44332211[ 	]*
-[ 	]*11[ 	]+0040 266766F3[ 	]+xrelease lock sub dword ptr es:\[eax\*2\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*11[ 	]+\?\?\?\? 266766F3[ 	]+xrelease lock sub dword ptr es:\[eax\*2\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*11[ 	]+F0812C45[ 	]*
 [ 	]*11[ 	]+00000000[ 	]*
 [ 	]*11[ 	]+44332211[ 	]*

gas/testsuite/gas/i386/oversized64.l

@@ -1,39 +1,39 @@
 .*: Assembler messages:
-.*:5: Warning: instruction length.*
-.*:6: Warning: instruction length.*
-.*:7: Warning: instruction length.*
-.*:9: Warning: instruction length.*
-.*:10: Warning: instruction length.*
+.*:5: Error: instruction length.*
+.*:6: Error: instruction length.*
+.*:7: Error: instruction length.*
+.*:9: Error: instruction length.*
+.*:10: Error: instruction length.*
 GAS LISTING .*
 
 
 [ 	]*1[ 	]+\.text
 [ 	]*2[ 	]+\.intel_syntax noprefix
 [ 	]*3[ 	]+
 [ 	]*4[ 	]+long64:
-[ 	]*5[ 	]+0000 64678FEA[ 	]+lwpins	rax, fs:\[eax\*8\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*5[ 	]+\?\?\?\? 64678FEA[ 	]+lwpins	rax, fs:\[eax\*8\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*5[ 	]+F81204C5[ 	]*
 [ 	]*5[ 	]+00000000[ 	]*
 [ 	]*5[ 	]+44332211[ 	]*
-[ 	]*6[ 	]+0010 64678FEA[ 	]+lwpval	eax, fs:\[eax\*4\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*6[ 	]+\?\?\?\? 64678FEA[ 	]+lwpval	eax, fs:\[eax\*4\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*6[ 	]+78120C85[ 	]*
 [ 	]*6[ 	]+00000000[ 	]*
 [ 	]*6[ 	]+44332211[ 	]*
-[ 	]*7[ 	]+0020 64678FEA[ 	]+bextr	rax, fs:\[eax\*2\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*7[ 	]+\?\?\?\? 64678FEA[ 	]+bextr	rax, fs:\[eax\*2\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*7[ 	]+F8100445[ 	]*
 [ 	]*7[ 	]+00000000[ 	]*
 [ 	]*7[ 	]+44332211[ 	]*
 [ 	]*8[ 	]+
-[ 	]*9[ 	]+0030 6567F2F0[ 	]+xacquire lock add qword ptr gs:\[eax\*8\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*9[ 	]+\?\?\?\? 6567F2F0[ 	]+xacquire lock add qword ptr gs:\[eax\*8\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*9[ 	]+488104C5[ 	]*
 [ 	]*9[ 	]+00000000[ 	]*
 [ 	]*9[ 	]+44332211[ 	]*
-[ 	]*10[ 	]+0040 6567F3F0[ 	]+xrelease lock sub qword ptr gs:\[eax\*8\], 0x11223344
-\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[ 	]*10[ 	]+\?\?\?\? 6567F3F0[ 	]+xrelease lock sub qword ptr gs:\[eax\*8\], 0x11223344
+\*\*\*\*  Error: instruction length of 16 bytes exceeds the limit of 15
 [ 	]*10[ 	]+48812CC5[ 	]*
 [ 	]*10[ 	]+00000000[ 	]*
 [ 	]*10[ 	]+44332211[ 	]*

gas/testsuite/gas/i386/x86-64-apx-inval.l

@@ -0,0 +1,3 @@
+.*: Assembler messages:
+.*:3: Error: instruction length of 16 bytes exceeds the limit of 15
+.*:4: Error: instruction length of 16 bytes exceeds the limit of 15

gas/testsuite/gas/i386/x86-64-apx-inval.s

@@ -0,0 +1,4 @@
+# Check illegal 64bit APX_F instructions
+	.text
+	addq $0xe0, %fs:0, %rdx
+	xorq $0xe0, foo(%eax,%edx), %rdx

gas/testsuite/gas/i386/x86-64.exp

@@ -371,6 +371,7 @@ run_dump_test "x86-64-avx512f-rcigrne-intel"
 run_dump_test "x86-64-avx512f-rcigrne"
 run_dump_test "x86-64-avx512f-rcigru-intel"
 run_dump_test "x86-64-avx512f-rcigru"
+run_list_test "x86-64-apx-inval"
 run_list_test "x86-64-apx-egpr-inval"
 run_dump_test "x86-64-apx-evex-promoted-bad"
 run_list_test "x86-64-apx-egpr-promote-inval" "-al"