[Nasm-bugs] [Bug 3392439] New: Missing operand size override prefix
no-reply at bugzilla-nasm.gorcunov.org
no-reply at bugzilla-nasm.gorcunov.org
Mon Sep 11 05:40:47 PDT 2017
https://bugzilla.nasm.us/show_bug.cgi?id=3392439
Bug ID: 3392439
Summary: Missing operand size override prefix
Product: NASM
Version: 2.13.xx
Hardware: Other x86
OS: Linux
Status: OPEN
Severity: normal
Priority: Medium
Component: Assembler
Assignee: nobody at nasm.us
Reporter: yaniv.0x01 at gmail.com
CC: gorcunov at gmail.com, hpa at zytor.com, nasm-bugs at nasm.us
Obtained from: From OS distribution
Missing operand size override prefix (66) while using 2.13
(nasm-2.13.01-3.fc26.x86_64). Is OK while using 2.12
(asm-2.12-2.fc24.x86_64.rpm).
Object dump while using nasm-2.12 output
---------------------------------------------------------------
objdump -b binary -m i386 -Maddr32,data32 -D bios32.bin | less
bios32.bin: file format binary
Disassembly of section .data:
00000000 <.data>:
0: 66 b8 10 00 mov $0x10,%ax
4: 8e d8 mov %eax,%ds
6: 8e c0 mov %eax,%es
8: 8e d0 mov %eax,%ss
a: 31 c0 xor %eax,%eax
c: 66 a1 0e 04 00 00 mov 0x40e,%ax
12: c1 e0 04 shl $0x4,%eax
15: 05 64 01 00 00 add $0x164,%eax
1a: 8b 20 mov (%eax),%esp
1c: e8 16 22 00 00 call 0x2237
21: f4 hlt
22: eb fd jmp 0x21
24: ea 02 00 00 00 18 00 ljmp $0x18,$0x2
2b: 90 nop
2c: 90 nop
Object dump while using nasm-2.13 output
---------------------------------------------------------------
objdump -b binary -m i386 -Maddr32,data32 -D bios32.bin | less
bios32.bin: file format binary
Disassembly of section .data:
00000000 <.data>:
0: b8 10 00 8e d8 mov $0xd88e0010,%eax
5: 8e c0 mov %eax,%es
7: 8e d0 mov %eax,%ss
9: 66 31 c0 xor %ax,%ax
c: a1 0e 04 66 c1 mov 0xc166040e,%eax
11: e0 04 loopne 0x17
13: 66 05 64 01 add $0x164,%ax
17: 00 00 add %al,(%eax)
19: 66 67 8b 20 mov (%bx,%si),%sp
1d: e8 25 22 f4 eb call 0xebf42247
22: fd std
23: 66 ea 02 00 00 00 ljmpw $0x0,$0x2
29: 18 00 sbb %al,(%eax)
2b: 90 nop
2c: 90 nop
Source code
---------------------------------------------------------------
segment _TEXT class=CODE USE32 align=1 CPU=686
group DGROUP _TEXT
%include "defs.inc"
extern _entry
extern _directory_service
extern _pcibios_service
start:
mov ax, DATA_SEGMENT_SELECTOR
mov ds, ax
mov es, ax
mov ss, ax
xor eax, eax
mov ax, [(BDA_SEG << 4) + BDA_OFFSET_EBDA]
shl eax, 4
add eax, EBDA_PRIVATE_START + PRIVATE_OFFSET_PM_STACK_BASE
mov esp, [eax]
call _entry
.infloop:
hlt
jmp .infloop
global _ret_16
_ret_16:
jmp dword CODE16_SEGMENT_SELECTOR:BACK_FROM_PM_START_ADDRESS
--
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