On Thu, Jul 01, 2021 at 06:22:45PM +0100, Alan Maguire wrote: > On Tue, 29 Jun 2021, Jiri Olsa wrote: > > > hi, > > adding bpf_get_func_ip helper that returns IP address of the > > caller function for trampoline and krobe programs. > > > > There're 2 specific implementation of the bpf_get_func_ip > > helper, one for trampoline progs and one for kprobe/kretprobe > > progs. > > > > The trampoline helper call is replaced/inlined by verifier > > with simple move instruction. The kprobe/kretprobe is actual > > helper call that returns prepared caller address. > > > > The trampoline extra 3 instructions for storing IP address > > is now optional, which I'm not completely sure is necessary, > > so I plan to do some benchmarks, if it's noticeable, hence > > the RFC. I'm also not completely sure about the kprobe/kretprobe > > implementation. > > > > Also available at: > > https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git > > bpf/get_func_ip > > > > thanks, > > jirka > > > > > > This is great Jiri! Feel free to add for the series: > > Tested-by: Alan Maguire <alan.maguire@xxxxxxxxxx> great, thanks for testing > > BTW I also verified that if we extend bpf_program__attach_kprobe() to > support the function+offset format in the func_name argument for kprobes, > the following test will pass too: > > __u64 test5_result = 0; > SEC("kprobe/bpf_fentry_test5+0x6") > int test5(struct pt_regs *ctx) > { > __u64 addr = bpf_get_func_ip(ctx); > > test5_result = (const void *) addr == (&bpf_fentry_test5 + 0x6); > return 0; > } right, I did not think of this test, I'll add it thanks, jirka
