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.
6 files changed
