[PATCH] x86: Disallow APX instruction with length > 15 bytes

[H.J. Lu]

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

[hjl@gnu-cfl-3 pr31323]$ cat z.s
	addq $0xe0, %fs:0, %rdx
[hjl@gnu-cfl-3 pr31323]$ 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 pr31323]$ 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]$

We should issue an error when APX instruction length exceeds the limit of
15 bytes.

	PR gas/31323
	* config/tc-i386.c (output_insn): Issue an error when APX
	instruction length exceeds the limit of 15 bytes.
	* testsuite/gas/i386/x86-64-apx-inval.l: New file.
	* testsuite/gas/i386/x86-64-apx-inval.s: Likewise.
---
 gas/config/tc-i386.c                      | 10 ++++++++--
 gas/testsuite/gas/i386/x86-64-apx-inval.l |  3 +++
 gas/testsuite/gas/i386/x86-64-apx-inval.s |  4 ++++
 gas/testsuite/gas/i386/x86-64.exp         |  1 +
 4 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 gas/testsuite/gas/i386/x86-64-apx-inval.l
 create mode 100644 gas/testsuite/gas/i386/x86-64-apx-inval.s

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 3c64057fd67..d1e522d3637 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -11772,8 +11772,14 @@ 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);
+	    {
+	      if (i.tm.cpu.bitfield.cpuapx_f)
+		as_bad (_("instruction length of %u bytes exceeds the limit of 15"),
+			j);
+	      else
+		as_warn (_("instruction length of %u bytes exceeds the limit of 15"),
+			 j);
+	    }
 	  else if (fragP)
 	    {
 	      /* NB: Don't add prefix with GOTPC relocation since
diff --git a/gas/testsuite/gas/i386/x86-64-apx-inval.l b/gas/testsuite/gas/i386/x86-64-apx-inval.l
new file mode 100644
index 00000000000..6c1a346fcbf
--- /dev/null
+++ b/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
diff --git a/gas/testsuite/gas/i386/x86-64-apx-inval.s b/gas/testsuite/gas/i386/x86-64-apx-inval.s
new file mode 100644
index 00000000000..bb57817bc8a
--- /dev/null
+++ b/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
diff --git a/gas/testsuite/gas/i386/x86-64.exp b/gas/testsuite/gas/i386/x86-64.exp
index 6932ba97a4d..b77e8c10029 100644
--- a/gas/testsuite/gas/i386/x86-64.exp
+++ b/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"
-- 
2.43.0