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semantic: 0.974
instruction: 0.931
device: 0.758
other: 0.732
graphic: 0.700
vnc: 0.544
assembly: 0.531
boot: 0.465
socket: 0.426
network: 0.393
mistranslation: 0.299
KVM: 0.192
x86 SSE/SSE2/SSE3 instruction semantic bugs with NaN
Description of problem
The result of SSE/SSE2/SSE3 instructions with NaN is different from the CPU. From Intel manual Volume 1 Appendix D.4.2.2, they defined the behavior of such instructions with NaN. But I think QEMU did not implement this semantic exactly because the byte result is different.
Steps to reproduce
Compile this code
void main() {
asm("mov rax, 0x000000007fffffff; push rax; mov rax, 0x00000000ffffffff; push rax; movdqu XMM1, [rsp];");
asm("mov rax, 0x2e711de7aa46af1a; push rax; mov rax, 0x7fffffff7fffffff; push rax; movdqu XMM2, [rsp];");
asm("addsubps xmm1, xmm2");
}
Execute and compare the result with the CPU. This problem happens with other SSE/SSE2/SSE3 instructions specified in the manual, Volume 1 Appendix D.4.2.2.
CPU xmm1[3] = 0xffffffff
QEMU xmm1[3] = 0x7fffffff
Additional information
This bug is discovered by research conducted by KAIST SoftSec.
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