x86: 1.000
assembly: 0.991
semantic: 0.982
i386: 0.980
debug: 0.687
register: 0.219
user-level: 0.151
operating system: 0.067
virtual: 0.044
files: 0.029
kernel: 0.023
hypervisor: 0.017
performance: 0.017
TCG: 0.016
architecture: 0.009
PID: 0.008
peripherals: 0.007
device: 0.007
network: 0.006
alpha: 0.003
risc-v: 0.003
VMM: 0.003
permissions: 0.002
socket: 0.002
KVM: 0.002
graphic: 0.002
boot: 0.002
ppc: 0.001
vnc: 0.001
mistranslation: 0.001
arm: 0.000

x86 BEXTR semantic bug
Description of problem
The result of instruction BEXTR is different with from the CPU. The value of destination register is different. I think QEMU does not consider the operand size limit.

Steps to reproduce

Compile this code

void main() {
    asm("mov rax, 0x17b3693f77fb6e9");
    asm("mov rbx, 0x8f635a775ad3b9b4");
    asm("mov rcx, 0xb717b75da9983018");
    asm("bextr eax, ebx, ecx");
}

Execute and compare the result with the CPU.

CPU
RAX = 0x5a

QEMU
RAX = 0x635a775a

Additional information
This bug is discovered by research conducted by KAIST SoftSec.