On 01/03/2018 02:14 PM, Andy Lutomirski wrote: > + /* Use %rsp as scratch reg. User ESP is stashed in r8 */ > + SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp > + > + /* Switch to the kernel stack */ > movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
The stack is unreadable at this point without the CR3 switch. > What's the issue that this is fixing? Users doing 32-bit SYSCALLs on the CPUs that support them double fault since they end up with an %rsp that they can't access.
