On Wed, Feb 21, 2018 at 07:53:22PM -0800, Eric Dumazet wrote: > > So what kinda comment there would make sense? > > I was thinking of something very explicit : > > /* byte sequence for following assembly code used by eBPF > call ... > ... > retq > */ > #define RETPOLINE_RAX_DIRECT_FOR_EBPF \ > EMIT1_off32(0xE8, 7); /* callq <set_up_target> */ \ > /* capture_spec: */ \ > EMIT2(0xF3, 0x90); /* pause */ \ > EMIT3(0x0F, 0xAE, 0xE8); /* lfence */ \ > EMIT2(0xEB, 0xF9); /* jmp <capture_spec> */ \ > /* set_up_target: */ \ > EMIT4(0x48, 0x89, 0x04, 0x24); /* mov %rax,(%rsp) */ \ > EMIT1(0xC3); /* retq */ \
got it. yeah. makes sense to me.