On Sun, 2018-02-04 at 19:43 +0100, Thomas Gleixner wrote: > > __x86_return_thunk would look like this: > > __x86_return_thunk: > testl $0xf, PER_CPU_VAR(call_depth) > jnz 1f > stuff_rsb > 1: > decl PER_CPU_VAR(call_depth) > ret > > The call_depth variable would be reset on context switch. Note that the 'jnz' can be predicted taken there, allowing the CPU to speculate all the way to the 'ret'... and beyond.
Attachment:
smime.p7s
Description: S/MIME cryptographic signature
