Linux Kernel 4.15 Released
lkml.iu.edu
lkml.iu.edu
You can do
cat /sys/devices/system/cpu/vulnerabilities/spectre_v2
and if you don't have a compiler that supports the retpoline mitigations, you'll get:
Vulnerable: Minimal generic ASM retpoline
because only the assembly code (not the C code) will have the retpoline mitigation. So keep that in mind.