instruction: 0.776 runtime: 0.160 syscall: 0.064 x86 LSL and LAR fault Description of problem: From the description of LSL and LAR instructions in manual, `If the segment descriptor cannot be accessed or is an invalid type for the instruction, the ZF flag is cleared and no value is loaded in the destination operand.`. When it happens at the CPU, it seems they do nothing (nop). However, in QEMU, it crashes. Steps to reproduce: 1. Compile this code ``` void main() { asm("mov rax, 0xa02e698e741f5a6a"); asm("mov rbx, 0x20959ddd7a0aef"); asm("lsl ax, bx"); } ``` 2. Execute. QEMU crashes but CPU does not. This problem happens with LAR, too. Additional information: This bug is discovered by research conducted by KAIST SoftSec.