On Wed, Mar 20, 2024 at 1:06 PM Andrii Nakryiko <andrii@xxxxxxxxxx> wrote: > > Dump of assembler code for function kprobe_multi_link_exit_handler: > 0xffffffff8122f1e0 <+0>: add $0xffffffffffffffc0,%rdi > 0xffffffff8122f1e4 <+4>: mov %rcx,%rdx > 0xffffffff8122f1e7 <+7>: jmp 0xffffffff81230080 <kprobe_multi_link_prog_run> > > This means that when trying to capture LBR that traces all indirect branches > we are wasting an entry just to record that kprobe_multi_link_exit_handler > called/jumped into kprobe_multi_link_prog_run. I don't follow. If LBR was configured to trace indirect branches then this direct jmp shouldn't be recorded. If LBR is capturing stack frames (those should be call/ret instructions) then this jmp also won't be recorded. If LBR is actually capturing all indirect, direct and conditional jmps, and calls then saving an entry won't make a difference. Maybe it's an LBR configuration issue on the retsnoop side?
