[PATCH] x86/APX: Add invalid checks for APX EVEX.X4.

[PATCH] x86/APX: Add invalid checks for APX EVEX.X4.

[Cui, Lili]

Hi Maintianer,

APX spec updated EVEX payload description for bit P[10], this patch is
to add invalid checks for APX EVEX.X4.

Regards,
Lili.


APX spec updated EVEX payload description for bit P[10] (now called
EVEX.U) to include usage between APX and AVX10 and how it is related
to EVEX.X4.

EVEX.X4 is defined only when ModRM.Mod != 3. When ModRM.Mod = 3,
the U bit must be 1 for all promoted instructions.

gas/ChangeLog:

        * config/tc-i386.c (build_apx_evex_prefix): Added invalid check for APX
        X4.
        * testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d: Added invalid
        testcase.
        * testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s: Ditto.

opcodes/ChangeLog:

        * i386-dis.c (get_valid_dis386): Added invalid check for APX X4.
---
 gas/config/tc-i386.c                                  | 6 +++++-
 gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d | 4 ++++
 gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s | 7 +++++++
 opcodes/i386-dis.c                                    | 4 ++++
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 56b2431b1bc..042e8a75296 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -4276,7 +4276,11 @@ build_apx_evex_prefix (void)
   if (i.rex2 & REX_B)
     i.vex.bytes[1] |= 0x08;
   if (i.rex2 & REX_X)
-    i.vex.bytes[2] &= ~0x04;
+    {
+      /* EVEX.X4 is defined only when ModRM.Mod != 3.  */
+      gas_assert (i.rm.mode != 3);
+      i.vex.bytes[2] &= ~0x04;
+    }
   if (i.vex.register_specifier
       && i.vex.register_specifier->reg_flags & RegRex2)
     i.vex.bytes[3] &= ~0x08;
diff --git a/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d b/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d
index 1a6b6656ff7..9ba62a7ca62 100644
--- a/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d
+++ b/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d
@@ -39,4 +39,8 @@ Disassembly of section .text:
 [ 	]*[a-f0-9]+:[ 	]+62 d4 24 18 8f[ 	]+\(bad\)
 [ 	]*[a-f0-9]+:[ 	]+c3[ 	]+.*
 [ 	]*[a-f0-9]+:[ 	]+62 fc 7d 0c 60 c7[ 	]+movbe  \{bad-nf\},%r23w,%ax
+[ 	]*[a-f0-9]+:[ 	]+62 fc 79 08 60[ 	]+\(bad\)
+[ 	]*[a-f0-9]+:[ 	]+c2 ff ff[ 	]+.*
+[ 	]*[a-f0-9]+:[ 	]+62 ec f8 08 f5[ 	]+\(bad\)
+[ 	]*[a-f0-9]+:[ 	]+c3[ 	]+.*
 #pass
diff --git a/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s b/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s
index bc55b5e726a..75c583d1a0e 100644
--- a/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s
+++ b/gas/testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s
@@ -53,3 +53,10 @@ _start:
 
 	#EVEX_MAP4 movbe %r18w,%ax set EVEX.nf = 1.
 	.insn EVEX.L0.66.M12.W0 0x60, %di, %ax {%k4}
+
+	# EVEX_MAP4 movbe %r18w,%ax set X4 (EVEX.P[10] = 0).
+	.byte 0x62, 0xfc, 0x79, 0x08, 0x60, 0xc2
+	.byte 0xff, 0xff
+
+	# EVEX from VEX bzhi %rax,%rbx,%r16 set X4 (EVEX.P[10] = 0).
+	.byte 0x62, 0xec, 0xf8, 0x08, 0xf5, 0xc3
diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 3efe65af940..c06dc094c42 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -9190,6 +9190,10 @@ get_valid_dis386 (const struct dis386 *dp, instr_info *ins)
       if (!fetch_modrm (ins))
 	return &err_opcode;
 
+      /* EVEX.X4 is defined only when ModRM.Mod != 3.  */
+      if (ins->modrm.mod == 3 && (ins->rex2 & REX_X))
+	return &bad_opcode;
+
       /* Set vector length. For EVEX-promoted instructions, evex.ll == 0b00,
 	 which has the same encoding as vex.length == 128 and they can share
 	 the same processing with vex.length in OP_VEX.  */
-- 
2.34.1

Re: [PATCH] x86/APX: Add invalid checks for APX EVEX.X4.

[Jan Beulich]

On 19.04.2024 06:24, Cui, Lili wrote:
> APX spec updated EVEX payload description for bit P[10] (now called
> EVEX.U) to include usage between APX and AVX10 and how it is related
> to EVEX.X4.
> 
> EVEX.X4 is defined only when ModRM.Mod != 3. When ModRM.Mod = 3,
> the U bit must be 1 for all promoted instructions.
> 
> gas/ChangeLog:
> 
>         * config/tc-i386.c (build_apx_evex_prefix): Added invalid check for APX
>         X4.
>         * testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d: Added invalid
>         testcase.
>         * testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s: Ditto.
> 
> opcodes/ChangeLog:
> 
>         * i386-dis.c (get_valid_dis386): Added invalid check for APX X4.

Okay.

Jan