Hello,
I have a questions regarding executing privileged instructions in gem5. I
tested the following program on the AtomicSimple and O3 CPU type (arch x86)
inside gem5 (version 20.0.0.2) running a full system Linux with kernel version
5.4.55:
static inline void invlpg(unsigned long addr) {
asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
}
int main() {
int mem;
invlpg((unsigned long) &mem);
}
The program was executed without an error. I would have expected, that some
kind of error occurs, because invlpg is a privileged instruction, so I should
not be able to execute it in user mode. To verify that this behaviour is indeed
special to gem5 and not related to my kernel, disk image or program, I booted
the same Linux system with the same kernel and disk image in qemu and executed
the same binary. Executing the program in qemu resulted in a general protection
fault.
Is gem5 missing some kind of check which prevents executing privileged
instruction in user mode, or is this somehow expected behaviour and I missed
something ?
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